Data Communication Apparatuses, Data Communication System and Methods using Reference Symbols

Description

Technical Field

Embodiments according to the invention are related to data communication apparatuses for transmitting one or more blocks of data within a frame comprising a two-dimensional grid of transmission symbol positions.

Further embodiments according to the invention are related to data communication apparatuses for receiving a plurality of blocks of data from other data communication apparatuses.

Other embodiments according to the invention are related to a data communication system.

Yet other embodiments according to the invention are related to a method for transmitting one or more blocks of data within a frame comprising a two-dimensional grid of transmission symbol positions and to a method for receiving a plurality of data blocks from other data communication apparatuses.

Other embodiments according to the invention are related to a data communication method.

Other embodiments according to the invention are related to a computer program for performing one of said methods.

Background of the Invention

In some communication systems, latency reduction has become an important aspect for improvement.

Goal of latency reduction is to modify the radio frame structure, PHY and MAC protocols in order to reduce the delay in next generation mobile communication systems, e.g. 3GPP radio access technology (RAT). This is especially of interest for smaller file sizes. Reducing the transmission time interval (TTI) and processing time can significantly reduce the user plane latency, and improve the TCP throughput. In addition, smaller latency would allow UEs to reduce the L2 memory needed to buffer the "data in flight", allow for more robustness due to the ability to re-transit more often within a certain delay bound. This directly increases the perceived quality of experience for today's delay-sensitive realtime applications like gaming, voice or video telephony/conferencing, and allow addressing new future use cases such as critical MTC applications in a better way.

It has been found that reducing the number of resources used for the transmission of control symbols, e.g. reference symbols in the uplink, will allow a more efficient use of resources with more resources available for data channels. Thus, the latency on data channels is reduced. Control channel optimization can be achieved by multiplexing signals.

Ericsson and Qualcomm proposed to support the multiplexing of the Demodulation Reference Symbols (DMRS) of several User Equipments (UEs) when using the short Physical Uplink Shared Channel (sPUSCH) to reduce the overhead of transmitting pilot tones in the uplink.

A legacy LTE uplink subframe is shown in Figure 1. Currently on the Physical Uplink Shared Channel (PUSCH). One UE occupies resources for 1 subframe consisting of 14 OFDM symbols. Each slot contains one DMRS symbol spanning the whole transmission bandwidth. In some subframes there can be a Sounding Reference Symbol (SRS) at the end. This depends on the SRS scheduling parameter settings.

In the 3GPP study item on latency reduction it is proposed to reduce the Transmission Time Interval (TTI) from 14 OFDM symbols (1 ms). Short TTIs with 2 or 3/3 OFDM symbols are up for discussion. Figure 2 shows an example for sTTI length of ¾ and 2 Symbols. It has been found that the overhead for DMRS symbols becomes larger when moving to shorter TTI lengths.

In view of this situation, there is a desire to create concepts which allow for a better tradeoff between latency and resource efficiency.

Summary of the Invention

An embodiment according to the invention creates a data communication apparatus for transmitting one or more blocks of data (for example, using one or more groups of transmission symbol positions, each transmission symbol position associated with one block of data) within a frame comprising a two-dimensional grid of transmission symbol positions. The data transmission apparatus is configured to select a group of transmission symbol positions (for example, OFDM symbols), which is a subset of the two-dimensional grid of transmission symbol positions, for a transmission of a data portion (or data block). The data communication apparatus is configured to select one or more reference symbol positions (for example, for reference OFDM symbols, i.e. OFDM symbols having a predetermined modulation content or a predetermined complex value and serving as a reference for a coherent reception of OFDM symbols encoding user data, application data or control data) associated to the selected group of transmission symbol positions, out of a plurality of possibilities, based on an information describing a desired relative position of the reference symbol positions with respect to (or within) the selected group of transmission symbol positions.

In other words, the data communication apparatus can, for example, select, where (at which transmission symbol position or positions) within a selected group of transmission symbol positions one or more reference symbols (for example, pilot-like symbols for estimating channel characteristics and for coherently detecting useful data at the side of another data communication apparatus) are inserted. The information describing a desired relative position of the reference symbol positions with respect to (or within) the selected group of transmission symbol positions may, for example, describe the (relative) position of the reference symbol positions with respect to (one or more) temporal borders or (one or more) frequency borders of the selected group of transmission symbol positions.

Thus, this embodiment according to the invention is based on the finding that a high degree of flexibility and an efficient signaling can be obtained by using an information describing a desired relative position of the reference symbol positions with respect to the selected group of transmission symbol positions. It has been found that such a relative

position information is easy to encode and allows for an efficient placement of reference symbol positions within a transmission scheme which, for example, enables a reuse (sharing) of reference symbol positions by multiple data communication apparatuses. In particular, it has been found that the relative position of the reference symbol positions with respect to the selected group of transmission symbol positions varies between different application scenarios. For example, locating the reference symbol positions at a temporal beginning or at a temporal end of the selected group of transmission symbol positions allows for a sharing of said reference symbol positions by multiple data transmission apparatuses. On the other hand, a placement of the reference symbol positions approximately in the middle of the selected group of transmission symbol positions typically brings along an optimum result in the case that no sharing of reference symbol positions between different data transmission devices is desired or required. On the other hand, it has been found that a signaling overhead, which would, for example, be caused by signaling reference symbol positions with respect to frame borders can be avoided, and that such "absolute" position information is also not required in many flexible resource allocation schemes.

To conclude, the above described concept allows for a highly efficient signaling of reference symbol positions even in the case of a flexible selection of transmission symbol positions with a fine granularity.

In a preferred embodiment, the data communication apparatus is configured to receive an information indicating whether a reference symbol position is at a beginning (for example, a temporal beginning) of a selected group of transmission symbol positions, or at an end (for example, at a temporal end) of a selected group of transmission symbol positions.

in yet another preferred embodiment, said information is a 1-bit information.

In another preferred embodiment, the data communication apparatus is configured to receive an information indicating whether the reference symbol position is at the beginning of a selected group of transmission symbol positions (for example, only at the beginning), or at an end of a selected group of transmission symbol positions (for example, only at the end), or in an inner part of a selected group of transmission symbol positions (for example, with at least one non-reference-symbol position before and at least non-reference-symbol position after the reference symbol position) or whether there are reference symbol positions both at a beginning and at an end of a selected group of

transmission symbol positions. These four choices are particularly well-adapted for a flexible decision about a sharing of reference symbols between different data communication apparatuses. If the reference symbol position is in an inner part of a selected group of transmission symbol positions, such that a symbol position of the selected group of transmission symbol positions which is associated to a useful data (e.g. application data or user data, rather than a fixed pilot symbol) is temporally before the reference symbol position and such that a symbol position (of the selected group of transmission symbol positions) associated with a transmission of useful data is behind the reference symbol position ensures that the reference symbol at the reference symbol position allows for a good channel estimation both for the useful data symbol before the reference symbol position and for the useful data symbol behind the reference symbol position. Moreover, arranging a reference symbol position at a beginning of the selected group of transmission symbol positions or at an end of the selected group of transmission symbol positions allows for sharing of a reference symbol position with another data communication apparatus. Furthermore, providing reference symbol positions both at the beginning and at the end of the selected group of transmission symbol positions allows for a sharing of reference symbol positions with two other data communication apparatuses.

In a preferred embodiment, said information indicating the relative position of the reference symbol position is a 2-bit information.

In a preferred embodiment, the communication apparatus is configured to selectively evaluate a 1-bit information describing a desired relative position of a (one or more) reference symbol positions with respect to the selected group of transmission symbol positions or a 2-bit information describing a desired relative position of a reference symbol position with respect to the selected group of transmission symbol positions in dependence on whether the selected group of transmission symbol positions comprises a length of two transmission symbol positions or a length of more than two transmission symbol positions (for example, in a temporal direction). Generally speaking, the decision whether a 1-bit information or a 2-bit information is used, can be made in dependence on a length of the selected group of transmission symbol positions.

Accordingly, a bitrate required for the information describing the desired relative position of the reference symbol positions with respect to the selected group of transmission symbol positions can be adapted to the length (for example, to the temporal extension) of the selected group of transmission symbol positions. Thus, a bitrate can be kept reasonably small, and a transmission of meaningless information can be avoided.

Generally speaking, the data communication apparatus may be configured to selectively evaluate a 1-bit information describing a desired relative position of a reference symbol position with respect to the selected group of transmission symbol positions or a 2-bit information describing a desired relative position of a reference symbol position with respect to the selected group of transmission symbol positions in dependence on whether the selected group of transmission symbol positions comprises two transmission symbol positions or more than two transmission symbol positions in dependence on a temporal extension of a selected group of transmission symbol positions. For example, a 2-bit information may be used when a temporal extension of a selected group of transmission symbol position has a length which is at least equal to a predetermined or defined number of OFDM symbols (e.g. 4 OFDM symbols), and a 1-bit information may be used otherwise.

In a further embodiment, the data communication apparatus is configured to receive the information describing a desired relative position of the reference symbol position from another data communication device coordinating the operation of multiple data communication devices (for example, from a base station). Accordingly, the data communication apparatus can select the (relative) reference symbol position in accordance with a resource allocation controlled by another data communication device.

Another embodiment according to the invention creates a data communication apparatus for transmitting one or more blocks of data within a frame comprising a two-dimensional grid of transmission symbol positions. The data communication apparatus is configured to select a group of transmission symbol positions (for example, having a length of a so-called short transmission time interval sTTI), which is a subset of the two-dimensional grid of transmission symbol positions, for a transmission of a data portion (for example, a data block which comprises a common channel coding). One or more reference symbol positions (which may, for example, be used for the transmission of a so-called demodulation reference signal, DMRS) are associated to the selected group of transmission symbol positions. The data communication apparatus is configured to determine which one or more symbol positions (for example, within the selected group of transmission symbol positions) are used as one or more reference symbol positions based on the selection of the group of transmission symbol positions. The reference

symbol positions may be variable with respect to borders of time slots of the frame or with respect to borders of sub-frames of the frames. Alternatively, or in addition, the one or more reference symbol positions may be variable with respect to the selected group of transmission symbol positions. In other words, the (relative) position (or location) of the reference symbol positions with respect to one or more borders of time slots of the frame or with respect to one or more borders of sub-frames of the frame may vary in dependence on where within a time slot or where within a sub-frame the selected group of transmission symbol positions lies. For example, the data communication apparatus may be configured such that a relative location of a reference symbol position with respect to a border of a time slot or with respect to a border of a sub-frame differs in dependence on where within the sub-frame the selected group of transmission symbol positions lies. For example, the data communication apparatus may be able to handle different scenarios like, for example, a first scenario in which the selected group of the transmission symbol positions is closer to a beginning of a time slot or a beginning of a sub-frame than in a second scenario, and also the second scenario. However, a relative position (for example, a temporal distance) between a reference symbol position associated with the selected group of transmission symbol positions in the first scenario may be different from a relative position or location (with respect to one or more borders of a time slot or with respect to one or more borders of a sub-frame) of a reference symbol position associated with the selected group of transmission symbol positions in the second scenario. Thus, the relative position of the reference symbol position(s) may vary between the different scenarios, which means that the reference symbol positions are no longer fixed with respect to one or more borders of a time slot (or of different time slots) or with respect to one or more borders of sub-frames. Consequently, a high degree of flexibility is gained when compared to a concept in which reference positions are fixed with respect to one or more borders of a time slot or with respect to one or more borders of a sub-frame. Consequently, a fine granularity for the selection of groups of transmission symbol positions is possible.

It should further be noted that it may also be possible that the relative positions of reference symbols (for example, relative one or more borders of a time slot and/or relative to one or more borders of a sub-frame) may be different for adjacent sub-carriers or at least for sub-carriers within a same physical resource block (PRB).

Moreover, the one or more reference symbol positions may be variable with respect to (for example, relative to) the selected group of transmission symbol positions (for example, even for selected groups of transmission symbol positions having identical temporal extensions or identical overall extensions, for example in a direction of time and in a direction of frequency). Accordingly, it is no longer necessary to have a fixed grid of reference symbol positions, which may be fixed with respect to borders of time slots of a frame or with respect to borders of sub-frames of a frame, or with respect to borders of selected groups of transmission symbol positions.

Thus, this embodiment according to the invention is based on the finding that the reference symbol positions, relative to borders of time slots or subframes of the frame, and/or relative to borders of the selected group of transmission symbol positions, should be variable and should depend on the selection of a group of transmission symbol positions. Accordingly, if a group of transmission symbol positions is selected having a certain extension (in time direction and/or in frequency direction), the actual reference symbol positions within the selected group of transmission symbol positions may vary depending on where (for example, measured relative to one or more borders of a time slot or relative to one or more borders of a sub-frame) the selected group of transmission symbol positions is arranged. Moreover, this concept allows for a fine granularity with respect to a positioning of selected groups of transmission symbol positions within a two-dimensional grid of symbol positions (for example, relative to borders of a time slot or with respect to borders of a sub-frame), wherein a small movement of a selected group of transmission symbol positions (for example, by one symbol position) may result in a corresponding movement of one or more reference symbol positions associated with said selected group of transmission symbol positions. Moreover, the concept allows to combine groups of transmission symbol positions associated to different data transmission apparatuses having different temporal extensions and/or frequency extensions within one time slot or sub-frame. Furthermore, obtaining flexibility with respect to a placement of reference symbol positions also allows to share reference symbol positions between different data communication apparatuses. This is due to the fact that the reference symbol positions within a selected group of transmission symbol positions having a certain temporal extension and/or frequency extension may vary depending on where within a two-dimensional grid of transmission symbol positions the selected group of transmission symbol positions is arranged, even for groups of transmission symbol positions having a same size (for example, a same extension in time direction and/or frequency direction).

In a preferred embodiment, the location of the reference symbol positions with respect to (one or more) borders of time slots of the frame or with respect to (one or more) borders of sub-frames of the frame varies in dependence on an actual selection of a group of transmission symbol positions (for example, even for groups of transmission symbol positions having a same size).

In a preferred embodiment, the data communication apparatus is configured to select, as one of multiple possible selection results, a case in which a reference symbol position is iocated at a beginning of a selected group of transmission symbol positions (for example, at the beginning of a selected group of transmission symbol positions having a given length or size).

Alternatively, or in addition, the data communication apparatus may be configured to select, as one of multiple possible selection results, a case in which a reference symbol position is Iocated at an end of a selected group of transmission symbol positions (for example, for a selected group of transmission symbol positions having the given length or size).

Alternatively, or in addition, the data communication apparatus may be configured to select, as one of multiple possible selection results, a case in which a reference symbol position is Iocated in an inner part of a selected group of transmission symbol positions (for example, for a selected group of transmission symbol positions having the given length or size).

Alternatively, or in addition, the data communication apparatus may be configured to select, as one of multiple possible selection results, a case in which a reference symbol position is Iocated both at the beginning of a selected group of transmission symbol positions and at an end of the selected group of transmission symbol positions (for example, for a selected group of transmission symbol positions having the given length or size).

In other words, the apparatus may be able to select one or, typically, even two, three or four of the above mentioned locations for the reference symbol positions, even for groups of transmission symbol positions having the same size. For example, for selected groups of transmission symbol positions having temporal extensions of, say, four symbol positions, all four different locations (only at the beginning, only at the end, in the inner part, both at the beginning and at the end) for the reference symbol positions may be chosen, depending on where the selected group of transmission symbol positions is located within a slot or within a sub-frame, and/or in dependence on which groups of transmission symbol positions are adjacent to the selected group of transmission symbol positions. Thus, a high flexibility can be achieved and the available physical resources can be used in a very efficient manner by configuring the apparatus to be able to use two, three or four different (relative) positions within a selected group of transmission symbol positions for the reference symbol positions.

In a preferred embodiment, the data communication apparatus may be configured to allow for a selection between groups of transmission symbol positions having different lengths. Also, the data communication apparatus may be configured to allow for a selection between groups of transmission symbol positions having the same length but different associated reference symbol positions (for example, relative to the selected group). For example, a first group of transmission symbol positions may comprise a length of four transmission symbol positions and may have a reference symbol position at a beginning, and another group of transmission symbol positions may also have a length of four transmission symbol positions but may have the associated reference symbol position at the end or in an inner part (for example at its second symbol position or at its third symbol position).

In a preferred embodiment, the data communication apparatus may be configured to select a group of transmission symbol positions with a granularity which is smaller than a length of a sub-frame, or which is even smaller than a length of a slot.

In yet another preferred embodiment, the data communication apparatus is configured to select a group of transmission symbol positions with a granularity of one transmission symbol position or with a granularity of two transmission symbol positions. Accordingly, it is possible to align the groups of transmission symbol positions in a very precise manner, thereby allowing for a good adaptation to the current requirements, for example, to the requirements of minimizing latency.

In a preferred embodiment, the data communication apparatus is configured to select a group of transmission symbol positions with a granularity such that there are multiple different groups of transmission symbol positions selectable within a sub-frame. This also allows for a good adjustment to low latency requirements.

In an embodiment, a sub-frame is a shortest time unit within the two-dimensional grid of transmission symbol positions for which a transmission direction is freely selectable. Thus, even within such a short sub-frame, the radio resources can be allocated to multiple data communication apparatuses. Choosing the granularity for the selection of groups of transmission symbol positions to be smaller than the granularity for changing the transmission direction brings along the advantage that the physical channel resources are in use with high efficiency, since switching the direction of the communication typically requires larger time overhead than handing over the physical resources between different data communication apparatus transmitting the same direction. Accordingly, a fine granularity for the transmission of short data packets is obtained without wasting a large number of physical resources.

In a preferred embodiment, the data communication apparatus is configured to vary a relative location of the one or more reference symbol positions in the grid of transmission symbol positions with reference to the selected group of transmission symbol positions in dependence on a temporal length of the selected group of transmission symbol positions (such that temporally short groups of transmission symbol positions have their reference symbol positions at a different place when compared to comparatively longer groups of transmission symbol positions), and/or in dependence on a temporal position of the selected group of transmission symbol positions (such that, for example, different selected groups of transmission symbol positions have their associated reference symbol positions at different locations even if the different selected groups of transmission symbol positions have the same temporal extension or the same size), and/or in dependence on a frequency position of the selected group of transmission symbol positions within a frame (such that, for example, a selected group of transmission symbol positions which is in a first frequency position has its associated reference symbol positions at a different location when compared to another same-length selected group of transmission symbol positions being in a different frequency position). Accordingly, one or more different criteria may be used to determine where (relative to the selected group of transmission symbol positions) the associated reference symbol positions should be (for example, even for selected groups of transmission symbol positions of a same length).

In a preferred embodiment, the data communication apparatus may be configured to choose a symbol position at a temporal start of the selected group of transmission symbol positions or a symbol position at a temporal end of the selected group of transmission

symbol positions as a reference symbol position. For example, the choice whether a symbol at a temporal start of the selected of transmission symbol positions or a symbol position at a temporal end of the selected group of transmission symbol positions is used as a reference symbol position may depend on where within the frame or sub-frame the selected group of transmission symbol positions is arranged (such that even selected groups of transmission symbol positions having the same length may have the associated reference symbol positions at different locations, for example relative to the respective selected group of transmission symbol positions).

In a preferred embodiment, the data communication apparatus may be configured to choose a symbol position, at which the selected group of transmission symbol positions neighbors or overlaps another group of transmission symbol positions, which is associated with another data communication apparatus, within a same sub-frame, as a reference symbol position. In other words, a decision, were within a selected group of transmission symbol positions the (one or more) reference symbol positions should be located is made such that the reference symbol position is at a location where the selected group of transmission symbol position neighbors another group of transmission symbol positions (associated to another data communication apparatus) which another group of transmission symbol positions lies within the same sub-frame as the selected group of transmission symbol positions. Accordingly, the reference symbol position associated with the selected group of transmission symbol positions can be shared with another group of transmission symbol positions within the same sub-frame. For example, if the selected group of transmission symbol positions is located right at the beginning of the sub-frame, the reference symbol position is chosen at the end of the selected group of transmission symbol positions. In contrast, if a selected group of transmission symbol positions of the same length is located right at the end of a sub-frame, the reference symbol position will be chosen at the beginning of said selected group of transmission symbol positions. Generally speaking, the reference symbol positions will be selected by the data communication apparatus such that they are not arranged at the very beginning of a sub-frame or at the very end of a sub-frame, but at an "inner" end (pointing to the inside of a sub-frame) of the respective selected group of transmission symbol positions. This also applies to different selected groups of transmission symbol positions of same length. Thus, a sharing of reference symbol positions by different data communication apparatuses is supported.

In a preferred embodiment, the data communication apparatus is configured to choose a number of reference symbol positions associated with the selected group of transmission symbol positions in dependence on a location of the selected group of transmission symbol positions within a sub-frame. Thus, for groups of transmission symbol positions of a same length, the number of associated reference symbol positions may vary depending on where the respective groups of transmission symbol positions are arranged within a sub-frame. This allows to adapt the number of reference symbol positions to find a good tradeoff between resource efficiency and communication quality.

In a preferred embodiment, the data communication apparatus may be configured to choose a number of reference symbol positions associated with the selected group of transmission symbol positions in dependence onO, a number of neighboring groups of transmission symbol positions within the sub-frame. For example, a larger number of reference symbol positions may be associated with groups of transmission symbol positions having more neighbors than with other groups of transmission symbol positions having less neighbors.

In an embodiment, the data communication apparatus may be configured to choose a number of reference symbol positions associated with the selected group of transmission symbol positions. In this case, only one reference symbol position may be associated with selectable groups of transmission symbol positions neighboring a temporal border of a sub-frame, and two or more reference symbol positions may be associated with at least one selectable group of transmission symbol positions which is (are) distant from both temporal borders of the sub-frame. Thus, it is avoided that a reference symbol position is arranged next to a border of a sub-frame, because such a reference symbol position typically contributes less to a channel estimation than a reference symbol position arranged within an inside of a sub-frame, and typically cannot be reused by a sharing with another data communication apparatus.

In a preferred embodiment, the data communication apparatus is configured to select a group of transmission symbol positions such that a temporal extension of the selected group of transmission symbol positions is smaller than a temporal extension of a sub-frame.

Another embodiment according to the invention creates a data communication apparatus for transmitting one or more blocks of data within a frame comprising a two-dimensional grid of transmission symbol positions. The data communication apparatus is configured to select a group of transmissions symbol positions, which is a subset of the two-dimensional grid of transmission symbol positions, for a transmission of a data portion. The data communication apparatus is configured to select a multiplexing characteristic of one or more reference symbols, which are associated to the selected group of transmission symbol positions, in dependence on the selection of the group of transmission symbol positions. The multiplexing characteristic may, for example, describe one out of a plurality of orthogonal, or approximately orthogonal frequency multiplexing patterns or code multiplexing patterns, such that reference symbols transmitted, for example, at the same time by different data communication apparatuses can be separated by a "central" data communication apparatuses receiving both transmissions. However, a data communication apparatus may, for example, recognize, on the basis of the selected group of transmission symbol positions, whether there is a sharing of a reference symbol position. Also, the data communication apparatus may, for example, recognize whether there is another data communication apparatus transmitting temporally before its own transmission. In this case, a specific multiplexing characteristic may be chosen. On the other hand, if the data communication apparatus recognizes that it is sharing a reference symbol position with another data communication apparatus, which transmits data later then itself, the data communication apparatus under consideration may use another multiplexing characteristic. As an example, the data communication apparatus may choose a first multiplexing characteristic if the selected group of transmission symbol positions is closer to a beginning of a sub-frame when compared to a case that the selected group of transmission symbol positions is further away from the beginning of the sub-frame. Consequently, it may be unnecessary to have a dedicated signaling which multiplexing characteristic should be used for the reference symbols.

Another embodiment according to the invention creates a data communication apparatus for transmitting one or more blocks of data within a frame comprising a two-dimensional grid of transmission symbol positions. The data communication apparatus is configured to select a group of transmission symbol position positions, which is a subset of the two-dimensional grid of transmission symbol positions, for a transmission of a data portion. The data communication apparatus is configured to select a multiplexing characteristic of one or more reference symbols, which are associated with the selected group of transmission symbol positions, in dependence on a multiplexing group selection information defining a group of multiplexing characteristics, and in dependence on a (individual) multiplexing characteristic selection information defining which multiplexing characteristic out of a plurality of multiplexing characteristics contained in a group of multiplexing characteristics defined by the multiplexing group selection information should be used. In other words, the data communication apparatus may use a two-stage selection of a multiplexing characteristic. Thus, a group of multiple different multiplexing characteristics may be determined by the multiplexing group selection information. Later on, the actual multiplexing characteristic may be selected out of the previously selected group of multiplexing characteristics, to obtain the multiplexing characteristic to be actually used. Thus, since the selection of the group of multiplexing characteristics is typically required only rarely, the amount of information (in terms of bits) required to signal the multiplexing characteristic may be reduced (when compared to a full signaling of the multiplexing characteristic every time the multiplexing characteristic should be changed. In other words, it is, for example, possible to associate different groups of multiplexing characteristics to temporally neighboring data communication apparatuses, to thereby reduce a mutual distortion of the data communication apparatuses.

In a preferred embodiment, the data communication apparatus is configured to derive the multiplexing group selection information from a cell identifier of a communication cell in which the data communication apparatus is registered. Accordingly, an overhead for the transmission of the multiplexing group selection information is avoided. Rather, the data communication apparatus can, by itself, derive the multiplexing group selection information from the cell identifier of the communication cell.

In a preferred embodiment, the multiplexing characteristics contained in different groups of multiplexing characteristics define orthogonal multiplexing codes or orthogonal multiplexing patterns (or at least approximately orthogonal multiplexing codes or multiplexing patterns, or at least multiplexing patterns or multiplexing codes which are distinguishable at the side of a central data communication apparatus). By using such a concept, a mutual distortion between other communication apparatuses using different groups of multiplexing characteristics can be minimized.

In a preferred embodiment, the data communication apparatus is configured to update or receive the multiplexing characteristic selection information more frequently than the multiplexing group selection information. Accordingly, data overhead can be minimized. Furthermore, the multiplexing group selection only needs the change rarely, for example, when a data communication apparatus is handed over to a new communication cell.

An embodiment according to the invention creates a data communication apparatus for transmitting one or more blocks of data within a frame comprising a two-dimensional grid of transmission symbol positions. The data communication apparatus is configured to select a group of transmission symbol positions, which is a subset of the two-dimensional grid of transmission symbol positions, for a transmission of a data portion. The data communication apparatus is configured to select a multiplexing characteristic of a plurality of reference symbols, which are associated with the selected group of transmission symbol positions. The data communication apparatus is configured to select the multiplexing characteristic out of this first multiplexing pattern describing transmission symbol positions and a second multiplexing pattern describing transmission symbol positions at which reference symbols are to be transmitted. The first multiplexing pattern comprises at least one shared transmission symbol position, which is also used by the second multiplexing pattern, and at least one exclusive transmission symbol position which is not used by the second multiplexing pattern. The second multiplexing pattern comprises the shared transmission symbol position and at least one exclusive transmission symbol position which is not used by the first multiplexing pattern. Accordingly, by having both shared transmission symbol positions and exclusive transmission symbol positions associated with the first and second multiplexing pattern, an efficiency can be improved. For example, transmission symbol positions which are of particular importance for an interpolation or extrapolation can be shared. On the other hand, there are also exclusive transmission symbol positions, which help to increase an accuracy of the channel estimation by the reference symbols transmitted using the multiplexing characteristics.

In a preferred embodiment, the first multiplexing pattern comprises an alternating sequence of used exclusive transmission symbol positions and one or more non-used transmission symbol positions in between. Moreover, the second multiplexing pattern also comprises an alternating sequence of used exclusive transmission symbol positions (used by the second multiplexing pattern but not used by the first multiplexing pattern) and one or more non-used transmission symbol positions (not used by the second multiplexing pattern, but maybe used by the first multiplexing pattern) in between. Moreover, a highest-frequency transmission symbol position and/or a lowest frequency transmission symbol position are shared between the first multiplexing pattern and the second multiplexing pattern. It has been found that the sharing of the highest-frequency transmission symbol position and/or of the lowest frequency transmission symbol position is helpful, because it is difficult to estimate the channel characteristic at the highest frequency or at the lowest frequency.

An embodiment according to the invention creates a data communication apparatus for receiving a plurality of data blocks from other data communication apparatuses, wherein the data blocks are represented by transmission symbols of multiple groups of transmission symbol positions within a frame comprising a two-dimensional grid of transmission symbol positions. The data communication apparatus is configured to signal to the other data communication apparatuses which group of transmission symbol position should be used by which of the other data communication apparatuses. For example, individual resource allocation information may be provided to different data communication apparatuses. Alternatively, an overall resource allocation scheme may be signaled to all data communication apparatuses (defining an overall resource allocation) wherein it is only signaled to the individual data communication apparatuses which of the resources defined by the overall resource allocation scheme are allocated to which of the data communication apparatuses. As an alternative example, the data communication apparatus may provide each of the other data communication apparatuses with very detailed information describing the resources allocated to the individual data communication apparatus. Thus, the data communication apparatus is configured to provide an information describing a group of transmission symbol positions to be used by a given one of the other data communication apparatuses and an information describing a desired relative position of reference symbol positions with respect to the group of transmission symbol positions to be used by the given one of the other data communication apparatuses. In other words, the data communication apparatus may define, in detail, where within a selected group of reference symbol positions the reference symbol positions should be located. This information may, for example, selectably describe "at the beginning of the selected group of transmission symbol positions", "at the end of the selected group of transmission symbol positions", "in an inner part of the selected group of transmission symbol positions" or "both at the beginning and at the end of the selected group of transmission symbol positions". This embodiment according to the invention is based on the same considerations mentioned above with respect to a data communication apparatus for transmitting a plurality of data blocks. Moreover, this data communication apparatus for receiving a plurality of data blocks from other data communication apparatuses may be supplemented by features which correspond to the features mentioned above for the corresponding data communication apparatuses for transmitting a plurality of data blocks. For example, the information

describing a desired relative position of reference symbol positions with respect to the selected group of transmission symbol positions may be a 1 -bit information or a 2-bit information.

Moreover, the information describing a desired relative position of reference symbol positions with respect to a group of transmission symbol positions to be used by a given one of the other data communication apparatuses may be a 1-bit information for a comparatively "short" group of transmission symbol positions, and may be a 2-bit information for a comparatively "longer" group of transmission symbol positions.

Another embodiment according to the invention creates a data communication apparatus for receiving a plurality of data blocks from other communication apparatuses, wherein a data block is represented by transmission symbols of a group of transmission symbol positions within a frame comprising a two-dimensional grid of transmission symbol positions. The data communication apparatus is configured to provide to the other data communication apparatuses a communication resource information. The communication resource information represents an allocation of transmission symbol positions and describes which group of transmission symbol positions should be used by which of the other data communication apparatuses and which of the transmission symbol positions should be used for a transmission of reference symbols by which of the other data communication apparatuses. The data communication apparatus is configured to signal different allocations of transmission symbol positions in dependence on a current communication state (for example, in dependence on how many other data communication apparatuses are connected to the data communication apparatus discussed here, and/or in dependence on latency requirements of one or more data communication apparatuses connected to the data communication apparatus discussed here). The transmission symbol positions to be used for the transmission of reference symbols are variable with respect to borders of time slots of the frames and/or with respect to borders of sub-frames of the frame between different allocations of transmission symbol positions (or even within a single allocation of transmission symbol positions). Alternatively or in addition, the transmission symbol positions to be used for the transmission of reference symbols may be variable with respect to a corresponding group of transmission symbol positions between different allocations of transmission symbol positions (or even within a single allocation of transmission symbol positions). For example, when there is a reallocation of transmission symbol positions, the location of reference symbols may vary, both with respect to borders of time slots or of respect to

borders of sub-frames. Also, when the transmission symbol positions are reallocated (for example, due to our change of the current communication state), the locations of the reference symbols with respect to a corresponding group of transmission symbol positions (for example, with respect to one or more borders of a group of transmission symbol positions to which the reference symbol is associated) may change. Thus, the locations of the reference symbol positions are not fixed with respect to borders of time slots and/or with respect to borders of sub-frames. Also, the position within groups of transmission symbol positions (which are allocated to a given data communication device) may vary, even if the temporal length or size of a group (for example, of a contiguous group) of transmission symbol positions associated to a data communication apparatus does not change. However, even at a single instance of time, relative positions of reference symbol positions may vary between groups of transmission symbol positions allocated to different data communication apparatuses.

In other words, the data communication apparatus for receiving a plurality of data blocks is based on the same considerations as the above-mentioned data communication apparatus for transmitting a plurality of data blocks. Thus, any of the considerations provided herein with respect to the data communication apparatus for transmitting a plurality of data blocks also apply to the data communication apparatus for receiving a plurality of data blocks. However, the data communication apparatus for receiving a plurality of data blocks may be a base station or a central station coordinating the operation of a plurality of data communication apparatuses for transmitting a plurality of data blocks, and may signal to other data communication apparatuses (for example, to data communication apparatuses for transmitting a plurality of data blocks) a location of transmission symbol positions. In contrast, the data communication apparatuses for transmitting a plurality of data blocks may, for example, be user equipment, and may allocate the resources as signaled from the coordinating "data communication apparatus for receiving a plurality of data blocks".

However, it should be noted that the "data communication apparatus for receiving a plurality of data blocks" may also have the functionality to transmit a plurality of data blocks. Similarly, the "data communication apparatuses for transmitting a plurality of data blocks" may also have a receiving functionality, which, however, is of subordinate importance in the data communication scenario discussed here.

The data communication apparatus discussed here may switch between a number of different communication states (and may, for example, provide information indicating the different communication states to the other data communication devices). The different communication states may signal to one or more other data communication apparatuses different communication resource information, which indicates different reference symbol positions. Thus, the data communication apparatus discussed here may instruct the one or more other data communication apparatuses to use different reference symbol positions for the transmission of reference symbols. For example, different reference symbol positions may be instructed even for groups of transmission symbol positions having the same length. Thus, the data communication apparatus described herein has the functionality to flexibly configure the other data communication apparatuses. In particular, the data communication apparatus discussed here typically has superior knowledge about the presence of multiple other data communication apparatuses within a communication cell, and can therefore instruct the different other data communication apparatuses to use different reference symbol positions (in some cases, even shared reference symbol positions) on the basis of its superior knowledge. The reference symbol positions are not fixed by the length (or size) of the groups of transmission symbol positions to be used by the individual other data communication apparatuses, but rather can be allocated flexibly by the data communication apparatus described here, wherein, even for a given length or size of a group of transmission symbol positions to be used by one of the other data communication apparatuses, the reference symbol position can be varied by the data communication apparatus discussed here.

In a preferred embodiment, the data communication apparatus is configured to allow for an allocation of groups of transmission symbol positions having different lengths. Moreover, the data communication apparatus is configured to allow for an allocation of groups of transmission symbols having the same length but different associated reference symbol positions during a single communication state and/or during different communication states. For example, the data communication apparatus described herein may signal that a first group of transmission symbol positions having a certain temporal extension should have the reference symbol position at the end, wherein another group of transmission symbol positions having the same length may have the reference symbol position at the very beginning.

Consequently, reference symbol positions may be varied and are not bound in a fixed manner by the temporal extension or size of the respective groups of transmission symbol positions.

Again, it should be noted that the data communication apparatus for receiving a plurality of data blocks corresponds to the above described data communication apparatus for transmitting a plurality of data blocks, such that the above explanations and clarifications also are applicable.

Another preferred embodiment creates a data communication apparatus for receiving a plurality of data blocks from other data communication apparatuses, wherein a data block is represented by transmission symbols of a group of transmission symbol positions within a frame comprising a two-dimensional grid of transmission symbol positions. The data communication apparatus is configured to provide to the other data communication apparatuses a communication resource information. The communication resource information represents an allocation of transmission symbol transmissions and describes which group of transmission symbol positions should be used by which of the other data communication apparatuses and which of the transmission symbol position should be used for a transmission of reference symbols by which of the other data communication apparatuses. The communication resource information may represent any details of the resource allocation individually for different of the other data communication apparatuses. However, it is also possible that a "overall" resource allocation scheme (out of a plurality of overall source allocation schemes) is signaled commonly to all other data communication apparatuses, and that there is only a short information which of the groups of transmission symbol positions (defined by the overall resource allocation scheme) is allocated to which of the other data communication apparatuses. The data communication apparatus is configured to provide the communication resource information to at least two other data communication apparatuses, to cause a sharing between at least two other data communication apparatuses of a transmission symbol position for a transmission of a reference symbol. In other words, the data communication apparatus provides configuration information (communication resource information) to at least two other data communication apparatuses, wherein the data communication apparatus chooses or adjusts the communication resource information in such a manner that at least two other data communication apparatuses share a transmission symbol position for a transmission of a reference symbol. Worded yet differently, the data communication apparatus configures (using the communication resource information) two other data communication apparatuses, such that both transmit a reference symbol within a shared transmission symbol position. However, the reference symbol transmissions by both of the other data communication apparatuses may be distinguishable if the at least two other data communication apparatuses use different codes or patterns or the like for the transmission of their reference symbols at the shared transmission symbol position (or at a plurality of shared transmission symbol positions). Thus, the data communication apparatus can configure the at least two other data communication apparatuses for an efficient resource usage, thereby saving physical resources and ensuring that an overhead caused by reference symbols due to the usage of "short transmission time intervals" (i.e. temporally short groups of transmission symbol positions) is kept reasonably small.

In a preferred embodiment, the data communication apparatus is configured to provide the communication resource information to at least two other data communication apparatuses, to cause a first data communication apparatus to which a comparatively shorter transmission length is associated, to share transmission symbol positions for a transmission of reference symbols with only one other data communication device, and to cause a second data communication apparatus, to which a comparatively longer transmission length is associated to share transmission symbol positions for transmission efficiently and selected by the data other data communication devices. Accordingly, an efficiency of the transmission can be optimized.

In a preferred embodiment, the data communication apparatus is configured to cause a second (other) data communication apparatus to share one or more transmission symbol positions at the beginning of a group of transmission symbol positions associated with the second (other) data communication apparatus, with a first (other) data communication apparatus for transmission of one or more reference symbols. Furthermore, the data communication apparatus is configured to cause the second data communication apparatus to share one or more transmission symbol positions at an end of a group of transmission symbol positions associated with a second data communication apparatus with a third data communication apparatus for the transmission of one or more reference symbols. Accordingly, there is an efficient resource sharing approach.

In a preferred embodiment, the data communication apparatus is configured to decide whether a given other data communication apparatus is instructed to share transmission symbol positions with one or more other data communication apparatuses for the transmission of one or more reference symbols in dependence on a length of a

transmission interval associated with the given data transmission apparatus, and/or in dependence on a channel condition and/or in dependence on a signal-to-noise ratio. Accordingly, the resource sharing approach is adapted to externa! conditions which determine the efficiency of a resource sharing.

In a preferred embodiment, the communication resource information defines an allocation of transmission symbol positions to the other data communication apparatuses using device-specific information items. Alternatively, the communication resource information comprises a joint information item describing a selection of a joint allocation of transmission symbol positions to a plurality of other data transmission apparatuses out of a plurality of predefined joint allocations of transmission symbol positions.

In a preferred embodiment, the data communication apparatus is configured to provide a multiplexing characteristic selection information defining which multiplexing characteristic out of a plurality of multiplexing characteristics defined in a group of multiplexing characteristics should be used by at least one other data communication apparatus. Accordingly, the data communication apparatus can ensure that there is a well-controlled multiplexing of reference symbols which are transmitted at shared reference symbol positions by multiple data communication devices.

In a preferred embodiment, the data communication apparatus is configured to provide a multiplexing characteristic selection information instructing another data communication apparatus in communication with the data communication apparatus described here to select a multiplexing characteristic out of at least the first multiplexing pattern describing transmission symbol positions and a second multiplexing pattern describing transmission symbol positions, wherein the first multiplexing pattern comprises at least one shared transmission symbol position, which is also used by the second multiplexing pattern, and at least one exclusive transmission symbol position which is not used by the second multiplexing pattern, and wherein the second multiplexing pattern comprises the shared transmission symbol position and at least one exclusive transmission symbol position which is not used by the first multiplexing pattern. Accordingly, the data communication apparatus can efficiently configure the multiplexing, to minimize distortions and/or to allow for good channel estimation using the reference symbols.

In yet another preferred embodiment, the data communication apparatus can signal a switching between a first multiplexing pattern and a second multiplexing pattern as already outlined above.

An embodiment according to the invention creates a data communication system. The data communication system comprises a first a data communication apparatus as described above (for example, a data communication apparatus for receiving one or more data blocks, or a first base station). The data communication system further comprises a second data communication apparatus as described herein (for example, another data communication apparatus for receiving data blocks or a second base station). The data communication system also comprises a first other data communication apparatus (as described herein, for example, a data communication apparatus for transmitting one or more data block, or a first user equipment), linked to the first data communication apparatus. The data communication system further comprises a second other data communication apparatus (for example, another data communication apparatus for transmitting one or more data blocks, or a second user equipment), linked to the second data communication apparatus. The first other data communication apparatus is configured to choose a multiplexing characteristic of one or more reference symbols, which are associated to a respective group of transmission symbol positions associated with the first other data communication apparatus, out of a plurality of multiplexing characteristics contained in a first group of multiplexing characteristics in dependence on a multiplexing characteristic selection information provided by the first data communication apparatus. The second other data communication apparatus is configured to choose a multiplexing characteristic of one or more reference symbols, which are associated to a selected group of transmission symbol positions associated with the second other data communication apparatus, out of a plurality of multiplexing characteristics contained in a second group of multiplexing characteristics, depending on a multiplexing characteristic selection information provided by the second data communication apparatus. Multiplexing characteristics contained in different groups of multiplexing characteristics define orthogonal or approximately orthogonal multiplexing codes or orthogonal or approximately orthogonal multiplexing patterns (which are defined to minimize or avoid a distortion). Thus, the first other data communication apparatus and the second other data communication apparatus can share a transmission symbol position (for example, the intersection of the selected group of transmission symbol positions associated to the first other data communication apparatus and of the selected group of transmission symbol positions associated to the second other data

communication apparatus). For each transmission of reference symbols, a multiplexing characteristic of the first group of multiplexing characteristics is used by the first other data communication apparatus, and a multiplexing characteristic out of the second group of multiplexing characteristics is used by the second other data communication apparatus. Thus, by using different groups of multiplexing characteristics, it can be automatically ensured that there is little or no distortion between the reference symbol transmitted by the first other data communication apparatus and the reference symbol transmitted by the second other data communication apparatus in the shared transmission symbol position. Furthermore, by using different groups of multiplexing characteristics, a signaling overhead for the controlling or coordinating the first other data communication apparatus and the second other data communication apparatus can be kept reasonably small.

In a preferred embodiment, the first other data communication apparatus is configured to derive a multiplexing group selection information, which is used to select the first group of multiplexing characteristics from a cell identifier of the first data communication apparatus. Similarly, the second other data communication apparatus may, optionally, also have such an ability. Accordingly, there is a "automatic" selection of different groups of multiplexing characteristics by the different data communication apparatuses, which does not even need any signaling overhead. Thus, it can be ensured, without a signaling overhead, that there is no or little distortion caused by the transmission of reference symbols at the shared transmission symbol position.

One embodiment according to the invention comprises respective methods. It should be noted that the methods are based on the same considerations as the above described apparatuses. Furthermore, it should be noted that the methods can be supplemented by any of the features and functionalities disclosed herein with respect to the apparatuses.

Further embodiments according to the invention create a computer program for performing one of said methods.

Brief description of the Figures

Embodiments according to the present application will subsequently be described taking reference to the enclosed figures, in which:

Fig. 1 shows a schematic representation of a legacy LTE uplink subframe;

Figs. 2a

and 2b show a schematic representation of an example of an uplink subframe with sTTI length 3/4 and 2 OFDM symbols;

Fig. 3 shows a schematic representation of sTTI possible DMRS positions;

Fig. 4 shows a schematic representation of an example (a) without an (b) with

DMRS multiplexing;

Fig. 5 shows a schematic representation of a multiplexing of user equipments (UEs) with different bandwidth allocations;

shows a schematic representation of a multiplexing of user equipments (UEs) with different transmission length;

shows a schematic representation of examples of a combination of DMRS multiplexing for a multi-user scenario over frequency and time domains;

shows a schematic representation of PUSCH sTTIs (short transmission time intervals) and corresponding DMRS slots in orange (or shown in a different hatching);

shows a schematic representation of a frequency multiplexing of DMRS, wherein a shared symbol is used at edges for better interpolation;

shows an ICIC (intra-cell-interference-coordination) for DMRS sequences by introducing orthogonal groups;

shows a schematic representation of an example representation of two patterns, wherein A to D are different users transmitting;

shows a schematic representation of an example assignment of TTl length and DMRS position in frequency and time on an LTE resource grid;

shows a table representing a DC I message with added 1-bit DC! position field;

Fig. 14 shows a table representing a DCI message with added 1-bit or 2-bit DCI position field;

Fig. 15 shows a table representing a grouping of OMRS multiplexing patterns;

Fig. 16 shows a list of acronyms and symbols;

Fig. 17 shows a block schematic diagram of a data communication apparatus, according to an embodiment of the present invention;

Fig. 18 shows a block schematic diagram of a data communication apparatus, according to another embodiment of the present invention;

Fig. 19 shows a block schematic diagram of a data communication apparatus, according to another embodiment of the present invention;

Fig. 20 shows a block schematic diagram of a data communication apparatus, according to another embodiment of the present invention;

Fig. 21 shows a flowchart of a method for transmitting one or more blocks of data, according to an embodiment of the present invention;

Fig. 22 shows a flowchart of a method for transmitting one or more blocks of data, according to an embodiment of the present invention;

Fig. 23 shows a flowchart of a method for transmitting one or more blocks of data, according to an embodiment of the present invention;

Fig. 24 shows a flowchart of a method for transmitting one or more blocks of data, according to an embodiment of the present invention;

Fig. 25 shows a flowchart of a method for transmitting one or more blocks of data, according to an embodiment of the present invention;

Fig. 26 shows a flowchart of a method for receiving one or more blocks of data, according to an embodiment of the present invention;

Fig. 27 shows a flowchart of a method for receiving one or more blocks of data, according to an embodiment of the present invention; and

Fig. 28 shows a flowchart of a method for receiving one or more blocks of data, according to an embodiment of the present invention.

Detailed description of the embodiments

1. Data communication apparatus according to Fig. 17

Fig. 17 shows a block schematic diagram of a data communication apparatus 1700, according to an embodiment of the present invention.

The data communication apparatus 1700 receives one or more blocks of data 1710 and provides, on the basis thereof, a transmission signal or modulation signal 1720. The data communication apparatus is configured to transmit the one or more blocks of data within a frame comprising a two-dimensional grid of transmission symbol positions, as illustrated at reference numeral 1730.

The data communication apparatus 1700 is configured to select a group of transmission symbol positions 1740 (a length of which may be a so-called "short transmission time interval" sTTi), which is a subset of the two-dimensional grid of transmission symbol positions (shown at reference numeral 1730), for transmission of a data portion (for example, a block of data). The data communication apparatus is configured to select one or more reference symbol positions 1750, 1752, 1754 associated to the selected group of transmission symbol positions (for example, lying within the selected group 1740 of transmission symbol positions), out of a plurality of possibilities, based on an information describing a desired relative position of the reference symbol position with respect to (or with reference to, or relative to) the selected group of transmission symbol positions.

An example is illustrated in Fig. 17. For example, if the selected group 1740 of transmission symbol positions comprises a given number of transmission symbol positions (for example, three transmission symbol positions), there are, for example, (at least) four possibilities for the allocation of reference symbol positions, wherein the data communication apparatus 1700 may make a choice between at least two of these possibilities, or even between all four of these possibilities. For example, the data communication apparatus may be configured to select one or more reference symbol positions (for example, the reference symbol position 1750 at the beginning of the selected group of transmission symbol positions (as shown at reference numeral 1740a), the reference symbol position 1752 at the end of the selected group of transmission symbol positions, as shown at reference numeral 1740b, the reference symbol position 1754 in an inner (or at the middle) of the selected group of transmission symbol positions, as shown at reference numeral 1740c, or two reference symbol positions 1756, 1758, both at the beginning at the end of the selected group of transmission symbol positions, as shown at reference numeral 1740d). In other words, the data communication apparatus may be configured to variably select one or more reference symbol positions within the selected group of transmission symbol positions, wherein the data communication apparatus may use an information describing a relative position of the reference symbol position(s) with respect to the selected group of transmission symbol positions. This information describing the relative positions may, for example, represent two or more of the relative positions "at the beginning", "at the end", "in an inner part", "in the middle", "both at the beginning and at the end". Thus, the reference symbol position can be encoded efficiently and selected by the data communication apparatus 1700.

Moreover, it should be noted that the data communication apparatus 1700 uses the selected group of transmission symbol positions in order to obtain a transmission signal or a modulated signal 1720. In particular, a data block to be transmitted may be provided with a channel coding (which, for example, allows for a detection and/or correction of transmission errors), and the resulting channel-coded data may then be represented in the form of modulation symbols (e.g. complex-valued OFDM modulation symbols) which are included in a transmission signal, or into a modulation signal, at transmission symbol positions within the selected group of transmission symbol positions. In this case, the reference symbol position, which typically lies within the selected group of transmission symbol positions, is occupied with a modulation symbol, which is independent from a data content of the block of data to be transmitted, to be used (or usable) for a channel estimation. In other words, the useful data of the block of data to be transmitted are reflected by modulation symbols placed at non-reference-symbol positions within the selected group of transmission symbol positions.

Thus, the data communication apparatus 1700 has a flexible scheme of selecting a group of transmission symbol positions for the transmission of a data block, and also has a flexible concept for selecting which symbol position (or which symbol positions) within the selected group of transmission symbol positions should be used for the transmission of one or more reference symbols. By flexibly assigning the reference symbol positions at different (relative) locations within the selected group of transmission symbol positions, it is possible to adapt the data communication to different scenarios, for example to scenarios in which a sharing of reference symbol positions between different data communication apparatuses is desired and to scenarios in which there is no sharing of reference symbol positions between data communication apparatuses.

Further details regarding the data communication apparatus 1700, and regarding the allocation of groups of transmission symbol positions will be described below.

In other words, the apparatus 1700 according to Fig. 17 can be supplemented by any of the features and functionalities described herein, either individually or in combination.

2. Data . communication, apparatus according to Fig. 18

Fig. 18 shows a block schematic diagram of a data communication apparatus 1800, according to an embodiment of the present invention. The data communication apparatus 1800 is configured to receive a block of data 1810 and to provide, on the basis thereof, a transmission signal or a modulated signal 1820. The data communication apparatus 1800 is configured to transmit one or more blocks of data within a frame comprising a two-dimensional grid of transmission symbol positions, which is represented at reference numeral 1830. The data communication apparatus is configured to select a group of transmission symbol positions (for example, a group 1840, a group 1841 , a group 1842, a group 1843, a group 1844, a group 1845 and/or a group 1846), which is a subset of the two-dimensional grid of transmission symbol positions, for a transmission of a data portion (for example, of the block of data). The selected group of transmission symbol positions may have a length which is designated as "short transmission time interval".

The data communication apparatus is configured to determine which one or more symbol positions (for example, within one or more of the groups 1840 to 1846) are used as one or more reference symbol positions based on the selection of the group of transmission symbol positions or together with the selection of the group of transmission symbol

positions. The reference symbol positions are variable with respect to the one or more borders of time slots of the frame or with respect to one or more borders of subframes of the frame. Alternatively or in addition, the one or more reference symbol positions may be variable with respect to the selected group of transmission symbol positions (to which the reference symbol positions are associated).

In other words, the data communication apparatus may be very flexible in selecting the groups 1840 to 1846 of transmission symbol positions, and the data communication apparatus 1800 is also very flexible in selecting the reference symbol positions.

Taking reference now to the example of Fig. 18, it can be seen that the selected groups 1840, 1841 of transmission symbol positions comprise a same length (in terms of a number of transmission symbol positions) but a shift in time with respect to each other. It should be noted that it is not necessary that the selected groups 1840, 1841 are associated with different frequencies or frequency bins or (sub-)carrier frequencies. Rather, the selected groups 1840 , 1841 may both be arranged at the same frequency or frequency bin or frequency carrier and may be used alternatively in dependence on a configuration information. As can be seen, a reference symbol position 1840a within the group 1840 has a distance of two symbol positions from a (left-sided) time border of a subframe 1850. In contrast, a reference symbol position 1841 a has a distance of three reference symbol positions from said left-sided border of the subframe 1850. Thus, it can be seen that the data communication apparatus 1800 is configured to select groups of transmission symbol positions (for example, groups 1840, 1841) (either simultaneously or successively), wherein the reference symbol positions 1840a, 1841a associated with these selected groups 1840, 1841 have different relative positions with respect to the closest border of a respective subframe in which the selected groups 1840, 1841 are located.

Similarly, it can be seen that the reference symbol position 1842a and the reference symbol position 1843a have different distance (or relative positions) with respect to a time border of a slot 1860 in which the groups 1842, 1843 are located. The (relative) position of the reference symbol position 1842a with respect to the time border of the slot 1860 can be defined as being separated from the border by one reference symbol position. In contrast, the (relative) position of the reference symbol position 1843a relative to the time border of the slot 1860 can be defined as having a different number of symbol positions (for example, two symbol positions) in between. Accordingly, it is apparent that the data communication apparatus 1800 is adapted to choose the reference symbol positions such that the reference symbol positions are variable with respect to borders of time slots of the frame or with respect to borders of subframes of the frame.

Taking reference now to groups 1844, 1845 and 1846, it can be seen that the associated reference symbol positions 1844a, 1845a and 1846a vary with respect to the respective groups 1844, 1845, 1846. As can be seen, the reference symbol position 1844a is at the beginning of the corresponding group 1844, the reference symbol position 1845a is in an inner part of the corresponding group 1845, and the reference symbol position 1846a is at an end of the corresponding group 1846. Thus, it can be said that the reference symbol positions are variable with respect to the corresponding selected group of transmission symbol positions (and with respect to the selected group of transmission symbol positions to which the reference symbol position is associated).

To conclude, the data communication apparatus 1800 may very flexibly choose both the groups of transmission symbol positions (which are associated to the transmission of a block of data) and the reference symbol positions within these selected groups of transmission symbol positions. In particular, the reference symbol positions are not bound to a fixed grid within a subframe or within a slot. Rather, the reference symbol positions can vary even for groups of transmission symbol positions having the same lengths or sizes. The variation of the reference symbol positions can be both relative with respect to (adjacent) borders of time slots of the respective frame or with respect to (adjacent) borders of subframes of the respective frame or with respect to borders of the corresponding group of transmission symbol positions (i.e. with respect to the selected group of transmission symbol positions itself).

Moreover, it should be noted that the selected groups of transmission symbol positions and the selected reference symbol positions may be used for the generation of the transmission signal/modulated signal 1820 in the same manner as described above with respect to the apparatus 1700.

Moreover, it should be noted that the data communication apparatus 1800 can be supplemented by any of the features and functionalities described herein, either individually or in combination.

3. Data communication apparatus according to Fig. 19

Fig. 19 shows a block schematic diagram of a data communication apparatus 1900, according to an embodiment of the present invention.

The data communication apparatus 1900 is similar to the data communication apparatuses 1700, 1800 as described herein. It should be noted that the data communication apparatus can therefore be supplemented by any of the features and functionalities described with respect to the data communication apparatuses 1700 and 1800.

The data communication apparatus 1900 is configured to receive a block of data 1910 and to provide, on the basis thereof, a transmission signal or a modulated signal 1920.

The data communication apparatus 1900 is configured to transmit one or more blocks of data within a frame comprising a two-dimensional grid of transmission symbol positions. The data communication apparatus is configured to select a group of transmission symbol positions, which is a subset of the two-dimensional grid of transmission symbol positions, for a transmission of a data portion.

However, the data communication apparatus is configured to allocate, within the selected group of transmission symbol positions, one or more reference symbol positions. For example, a selected group of transmission symbol positions is designated with 1940 and an associated reference symbol position is designated with 1940a. Another possible group of transmission symbol positions is designated with 1942, and the associated reference symbol position is designated with 1942a.

To allow for a sharing of a reference symbol position with another data communication apparatus, the data communication apparatus 1900 is configured to apply a multiplexing scheme to one or more reference symbols transmitted on a reference symbol position.

The data communication apparatus 1900 comprises one or more of the mechanisms for the selection of the multiplexing characteristic which will be discussed in the following.

According to an aspect, the data communication apparatus is configured to select a multiplexing characteristic of one or more reference symbols, which are associated to the selected group of transmission symbol positions, in dependence on the selection of the group of transmission symbol positions. For example, the data communication apparatus 1900 may choose a first multiplexing characteristic for one or more reference symbols transmitted at reference symbol position 1940a, which is associated with the group 1940 of transmission symbol positions. On the other hand, the data communication apparatus 1900 may select a different multiplexing characteristic for one or more reference symbols transmitted at reference symbol position 1942a, which is associated to the group 1942. Even if the reference symbol positions 1940a and 1942a were at the same position within the two-dimensional time-frequency-grid, different multiplexing characteristics would be chosen by the data communication apparatus 1900 in dependence on whether the data communication apparatus has selected the group 1940 or the group 1942. In other words, the data communication apparatus 1900 may, for example, use a different multiplexing characteristics for a reference symbol which is located at an end of a selected group of transmission symbol positions when compared to a reference symbol which is located at a beginning of a selected group of reference symbol positions. By using such a mechanism (which may be implemented in the same manner in a plurality of data communication apparatuses), it can be ensured that there is no significant distortion between reference symbols transmitted at the same reference symbol position by different data communication apparatuses. In particular, by using such a concept, a large signaling overhead can be avoided.

According to another aspect, the data communication apparatus may be configured to select a multiplexing characteristic of one or more reference symbols, which are associated to the selected group of transmission symbol positions, in dependence on a multiplexing characteristic group selection information defining a group of multiplexing characteristics, and in dependence on a (individual) multiplexing characteristic selection information defining which multiplexing characteristic out of a plurality of multiplexing characteristics contained in a group of multiplexing characteristics defined by the multiplexing group selection information should be used. As shown at reference numeral 1960, the data communication apparatus 1900 may, for example, have a table of multiplexing characteristics, wherein this table comprises at least two groups of multiplexing characteristics. Thus, a multiplexing characteristic group selection information may be used to select a group of multiplexing characteristics for use by the data communication apparatus 1900. On the other hand, a multiplexing characteristic selection information 1964 may be used to select which characteristic out of the selected group of multiplexing characteristics (as defined by the multiplexing characteristic groups selection information 1962) is to be used. Thus, there can be a two-step selection of a multiplexing characteristic. The multiplexing characteristic group selection information 1962 may, for example, be derived in a different manner when compared to the multiplexing characteristic selection information 1964. For example, the multiplexing characteristic groups selection information 1964 may be derived (or changed) only "rarely", for example when handing over from one communication cell to another communication cell. Also, an information item representing the multiplexing characteristic group selection information 1962 may, for example, only be included in a control information at comparatively large time intervals. In contrast, an information item representing the multiplexing characteristic selection information 1964 may be determined (or changed, or updated) more frequently than the multiplexing characteristic group selection information 1962. For example, an information item representing the multiplexing characteristic selection information 1964 may be included in a control information more frequently than an information item defining the multiplexing characteristic groups selection information 1962.

Moreover, the multiplexing characteristics within the first multiplexing characteristic group and the multiplexing characteristic within the second multiplexing characteristic group may be chosen such that any multiplexing characteristic within the first multiplexing characteristic group does not substantively interfere with any of the multiplexing characteristics contained in the second multiplexing characteristic group. Thus, if a data communication apparatus transmits a reference symbol using any of the multiplexing characteristics of the multiplexing characteristic group and, at the same time, another data communication apparatus transmits a reference symbol using any of the multiplexing characteristics defined by the second multiplexing characteristic group, there will be only little or no interference between said transmissions. Thus, if it is ensured that two data communication apparatuses use multiplexing characteristics of different multiplexing characteristic groups, it is not necessary to strictly coordinate which data communication apparatus uses which multiplexing characteristics of its multiplexing characteristic group at which time. Thus, the definition of multiplexing characteristic groups, and the usage of such multiplexing characteristic groups on the side of data communication apparatuses helps to avoid interference between different data communication apparatuses sharing a reference symbol position.

Moreover, it should be noted that the multiplexing characteristics may, for example, be a code division scheme, a frequency division scheme and/or a space division scheme, which has the effect that reference symbols transmitted using different multiplexing

characteristics exhibit little or no interference (even if transmitted at the same reference symbol position or groups of reference symbol positions).

According to yet another aspect, the data communication apparatus is configured to select a multiplexing characteristic out of at least a first multiplexing pattern describing transmission symbol positions and a second multiplexing pattern describing transmission symbol positions. The first multiplexing pattern comprises at least one shared transmission symbol position, which is also used by the second multiplexing pattern, and at least one exclusive transmission symbol position which is not used by the second multiplexing pattern. Similarly, the second multiplexing pattern comprises the shared transmission symbol position and at least one exclusive transmission symbol position which is not used by the first multiplexing pattern. Examples for the first multiplexing pattern (which can be understand as a first multiplexing characteristic) and for the second multiplexing pattern (which can be understood as a second multiplexing characteristic) are shown at reference numerals 1980 and 1990. For example, the first multiplexing pattern and the second multiplexing pattern 1980, 1990 comprise, at a first transmission symbol position, a shared transmission symbol position 1982, 1992. However, a second transmission symbol position 1984 is a "exclusive" transmission symbol position, such that there is only a transmission at the second transmission symbol position 1984 if the first multiplexing pattern 1980 is chosen. In contrast, if the second multiplexing pattern 1990 is chosen, there is no transmission at the transmission symbol position 1984 (as shown by a blank rectangle in the multiplexing pattern 1990. Similarly, the first multiplexing pattern 1986 does not comprise a transmission at a third multiplexing pattern position 1986, which is indicated by a blank rectangle of the first multiplexing pattern 1980. On the other hand, the transmission symbol position 1986 is associated with the second multiplexing pattern 1990 as a "exclusive" transmission symbol position.

To conclude, the transmission symbol position 1982 is shared between the first multiplexing pattern 1980 and the second multiplexing pattern 1990, and can therefore be considered as a shared transmission symbol position. The second transmission symbol position 1982 is only associated with the first multiplexing pattern 1980 but not to the second multiplexing pattern 1990, and is therefore an exclusive transmission symbol position for the first multiplexing pattern 1980. The third transmission symbol position 1986 is exclusively associated to the second multiplexing pattern 1990 but not associated to the first multiplexing pattern 1980. It should be noted that, for example, the transmission symbol positions 1982, 1984, 1986 may be associated with a same time but different

frequencies. Moreover, it should be noted that usage of such multiplexing patterns may, on the one hand, reduce interference and, on the other hand, allow for a good estimation of channel characteristics (for example, even at an upper frequency bound or at a lower frequency bound).

It should be noted here that the different aspects regarding the selection of the multiplexing characteristic can be used individually, or can be combined.

Moreover, it should be noted that the data communication apparatus 1900 can be supplemented by any of the features and functionalities described herein, either individually or in combination.

Claims

1. A data communication apparatus (1700), for transmitting one or more blocks of data (1710) within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the data communication apparatus is configured to select a group (1740) of transmission symbol positions, which is a subset of the two-dimensional grid (1730) of transmission symbol positions, for a transmission of a data portion; and

wherein the data communication apparatus is configured to select one or more reference symbol positions (DMRS; 312; 1750, 1752,1754,1756,1758) associated to the selected group (1740) of transmission symbol positions, out of a plurality of possibilities, based on an information (DMRS_position) describing a desired relative position of the reference symbol position with respect to the selected group of transmission symbol positions.

2. The data communication apparatus according to claim 1 , wherein the data

communication apparatus is configured to receive an information (1711 ; DMRS_Position) indicating whether a reference symbol position is at a beginning of a selected group of transmission symbol positions or at an end of a selected group of transmission symbol positions.

3. The data communication apparatus according to claim 2, wherein the information (1711 ; DMRS_position) indicating whether a reference symbol position is at a beginning of a selected group of transmission symbol positions or at an end of a selected group of transmission symbol positions is a 1-bit information.

4. The data communication apparatus according to claim 1 , wherein the data communication apparatus is configured to receive an information (1711 ; DMRS_position) indicating whether a reference symbol position is at a beginning of a selected group of transmission symbol positions or at an end of a selected group of transmission symbol positions or in an inner part of a selected group of transmission symbol positions or whether there are reference symbol positions both at a beginning and at an end of a selected group of transmission symbol positions.

5. The data communication apparatus according to claim 4, wherein the information indicating whether a reference symbol position is at a beginning of a selected group of transmission symbol positions or at an end of a selected group of transmission symbol positions or in an inner part of a selected group of transmission symbol positions or whether there are reference symbol positions both at a beginning and at an end of a selected group of transmission symbol positions is a 2-bit information.

6. The data communication apparatus according to one of claims 1 to 5, wherein data communication apparatus is configured to selectively evaluate a 1 -bit information describing a desired relative position of a reference symbol position with respect to the selected group of transmission symbol positions or a 2-bit information describing a desired relative position of a reference symbol position with respect to the selected group of transmission symbol positions in dependence on whether the selected group of transmission symbol positions comprises a length of two transmission symbol positions or a length or more than two transmission symbol positions; or

wherein data communication apparatus is configured to selectively evaluate a 1-bit information describing a desired relative position of a reference symbol position with respect to the selected group of transmission symbol positions or a 2-bit information describing a desired relative position of a reference symbol position with respect to the selected group of transmission symbol positions in dependence on whether the selected group of transmission symbol positions comprises two transmission symbol positions or more than two transmission symbol positions in dependence on a temporal extension of a selected group of transmission symbol positions.

7. The data communication apparatus according to one of claims 1 to 6, wherein the data communication apparatus is configured to receive the information (2040) describing a desired relative position of the reference symbol position with respect to the selected group of transmission symbol positions from another data communication device (2000) coordinating the operation of multiple data communication devices.

8. A data communication apparatus (1800), for transmitting one or more blocks of data (1810) within a frame comprising a two-dimensional grid of transmission symbol positions (1830),

wherein the data communication apparatus is configured to select a group (1840, 1841 , 1842, 1843, 1844, 1845, 1846) of transmission symbol positions, which is a subset of the two-dimensional grid of transmission symbol positions, for a transmission of a data portion,

wherein one or more reference symbol positions (OMRS;

1840a, 1841 a, 1842a, 1843a, 1844a, 1845a, 1846a) are associated to the selected group of transmission symbol positions;

wherein the data communication apparatus is configured to determine which one or more symbol positions are used as one or more reference symbol positions based on the selection of the group of transmission symbol positions or together with the selection of the group of transmission symbol positions; and

wherein the reference symbol positions are variable with respect to one or more borders of time slots of the frame or with respect to one or more borders of sub-frames of the frame, and/or

wherein the one or more reference symbol positions (OMRS;

1840a, 1841 a, 1842a, 1843a, 1844a, 1845a, 1846a) are variable with respect to the selected group (1840, 1841 , 1842, 1843, 1844, 1845, 1846) of transmission symbol positions.

9. The data communication apparatus according to claim 8, wherein the location of the reference symbol positions with respect to one or more borders of time slots of the frame or with respect to one or more borders of sub-frames of the frame vary in dependence on an actual selection of a group of transmission symbol positions.

10. The data communication apparatus according to claim 8 or claim 9, wherein the data communication apparatus is configured to select, as one of multiple possible section results, a case in which a reference symbol position (1844a) is located at a beginning of a selected group (1844) of transmission symbol positions.

1 1. The data communication apparatus according to claim 8 or 9 or 10, wherein the data communication apparatus is configured to select, as one of multiple possible selection results, a case in which a reference symbol position (1846a) is located at an end of a selected group (1846) of transmission symbol positions.

12. The data communication apparatus according to one of claim 8 to 1 1 , wherein the data communication apparatus is configured to select, as one of multiple possible

selection results, a case in which a reference symbol position (1845a) is located in an inner part of a selected group (1845) of transmission symbol positions.

13. The data communication apparatus according to one of claims 8 to 12, wherein the data communication apparatus is configured to select, as one of muftiple possible selection results, a case in which a reference symbol position is located both at the beginning of a selected group of transmission symbol positions and at an end of a selected group of transmission symbol positions.

14. The data communication apparatus according to one of claims 8 to 13, wherein the data communication apparatus is configured to allow for a selection between groups (1840, 1842; 1842,1843; 1844, 1845,1846) of transmission symbol positions having different lengths, and wherein the data communication apparatus is configured to allow for a selection between groups of transmission symbol positions (1844,1845,1846) having same length but different associated reference symbol positions (1844a, 1845a, 1846a).

15. The data communication apparatus according to one of claims 8 to 14, wherein the data communication apparatus is configured to select a group of transmission symbol positions with a granularity which is smaller than a length of a sub-frame or which is smaller than a length of a slot.

16. The data communication apparatus according to one of claims 8 to 15, wherein the data communication apparatus is configured to select a group of transmission symbol positions with a granularity of one transmission symbol position or with a granularity of two transmission symbol positions.

17. The data communication apparatus according to one of claims 8 to 16, wherein the data communication apparatus is configured to select a group of transmission symbol positions with a granularity such that there are multiple different groups of transmission symbol positions selectable within a sub-frame.

18. The data communication apparatus according to one of claims 8 to 17, wherein the data communication apparatus is configured to vary a relative location of the one or more reference symbol positions in the grid of transmission symbol positions with reference to the selected group of transmission symbol positions in dependence on a temporal extension of the selected group of transmission symbol positions and/or in dependence on a temporal position of the selected group of transmission symbol positions within a sub- frame, and/or in dependence on a frequency position of the selected group of

transmission symbol positions within a sub-frame .

19 The data communication apparatus according to one of claims 8 to 18,

wherein the data communication apparatus is configured to choose a symbol position at a temporal start of the selected group of transmission symbol positions or a symbol position at a temporal end of the selected group of transmission symbol positions as a reference symbol position.

20. The data communication apparatus according to one of claims 8 to 19,

wherein the data communication apparatus is configured to choose a symbol position (1940a) at which the selected group (1940) of transmission symbol positions neighbors or overlaps another group (1942) of transmission symbol portions, which is associated with another data communication apparatus, within a same sub-frame as a reference symbol position.

21. The data communication apparatus according to one of claims 8 to 20,

wherein the data communication apparatus is configured to choose a number of reference symbol positions associated with the selected group of transmission symbol positions in dependence on a location of the selected group of transmission symbol positions within a sub-frame.

22. The data communication apparatus according to claim 21 , wherein the data communication apparatus is configured to choose a number of reference symbol positions associated with the selected group of transmission symbol positions in dependence on a number of neighboring groups of transmission symbol positions within the sub-frame.

23. The data communication apparatus according to claim 21 or 22, wherein the data communication apparatus is configured to choose a number of reference symbol positions associated with the selected group of transmission symbol positions,

wherein only one reference symbol positional 0; 620) is associated with selectable groups (608;622) of transmission symbol positions neighboring a temporal border of the sub-frame, and

wherein two or more reference symbol positions (610,620) are associated with at least one selectable group (614) of transmission symbol positions which is distant from both temporal borders of the sub-frame.

24. The data communication apparatus according to one of claims 8 to 23, wherein the data communication apparatus is configured to select the group of transmission symbol positions such that a temporal extension of the selected group of transmission symbol positions is shorter than a temporal extension of a sub-frame.

25. A data communication apparatus (1900), for transmitting one or more blocks of data (1910) within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the data communication apparatus is configured to select a group of transmission symbol positions, which is a subset of the two-dimensional grid of transmission symbol positions, for a transmission of a data portion; and

wherein the data communication apparatus is configured to select a multiplexing characteristic (910; 920; 1980; 1990) of one or more reference symbols (1940a; 1942a), which are associated to the selected group (1940; 1942) of transmission symbol positions, in dependence on the selection of the group of transmission symbol positions.

26. A data communication apparatus (1900), for transmitting one or more blocks of data (1941) within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the data communication apparatus is configured to select a group (1940; 1942) of transmission symbol positions, which is a subset of the two-dimensional grid of transmission symbol positions, for a transmission of a data portion; and

wherein the data communication apparatus is configured to select a multiplexing characteristic (1980,1990) of one or more reference symbols (1940a, 1942a), which are associated to the selected group of transmission symbol positions, in dependence on a multiplexing group selection information (1962) defining a group of multiplexing characteristics, and in dependence on a multiplexing characteristic selection (1964) information defining which multiplexing characteristic out of a plurality of multiplexing characteristics contained in a group of multiplexing characteristics defined by the multiplexing group selection information should be used.

27. The data communication apparatus according to claim 26, wherein the data communication apparatus is configured to derive the multiplexing group selection information from a cell identifier of a communication cell in which the data communication apparatus is registered.

28. The data transmission apparatus according to claim 26 or 27, wherein multiplexing characteristics contained in different groups of multiplexing characteristics define orthogonal multiplexing codes or orthogonal multiplexing patterns.

29. The data communication apparatus according to one of claims 26 to 28, wherein the data communication apparatus is configured to update or receive the multiplexing characteristic selection information more frequently than the multiplexing group selection information.

30. A data communication apparatus (1900), for transmitting one or more blocks of data (1910) within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the data communication apparatus is configured to select a group of transmission symbol positions(1940, 1942), which is a subset of the two-dimensional grid of transmission symbol positions, for a transmission of a data portion; and

wherein the data communication apparatus is configured to select a multiplexing characteristic (1980,1990) of a plurality of reference symbols (1940a, 1942a), which are associated to the selected group of transmission symbol positions,

wherein the data communication apparatus is configured to select the multiplexing characteristic out of at least a first multiplexing pattern (1980) describing transmission symbol positions and a second multiplexing pattern (1990) describing transmission symbol positions,

wherein the first multiplexing pattern comprises at least one shared transmission symbol position (1982), which is also used by the second multiplexing pattern, and at least one exclusive transmission symbol position (1984) which is not used by the second

multiplexing pattern, and

wherein the second multiplexing pattern comprises the shared transmission symbol position and at least one exclusive transmission symbol position (1986) which is not used by the first multiplexing pattern.

31. The data communication apparatus according to claim 30, wherein the first multiplexing pattern comprises an alternating sequence of used exclusive transmission symbol positions and one or more non-used transmission symbol positions in between, wherein the second multiplexing pattern comprises an alternating sequence of used exclusive transmission symbol positions and one or more non-used transmission symbol positions in between,

and wherein a highest-frequency transmission symbol position and/or a lowest-frequency transmission symbol position are shared between the first multiplexing pattern and the second multiplexing pattern.

32. A data communication apparatus(2000) for receiving a plurality of data blocks (2020) from other data communication apparatuses (1700, 1800, 1900), wherein the data blocks are represented by transmission symbols of multiple groups of transmission symbol positions within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the data communication apparatus is configured to signal to the other data communication apparatuses which group of transmission symbol positions (1740;

1840,1841 , 1842, 1843,1844,1845,1846) should be used by which of the other data communication apparatuses,

wherein the data communication apparatus is configured to provide an information (2040) describing a group of transmission symbol positions to be used by a given one of the other data communication apparatuses, and an information (1711 ; DMRS_position) describing a desired relative position of reference symbol positions

(1750; 1752; 1754; 1756, 1758; 1840a, 1841 a, 1842a, 1843a, 1844a, 1845a, 1846a) with respect to the group of transmission symbol positions to be used by the given one of the other data communication apparatuses.

33. The data communication apparatus according to claim 32, wherein the data communication apparatus is configured to provide an information indicating whether a reference symbol position is at a beginning of a group of transmission symbol positions to be used by the given one of the other data communication apparatuses or at an end of a group of transmission symbol positions to be used by the given one of the other data communication apparatuses.

34. The data communication apparatus according to claim 33, wherein the information (OMRS position) indicating whether a reference symbol position is at a beginning of a group of transmission symbol positions to be used by the given one of the other data communication apparatuses or at an end of a group of transmission symbol positions to be used by the given one of the other data communication apparatuses is a 1-bit information.

35. The data communication apparatus according to claim 32, wherein the data communication apparatus is configured to provide an information indicating whether a reference symbol position is at a beginning of a group of transmission symbol positions to be used by the given one of the other data communication apparatuses or at an end of a group of transmission symbol positions to be used by the given one of the other data communication apparatuses or in an inner part of a group of transmission symbol positions to be used by the given one of the other data communication apparatuses or whether there are reference symbol positions both at a beginning and at an end of a group of transmission symbol positions to be used by the given one of the other data communication apparatuses.

36. The data communication apparatus according to claim 35, wherein the information indicating whether a reference symbol position is at a beginning of a group of transmission symbol positions to be used by the given one of the other data communication

apparatuses or at an end of a group of transmission symbol positions to be used by the given one of the other data communication apparatuses or in an inner part of a group of transmission symbol positions to be used by the given one of the other data

communication apparatuses or whether there are reference symbol positions both at a beginning and at an end of a group of transmission symbol positions to be used by the given one of the other data communication apparatuses is a 2-bit information.

37. The data communication apparatus according to one of claims 32 to 36, wherein data communication apparatus is configured to selectively provide the information describing a desired relative position of reference symbol positions with respect to the group of transmission symbol positions to be used by the given one of the other data

communication apparatuses as a 1-bit information in case the respective group of transmission symbol positions comprises 2 transmission symbol positions and as a 2-bit information in case the respective group of transmission symbol positions comprises more than 2 transmission symbol positions; or

wherein data communication apparatus is configured to selectively provide the information describing a desired relative position of reference symbol positions with respect to the group of transmission symbol positions to be used by the given one of the other data communication apparatuses as a 1-bit information or as a 2-bit information in dependence on a temporal extension of the respective group of transmission symbol positions.

38. A data communication apparatus (2000) for receiving a plurality of data blocks (2020) from other data communication apparatuses (1700,1800,1900), wherein a data block is represented by transmission symbols of a group of transmission symbol positions within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the data communication apparatus is configured to provide to the other data communication apparatuses a communication resource information (2040),

the communication resource information representing an allocation of transmission symbol positions and describing which group of transmission symbol positions should be used by which of the other data communication apparatuses and which of the

transmission symbol positions should be used for a transmission of reference symbols by which of the other data communication apparatuses,

wherein data communication apparatus is configured to signal different allocations of transmission symbol positions in dependence on a current communication state;

wherein the transmission symbol positions to be used for the transmission of reference symbols are variable with respect to borders of time slots of the frame or with respect to borders of sub-frames of the frame between different allocations of transmission symbol positions or for a given allocation of transmission symbol positions, and/or

wherein the transmission symbol positions to be used for the transmission of reference symbols are variable with respect a corresponding group of transmission symbol positions between different allocations of transmission symbol positions or for a given allocation of transmission symbol positions.

39. The data communication apparatus according to one of claims 32 to 38, wherein the data communication apparatus is configured to provide, in at least one of the possible communication states, a communication resource information which indicates that a reference symbol position is located at a beginning of a group of transmission symbol positions to be used by one of the other data communication apparatuses.

40. The data communication apparatus according to one of claims 32 to 39, wherein the data communication apparatus is configured to provide, in at least one of the possible communication states, a communication resource information which indicates that a

reference symbol position is located at an end of a group of transmission symbol positions to be used by one of the other data communication apparatuses.

41. The data communication apparatus according to one of claims 32 to 40, wherein the data communication apparatus is configured to provide, in at least one of the possible communication states, a communication resource information which indicates that a reference symbol position is located in an inner part of a group of transmission symbol positions to be used by one of the other data communication apparatuses.

42. The data communication apparatus according to one of claims 32 to 41 , wherein the data communication apparatus is configured to provide, in at least one of the possible communication states, a communication resource information which indicates that reference symbol positions are located both at the beginning and at the end of a group of transmission symbol positions to be used by one of the other data communication apparatuses.

43. The data communication apparatus according to one of claims 32 to 42, wherein the data communication apparatus is configured to allow for allocation of groups of transmission symbol positions having different lengths, and wherein the data

communication apparatus is configured to allow for an allocation of groups of transmission symbol positions having same length but different associated reference symbol positions during a single communication state and/or during different communication states.

44. A data communication apparatus (2000) for receiving a plurality of data blocks (2020) from other data communication apparatuses (1700, 1800, 1900), wherein a data block is represented by transmission symbols of a group of transmission symbol positions within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the data communication apparatus is configured to provide to the other data communication apparatuses a communication resource information (2040),

the communication resource information representing an allocation of transmission symbol positions and describing which group of transmission symbol positions should be used by which of the other data communication apparatuses and which of the

transmission symbol positions should be used for a transmission of reference symbols by which of the other data communication apparatuses,

wherein the data communication apparatus is configured to provide the communication resource information to at least two other data communication apparatuses, to cause a sharing between the at least two other data communication apparatuses of a transmission symbol positional 0;610,620;705,710,715,720;810;820;910,914) for a transmission of a reference symbol.

45. The data communication apparatus according to claim 44, wherein the data communication apparatus is configured to provide the communication resource information to at least two other data communication apparatuses, to cause a sharing of transmission symbol positions (510;710) for a transmission of reference symbols between a first other data communication device, to which a first group of transmission symbol positions is allocated, the first group of transmission symbol positions covering a first temporal range and a first frequency range,

a second data communication device, to which a second group of transmission symbol positions is allocated, the second group of transmission symbol positions covering a second temporal range and a second frequency range which partially overlaps the first frequency range, and

a third data communication device, to which a third group of transmission symbol positions is allocated, the third group of transmission symbol positions covering a third temporal range and a third frequency range which partially overlaps the first frequency range.

46. The data communication apparatus according to one of claims 44 to 45, wherein the data communication apparatus is configured to provide the communication resource information to at least two other data communication apparatuses,

to cause a first data communication apparatus, to which a comparatively shorter transmission length is associated, to share transmission symbol positions (610) for a transmission of reference symbols with only one other data communication device, and to cause a second data communication apparatus, to which a comparatively longer transmission length is associated, to share transmission symbol positions (610,620) for a transmission of reference symbols with two or more other data communication devices.

47. The data communication apparatus according to claim 46, wherein the data communication apparatus is configured to cause the second data communication apparatus to share one or more transmission symbol positions (610) at a beginning of a group of transmission signal positions associated with the second data communication apparatus, with the first data communication apparatus for a transmission of one or more reference symbols, and

/ wherein the data communication apparatus is configured to cause the second data communication apparatus to share one or more transmission symbol positions (620) at an end of a group of transmission symbol positions associated with the second data

communication apparatus, with a third data communication apparatus for a transmission of one or more reference symbols.

48. The data communication apparatus according to one of claims 44 to 47, wherein the data communication apparatus is configured to decide whether a given other data communication apparatus is instructed to share transmission symbol positions with one or more other data communication apparatuses for the transmission of one or more reference symbols in dependence on a length of a transmission interval associated to the given data transmission apparatus, and/or in dependence on a channel condition, and/or in dependence on a signal-to-noise ratio.

49. The data communication apparatus according to one of claims 44 to 48, wherein communication resource information defines an allocation of transmission symbol positions to the other data communication devices using device specific information items, or

wherein the communication resource information comprises an joint information item describing a selection of a joint allocation of transmission symbol positions to a plurality of other data transmission apparatuses out of a plurality of predefined joint allocations of transmission symbol positions.

50. The data communication apparatus according to one of claims 44 to 49, wherein the data communication apparatus is configured to provide a multiplexing characteristic selection information defining which multiplexing characteristic out of a plurality of multiplexing characteristics contained in a group of multiplexing characteristics should be used by at least one other data communication apparatus.

51. The data communication apparatus according to one of claims 44 to 50, wherein the data communication apparatus is configured provide a multiplexing characteristic selection information (1962,1964) instructing another data communication apparatus in communication with the data communication apparatus to select a multiplexing

characteristic out of at least a first multiplexing pattern describing transmission symbol positions and a second multiplexing pattern describing transmission symbol positions, wherein the first multiplexing pattern (1980) comprises at least one shared transmission symbol position, which is also used by the second multiplexing pattern, and at least one exclusive transmission symbol position which is not used by the second multiplexing pattern, and

wherein the second multiplexing pattern (1990) comprises the shared transmission symbol position and at least one exclusive transmission symbol position which is not used by the first multiplexing pattern.

52. The data communication apparatus according to claim 51 , wherein the first multiplexing pattern comprises an alternating sequence of used exclusive transmission symbol positions and one or more non-used transmission symbol positions in between, wherein the second multiplexing pattern comprises an alternating sequence of used exclusive transmission symbol positions and one or more non-used transmission symbol positions in between,

and wherein a highest-frequency transmission symbol position and/or a lowest-frequency transmission symbol position of are shared between the first multiplexing pattern and the second multiplexing pattern.

53. A data communication system, comprising:

a first data communication apparatus (1010;2000) according to one of claims 32 to 52; a second data communication apparatus (1020;2000) according to one of claims 32 to 52; a first other data communication apparatus (1030; 1700, 1800, 1900) linked with the first data communication apparatus;

a second other data communication apparatus (1030; 1700,1800,1900) linked with the second data communication apparatus;

Wherein the first other data communication apparatus is configured to choose a multiplexing characteristic of one or more reference symbols, which are associated to a selected group of transmission symbol positions associated with the first other data communication apparatus, out of a plurality of multiplexing characteristics contained in a first group of multiplexing characteristics in dependence on a multiplexing characteristic selection information^ 964) provided by the first data communication apparatus, and Wherein the second other data communication apparatus is configured to choose a multiplexing characteristic of one or more reference symbols, which are associated to a selected group of transmission symbol positions associated with the second other data communication apparatus, out of a plurality of multiplexing characteristics contained in a second group of multiplexing characteristics in dependence on a multiplexing

characteristic selection information (1964) provided by the second data communication apparatus.

54. The data communication system according to claim 53, wherein the first other data communication apparatus is configured to derive a multiplexing group selection information (1962), which is used to select the first group of multiplexing characteristics, from a cell identifier of the first data communication apparatus.

55. A method for transmitting one or more blocks of data within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the method comprises selecting a group of transmission symbol positions, which is a subset of the two-dimensional grid of transmission symbol positions, for a

transmission of a data portion; and

wherein the method comprises selecting one or more reference symbol positions (DMRS) associated to the selected group of transmission symbol positions, out of a plurality of possibilities, based on an information (DMRS_position) describing a desired relative position of the reference symbol positions with respect to the selected group of transmission symbol positions.

56. A method for transmitting one or more blocks of data within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the method comprises selecting a group of transmission symbol positions, which is a subset of the two-dimensional grid of transmission symbol positions, for a

transmission of a data portion,

wherein one or more reference symbol positions (DMRS) are associated to the selected group of transmission symbol positions;

wherein the method comprises determining which one or more symbol positions are used as one or more reference symbol positions based on the selection of the group of transmission symbol positions or together with the selection of the group of transmission symbol positions; and

wherein the reference symbol positions are variable with respect to borders of time slots of the frame or with respect to borders of sub-frames of the frame, or

wherein the one or more reference symbol positions are variable with respect to the selected group of transmission symbol positions.

57. A method for transmitting one or more blocks of data within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the method comprises selecting a group of transmission symbol positions, which is a subset of the two-dimensional grid of transmission symbol positions, for a

transmission of a data portion; and

wherein the method comprises selecting a multiplexing characteristic of one or more reference symbols, which are associated to the selected group of transmission symbol positions, in dependence on the selection of the group of transmission symbol positions.

58. A method transmitting one or more blocks of data within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the method comprises selecting a group of transmission symbol positions, which is a subset of the two-dimensional grid of transmission symbol positions, for a

transmission of a data portion; and

wherein the method comprises selecting a multiplexing characteristic of one or more reference symbols, which are associated to the selected group of transmission symbol positions, in dependence on a multiplexing group selection information defining a group of multiplexing characteristics, and in dependence on a multiplexing characteristic selection information defining which multiplexing characteristic out of a plurality of multiplexing characteristics contained in a group of multiplexing characteristics defined by the multiplexing group selection information should be used.

59. A method for transmitting one or more blocks of data within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the method comprises selecting a group of transmission symbol positions, which is a subset of the two-dimensional grid of transmission symbol positions, for a

transmission of a data portion; and

wherein the method comprises selecting a multiplexing characteristic of a plurality of reference symbols, which are associated to the selected group of transmission symbol positions,

wherein the multiplexing characteristic is selected out of at least a first multiplexing pattern describing transmission symbol positions and a second multiplexing pattern describing transmission symbol positions,

wherein the first multiplexing pattern comprises at least one shared transmission symbol position, which is also used by the second multiplexing pattern, and at least one exclusive transmission symbol position which is not used by the second multiplexing pattern, and wherein the second multiplexing pattern comprises the shared transmission symbol position and at least one exclusive transmission symbol position which is not used by the first multiplexing pattern.

60. A method receiving a plurality of data blocks from other data communication apparatuses at a data communication apparatus, wherein the data blocks are represented by transmission symbols of multiple groups of transmission symbol positions within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the method comprises signaling to the other data communication apparatuses which group of transmission symbol positions should be used by which of the other data communication apparatuses,

wherein the method comprises providing an information describing a group of

transmission symbol positions to be used by a given one of the other data communication apparatuses, and an information describing a desired relative position of reference symbol positions with respect to the group of transmission symbol positions to be used by the given one of the other data communication apparatuses.

61. A method for receiving a plurality of data blocks from other data communication apparatuses at a data communication apparatus, wherein a data block is represented by transmission symbols of a group of transmission symbol positions within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the method comprises providing to the other data communication apparatuses a communication resource information,

the communication resource information representing an allocation of transmission symbol positions and describing which group of transmission symbol positions should be used by which of the other data communication apparatuses and which of the

transmission symbol positions should be used for a transmission of reference symbols by which of the other data communication apparatuses,

wherein the method comprises signaling different allocations of transmission symbol positions in dependence on a current communication state;

wherein the transmission symbol positions to be used for the transmission of reference symbols are variable with respect to borders of time slots of the frame or with respect to borders of sub-frames of the frame between different allocations of transmission symbol positions, or

wherein the transmission symbol positions to be used for the transmission of reference symbols are variable with respect a corresponding group of transmission symbol positions between different allocations of transmission symbol positions.

62. A method for receiving a plurality of data blocks from other data communication apparatuses at a data communication apparatus, wherein a data block is represented by transmission symbols of a group of transmission symbol positions within a frame comprising a two-dimensional grid of transmission symbol positions,

wherein the method comprises providing to the other data communication apparatuses a communication resource information,

the communication resource information representing an allocation of transmission symbol positions and describing which group of transmission symbol positions should be used by which of the other data communication apparatuses and which of the

transmission symbol positions should be used for a transmission of reference symbols by which of the other data communication apparatuses,

wherein the method comprises providing the communication resource information to at least two other data communication apparatuses, to cause a sharing between the at least two other data communication apparatuses of a transmission symbol position for a transmission of a reference symbol.

63. A data communication method, for communicating between a first data communication apparatus and a first other data communication apparatus linked to the first data communication apparatus, and for communicating between a second data communication apparatus and a second other data communication apparatus linked to the second data communication apparatus, the method comprising:

at the first other data communication apparatus, choosing a multiplexing characteristic of one or more reference symbols, which are associated to a selected group of transmission symbol positions associated with the first other data communication apparatus, out of a plurality of multiplexing characteristics contained in a first group of multiplexing

characteristics in dependence on a multiplexing characteristic selection information provided by the first data communication apparatus, and

at the second other data communication apparatus, choosing a multiplexing characteristic of one or more reference symbols, which are associated to a selected group of

transmission symbol positions associated with the second other data communication apparatus, out of a plurality of multiplexing characteristics contained in a second group of multiplexing characteristics in dependence on a multiplexing characteristic selection information provided by the second data communication apparatus,

wherein multiplexing characteristics contained in different groups of multiplexing

characteristics define orthogonal multiplexing codes or orthogonal multiplexing patterns.

64. A computer program for performing the method according to one of claims 56 to 64 when the computer program runs on a computer.