METHOD AND APPARATUS FOR PERFORMING
FRACTIONAL SUBFRAME TRANSMISSION
FIELD OF THE INVENTION
[0001] Embodiments of the present invention generally relate to communication
techniques. More particularly, embodiments of the present invention relate to a
method and apparatus for performing fractional subframe transmission.
BACKGROUND OF THE INVENTION
[0002] In 3rd Generation Partnership Project (3GPP), the network structure and various
technologies needed for a terminal's movement between a 3GPP wireless
communication network and a Wireless Local Area Network (WLAN) network are
called interworking WLAN. The multi-mode wireless communication technology has
evolved to use multiple wireless communication technologies at the same time. The
use of multiple wireless communication technologies simultaneously thereby increases
transfer rates per unit time or improves the reliability of the terminal.
[0003] In wireless communication, spectrum is very rare resource. A licensed band
represents a frequency band that is exclusively licensed to a specific operator to provide
specific wireless services. On the other hand, an unlicensed band represents a
frequency band that is not allocated to a specific operator, but is opened so that all
entities meeting the predefined requirements may use the frequency band.
[0004] In some regions in the world, unlicensed band technologies need to abide to
certain regulations, for example, Listen-Before-Talk (LBT), and channel bandwidth
occupancy requirements. LBT results in an uncertainty of channel availability. For
instance, an unlicensed band may be available at any time during a subframe.
[0005] WLAN that uses Wireless Fidelity (WiFi) is the typical wireless communication
technology used in the unlicensed band. Time granularity of current Long Term
Evolution (LTE) is much larger than that of WiFi, which leads to the low competitive
strength of License Assisted Access (LAA) with LBT As such, fair coexistence
between LTE and other technologies such as WiFi as well as between LTE operators is
expected. In order to be more competitive in the unlicensed band, fractional subframe
transmission may be performed.
[0006] The fractional subframe transmission may use at least one fractional subframe.
Since merely a portion of symbols of a factional subframe are available for data
transmission, the end of the fractional subframe transmission may be uncertain.
However, for both a transmitter and a receiver, the end of the fractional subframe
transmission is an important factor for perform the fractional subframe transmission
efficiently. Therefore, there is a need to estimate the end of the fractional subframe
transmission.
SUMMARY OF THE INVENTION
[0007] The present invention proposes a solution regarding fractional subframe
transmission. Specifically, the present invention provides a method and apparatus for
estimate the end of the fractional subframe transmission.
[0008] According to a first aspect of embodiments of the present invention,
embodiments of the invention provide a method for performing fractional subframe
transmission. The method may comprise: determining first temporal information that
indicates when a channel becomes available; and determining, based on the first
temporal information and transmission opportunity information, second temporal
information that indicates an end of the fractional subframe transmission. The method
may be performed at a transmitter or a receiver.
[0009] According to a second aspect of embodiments of the present invention,
embodiments of the invention provide an apparatus for performing fractional subframe
transmission. The apparatus may comprise: a first determining unit configured to
determine first temporal information that indicates when a channel becomes available;
and a second determining unit configured to determine, based on the first temporal
information and transmission opportunity information, second temporal information that
indicates an end of the fractional subframe transmission. The apparatus may be
implemented at a transmitter or a receiver.
[0010] Other features and advantages of the embodiments of the present invention will
also be apparent from the following description of specific embodiments when read in
conjunction with the accompanying drawings, which illustrate, by way of example, the
principles of embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Embodiments of the invention are presented in the sense of examples and their
advantages are explained in greater detail below, with reference to the accompanying
drawings, where
[0012] FIG. 1 illustrates a flow chart of a method 100 for performing fractional
subframe transmission according to an embodiment of the invention;
[0013] FIG. 2 illustrates a flow chart of a method 200 for performing fractional
subframe transmission at a transmitter according to an embodiment of the invention;
[0014] FIG. 3 illustrates a flow chart of a method 300 for performing fractional
subframe transmission at a receiver according to an embodiment of the invention;
[0015] FIG. 4 illustrates a schematic diagram 400 of fractional subframe transmission
according to embodiments of the invention;
[0016] FIG. 5 illustrates a schematic diagram 500 of fractional subframe transmission
according to embodiments of the invention;
[0017] FIG. 6 illustrates a schematic diagram 600 of fractional subframe transmission
according to embodiments of the invention; and
[0018] FIG. 7 illustrates a block diagram of an apparatus 710 of a transmitter and an
apparatus 720 of a receiver for performing fractional subframe transmission according
to embodiments of the invention.
[0019] Throughout the figures, same or similar reference numbers indicate same or
similar elements.
DETAILED DESCRIPTION OF EMBODIMENTS
[0020] The subject matter described herein will now be discussed with reference to
several example embodiments. It should be understood these embodiments are
discussed only for the purpose of enabling those skilled persons in the art to better
understand and thus implement the subject matter described herein, rather than
suggesting any limitations on the scope of the subject matter.
[0021] The terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting 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," "includes" and/or "including,"
when used herein, specify the presence of stated features, integers, steps, operations,
elements and/or components, but do not preclude the presence or addition of one or
more other features, integers, steps, operations, elements, components and/or groups
thereof.
[0022] It should also be noted that in some alternative implementations, the
functions/acts noted may occur out of the order noted in the figures. For example, two
functions or acts shown in succession may in fact be executed concurrently or may
sometimes be executed in the reverse order, depending upon the functionality/acts
involved.
[0023] Embodiments of the present invention are directed to a solution for performing
fractional subframe transmission. The solution may be carried out between a receiver
and a transmitter. In particular, the transmitter may determine first temporal
information that indicates when a channel becomes available and determine second
temporal information that indicates an end of the fractional subframe transmission based
on the first temporal information and transmission opportunity information. The
receiver may determine the second temporal information in a similar way. As such,
both the transmitter and the receiver may determine the end of the fractional subframe
transmission without introducing signalling overhead.
[0024] In embodiments of the present invention, a fractional subframe may refer to a
subframe for downlink transmission or a subframe for uplink transmission, wherein one
part of the fractional subframe is used for transmission of control information or data
and the other part is not used for the transmission. For example, for a subframe
comprising 14 symbols, if only the last 6 symbols are used for transmission while the
first 8 symbols are not used for the transmission, this subframe may be considered as a
factional subframe. For another example, if the first 7 symbols of a subframe are used
for transmission while the remaining symbols of the subframe are not used for the
transmission, this subframe may be considered as a factional subframe as well.
[0025] In the disclosure, the fractional subframe transmission may refer to the
transmission performed on one or more subframes, and at least one of the one or more
subframes is a fractional subframe. By way of example, the fractional subframe
transmission may comprise various cases, such as the first subframe being a fractional
subframe, the last subframe being a fractional subframe, both the first and the last
subframes being fractional subframes, and the like.
[0026] In some embodiments, the fractional subframe transmission may be downlink or
uplink cellular transmission. In downlink transmission, the receiver may comprise
user equipment (UE), such as a terminal, a Mobile Terminal (MT), a Subscriber Station
(SS), a Portable Subscriber Station (PSS), Mobile Station (MS), or an Access Terminal
(AT). Meanwhile, the transmitter may comprise a base station (BS), such as a node B
(NodeB or NB), or an evolved NodeB (eNodeB or eNB). In uplink transmission, the
transmitter may comprise a UE and the receiver may comprise a BS.
[0027] According to some other embodiments of the present invention, the fractional
subframe transmission may be D2D transmission. In this regard, the receiver may be a
Device-to-Device (D2D) receiver and the transmitter may be a D2D transmitter.
[0028] Embodiments of the present invention may be applied in various communication
systems, including but not limited to a Long Term Evolution (LTE) system or a Long
Term Evolution Advanced (LTE-A) system. Given the rapid development in
communications, there will of course also be future type wireless communication
technologies and systems with which the present invention may be embodied. It
should not be seen as limiting the scope of the invention to only the aforementioned
system.
[0029] Now some exemplary embodiments of the present invention will be described
below with reference to the figures. Reference is first made to FIG. 1, which illustrates
a flow chart of a method 100 for performing fractional subframe transmission at a
transmitter according to an embodiment of the invention. The method 100 may be
performed at a transmitter and other suitable device. Alternatively, the method 100
may be performed at a receiver and other suitable device.
[0030] The method 100 starts at step SI 10, in which first temporal information is
determined, wherein the first temporal information indicates when a channel becomes
available.
[0031] In context of the disclosure, a subframe may comprise a plurality of symbols.
By way of example, a subframe may be 1 ms and comprise 14 symbols, for example,
symbols 0 to 13. A position, such as a potential position, a target position, a current
position, a next position, may refer to a time point or a time period in the subframe. In
some embodiments, a position may correspond to an instant in a subframe. As an
alternative, a position may correspond to a symbol of a subframe. In this regard, the
position may occupy a time period, for example, the time period of a symbol. A target
position may refer to a position from which the fractional transmission may start, and a
potential position may refer to a predefined position that is a candidate of the target
position.
[0032] There may be one or more potential positions predefined in a subframe. Each
of the potential positions may correspond to a symbol of the subframe periodically or
aperiodically. In some embodiments, the potential positions may comprise every three
symbols, for example, symbols 0, 3, 6, 9 and 12. For instance, the potential positions
may be set at
mod (N, Nd) = x ( [0,Nd-l]), (1)
where N represents the index of a symbol in a subframe, and Nd represents the interval
between two potential positions and may be an integer ranged from 1 to the total
number of symbols in the subframe, for example 14. According to equation (1), it may
be determined that the smaller the Nd is, the denser the potential positions are. In
some embodiments, each symbol in a subframe may be predefined as a potential
position.
[0033] It is to be noted that the above examples are illustrated for example, rather than
limitation. It can be appreciated that, in alternative embodiments, there may be
aperiodic configurations of the potential positions. For instance, the potential positions
may correspond to the symbols 0, 3, 8 and .
[0034] Clear Chanel Assessment (CCA) or Extended Clear Chanel Assessment (eCCA)
may be performed, for example by the transmitter, to detect whether a channel is
available. In response to detecting that the channel becomes available, whether a
current position is a potential position may be detected. If the current position is a
potential position, the current position may be determined as the target position;
otherwise, a channel occupation signal may be transmitted from the current position
until a potential position, and this potential position may be determined as the target
position. In some embodiments, this potential position may be a potential position
immediately following the current position. For example, if the current position
corresponds to symbol 5, and there are three predefined potential positions
corresponding to symbols 0, 7 and 11, it may be determined that the potential position
corresponding to symbol 7 is a potential position immediately following the current
position and may be determined as the target position.
[0035] According to embodiments of the present invention, the fractional subframe
transmission may be symbol-level transmission. In other words, the fractional
subframe transmission may be ended at any symbol of a subframe. In this case, it is
possible that the last subframe of the fractional subframe transmission is a fractional
subframe. The first temporal information may be determined in several ways. In
some embodiments, whether the channel becomes available at a symbol of a first
subframe may be determined. In response to determining that the channel becomes
available, the first temporal information may be determined as comprising an index of
the symbol. Alternatively, in some embodiments, in response to determining that the
channel becomes available, the first temporal information may be determined as
comprising a potential position predefined in the first subframe, wherein the potential
position is immediately prior to the symbol. Details will be described with reference
to FIGs. 2 and 3.
[0036] Alternatively, the fractional subframe transmission may be subframe-level
transmission. In this case, the fractional subframe transmission may be ended at a
complete subframe. In other words, the last subframe of the fractional subframe
transmission is a complete subframe, instead of a fractional subframe. According to
embodiments of the present invention, at step SI 10, a first subframe at which the
channel becomes available may be determined. Then, the first temporal information
may be determined as comprising an index of the first subframe.
[0037] In some embodiments, step S110 may be performed by the transmitter. In this
case, the first subframe may be determined based on CCA/eCCA performed by the
transmitter. In particular, when the transmitter detect a channel becomes available at a
subframe, this subframe may be determined as the first subframe.
[0038] In some other embodiments, step SI 10 may be performed by the receiver. In
an exemplary embodiment, the transmitter may notify the first temporal information, for
example, by sending an indicator regarding the first temporal information to the receiver.
In this way, the index of the first subframe at which a channel becomes available may
be indicated explicitly. Thus, at step SI 10, the receiver may determine the first
temporal information by detecting the indicator. In an alternative embodiment, the
transmitter may not send the indicator, and the receiver may make blind decoding for
control information of the fractional subframe transmission at a potential position. In
response to that the blind decoding is success, the receiver may determine the index of
the first subframe of the fractional subframe transmission.
[0039] At step SI20, second temporal information that indicates an end of the fractional
subframe transmission may be determined based on the first temporal information and
transmission opportunity information.
[0040] According to embodiments of the present invention, the transmission
opportunity information may include channel occupancy time, for example, maximum
channel occupancy time, average channel occupancy time, and so on. The
transmission opportunity information may be determined based on regulations or other
possible aspects. Additionally or alternatively, the transmission opportunity
information may be configured by higher layer signalling or may be preset as being
fixed.
[0041] In some embodiments where the symbol-level transmission is performed, at step
SI20, a number of symbols used by the fractional subframe transmission may be
determined based on the transmission opportunity information. Then, a number of end
symbols may be determined based on the first temporal information and the number of
symbols used by the fractional subframe transmission, wherein the end symbols are
used by the fractional subframe transmission and belong to a last subframe of the
fractional subframe transmission. Details will be described with reference to FIGs. 2
and 3.
[0042] Alternatively, in some embodiments where the subframe-level transmission is
performed, at step SI20, an index of a last subframe used by the fractional subframe
transmission may be determined based on the first temporal information and
transmission opportunity information.
[0043] In an exemplary embodiment, the index of the last subframe may be determined
as follows:
Ne=Nl +floor (TXOP) -1 (2)
where Nl represents the index of the first subframe, Ne represents the index of the last
subframe, TXOP represents the channel occupancy time in millisecond (i.e., ms), and
floorQ indicates an operation of rounding down.
[0044] FIG. 6 illustrates a schematic diagram 600 of subframe-level fractional subframe
transmission according to embodiments of the invention. As shown in FIG. 6, there
are 4 subframes, i.e., subframes 0 to 3. With respect to subframe 0, there are two
potential positions 621 and 622, wherein the first potential position 621 corresponds to
the start of subframe 0. CCA/eCCA may start from the first potential position 621 , and
the potential position 622 may be determined as the target position. The factional
subframe transmission then may start from the target position and ends at the end of
subframe 2. Thus, the real channel occupation time, which indicates the actual time
period occupied by the fractional subframe transmission, may correspond to a time
period from the positions 622 to 623. Assuming that TXOP is 3ms and corresponds to
a time period from the position 622 to the position 624, it may be determined that the
actual channel occupation time is from the position 622 to the position 623 and a time
period from the position 623 to the position 624 is not occupied. In the embodiments
of FIG. 6, since the first subframe is subframe 0, the index of the first subframe is 0.
Thus, according to equation (2), it may be determined that the index of the last subframe
Ne is 0+3-1=2. In other words, the last subframe may be determined as subframe 2.
[0045] According to embodiments of the present invention, optionally, if the
symbol-level transmission is performed, the method 100 may further comprise a step of
comparing the number of end symbols with a predetermined threshold. Responsive to
that the number of end symbols is less than or equal to a predetermined threshold, the
last subframe may be released. In an alternative embodiment, responsive to that the
number of end symbols is less than or equal to a predeteraiined threshold, the end
symbols may be combined with a subframe immediately prior to the last subframe. In
the disclosure, the combination of the end symbols and the subframe immediately prior
to the last subframe may be referred as to a "super subframe". According to
embodiments of the present invention, the predetermined threshold may be set as a
fixed value, for example, 3 or a value that is changed dynamically. It is to be
understood that the above example embodiments are only for the purpose of illustration,
without suggesting any limitations on the subject matter described herein. The
predetermined threshold may be implemented in any other suitable ways.
[0046] According to embodiments of the present invention, optionally, if the transmitter
performs the method 100, the transmitter may determine a transport block size based on
the number of end symbols and transmit data of the transport block size in the last
subframe. Details may be described with reference to FIG. 2.
[0047] According to embodiments of the present invention, optionally, if the receiver
performs the method 100, the receiver may determine a transport block size based on
the number of end symbols and receive data of the transport block size in the last
subframe. Details may be described with reference to FIG. 3.
[0048] Reference is now made to FIG. 2, which illustrates a flow chart of a method 200
for performing fractional subframe transmission at a transmitter according to an
embodiment of the invention. The method 200 may be considered as a specific
implementation of the method 100 described above with reference to Fig. 1 and
performed by the transmitter. However, it is noted that this is only for the purpose of
illustrating the principles of the present invention, rather than limiting the scope thereof.
[0049] Method 200 begins at step S210, a symbol of a first subframe at which the
channel becomes available is determined.
[0050] According to embodiments of the present invention, whether a channel is
available may be determined in several ways, such as energy detection, carrier sensing,
and so on. In some embodiments, strength of energy from a further transmitter may be
measured on the channel. The further transmitter may be a transmitter that may use
the same channel and is different from the transmitter performing the method according
to embodiments of the present invention. If the energy strength is not strong, it may be
determined that the channel is idle. In this regard, the energy strength may be
compared with a strength threshold. In response to that the measured strength is less
than the strength threshold, the channel may be determined as being available. The
strength threshold may be a predetermined threshold, which may be set according to
system requirements, specifications, channel quality, and so on. According to
embodiments of the present invention, the strength threshold may be set as a fixed value
or a value that is changed dynamically. It is to be understood that the above example
embodiments are only for the purpose of illustration, without suggesting any limitations
on the subject matter described herein. The strength threshold may be implemented in
any other suitable ways.
[0051] Alternatively, the channel availability may be detected based on carrier sensing.
By way of example, a signalling from a further transmitter may be detected on the
channel. The further transmitter may be a transmitter that may use the channel and is
different from the transmitter performing the method according to embodiments of the
present invention. Based on the signalling, whether the channel is available may be
determined. When the transmitter detect a channel becomes available at a symbol, the
subframe comprising the symbol may be determined as the first subframe.
[0052] It is to be noted although the above embodiments illustrate a further transmitter,
there may be a plurality of further transmitters in a communication system according to
embodiments of the present invention. In such embodiments, energy detection and
carrier sensing may be performed with respect to the plurality of further transmitters.
[0053] At step S220, the first temporal information is determined as comprising a
potential position immediately prior to the symbol, wherein the potential position is
predefined in the first subframe.
[0054] In an exemplary embodiment, if the symbol determined at step S210 is symbol 5,
and there are three predefined potential positions corresponding to symbols 0, 7 and 11,
respectively, the transmitter may determine that the potential position corresponding to
symbol 0 is a potential position immediately prior to the current position. As such, at
step S220, the first temporal information may comprise the potential position
corresponding to symbol 0.
[0055] It is to be noted that, in some alternative embodiments, the first temporal
information may be determined as comprising an index of the symbol determined at
step S210. By way of example, if the symbol detemiined at step S210 is symbol 5, the
first temporal information may be determined as comprising an index of symbol 5. As
can be appreciated by those skilled in the art, the first temporal information may
comprise an index of the symbol determined at step S210, a potential position
immediately prior to the symbol, or any symbol between the symbol determined at step
S 10 and the potential position immediately prior to the symbol. The above example
embodiments are only for the purpose of illustration, without suggesting any limitations
on the subj ect matter described herein.
[0056] At step S230, the number of symbols used by the fractional subframe
transmission is determined based on the transmission opportunity information.
[0057] In some embodiments, the transmission opportunity information may comprise
channel occupancy time. In an exemplary embodiment, the channel occupancy time
may be 3.5 ms, for example. For a subframe of 1ms which includes M symbols, for
example M=14, it may be determined that 1 symbol may occupy about 0.071 ms. In
view of the length of the channel occupancy time and the symbol, for example, by
means of dividing the channel occupancy time by 0.071, the transmitter may determine
that the number of symbols used by the fractional subframe transmission as 49.
[0058] At step S240, the number of end symbols is determined based on the first
temporal information and the number of symbols used by the fractional subframe
transmission, wherein the end symbols are used by the fractional subframe transmission
and belong to a last subframe of the fractional subframe transmission.
[0059] As discussed above, the first temporal infonnation may comprise the potential
position immediately prior to the symbol detemiined at step S210. In some
embodiments, the last symbol of the fractional subframe transmission may be
determined as follows:
Se = SI + TXOP (3)
where SI represents the potential position immediately prior to the symbol determined
at step S210, Se represents the index of the last symbol, and TXOP represents the
channel occupancy time (for example, how many symbols).
[0060] In an exemplary embodiment, SI is the first symbol (i.e., symbol 0) of the first
subframe and TXOP is 49 symbols. Thus, the last symbol may be determined as the
49th symbol of the fractional subframe transmission. If a subframe comprises M
symbols, for example M=14, it may be determined that the fractional subframe
transmission occupy 4 subframes, wherein the first three subframes are fully occupied
and the first seven symbols (symbol 0 to 6) of the last subframe are occupied.
According to embodiments of the present invention, the first seven symbols (symbol 0
to 6) of the last subframe may be determined as ending symbols. Accordingly, at step
S240, it may be determined that the number of the ending symbols is 7.
[0061] At step S250, a transport block size is determined based on the number of end
symbols.
[0062] The transport block size indicates the size of a data block to be transmitted in the
fractional subframe transmission. According to embodiments of the present invention,
the transport block size may be determined in various ways. In some embodiments,
the end symbols of the last subframe may be considered as available symbols of a
fractional subframe. The transmitter may determine a scaling factor associated with
the number of the available symbols, and then determine the transport block size based
on the scaling factor. The scaling factor may be defined in several ways. Table 1
illustrates an example of scaling factors associated with different numbers of available
symbols.
Table 1
[0063] In some embodiments, if the number of the available symbols is 1, 2 or 3, the
transmitter may use the available symbols to transmit control information of the
fractional subframe transmission, and may determine that the available symbols are not
enough for transmitting data after the transmission of the control information. In this
regard, the scaling factor may be designed as a value of "N/A", which indicates that the
scaling factor is "not available". In an exemplary embodiment, if the number of the
available symbols is 4, the transmitter may determine that the associated scaling factor
is 0.25. In an exemplary embodiment, if the number of the available symbols is 5, the
transmitter may determine that the associated scaling factor is 0.25 or 0.375. In an
exemplary embodiment, if the number of the available symbols is 6, the transmitter may
determine that the associated scaling factor is 0.375. In an exemplary embodiment, if
the number of the available symbols is 7, the transmitter may determine that the
associated scaling factor is 0.375 or 0.5. In an exemplary embodiment, if the number
of the available symbols is 8, the transmitter may determine that the associated scaling
factor is 0.5 or 0.75. In an exemplary embodiment, if the number of the available
symbols is 9, 10, 11 or 12, the transmitter may determine that the associated scaling
factor is 0.75. In an exemplary embodiment, if the number of the available symbols is
13 or 14, the transmitter may determine that the associated scaling factor is 1.
[0064] In some embodiments, the transport block size may be determined based on the
scaling factor in several ways. By way of example, a first resource block number
which indicates a number of resource blocks allocated for transmission may be obtained.
For the transmitter, the first resource block number may be determined by the
transmitter in real time. Then, a second resource block number may be determined
based on the first resource block number and the scaling factor. In an exemplary
embodiment, the second resource block number may be determined as follows:
NPRB =max NpRB Factor , l
wherein N ' B represents the first resource block number, NPR represents the second
resource block number, Factor represents the scaling factor.
[0065] Based on the second resource block number, the transport block size may be
determined. In some embodiments, a transport block size table may be used for
determining the transport block size. Table 2 illustrates an exemplary transport block
size table.
Table 2
[0066] The horizontal direction of Table 2 may correspond to a resource block number,
for example, the second resource block number in the embodiments, and the vertical
direction may correspond to a Modulation and Coding Scheme (MCS). In the
embodiments, when the transmitter determines the second resource block number as
well as the MCS that is employed currently, it may determine the transport block size by
looking up the Table 2 based on the second resource block number and the MCS. By
way of example, if the second resource block number is 8, and the MCS is 8 the
transport block size may be determined as 1096.
[0067J It is to be noted that although the dimension of Table 2 is 10 X 27, it is
simplification of 3GPP TS36.213 whose dimension is 34X 110. It is further to be
noted that the above example table is only for the purpose of illustration, without
suggesting any limitations on the subject matter described herein. Any other suitable
table may be used in the determination of the transport block size.
[0068] At step S260, data of the transport block size is transmitted in the last subframe.
[0069] In some embodiments, the transmitter may transmit other possible information,
such as Reference Signal (RS), Primary Synchronous Signal (PSS), Secondary
Synchronous Signal (SSS), and so on in data region of the factional subframe
transmission, for example, Physical Downlink Shared Channel (PDSCH), if necessary.
[0070] Reference is now made to FIG. 3, which illustrates a flow chart of a method 300
for performing fractional subframe transmission at a receiver according to an
embodiment of the invention. The method 300 may be considered as a specific
implementation of the method 100 described above with reference to Fig. 1 and
performed by the receiver. However, it is noted that this is only for the purpose of
illustrating the principles of the present invention, rather than limiting the scope thereof.
[0071] Method 300 begins at step S3 10, a symbol of a first subframe at which the
channel becomes available is determined.
[0072] In some embodiments, the transmitter may notify the receiver the first temporal
information, for example, the index of the symbol of the first subframe at which a
channel becomes available. In an exemplary embodiment, the transmitter may send an
indicator regarding the first temporal information to the receiver. In this way, the
index of the symbol of the first subframe may be indicated explicitly. Thus, at step
S 10, the receiver may determine the symbol of the first subframe by detecting the
indicator. In an alternative embodiment, the transmitter may not send the indicator,
and the receiver may make blind decoding for control information of the fractional
subframe transmission at a potential position. In response to that the blind decoding is
success, the receiver may determine the symbol of a first subframe at which the channel
becomes available.
[0073] At step S320, the first temporal information is determined as comprising a
potential position immediately prior to the symbol, wherein the potential position is
predefined in the first subframe.
[0074] In an exemplary embodiment, if the symbol determined at step S320 is symbol 5,
and there are three predefined potential positions corresponding to symbols 0, 7 and 11,
respectively, the receiver may determine the potential position corresponding to symbol
0 is a potential position immediately prior to the current position. As such, at step
S320, the first temporal information may comprise the potential position corresponding
to symbol 0.
[0075] It is to be noted that, in some alternative embodiments, the first temporal
information may be determined as comprising an index of the symbol determined at
step S320. By way of example, if the symbol determined at step S320 is symbol 5, the
first temporal information may be determined as comprising an index of symbol 5. As
can be appreciated by those skilled in the art, the first temporal information may
comprise an index of the symbol determined at step S320, a potential position
immediately prior to the symbol, or any symbol between the symbol determined at step
S320 and the potential position immediately prior to the symbol. The above example
embodiments are only for the purpose of illustration, without suggesting any limitations
on the subject matter described herein.
[0076] At step S330, the number of symbols used by the fractional subframe
transmission is determined based on the transmission opportunity information.
[0077] In some embodiments, the transmission opportunity information may comprise
channel occupancy time. In an exemplary embodiment, the channel occupancy time
may be 3.5 ms, for example. For a subframe of 1ms which includes M symbols, for
example M=14, it may be determined that 1 symbol may occupy about 0.071 ms. In
view of the length of the channel occupancy time and the symbol, for example, by
means of dividing the channel occupancy time by 0.071, the receiver may determine
that the number of symbols used by the fractional subframe transmission as 49.
[0078] At step S340, the number of end symbols is determined based on the first
temporal information and the number of symbols used by the fractional subframe
transmission, wherein the end symbols are used by the fractional subframe transmission
and belong to a last subframe of the fractional subframe transmission.
[0079] As discussed above, the first temporal infomiation may comprise the potential
position immediately prior to the symbol detemiined at step S3 10. In some
embodiments, the receiver may determine the last symbol of the fractional subframe
transmission according to equation (3), for example.
[0080] At step S350, a transport block size is determined based on the number of end
symbols.
[0081] The transport block size indicates the size of a data block to be transmitted in the
fractional subframe transmission. According to embodiments of the present invention,
the transport block size may be determined in various ways. In some embodiments,
the end symbols of the last subframe may be considered as available symbols of a
fractional subframe. The receiver may determine a scaling factor associated with the
number of the available symbols, and then determine the transport block size based on
the scaling factor. The scaling factor may be defined in several ways. As discussed
above, Table 1 illustrates an example of scaling factors associated with different
numbers of available symbols.
[0082] In an exemplary embodiment, if the number of the available symbols is 4, the
receiver may determine that the associated scaling factor is 0.25. In an exemplary
embodiment, if the number of the available symbols is 5, the receiver may determine
that the associated scaling factor is 0.25 or 0.375. In an exemplary embodiment, if the
number of the available symbols is 6, the receiver may determine that the associated
scaling factor is 0.375. In an exemplary embodiment, if the number of the available
symbols is 7, the receiver may determine that the associated scaling factor is 0.375 or
0.5. In an exemplary embodiment, if the number of the available symbols is 8, the
receiver may determine that the associated scaling factor is 0.5 or 0.75. In an
exemplary embodiment, if the number of the available symbols is 9, 10, 11 or 12, the
receiver may determine that the associated scaling factor is 0.75. In an exemplary
embodiment, if the number of the available symbols is 13 or 14, the receiver may
determine that the associated scaling factor is 1.
[0083] In some embodiments, the transport block size may be determined based on the
scaling factor in several ways. By way of example, a first resource block number
which indicates a number of resource blocks allocated for transmission may be obtained.
For the receiver, the first resource block number may be notified by the transmitter.
Then, a second resource block number may be determined based on the first resource
block number and the scaling factor. In an exemplary embodiment, the second
resource block number may be determined according to equation (4). Based on the
second resource block number, the transport block size may be determined. In some
embodiments, a transport block size table, for example Table 2, may be used for
determining the transport block size. In particular, if the receiver determines the
second resource block number as well as the MCS which is employed currently, it may
determine the transport block size by looking up the Table 2.
[0084] At step S360, data of the transport block size is received in the last subframe.
[0085] In some embodiments, the receiver may receive other possible information, such
as Reference Signal (RS), Primary Synchronous Signal (PSS), Secondary Synchronous
Signal (SSS), and so on in data region of the factional subframe transmission, for
example, Physical Downlink Shared Channel (PDSCH), if necessary.
[0086] FIG. 4 illustrates a schematic diagram 400 of fractional subframe transmission
according to embodiments of the invention. FIG. 4 exemplarily shows four subframes,
subframes 0 to 3. With respect to subframe 0, there are three potential positions 421,
422 and 423, wherein the first potential position 421 corresponds to the start of
subframe 0, for example, symbol 0 of subframe 0. CCA/eCCA 401 may start from the
first potential position 421. During the CCA/eCCA 401, the transmitter may
determine that the channel is available at a position 424. Since the position 424 is not
a potential position, the transmitter may transmit channel occupation signals from the
position 424 until a potential position, for example, the potential position 422, and
determine the potential position 422 as the target position. The factional subframe
transmission then may start from the target position, wherein control information may
be transmitted on Physical Downlink Control Channel (PDCCH) at time periods 403,
405, 407 and 409, and data may be transmitted on PDSCH at time periods 404, 406, 408
and 410. As shown, the factional subframe transmission ends at a position 425.
[0087] As shown in FIG. 4, the symbol of a first subframe at which the channel
becomes available may be determined as a symbol corresponding to the position 424.
Since the potential position immediately prior to the determined symbol is the potential
position 421, it may be determined that the channel occupation time starts at the
potential position 421. Assuming the transmission opportunity information comprises
TXOP of 3.5 ms, it may be determined that the number of symbols used by the
fractional subframe transmission is 49. As illustrated by FIG. 5, the TXOP
corresponds to a time period from the position 421 to the position 425, and the actual
channel occupation time is from the position 424 to the position 425. Thus, a time
period from the position 421 to the position 424 is not occupied. Then, based on the
potential position 421 and the number of symbols used by the fractional subframe
transmission, the end symbols may be determined as the first seven symbols of
subframe 3, and the number of the end symbols is 7. In this way, the end of the
fractional subframe transmission can be estimated.
[0088] According to embodiments of the present invention, optionally, the method 200
or 300 may further comprise a step of comparing the number of end symbols with a
predetermined threshold. Responsive to that the number of end symbols is less than or
equal to a predetermined threshold, the last subframe may be released. In an
alternative embodiment, responsive to that the number of end symbols is less than or
equal to a predetermined threshold, the end symbols may be combined with a subframe
immediately prior to the last subframe as a super subframe. The super subframe is
exemplarily shown in FIG. 5, which illustrates a schematic diagram 500 of fractional
subframe transmission according to embodiments of the invention. As shown in FIG.
5, there are four subframes, subframe 0 to 3. Since the number of end symbols of the
last subframe (subframe 3) is less than the predetermined threshold, for example, 3, the
end symbols may be combined with subframe 2 as a super subframe. As shown, the
super subframe may correspond to a time period from the start of subframe 2 501 to the
last one of the end symbols 502.
[0089] FIG. 7 illustrates a block diagram of an apparatus 710 of a transmitter and an
apparatus 720 of a receiver for performing fractional subframe transmission according
to embodiments of the invention. As shown in FIG. 7, the apparatus 710 may transmit
data in a fractional subframe to the apparatus 720. According to embodiments of the
present invention, the apparatus 710 may be implemented in the transmitter or may be
coupled with the transmitter in any suitable way. Similarly, the apparatus 720 may be
implemented in the receiver or may be coupled with the receiver in any suitable way.
[0090] As shown, the apparatus 710 comprises: a first determining unit 711 configured
to determine first temporal information that indicates when a channel becomes available;
and a second determining unit 712 configured to determine, based on the first temporal
information and transmission opportunity information, second temporal information that
indicates an end of the fractional subframe transmission.
[0091] According to embodiments of the present invention, the first determining unit
7 1 may comprise: a first symbol determining unit configured to determine a symbol of
a first subframe at which the channel becomes available; and a first information
determining unit configured to determine detemiining the first temporal information as
comprising an index of the symbol.
[0092] According to embodiments of the present invention, the first determining unit
711 may comprise: a second symbol determining unit configured to determine a symbol
of a first subframe at which the channel becomes available; and a second information
determining unit configured to determine the first temporal information as comprising a
potential position immediately prior to the symbol, wherein the potential position is
predefined in the first subframe.
[0093] According to embodiments of the present invention, the second determining unit
712 may comprise: a first number determining unit configured to determine a number of
symbols used by the fractional subframe transmission based on the transmission
opportunity information; and a second number determining unit configured to determine
a number of end symbols based on the first temporal information and the number of
symbols used by the fractional subframe transmission, wherein the end symbols are
used by the fractional subframe transmission and belong to a last subframe of the
fractional subframe transmission.
[0094] According to embodiments of the present invention, the apparatus 710 may
further comprise a comparing unit configured to compare the number of end symbols
with a predetermined threshold; and a processing unit configured to, responsive to that
the number of end symbols is less than or equal to a predetermined threshold, release
the last subframe, or combine the end symbols with a subframe immediately prior to the
last subframe.
[0095] According to embodiments of the present invention, the apparatus 710 may
further comprise a first size determining unit configured to determine a transport block
size based on the number of end symbols; and a transmitting unit configured to transmit
data of the transport block size in the last subframe.
[0096] According to embodiments of the present invention, the first determining unit
711 may comprise: a first subframe determining unit configured to determine a first
subframe at which the channel becomes available; and a third information determining
unit configured to determine the first temporal information as comprising an index of
the first subframe.
[0097] According to embodiments of the present invention, the second determining unit
712 may comprise: a last subframe determining unit configured to determine, based on
the first temporal information and transmission opportunity information, an index of a
last subframe used by the fractional subframe transmission.
[0098] As shown, the apparatus 720 comprises: a first determining unit 721 configured
to determine first temporal information that indicates when a channel becomes available;
and a second determining unit 722 configured to determine, based on the first temporal
information and transmission opportunity information, second temporal information that
indicates an end of the fractional subframe transmission.
[0099] According to embodiments of the present invention, the first determining unit
721 may comprise: a first symbol determining unit configured to determine a symbol of
a first subframe at which the channel becomes available; and a first information
determining unit configured to determine determining the first temporal information as
comprising an index of the symbol.
[00100] According to embodiments of the present invention, the first determining unit
721 may comprise: a second symbol determining unit configured to determine a symbol
of a first subframe at which the channel becomes available; and a second information
determining unit configured to determine the first temporal information as comprising a
potential position immediately prior to the symbol, wherein the potential position is
predefined in the first subframe.
[00101] According to embodiments of the present invention, the second determining
unit 722 may comprise: a first number determining unit configured to determine a
number of symbols used by the fractional subframe transmission based on the
transmission opportunity information; and a second number determining unit configured
to determine a number of end symbols based on the first temporal information and the
number of symbols used by the fractional subframe transmission, wherein the end
symbols are used by the fractional subframe transmission and belong to a last subframe
of the fractional subframe transmission.
[00102] According to embodiments of the present invention, the apparatus 720 may
further comprise a comparing unit configured to compare the number of end symbols
with a predetermined threshold; and a processing unit configured to, responsive to that
the number of end symbols is less than or equal to a predetermined threshold, release
the last subframe, or combine the end symbols with a subframe immediately prior to the
last subframe.
[00103] According to embodiments of the present invention, the apparatus 720 may
further comprise a first size determining unit configured to determine a transport block
size based on the number of end symbols; and a receiving unit configured to receive
data of the transport block size in the last subframe.
[00104] According to embodiments of the present invention, the first determining unit
721 may comprise: a first subframe determining unit configured to determine a first
subframe at which the channel becomes available; and a third information determining
unit configured to determine the first temporal information as comprising an index of
the first subframe.
[00105] According to embodiments of the present invention, the second determining
unit 722 may comprise: a last subframe determining unit configured to determine, based
on the first temporal information and transmission opportunity information, an index of
a last subframe used by the fractional subframe transmission.
[00106] It is also to be noted that the apparatuses 710 and 720 may be respectively
implemented by any suitable technique either known at present or developed in the
future. Further, a single device shown in FIG. 7 may be alternatively implemented in
multiple devices separately, and multiple separated devices may be implemented in a
single device. The scope of the present invention is not limited in these regards.
[00107] It is noted that the apparatus 710 may be configured to implement
functionalities as described with reference to FIGs. 1 and 2, and the apparatus 720 may
be configured to implement functionalities as described with reference to FIGs. 1 or 3.
Therefore, the features discussed with respect to the method 100 or 200 may apply to
the corresponding components of the apparatus 710, and the features discussed with
respect to the method 100 or 300 may apply to the corresponding components of the
apparatus 720. It is further noted that the components of the apparatus 710 or the
apparatus 720 may be embodied in hardware, software, firmware, and/or any
combination thereof. For example, the components of the apparatus 710 or the
apparatus 720 may be respectively implemented by a circuit, a processor or any other
appropriate device. Those skilled in the art will appreciate that the aforesaid examples
are only for illustration not limitation.
[00108] In some embodiment of the present disclosure, the apparatus 710 or the
apparatus 720 may comprise at least one processor. The at least one processor suitable
for use with embodiments of the present disclosure may include, by way of example,
both general and special purpose processors already known or developed in the future.
The apparatus 710 or the apparatus 720 may further comprise at least one memory.
The at least one memory may include, for example, semiconductor memory devices,
e.g., RAM, ROM, EPROM, EEPROM, and flash memory devices. The at least one
memory may be used to store program of computer executable instructions. The
program can be written in any high-level and/or low-level compilable or interpretable
programming languages. In accordance with embodiments, the computer executable
instructions may be configured, with the at least one processor, to cause the apparatus
710 to at least perform according to the method 100 or 200 as discussed above, or to
cause the apparatus 720 to at least perform according to the method 100 or 300 as
discussed above.
[00109] Based on the above description, the skilled in the art would appreciate that the
present disclosure may be embodied in an apparatus, a method, or a computer program
product. In general, the various exemplary embodiments may be implemented in
hardware or special purpose circuits, software, logic or any combination thereof. For
example, some aspects may be implemented in hardware, while other aspects may be
implemented in firmware or software which may be executed by a controller,
microprocessor or other computing device, although the disclosure is not limited thereto.
While various aspects of the exemplary embodiments of this disclosure may be
illustrated and described as block diagrams, flowcharts, or using some other pictorial
representation, it is well understood that these blocks, apparatus, systems, techniques or
methods described herein may be implemented in, as non-limiting examples, hardware,
software, firmware, special purpose circuits or logic, general purpose hardware or
controller or other computing devices, or some combination thereof.
[00110] The various blocks shown in FIGs. 1-3 may be viewed as method steps, and/or
as operations that result from operation of computer program code, and/or as a plurality
of coupled logic circuit elements constructed to carry out the associated function(s).
At least some aspects of the exemplary embodiments of the disclosures may be
practiced in various components such as integrated circuit chips and modules, and that
the exemplary embodiments of this disclosure may be realized in an apparatus that is
embodied as an integrated circuit, FPGA or ASIC that is configurable to operate in
accordance with the exemplary embodiments of the present disclosure.
[00111] While this specification contains many specific implementation details, these
should not be construed as limitations on the scope of any disclosure or of what may be
claimed, but rather as descriptions of features that may be specific to particular
embodiments of particular disclosures. Certain features that are described in this
specification in the context of separate embodiments can also be implemented in
combination in a single embodiment. Conversely, various features that are described
in the context of a single embodiment can also be implemented in multiple
embodiments separately or in any suitable sub-combination. Moreover, although
features may be described above as acting in certain combinations and even initially
claimed as such, one or more features from a claimed combination can in some cases be
excised from the combination, and the claimed combination may be directed to a
sub-combination or variation of a sub-combination.
[00112] Similarly, while operations are depicted in the drawings in a particular order,
this should not be understood as requiring that such operations be performed in the
particular order shown or in sequential order, or that all illustrated operations be
performed, to achieve desirable results. In certain circumstances, multitasking and
parallel processing may be advantageous. Moreover, the separation of various system
components in the embodiments described above should not be understood as requiring
such separation in all embodiments, and it should be understood that the described
program components and systems can generally be integrated together in a single
software product or packaged into multiple software products.
[00113] Various modifications, adaptations to the foregoing exemplary embodiments of
this disclosure may become apparent to those skilled in the relevant arts in view of the
foregoing description, when read in conjunction with the accompanying drawings.
Any and all modifications will still fall within the scope of the non-limiting and
exemplary embodiments of this disclosure. Furthermore, other embodiments of the
disclosures set forth herein will come to mind to one skilled in the art to which these
embodiments of the disclosure pertain having the benefit of the teachings presented in
the foregoing descriptions and the associated drawings.
[00114] Therefore, it is to be understood that the embodiments of the disclosure are not
to be limited to the specific embodiments disclosed and that modifications and other
embodiments are intended to be included within the scope of the appended claims.
Although specific terms are used herein, they are used in a generic and descriptive sense
only and not for purpose of limitation.

WHATIS CLAIMED IS:
1.A method of performing fractional subframe transmission, comprising:
determining first temporal information that indicates when a channel becomes
available; and
determining, based on the first temporal information and transmission opportunity
information, second temporal information that indicates an end of the fractional
subframe transmission.
2. The method of Claim 1, wherein determining first temporal information that
indicates when a channel becomes available comprises:
determining a symbol of a first subframe at which the channel becomes available;
and
determining the first temporal information as comprising an index of the symbol.
3. The method of Claim 1, wherein determining first temporal information that
indicates when a channel becomes available comprises:
determining a symbol of a first subframe at which the channel becomes available;
and
determining the first temporal information as comprising a potential position
immediately prior to the symbol, wherein the potential position is predefined in the first
subframe.
4. The method of Claim 2 or 3, wherein determining, based on the first temporal
information and transmission opportunity information, second temporal information that
indicates an end of the fractional subframe transmission comprises:
determining a number of symbols used by the fractional subframe transmission
based on the transmission opportunity information; and
determining a number of end symbols based on the first temporal infomiation and
the number of symbols used by the fractional subframe transmission, wherein the end
symbols are used by the fractional subframe transmission and belong to a last subframe
of the fractional subframe transmission.
5. The method of Claim 4, further comprising:
comparing the number of end symbols with a predetermined threshold; and
responsive to that the number of end symbols is less than or equal to a
predetermined threshold, releasing the last subframe, or combining the end symbols
with a subframe immediately prior to the last subframe.
6. The method of Claim 4, further comprising:
determining a transport block size based on the number of end symbols; and
transmitting data of the transport block size in the last subframe.
7. The method of Claim 4, further comprising:
determining a transport block size based on the number of end symbols; and
receiving data of the transport block size in the last subframe.
8. The method of Claim 1, wherein determining first temporal information that
indicates when a channel becomes available comprises:
determining a first subframe at which the channel becomes available; and
determining the first temporal information as comprising an index of the first
subframe.
9. The method of Claim 8, wherein determining, based on the first temporal
information and transmission opportunity information, second temporal information that
indicates an end of the fractional subframe transmission comprises:
determining, based on the first temporal information and transmission opportunity
information, an index of a last subframe used by the fractional subframe transmission.
10. An apparatus of performing fractional subframe transmission, comprising:
a first determining unit configured to determine first temporal information that
indicates when a channel becomes available; and
a second determining unit configured to determine, based on the first temporal
information and transmission opportunity information, second temporal information that
indicates an end of the fractional subframe transmission.
11. The apparatus of Claim 10, wherein the first determining unit comprises:
a first symbol determining unit configured to determine a symbol of a first
subframe at which the channel becomes available; and
a first information determining unit configured to determine determining the first
temporal information as comprising an index of the symbol.
12. The apparatus of Claim 10, wherein the first determining unit comprises:
a second symbol determining unit configured to determine a symbol of a first
subframe at which the channel becomes available; and
a second information determining unit configured to determine the first temporal
information as comprising a potential position immediately prior to the symbol, wherein
the potential position is predefined in the first subframe.
13. The apparatus of Claim 11 or 12, wherein the second determining unit
comprises:
a first number determining unit configured to determine a number of symbols used
by the fractional subframe transmission based on the transmission opportunity
information; and
a second number determining unit configured to determine a number of end
symbols based on the first temporal information and the number of symbols used by the
fractional subframe transmission, wherein the end symbols are used by the fractional
subframe transmission and belong to a last subframe of the fractional subframe
transmission.
14. The apparatus of Claim 13, further comprising:
a comparing unit configured to compare the number of end symbols with a
predetermined threshold; and
a processing unit configured to, responsive to that the number of end symbols is
less than or equal to a predetermined threshold, release the last subframe, or combine
the end symbols with a subframe immediately prior to the last subframe.
15. The apparatus of Claim 13, further comprising:
a first size determining unit configured to determine a transport block size based on
the number of end symbols; and
a transmitting unit configured to transmit data of the transport block size in the last
subframe.
16. The apparatus of Claim 13, further comprising:
a second size determining unit configured to determine a transport block size based
on the number of end symbols; and
a receiving unit configured to receive data of the transport block size in the last
subframe.
17. The apparatus of Claim 10, wherein the first determining unit comprises:
a first subframe determining unit configured to determine a first subframe at which
the channel becomes available; and
a third information determining unit configured to determine the first temporal
information as comprising an index of the first subframe.
18. The apparatus of Claim 17, wherein the second determining unit comprises:
a last subframe determining unit configured to determine, based on the first
temporal information and transmission opportunity information, an index of a last
subframe used by the fractional subframe transmission.