FIELD OF THE INVENTION
[0001]
The non-limiting and exemplary embodiments of the present disclosure generally relate to the field of wireless communication techniques, and more particularly relate to a method, device and computer readable medium for slot format configuration in a wireless communication system.
BACKGROUND OF THE INVENTION
[0002]
This section introduces aspects that may facilitate better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
[0003]
New radio access system, which is also called as NR system or NR network, is the next generation communication system. In Radio Access Network (RAN) #71 meeting for the third generation Partnership Project (3GPP) working group, study of the NR system was approved. The NR system will consider frequency ranging up to 100Ghz with an object of a single technical framework addressing all usage scenarios, requirements and deployment scenarios defined in Technical Report TR 38.913, which includes requirements such as enhanced mobile broadband, massive machine-type communications, and ultra-reliable and low latency communications.
[0004]
Amongst other, the NR system is desired to support wireless backhaul and relay links enabling flexible and very dense deployment of NR cells without the need for densifying the transport network proportionately. The larger bandwidth available for the NR system along with the native deployment of Massive Multiple Input and Multiple Output (MIMO) or multi-beam systems in the NR system creates an opportunity to develop integrated access and backhaul links. Example networks with such IAB links are shown in Figs. 1A and 1B. As illustrated in Fig. la, a relay device 120 called as IAB-node is arranged between user equipment (UE) 130-2 and a base station 110 (called as an IAB-donor) . The link between UE 130-2 and the IAB-node 120 is called as an access link including downlink (DL) access link and uplink (UL) access link, and the link between the IAB-node 120 and the IAB-donor 110 is called as backhaul links, including DL backhaul link and UL backhaul link. In the example network as illustrated in Fig. lb, the IAB-node 220 is located between a parent node 210 (for example, an IAB-donor) and a child node 240 (for example, another IAB-node) . The link between the IAB-node 220 and the IAB-donor 210 is called as parent backhaul links, including DL parent backhaul link and UL parent backhaul link, and the link between the IAB-node 220 and the child node 240 is called as child backhaul links including UL child backhaul link and DL child backhaul link. Within such a network, the relay nodes could multiplex access and backhaul links in time, frequency, or space (e.g. beam-based operation) .
[0005]
In 3GPP RAN1 #94 meeting, IAB timing was agreed for at least case 1, wherein DL transmission timing is aligned across IAB-nodes and the IAB-donor nodes. In this meeting, it was also agreed to further study indication of resources within the configuration which can be dynamically and flexibly used for different links, including:
[0006]
·Considering the scheduling delay, IAB node processing delay, or information required to be available for use of flexible resources
[0007]
·Mechanisms to schedule flexible resources (e.g. GC-PDCCH)
[0008]
SUMMARY OF THE INVENTION
[0009]
In general, example embodiments of the present disclosure provide a new solution for slot format configuration in a wireless communication system.
[0010]
According to a first aspect of the present disclosure, there is provided a method for slot format configuration in a wireless communication system. The method may be implemented at a first network device like an IAB-donor or a parent node. The method may include transmitting link configuration information indicating a configuration for access and backhaul links for a time period and transmitting slot format configuration information indicating one or more slot formats for at least one of the access and backhaul links to be used in the configuration for access and backhaul links for the time period.
[0011]
According to a second aspect of the present disclosure, there is provided a method for receiving slot format configuration in a wireless communication system. The method may be implemented at a second network device such as an IAB-node. The method may include receiving link configuration information indicating a configuration for access and backhaul links for a time period and receiving slot format configuration information indicating one or more slot formats for at least one of the access and backhaul links to be used in the configuration for access and backhaul links for the time period.
[0012]
According to a third aspect of the present disclosure, there is provided a first network device. The first network device may be an IAB-donor or a parent node. The first network device may comprise at least one processor and at least one memory coupled with the at least one processor. The at least one memory has computer program codes stored therein which are configured to, when executed on the at least one processor, cause the first network device to perform operations of the first aspect.
[0013]
According to a fourth aspect of the present disclosure, there is provided a second network device. The second network device may be for example an IAB-node. The second device may comprise at least one processor and at least one memory coupled with the at least one processor. The at least one memory has computer program codes stored therein which are configured to, when executed on the at least one processor, cause the second network device to perform operations of the second aspect.
[0014]
According to a fifth aspect of the present disclosure, there is provided a computer-readable storage medium having a computer program stored thereon which, when executed by at least one processor of a device, causes the device to perform actions in the method according to any embodiment in the first aspect.
[0015]
According to a sixth aspect of the present disclosure, there is provided a computer-readable storage medium having a computer program stored thereon which, when executed by at least one processor of a device, causes the device to perform actions in the method according to any embodiment in the second aspect.
[0016]
According to a seventh aspect of the present disclosure, there is provided a computer program product comprising a computer-readable storage medium according to the fifth aspect.
[0017]
According to an eighth aspect of the present disclosure, there is provided a computer program product comprising a computer-readable storage medium according to the sixth aspect.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018]
The above and other aspects, features, and benefits of various embodiments of the present disclosure will become more fully apparent from the following detailed description with reference to the accompanying drawings, in which like reference signs are used to designate like or equivalent elements. The drawings are illustrated for facilitating better understanding of the embodiments of the disclosure and are not necessarily drawn to scale, in which:
[0019]
Figs. 1A and 1B illustrates example networks with IAB links;
[0020]
Fig. 2 illustrates slot formats for normal cyclic prefix in the NR system;
[0021]
Figs. 3A and 3B schematically illustrate a slot-level resource allocation between backhaul and access links in the prior art;
[0022]
Fig. 4 schematically illustrates a flow chart of a method for slot format configuration at a first network device (for example at an IAB-donor or a parent node) in a wireless communication system according to some embodiments of the present disclosure;
[0023]
Fig. 5 schematically illustrates a set of link configurations in form of bitmaps according to some embodiments of the present disclosure;
[0024]
Fig. 6 schematically illustrates activated link configurations according to some embodiment of the present disclosure;
[0025]
Fig. 7 schematically illustrates an example slot format configuration for an activated link configuration according to some embodiments of the present disclosure;
[0026]
Fig. 8 schematically illustrates example slot format configurations for switching between access and backhaul links according to some embodiments of the present disclosure;
[0027]
Fig. 9 schematically illustrates another example slot format configurations for switching between access and backhaul links according to some embodiments of the present disclosure;
[0028]
Fig. 10 schematically illustrates example forms of slot format configurations for switching between access and backhaul links according to some embodiments of the present disclosure;
[0029]
Fig. 11 schematically illustrates further example slot format configurations for switching between access and backhaul links according to some embodiments of the present disclosure;
[0030]
Fig. 12 schematically illustrates example diagram of slot format configuration with two guard periods of 0.5F at a starting symbol and an ending symbol of a slot according to some embodiments of the present disclosure;
[0031]
Fig. 13 schematically illustrates another example forms of slot format configurations for switching between access and backhaul links according to some embodiments of the present disclosure;
[0032]
Fig. 14 schematically illustrates serval transmission cases in which guard period may be set within any of the access link slot or backhaul link slot according to some embodiments of the present disclosure;
[0033]
Fig. 15 schematically illustrates example guard period setting for transmission cases illustrated in Fig. 14 according to some embodiments of the present disclosure;
[0034]
Fig. 16 schematically illustrates example slot format configurations for transmission cases illustrated in Fig. 14 according to some embodiments of the present disclosure;
[0035]
Fig. 17A schematically illustrates example switching cases in Frequency Division Duplex (FDD) system according to some embodiments of the present disclosure;
[0036]
Fig. 17B schematically illustrates example switching cases and guard period setting in FDD system according to some embodiments of the present disclosure;
[0037]
Fig. 17C schematically illustrates example slot format configurations for switching between access and backhaul links in FDD system according to some embodiments of the present disclosure;
[0038]
Figs. 18A and 18B schematically illustrates switching cases in Time Division Duplex (TDD) system according to some embodiments of the present disclosure;
[0039]
Figs. 19A and 19B schematically illustrate transmission scenarios corresponding to those cases as illustrated in Figs. 18A and 18B according to some embodiments of the present disclosure, wherein DL transmissions are aligned across IAB nodes and IAB-donor nodes;
[0040]
Figs. 20A and 20B schematically illustrate transmission scenarios corresponding to those cases as illustrated in Figs. 18A and 18B according to some embodiments of the present disclosure, wherein DL transmission and UL transmission are aligned at an IAB node;
[0041]
Figs. 21A and 21B schematically illustrate transmission scenarios corresponding to those cases as illustrated in Figs. 18A and 18B according to some embodiments of the present disclosure, wherein DL reception and UL reception are aligned at an IAB node;
[0042]
Figs. 22A and 22B schematically illustrate transmission scenarios corresponding to those cases as illustrated in Figs. 18A and 18B according to some embodiments of the present disclosure, wherein DL transmission and UL transmission are aligned at an IAB node during transmitting and DL reception and UL reception are aligned at an IAB node during receiving;
[0043]
Figs. 23A and 23B schematically illustrate transmission scenarios corresponding to those cases as illustrated in Figs. 18A and 18B according to some embodiments of the present disclosure, wherein DL transmission and UL transmission are aligned at an IAB node and UL and DL transmission are aligned at an IAB node;
[0044]
Figs. 24A and 24B schematically illustrate transmission scenarios corresponding to those cases as illustrated in Figs. 18A and 18B according to some embodiments of the present disclosure, wherein DL transmissions are aligned across IAB nodes and IAB-donor nodes and DL reception and UL reception are aligned at an IAB node;
[0045]
Fig. 25 schematically illustrates a flow chart of a method for receiving slot format indication at a second network node (for example IAB-node) according to some embodiments of the present disclosure;
[0046]
Fig. 26 schematically illustrates a block diagram of an apparatus for uplink resource mapping in a wireless communication system according to some embodiments of the present disclosure;
[0047]
Fig. 27 schematically illustrates a block diagram of an apparatus 2700 for receiving slot format configuration according to some embodiments of the present disclosure; and
[0048]
Fig. 28 schematically illustrates a simplified block diagram of an apparatus 2810 that may be embodied as or comprised in a first network device like an IAB-donor or a parent node, and an apparatus 2820 that may be embodied as or comprised in a second network device like IAB-node as a relay as described herein.
[0049]
DETAILED DESCRIPTION OF EMBODIMENTS
[0050]
Hereinafter, the solutions as provided in the present disclosure will be described in details through embodiments with reference to the accompanying drawings. It should be appreciated that these embodiments are presented only to enable those skilled in the art to better understand and implement the present disclosure, not intended to limit the scope of the present disclosure in any manner. For example, features illustrated or described as part of one embodiment may be used with another embodiment to yield still a further embodiment. In the interest of clarity, not all features of an actual implementation are described in this specification.
[0051]
In the accompanying drawings, various embodiments of the present disclosure are illustrated in block diagrams, flow charts and other diagrams. Each block in the flowcharts or blocks may represent a module, a program, or a part of code, which contains one or more executable instructions for performing specified logic functions, and in the present disclosure, a dispensable block is illustrated in a dotted line. Besides, although these blocks are illustrated in particular sequences for performing the steps of the methods, as a matter of fact, they may not necessarily be performed strictly according to the illustrated sequence. For example, they might be performed in reverse sequence or simultaneously, which is dependent on natures of respective operations. It should also be noted that block diagrams and/or each block in the flowcharts and a combination of thereof may be implemented by a dedicated hardware-based system for performing specified functions/operations or by a combination of dedicated hardware and computer instructions.
[0052]
References in the specification to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
[0053]
It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.
[0054]
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be liming of example embodiments. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.
[0055]
As used herein, the term “wireless communication network” refers to a network following any suitable wireless communication standards, such as New Radio (NR) , Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , and so on. The “wireless communication network” may also be referred to as a “wireless communication system. ” Furthermore, communications between network devices, between a network device and a terminal device, or between terminal devices in the wireless communication network may be performed according to any suitable communication protocol, including, but not limited to, Global System for Mobile Communications (GSM) , Universal Mobile Telecommunications System (UMTS) , Long Term Evolution (LTE) , New Radio (NR) , wireless local area network (WLAN) standards, such as the IEEE 802.11 standards, and/or any other appropriate wireless communication standard either currently known or to be developed in the future.
[0056]
As used herein, the term “network device” refers to a node in a wireless communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP) , for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a NR NB (also referred to as a gNB) , a Remote Radio Unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology.
[0057]
The term “terminal device” refers to any end device that may be capable of wireless communications. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE) , a Subscriber Station (SS) , a Portable Subscriber Station, a Mobile Station (MS) , or an Access Terminal (AT) . The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA) , portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , USB dongles, smart devices, wireless customer-premises equipment (CPE) and the like. In the following description, the terms “terminal device” , “communication device” , “terminal” , “user equipment” and “UE” may be used interchangeably.
[0058]
As yet another example, in an Internet of Things (IOT) scenario, a terminal device may represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another terminal device and/or network equipment. The terminal device may in this case be a machine-to-machine (M2M) device, which may in a 3GPP context be referred to as a machine-type communication (MTC) device. As one particular example, the terminal device may be a UE implementing the 3GPP narrow band internet of things (NB-IoT) standard. Examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances, for example refrigerators, televisions, personal wearables such as watches etc. In other scenarios, a terminal device may represent a vehicle or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation.
[0059]
As used herein, a downlink (DL) transmission refers to a transmission from a network device to UE, or from a network device as a parent node to another network device as a child node, and an uplink (UL) transmission refers to a transmission in an opposite direction.
[0060]
As mentioned above, the IAB technology was already introduced into the NR system. With the introduction of the IAB technology, switching between the access link and the backhaul link will occur at the IAB node. In the existing LTE system, the subframe configuration is fixed and thus one symbol can be punctured to use as a guard period. However, in the NR system, the slot format is rather flexible and it is more desirable to configure a flexible guard period.
[0061]
Only for illustrative purposes, Fig. 2 illustrates example slot formats for normal cyclic prefix in the NR system. As illustrated in Fig. 2, there are 56 different formats (Formats 0 to 55) and the UE may also determine the slot format for the slot based on TDD-UL-DL-Configuration common parameter, or TDD-UL-DL-ConfigDedicated parameter, and based on, if any, detected DCI formats. Particularly, most of Formats 0 to 55 have one or more flexible symbols (indicated as “F” in Fig. 2) , in addition to uplink and the downlink symbols (indicated as “U” and “D” respectively) . Thus, due to the flexibility in slot formats, the switching scheme in the LTE system does not apply the NR system. For extended cyclic prefix, there are flexible slot formats analogous to those for normal cyclic prefix case.
[0062]
In 3GPP technical document R1-1808580, titled “Resource allocation between backhaul and access links, ” there is proposed a resource allocation for NR IAB system on a slot level. For illustrative purposes, Figs. 3A and 3B illustrate fixed and dynamic backhaul and access resource allocations as proposed in this document, which “1a” indicates the access link between UE and BS, “1b” means the backhaul link between the BS as an IAB-donor and an IAB-node, and “2a” means the access link between the IAB-node and UE.
[0063]
In the fixed backhaul and access resource allocation as illustrated in 3A, the resource allocation is fixed without any flexibility, wherein a slot is either a DL slot or an UL slot, and the access link 2a and the backhaul link 1b are allocated with resource alternatively and transmissions cannot be performed on the two links simultaneously. Amongst others, in the dynamic backhaul and access resource allocation as illustrated in 3B, in addition to some fixed slots, there are also some flexible slots indicated as “F” , which may an UL slot or D1 slot. In the proposed resource allocation solution, resource is allocated at the slot level, which means the slot is either a DL or a UL slot.
[0064]
However, in the NR system, more flexible slot formats are used, wherein many slot formats contain any of downlink, uplink or flexible symbols within a slot. In addition, the introduction of flexible slots in the proposed dynamic backhaul and access resource allocation causes some cases in which the IAB-node does not have any prior information about adjacent slots either. Thus, in such a case, the switching remains an issue.
[0065]
Embodiments of the present disclosure provide a new solution for slot format configuration in a wireless communication to mitigate or at least alleviate at least one of the above problems. In embodiments of the present disclosure, a first network device transmit link configuration information to a second network device to indicate a configuration for access and backhaul links for a time period and the first network device may further transmit slot format configuration information to the second network device to indicate one or more slot formats for at least one of the access and backhaul links to be used in the configuration for access and backhaul links for the time period. Therefore, with embodiments of the present disclosure, resources for access and backhaul links are first indicated and then a slot format configuration is used to indicate the link configuration within these links (for example for the backhaul links) . In such a way, it could achieve a slot-level link resource allocation for access and backhaul links while supporting flexible slot formats within respective links.
[0066]
It shall be appreciated that in the present disclosure, especially in embodiments disclosed herein and also in the appended claims, backhaul link and access link are associated with an IAB node as a relay. In particular, the backhaul link refers to the link between the IAB node and IAB-donor or its parent IAB node, and the access link refers to the link between the IAB node and its child IAB node or UE. Especially, for the network topology as illustrated in Fig. 1B, the UL and DL parent backhaul links belong to the backhaul links while the DL and UL child backhaul links belong to the access links.
[0067]
It shall also be appreciated that in the present disclosure, especially in embodiments disclosed herein and also in the appended claims, the first network device and the second network device refers to network devices associated with IAB technology. The first networks may be IAB-node or a parent node and the second network device may be IAB-node as a relay.
[0068]
Hereinafter, reference will be further made to accompanying drawings to describe the solutions as proposed in the present disclosure in details. However, it shall be appreciated that the following embodiments are given only for illustrative purposes and the present disclosure is not limited thereto. It shall be also appreciated that slot format configuration for backhaul link will be taken as an example to describe the solution as proposed herein with reference to embodiments of the present disclosure. However, it is also possible to, additionally or alternatively, use the solution as proposed herein to indicate the slot format for the access link.
[0069]
Fig. 4 schematically illustrates a flow chart of a method for slot format configuration in a wireless communication system according to some embodiments of the present disclosure. The method 400 can be implemented at a first network device. The first network device could be an IAB-donor for the network topology as illustrated in Fig. 1A, a parent node (IAB-donor or another relay node) for the network topology as illustrated in Fig. 1B or any other network device.
[0070]
As illustrated in Fig. 4, in step 410, the first network device may transmit link configuration information to indicate a configuration for access and backhaul links for a time period. The link configuration means resource allocation pattern for access and backhaul links for the time period. For example, the link configuration may indicate that each slot among all the slots in a time period of lms is configured for an access link or a backhaul link. In other words, the link configuration can have a slot-level granularity and lms adaptation period. The link configuration information is used to indicate the link configuration to the IAB-node for example the one functioning as a relay
[0071]
The link configuration information can be in a form of for example bitmap associated with the time period. For example, “0” in the bitmap indicates a slot for the access link, “1” in the bitmap indicates a slot for the backhaul link and vice versa. In some embodiments of the present disclosure, link configuration information in form of bitmap may be transmitted to the second network device like IAB-node to indicate the link configuration for access and backhaul link to be used during the time period.
[0072]
Periodic backhaul or access link can be supported by the link configuration. For example, if only one “1” is contained in the bitmap, it means that one backhaul link transmission per the time period is configured. By setting more equally spaced “1” or “0” in the bitmap, the smaller periodic backhaul or access link can be configured.
[0073]
In some embodiments of the present disclosure, the link configuration information can be informed to the second network device in two-layer signaling. For example, the link configuration may be indicated to the IAB-node as a relay by means of two signaling. First, a link configuration set indication can be transmitted to the second network device to indicate a set of available configurations for the access and backhaul links for a time period. Then, a link configuration activation indication may be further transmitted to the second network device to activate or change one of the set of available configurations for the time period. In this way, the link configuration can be adapted to different demands of traffic loads between access and backhaul links during different time periods. Hereinafter, reference will be made to Figs. 5 to 6 to describe an example implementation of link configuration indication according to some embodiments of the present disclosure.
[0074]
Fig. 5 illustrates a set of link configurations in form of bitmaps configured by Radio Resource Control signaling according to some embodiments of the present disclosure. As illustrated in Fig. 5, a set of link configurations are configured by RRC signaling, which includes a plurality of link configurations, link configuration 1 and link configuration 2. In the link configuration, “0” indicates a slot for an access link, and “1” indicates a slot for a backhaul link. For the above two link configurations in the set of link configurations, a MAC-CE can be further used to activate one of the link configurations so as to activate a link configuration to change the current link configuration, as indicated in Fig. 6. In such a way, the second network device could know the current link configuration, for example, which slot is an access link or which slot is a backhaul link.
[0075]
Reference is further made back to Fig. 4, in step 420, the first network device may further transmit slot format configuration information to indicate one or more slot formats for at least one of the access and backhaul links to be used in the configuration for access and backhaul links for the time period. The slot format used herein denotes configuration for uplink and downlink for symbols within a slot. Only for illustrative purposes, some examples of slot formats could be found in Fig. 2. The slot format can be configured dynamically or semi-dynamically. For example, the slot format can be configured by means of downlink control channel. Group common physical downlink control channel (GC-PDCCH) is a robust control channel on which information could be transmitted accurately, and thus GC-PDCCH could be used to carry the slot format configuration information.
[0076]
As illustrated in Fig. 7, SFI carried on GC-PDCCH indicates SF1, SF2, and SF3, which may indicate slot formats to be respectively used in the backhaul slot in the activated link configuration, configuration 1. It shall be appreciated that although Fig. 7 illustrates slot format for the backhaul links, it is also alternatively or additionally to indicate the slot formats for the access link. In some embodiments of the present disclosure, the slot formats SF1, SF2 and SF3 can be identical to each other; in some other embodiments of the present disclosure, at least some of SF1, SF2 and SF3 are different from others of SF1, SF2 and SF3.
[0077]
In such a way, the first network device could inform the second network device of the slot format used in respective links so that they could perform data transmission/reception based on the link configuration and the indicated slot format. Thus, it is possible to allocate the resource link resource at the slot level by means of link configuration information and also support the flexible slot formats with the slot format configuration information.
[0078]
In addition, to ensure switching between the backhaul link and the access link, a guard period may be set for, for example, a slot format for a backhaul link, For example, the first network device may configure the backhaul link with some specific slot formats.
[0079]
Fig. 8 schematically illustrates example slot formats which can be used for backhaul links according to embodiments of the present disclosure, wherein G1 and G2 denote guard periods, “U” denotes an uplink symbol, “D” denotes a downlink symbol and “X” can be either a “U” , “D” or “F” symbol as in NR. As illustrated in Fig. 8, guard periods can be set at both starting symbol and ending symbol of a slot, wherein G1 and G2 may have same time length or different time length. By means of the slot formats, the switching can be performed smoothly while access link could be scheduled freely without considering the switching between access link and backhaul link. The guard period G1 or G2 each may have a fixed time length, for example, 20us. Or alternatively, the guard period G1 or G2 may have a variable time length. The time length may be dependent on subcarrier spacing (SCS) of OFDM system. For example, for SCS=15KHz, G could be 1 OFDM symbol configured as “F” in the backhaul link; for SCS =30KHz, G could be 1 to 2 OFDM symbol configured as “F” in the backhaul link; for SCS=15*2 u KHz, G could be 1 to 2 u OFDM symbol configured as “F” in backhaul link, wherein F means a flexible OFDM symbol as defined in NR.
[0080]
In some embodiments of the present disclosure, G1 have the same time length as G2. Fig. 9 schematically illustrates another example slot format configurations for switching between access and backhaul links according to some embodiments of the present disclosure. As illustrated in Fig. 9, these example slot formats can be used for backhaul link, wherein G denotes guard periods, “U” denotes an uplink symbol, “D” denotes a downlink symbol and “X” denotes “U” , “D” or “F” . The guard period G may have a fixed time length; for example, G could be 1 OFDM symbol, e.g., configured as “F” . Or alternatively, the guard period G may have a variable time length. Similarly, the guard period G may be dependent on subcarrier spacing. For example, for SCS=15KHz, G could be 1 OFDM symbol configured as “F” in the backhaul link; for SCS =30KHz, G could be 1 to 2 OFDM symbol configured as “F” in the backhaul link; for SCS=15*2 uKHz, G could be 1 to 2 u OFDM symbol configured as “F” in backhaul link, wherein F means a flexible OFDM symbol as defined in NR. Fig. 10 illustrates example forms of slot format configurations for switching between access and backhaul links according to some embodiments of the present disclosure, wherein the guard period G could be 1F, 2F, 3F, or 4F.
[0081]
In some embodiments of the present disclosure, the guard period only occupies a part of symbol instead of one or more symbols. For example, G could be 0.5F as illustrated in Fig. 11. In such a case, 13 symbols are totally remaining for data transmission, as illustrated in Fig. 12.
[0082]
In some embodiments of the present disclosure, G1 and G2 have different time lengths. In such a base, the slot formats could have example forms as illustrated in Fig. 13, wherein G1 might occupy flexible symbol one more than G2. It shall be appreciated that it is also possible that G1 occupies flexible symbols less than G2.
[0083]
For the slot formats as illustrated in Fig. 8, guard periods are set at both starting and ending symbol of a slot for backhaul link and in such a case the preceding and following access link could be scheduled freely without considering the transmission direction of the first or last symbol of the backhaul link. In some embodiments of the present disclosure, the guard period could also be arranged at starting symbols or ending symbols within a slot.
[0084]
Fig. 14 illustrates example transmission cases in which a guard period can be set within any of the access link slot or backhaul link slot As illustrated in Fig. 14, for the first group of cases, in both TDD and FDD modes, it involves switching between the reception and transmission at the second network device like IAB-node, which means RF switching; for the second group of cases, it involves switching either from transmission towards UE to transmission towards BS, or switching from reception from BS to reception from UE, which might cause cross-link interference (CLI) in TDD mode; for the third group of cases, it involves either from reception from UE to reception from BS or from transmission towards BS to transmission towards UE, which might require beam or panel switching (and thus cause a panel or beam switching delay) . In these cases, it requires a guard period for RF switching, CLI protection, or panel or beam switching delay.
[0085]
For the cases as illustrated in Fig. 14, the guard period could be set at the last symbol of the preceding slot n-1 or at the first symbol of the following slot, as illustrated in Fig. 15. Fig. 16 further illustrates example slot formats which can be used for these cases wherein G1 and G2 denote guard periods, “U” denotes an uplink symbol, “D” denotes a downlink symbol and “X” denotes a “U” , “D” or “F” symbol. Similarly the guard period G1 or G2 each may have a fixed time length. Or alternatively, the guard period G1 or G2 may have a variable time length. The time length may be dependent on subcarrier spacing. For example, for SCS=15KHz, G could be 1 OFDM symbol configured as “F” in the backhaul link; for SCS =30KHz, G could be 1 to 2 OFDM symbol configured as “F” in the backhaul link; for SCS=15*2 u KHz, G could be 1 to 2 u OFDM symbol configured as “F” in backhaul link, wherein F means a flexible OFDM symbol as defined in NR..
[0086]
Figs. 17A to 17C illustrate an example solution for the slot format in FDD mode according some embodiments of the present disclosure. In the FDD mode, the access and backhaul uplinks share a radio frequency and the access and backhaul downlinks share another radio frequency. Thus, guard periods are required only during switching between access and backhaul uplinks or between access and backhaul downlinks.
[0087]
Fig. 17A schematically illustrates four scenarios requiring guard periods in the slot format. The first one is switching when the access link (AL) ending symbol is for transmission “T” at the IAB-node and the backhaul link (BH) starting symbol is for reception “R” at the IAB-node. The second one is switching when the BH ending symbol is for reception “R” at the IAB-node and the AL starting symbol is for transmission “T” at the IAB-node. The third one is switching when the AL ending symbol is for reception “R” at the IAB-node and the BH starting symbol is for transmission “T” at the IAB-node. The fourth one is switching when the BH ending symbol is for transmission “T” at the IAB-node and the AL starting symbol is for reception “R” at the IAB-node.

We Claims:

[Claim 1]
A method for slot format configuration, comprising: at a network device, transmitting link configuration information indicating a configuration for access and backhaul links for a time period; and transmitting slot format configuration information indicating one or more slot formats for at least one of the access and backlinks to be used in the configuration for access and backhaul links for the time period.
[Claim 2]
The method of Claim 1, wherein the transmitting link configuration information further comprises: transmitting a link configuration set indication indicating a set of available configurations for the access and backhaul links for the time period; and transmitting a link configuration activation indication to activate one of the set of available configurations.
[Claim 3]
The method of Claim 2, wherein the link configuration set indication is transmitted by a radio resource control signaling, and/or wherein the link configuration activation indication is transmitted in a Media Access Control-Control Element (MAC-CE) , and/or wherein the slot format configuration information is transmitted on a downlink control channel.
[Claim 4]
The method of any of Claims 1 to 3, wherein the slot format comprises a guard period at any of: a starting symbol within a slot; an ending symbol within a slot; and both the starting symbol and the ending symbol within a slot.
[Claim 5]
The method of Claim 4, wherein the guard period has a fixed time length.
[Claim 6]
The method of Claim 4, wherein the number of symbols for the guard period is dependent on subcarrier spacing.
[Claim 7]
The method of Claim 4, wherein the guard period has a time length dependent on a timing alignment mode of link transmission.
[Claim 8]
The method of any of Claims 4 to 7, wherein guard periods at the staring symbol and at the ending symbol have different time lengths.
[Claim 9]
The method of any of Claims 1 to 8, wherein the slot format configuration information indicates one or more slot formats for one or more backhaul links in the configuration for access and backhaul links for the time period.
[Claim 10]
A method for receiving slot format configuration, comprising: at a second network device, receiving link configuration information indicating a configuration for access and backhaul links for a time period; and receiving slot format configuration information indicating one or more slot formats for at least one of the access and backlinks to be used in the configuration for access and backhaul links for the time period.
[Claim 11]
The method of Claim 10, wherein the receiving link configuration information further comprises: receiving a link configuration set indication indicating a set of available configurations for the access and backhaul links for the time period; and receiving a link configuration activation indication activating one of the set of available configurations.
[Claim 12]
The method of Claim 11, wherein the link configuration set indication is received in a radio resource control signaling, and/or wherein the link configuration activation indication is received in a Media Access Control-Control Element (MAC-CE) , and/or wherein the slot format configuration information is received on a downlink control channel.
[Claim 13]
The method of any of Claims 10 to 12, wherein the slot format comprises a guard period at any of: a starting symbol within a slot; an ending symbol within a slot; and both the starting symbol and the ending symbol within a slot.
[Claim 14]
The method of Claim 13, wherein the guard period has a fixed time length.
[Claim 15]
The method of Claim 13, wherein the number of symbols for the guard period is dependent on subcarrier spacing.
[Claim 16]
The method of Claim 13, wherein the guard period has a time length dependent on a timing alignment mode of link transmission.
[Claim 17]
The method of any of Claims 13 to 16, wherein guard periods at the staring symbol and at the ending symbol have different time lengths.
[Claim 18]
The method of any of Claims 10 to 17, wherein the slot format configuration information indicates one or more slot formats for one or more backhaul links in the configuration for access and backhaul links for the time period.
[Claim 19]
A network device, comprising: at least one processor; and at least one memory coupled with the at least one processor; the at least one memory having computer program codes therein which are configured to, when executed on the at least one processor, cause the network device at least to perform the method of any of Claims 1-9.
[Claim 20]
A network device, comprising: at least one processor; and at least one memory coupled with the at least one processor; the at least one memory having computer program codes therein which are configured to, when executed on the at least one processor, cause the network device at least to perform the method of any of Claims 10-18.
[Claim 21]
A computer readable medium having a computer program stored thereon which, when executed by at least one processor of a device, causes the device to perform the method of any of Claims 1-9.
[Claim 22]
A computer readable medium having a computer program stored thereon which, when executed by at least one processor of a device, causes the device to perform the method of any of Claims 10-18.