DESCRIPTION
Title of Invention
A WIRELESS COMMUNICATION SYSTEM, A BASE STATIONAND A MEATHOD
THEREIN
Technical Field
[0001]
The present invention relates to control signalling in communication networks and
systems. In particular, although not necessarily exclusively, the present invention is concerned
with reserving PUCCH resource for HARQ-ACK feedback, and concatenating HARQ-ACK bits,
in wireless communication systems that support flexible-TDD UL-DL configuration.
Background Art
[0002]
The following abbreviations may be found herein:
3GPP third generation partnership project
ACK acknowledgement
CCE control channel element
CRC cyclic redundancy check
DAI downlink assignment index
DL downlink
eNB node B base station
HARQ hybrid automatic repeat request
LTE long term evolution
LTE-A long term evolution advanced
NACK negative acknowledgement
OFDM orthogonal frequency division multiplex
PDCCH physical downlink control channel
PDSCH physical downlink shared channel
PUCCH physical uplink control channel
PUSCH physical uplink shared channel
RRC radio resource control
SPS semi-persistent scheduling
TDD time division duplex
UE user equipment
UL uplink
[0003]
LTE wireless communication systems aim to provide enhanced services by means of
higher data rates and lower latency with reduced cost. One benefit of deploying LTE TDD
systems is to enable asymmetric UL-DL allocations in a radio frame. Typically if more data is
to be sent in DL, there can be a higher number of DL subframes in a radio frame to
accommodate that greater data volume. In LTE TDD systems, the asymmetric resource
allocation is realized by providing seven different semi-statically configured UL-DL subframe
configurations for a given radio frame, as specified in Table 4.2-2 of 3GPP TS 36.211 v 10.5.0
(2012-06) which is extracted below.
[0004]
These allocations, it can be seen, can provide between 40% and 90% DL subframes, and
in conventional practice the UL-DL configuration in use is informed to the UE (and changed)
only via system information on the broadcast channel. The UL-DL configuration is only
configured semi-statically and so may not adapt to the instantaneous traffic situation. This is
inefficient in terms of resource utilization, particularly in small cells/cells with a small number of
users where the traffic situation can often change rapidly.
[0005]
To address this inefficiency, a flexible TDD configuration study item for LTE-A Release
11 was completed. Evaluations in the study item revealed possibly significant performance
benefits by allowing TDD UL-DL reconfiguration based on traffic adaptation in small cells.
The studies also recommend interference mitigation scheme(s) for systems with TDD UL-DL
reconfiguration.
[0006]
As with asymmetric UL-DL configuration and flexible TDD allocation, there are several
challenges to overcome before any implementation may be considered viable. One particular
challenge is to allow the reconfiguration of TDD UL-DL configuration on at most a radio frame
basis without significant impact on the current 3GPP specification, and to allow coexistence with
legacy (i.e. Rel. 8, 9, 10) UEs. It is thought that providing an improved method for PUCCH
resource allocation, and for HARQ-ACK concatenation, for use in wireless communication
systems that support flexible-TDD UL-DL configuration may help in this regard.
[0007]
As specified in LTE Rel. 8, 9 and 10 and further illustrated in Fig. 1, one UL subframe is
responsible for carrying HARQ-ACK feedback of M DL subframes and/or special subframes,
where M is the size of a DL association set as specified in Table 10.1.3.1-1 of 3GPP TS 36.213
(which is the lower table (120) in Fig. 1). In table (120), the DL association set is defined for
each UL subframe for different UL-DL configurations. For instance, UL subframe #2 (124) in
TDD configuration #3 (125) is responsible for DL transmission which happened k subframes
earlier, where the value of k is specified in table (120) by (123), (122) and (121) - that is 7, 6 and
11 subframes earlier. As a result, UL subframe #2 ( 114) in Frame n+1 is responsible for
carrying HARQ-ACK feedback for special subframe # 1 ( 111) (for k = 11), DL subframe #5 ( 112)
(for k =7) and DL subframe #6 (113) (for k = 6) transmitted in Frame n.
[0008]
In order to aggregate reserved but unused PUCCH for PUSCH transmission, PUCCH
resource for M DL subframes is interleaved. Since at most two OFDM symbols can be used for
PDCCH transmission on a special subframe, PUCCH resource for special subframes is mapped
later than that of normal DL subframes.
[0009]
Depicted in Fig. 2 is PUCCH resource reserved in UL subframe #2 in Rel. 10 when
UL-DL TDD configuration #3 is used. (211), (221) and (231) is the first CCE (Control Channel
Element) and (212), (222) and (232) is the last CCE in PDCCH region of DL subframe #5 (210),
DL subframe #6 (220) and special subframe # 1 (230), respectively. There is a one-one mapping
between CCE index and PUCCH index, and the PUCCH resource for these three DL subframes
and special subframes is block interleaved. For instance, PUCCH with index of
P C (241) is associated with PDCCH transmission with first CCE index of 11 in DL
subframe #5 (210). PUCCH with index N ™ + (2 42) is associated with PDCCH
transmission with first CCE index of 12 in DL subframe #5 (210).
[0010]
As one candidate solution for maintaining HARQ-timing for Flexible-TDD system,
HARQ-timing of reference configuration could be followed for HARQ-ACK feedback for
Flexible-TDD UEs. For instance, UL-DL TDD configuration #2 could be used as the reference
configuration for UL-DL TDD configuration #0, # 1, #2, #6 for DL HARQ-ACK timing. As
another example, configuration #5 could be used as the reference configuration for all 7 UL-DL
TDD configurations.
[0011]
As illustrated in Fig. 3, in Flexible-TDD system (310), there are at least two kinds of
UEs: (i) legacy UEs (312) which are not aware of the Flexible-TDD configuration, and (ii)
Flexible-TDD UEs (313) which have knowledge of both legacy TDD configuration by detecting
SIB1 information and Flexible-TDD configuration indicated by the eNB explicitly or implicitly.
It is highly likely that the Flexible-TDD configuration may be different from the legacy TDD
configuration. For instance with reference to Fig. 3, in subframe n-l, the legacy UE is
configured with UL-DL TDD configuration #0 (320) while the Flexible-TDD UE is configured
with instantaneous UL-DL configuration #2 (330). Assuming UL-DL TDD configuration #2 is
used as reference configuration for HARQ-timing for Flexible-TDD UE, then on UL subframe
#2, the legacy UE should feedback HARQ-ACK in UL subframe #2 (334) for DL transmission in
special subframe #6 (321) and the Flexible-TDD UE should feedback HARQ-ACK for DL
transmission in subframe #4 (331), #5 (332), #6 (333) and #8 (334).
[0012]
As a result, for the same UL subframe, different DL association sets are used by the
legacy UE and Flexible-TDD UE. To be specific, in the above example, DL association set
containing only special subframe #6 (321) is used by legacy UE and DL association set
containing subframes #4 (33 1), #5 (332), #6 (333) and #8 (334) is used by Flexible-TDD UE.
Since PUCCH is reserved according to the DL association set, if Rel. 10 resource mapping is
followed directly by Flexible-TDD UE, then PUCCH collision or low PUCCH efficiency may
occur.
[0013]
By way of further explanation, Option 1 (340) (overlap) in Fig. 3 depicts where the
same offset value of NP
m
CH is used by legacy UEs and Flexible-TDD UEs. Assuming the
first CCE index of PDCCH for one legacy UE in special subframe #6 (321) and one
Flexible-TDD UE in DL subframe #4 (33 1) are both 0, then they will both be mapped to the first
PUCCH in the dynamic PUCCH region (i.e. (341) for legacy UE and (342) for Flexible-TDD
UE) leading to PUCCH collision. Alternatively, Option 2 (350) (no overlap) in Fig. 3 depicts
where PUCCH (353) reserved for Flexible-TDD UE is adjacent to PUCCH (351) reserved for
legacy UE. Two copies of PUCCH (351,352) are reserved for special subframe #6 (321,333),
thus resulting in low PUCCH efficiency.
[0014]
It is therefore thought that a new PUCCH resource allocation method for Flexible-TDD
UEs which reduces or avoids PUCCH collision and/or achieves higher PUCCH resource
efficiency may be desirable.
[0015]
In PTL1 there is determined a first UL-DL configuration for subframes in a frame,
which in various examples is fixed or dynamically allocated. A second UL-DL configuration is
semi-statically allocated such as in system information. When mapping automatic repeat
request signalling for a first UE which is dynamically allocated an UL-DL configuration, at least
some DL subframes mapped by the second UL-DL configuration are excluded by the mapping.
In one example, UL resources mapped from a first group of DL subframes are indexed according
to the second configuration, and then UL resources mapped from a second group of DL
subframes are indexed according to the first configuration, and the excluded DL subframes are
within the first group and excluded from the second group and the automatic repeat request
signalling is in an uplink resource mapped from the second group.
[0016]
As well as being fed back on PUCCH, HARQ-ACK can be transmitted on PUSCH even
when PUCCH format la/ lb/3 is configured. For instance when a UE receives an UL grant and
simultaneous PUSCH+PUCCH transmission is not configured, then HARQ-ACK bits are
concatenated, coded and transmitted with UL data on PUSCH. If a reference configuration is
followed for HARQ-timing, the concatenation of HARQ-ACK bits for Flexible-TDD system
should also be specified.
[0017]
It is to be clearly understood that mere reference herein to previous or existing apparatus,
systems, methods, practices, publications or other information, or to any associated problems or
issues, does not constitute an acknowledgement or admission that any of those things
individually or in any combination formed part of the common general knowledge of those
skilled in the field, or that they are admissible prior art.
Citation List
Patent Literature
[0018]
PTL 1:WO 2012/106840
Summary of Invention
Technical Problem
[0019]
A purpose of the present invention is to provide a wireless communication system, a
base system and a method therein that are capable of reducing or avoiding PUCCH collision
and/or achieving higher PUCCH resource efficiency.
Solution to Problem
[0020]
In one form, the present invention relates broadly to a method for PUCCH resource
allocation in a wireless communication system that supports flexible-TDD UL-DL configuration,
wherein:
different UL-DL TDD configurations are provided and the UL-DL TDD configuration
used for flexible-TDD configuration can be different to the UL-DL TDD configuration used for
long term UL-DL TDD configuration; and
for a given UL-DL TDD configuration, an UL subframe carries HARQ-ACK feedback of
one or more DL and/or special subframes from a previous frame or current frame;
a first DL association set contains one or more DL and or special subframes for which
HARQ-ACK feedback is carried in the UL subframe for the UL-DL TDD configuration in use
by a first type of UE;
a second DL association set contains one or more DL and/or special subframes for which
HARQ-ACK feedback is carried in the UL subframe for a reference UL-DL TDD configuration
in use by a second type of UE;
a third DL association set contains the subframes which are in the second DL association
set but excludes any of those subframes which are also in the first DL association set;
the method comprising:
performing PUCCH resource allocation for subframes in the first DL association set by block
interleaving and, for subframes in the third DL association set, performing PUCCH resource
allocation such that the PUCCH region either follows that of the first DL association set or a
specified PUCCH offset is used.
[0021]
In a slightly more specific embodiment, the invention relates to a method for PUCCH
resource allocation in a wireless communication system that supports flexible-TDD UL-DL
configuration, wherein:
different UL-DL TDD configurations are provided in which individual subframes are
differently allocated as UL, DL or special subframes, and the UL-DL TDD configuration used
for flexible-TDD configuration is the same as, or different to, the UL-DL TDD configuration
used for long term UL-DL TDD configuration;
a first type of UE is aware of the long term UL-DL TDD configuration in use but is not
aware of the flexible-TDD configuration in use, and a second type of UE is aware of both the
long term UL-DL TDD configuration in use and the flexible-TDD configuration in use; and
for a given UL-DL TDD configuration, an UL subframe carries HARQ-ACK feedback of
one or more DL and/or special subframes from a previous frame;
a first DL association set contains one or more DL and/or special subframes for which
HARQ-ACK feedback is carried in the UL subframe for the UL-DL TDD configuration in use
by the first type of UE;
a second DL association set contains one or more DL and/or special subframes for which
HARQ-ACK feedback is carried in the UL subframe for a reference UL-DL TDD configuration
in use by the second type of UE;
a third DL association set contains the subframes which are in the second DL association
set but excludes any of those subframes which are also in the first DL association set;
the method comprising:
performing PUCCH resource allocation for subframes in the first DL association set according to
the Rel. 10 specification and, for subframes in the third DL association set, performing PUCCH
resource allocation such that the PUCCH region either follows that of the first DL association set
or a specified PUCCH offset is used.
[0022]
In some embodiments of the above form of the invention, the third DL association set
may comprise a first subset containing fixed DL and/or special subframes, and a second subset
containing flexible subframes. The method may then comprise performing PUCCH resource
allocation for the first subset and the second subset independently. PUCCH resource allocation
for subframes in the first subset may be interleaved and reserved according to Rel. 10
specification (block interleaving) and, for subframes in the second subset, PUCCH resource may
be allocated to flexible subframes with a higher probability of being used as DL subframes ahead
of flexible subframes with lower probability of being used as DL subframes. Alternatively, a
UE-specific PUCCH offset may be indicated by RRC-signalling, and the method may then
comprise configuring EPDCCH for DL transmission in flexible subframe for the second type of
UE wherein PUCCH associated with the EPDCCH set is reserved for subframes with a higher
probability of being used as DL subframes, followed by PUCCH for subframes with lower
probability of being used as DL subframes.
[0023]
In some embodiments of the invention there may be one or more particular subframes
which are DL subframes in the UL-DL TDD configuration used by the first type of UE, but the
corresponding subframe(s) in the UL-DL TDD configuration used by the second type of UE
is/are UL subframe(s). Where this is the case, the method may include assigning unused
PUCCH resource associated with the UL-DL TDD configuration used by the first type of UE to
fixed DL subframe(s) in the UL-DL TDD configuration used by the second type of UE and
scheduling only the first type of UE on the fixed DL subframe(s). Also, in these embodiments,
collision of transmission may be avoided by following the transmission direction of the second
type of UE such that PUCCH reserved for the first type of UE is neither used by the first type of
UE because no DL transmission to the first type of UE occurs in the said particular subframe(s),
nor is/are the particular subframe(s) used by the second type of UE because it/they is/are UL
subframe(s).
[0024]
There may also be embodiments of the invention where the third DL association set
mentioned above comprises a first subset the size of which is dependent on the number of
subframes in the first DL association set, a second subset which contains the remaining fixed
subframes in the third DL association set, and a third subset which contains flexible subframes in
the third DL association set. In these embodiments the method may comprise performing
PUCCH resource allocation for the first, second and third subsets independently. PUCCH
allocation for any subframes in the second subset may be interleaved and reserved according to
Rel. 10 specification and, for subframes in the third subset, PUCCH resource may be allocated
after the PUCCH allocation for subframes in the second subset. Furthermore, for subframes in
the third subset, PUCCH resource may be allocated to flexible subframes with a higher
probability of being used as DL subframes ahead of flexible subframes with lower probability of
being used as DL subframes. Alternatively, for subframes in the third subset, a UE-specific
PUCCH offset may be indicated by RRC-signalling, and the method may comprise configuring
EPDCCH for DL transmission in flexible subframe for the second type of UE wherein PUCCH
associated with two EPDCCH set is reserved for subframes with a higher probability of being
used as DL subframes, followed by PUCCH for subframes with lower probability of being used
as DL subframes.
[0025]
In another form, the invention relates to a wireless communication system that supports
flexible-TDD UL-DL configuration and which operates according to the method in the form of
the invention described above. In this other form of the invention, the wireless communication
system may include a wireless base station, one or more of the first type of UE and one or more
of the second type of UE. The wireless base station may broadcast the long-term TDD UL-DL
configuration to the first type of UE and the second type of UE using System Information Block
Type 1, and it may broadcast the short-term TDD UL-DL configuration to only the second type
of UE in the form of Downlink Control Information transmitted on PDCCH or EPDCCH. The
second type of UE may also have a TDD reconfiguration processing function which performs
blind detection of the Downlink Control Information and also performs PDSCH HARQ
encoding and selects the appropriate UL subframe(s) for sending PDSCH HARQ feedback to the
base station.
[0026]
In yet another form, the invention relates to a method for concatenation of a
HARQ-ACK bit set used for HARQ-ACK feedback in a wireless communication system that
supports flexible-TDD UL-DL configuration, wherein the HARQ-ACK bit set is divided into: a
first part which is based on the value of a DL assignment index which is last detected, a second
part which is generated by following a reference configuration, and a third part which is a
HARQ-ACK bit for SPS PDSCH. In embodiments of this form of the invention, HARQ-ACK
for dynamic PDSCH or PDCCH for DL SPS release may be set to either ACK or NACK
depending on the detection result, and if there is no dynamic PDSCH or PDCCH for DL SPS
release for one DL DAI value then the HARQ-ACK feedback may be set to NACK.
[0027]
In a yet further form, the invention relates to a method for concatenation of a
HARQ-ACK bit set used for HARQ-ACK feedback in a wireless communication system that
supports flexible-TDD UL-DL configuration, wherein the first bit of the HARQ-ACK feedback
bits set is dedicated to SPS PDSCH HARQ-ACK no matter whether SPS is activated or not, and
the HARQ-ACK bit set is divided into: a first part which includes one HARQ-ACK bit for SPS
PDSCH, and a second part which is for dynamic PDSCH or PDCCH for DL SPS release.
[0028]
In another form, the invention relates to a wireless communication system that supports
flexible-TDD UL-DL configuration and which operates according to the method in the form of
the invention described in one or other of the previous two paragraphs.
[0029]
Any of the features described herein can be combined in any combination with any one
or more of the other features described herein within the scope of the invention.
Advantageous Effects of Invention
[0030]
According to embodiments of the above form of the invention stated above, it is
possible to provide a wireless communication system, a base system and a method therein for
reducing or avoiding PUCCH collision and/or achieving higher PUCCH resource efficiency.
Brief Description of Drawings
[0031]
Preferred features, embodiments and variations of the invention may be discerned from
the following Detailed Description which provides sufficient information for those skilled in the
art to perform the invention. The Detailed Description is not to be regarded as limiting the
scope of the preceding Summary of the Invention in any way. The Detailed Description will
make reference to a number of drawings as follows:
[0032]
[Fig- 1]
Fig. 1 contains two tables. The upper table is Table 4.2-2 of 3GPP TS 36.21 1 v 10.5.0
(2012-06) and sets out the allocation of subframes as UL, DL or special subframes in different
UL-DL TDD configurations. The lower table is Table 10.1 .3.1-1 from 3GPP TS 36.213 and
sets out DL association set index , t fo TDD systems.
[Fig. 2]
Fig. 2 schematically represents PUCCH resource mapping for TDD systems.
[Fig. 3]
Fig. 3 schematically illustrates previous ways of PUCCH resource mapping for
Flexible-TDD systems, and problems therewith.
[Fig. 4]
Fig. 4 is a schematic illustration of a Flexible-TDD wireless communication system.
[Fig. 5]
Fig. 5 is schematically represents PUCCH resource allocation for Flexible-TDD systems
according to one possible embodiment of the invention referred to herein as Option-X. Note
that Option-X includes Option 1 and Option 2 as illustrated in Fig. 5 and discussed below.
[Fig. 6]
Fig. 6 illustrates DL association sets for Flexible-TDD systems according to Option-X
in Fig. 5.
[Fig- 7]
Fig. 7 schematically represents PUCCH resource allocation for Flexible-TDD systems
according to another possible embodiment of the invention referred to herein as Option-Y.
Note that Option-Y includes Option 1 and Option 2 as illustrated in Fig. 7 and discussed below
in Fig. 7
[Fig. 8]
Fig. 8 illustrates DL association sets for Flexible-TDD systems according to Option-Y.
[Fig. 9]
Fig. 9 illustrates HARQ-ACK bit concatenation by following a reference configuration.
[Fig. 10]
Fig. 10 illustrates an example relating to a different embodiment referred to as Option A
for HARQ-ACK concatenation.
[Fig. 11]
Fig. 1 illustrates another example relating to the Option A embodiment.
[Fig- 12]
Fig. 12 illustrates an example relating to yet another embodiment referred to as Option
B for HARQ-ACK concatenation.
Description of Embodiments
[0033]
The present invention may be implemented in a wireless communication system that
supports Flexible-TDD UL-DL configuration, one example cell of which is shown schematically
in Fig. 4. The depicted wireless communication system cell (400) consists of at least one Rel.
11& beyond eNB (401) which is backward compatible with previous releases such as Rel. 8, Rel.
9 and Rel. 10. The eNB (401) provides wireless connectivity, network access and coverage for
one or more legacy UEs (403) as well as one or more Rel. 11 & beyond UEs (404). Rel. 11 &
beyond UEs are also referred to herein as Flexible-TDD UEs. The eNB (401) has a TDD
reconfiguration processing function (402) which takes the UL-DL traffic ratio observed in
unrestricted timeframe into consideration when it performs a TDD configuration switching
algorithm for the selection of appropriate long term and short term TDD UL-DL configuration
for legacy UEs (403) and Rel. 11 & beyond UEs (404).
[0034]
The eNB (401) will broadcast a long term TDD UL-DL configuration to legacy UEs
(403) and Rel. 11 & beyond UEs (404) using previously proposed SIB1 (System Information
Block type 1) (406). The TDD UL-DL configuration transmitted on SIB1 is considered "long
term" as the period for SIB1 update is the order of 640ms. The eNB (401) will also
communicate a short term TDD UL-DL configuration to only Rel. 1 & beyond UEs (404) using
a fast signalling approach. The eNB (401) transmits the short term TDD UL-DL configuration
in the form of a DCI (Downlink Control Information) that is transmitted on PDCCH or EPDCCH
(Enhanced PDCCH) within common search space (407). The CRC of this DCI is scrambled
with a RNTI (radio network temporary identifier) named "elMTA-RNTI", which indicates the
DCI is used for the purpose of fast TDD UL-DL reconfiguration. The TDD UL-DL
configuration included on the new DCI is considered "short term" as the period for TDD UL-DL
configuration update can be as low as 10ms (i.e. radio frame basis).
[0035]
In addition to receiving and using the TDD UL-DL configuration broadcasted on SIB1,
Rel. 11& beyond UEs (404) operating within range of Rel. 11& beyond eNB (40 1) will further
have a TDD reconfiguration processing function (405) which performs blind detection of the
DCI carrying the updated short term UL-DL configuration information. This function (405) will
also perform PDSCH HARQ encoding and select the appropriate UL subframe(s) for sending
PDSCH HARQ feedback to the eNB (401). This function (405) will further perform the
determination of the DL subframe on which it will monitor for its UL grant and determination of
DL subframe on which it will receive PHICH (physical HARQ indicator channel) carrying
HARQ corresponding to UL-SCH that it sends in previously granted UL-subframe(s).
[0036]
For a legacy UE (403) operating within range of the Rel. 11& beyond eNB (401), it
shall use the TDD UL-DL configuration broadcasted on SIB1 and operate according to the
legacy specifications that it complies to. The eNB (401) may not schedule legacy UE(s) (403)
to perform the reception of PDSCH(s) or transmission of PUSCH(s) on the "flexible subframes".
[0037]
A first important aspect of at least some embodiments of the present invention relates to
the issue of backward compatibility. As a legacy UE has no idea of the Flexible-TDD system,
the PUCCH resource reservation method specified in previous Rel. 0 may be (and preferably
should be) followed by legacy UEs.
[0038]
As represented in Fig. 5, UL-DL TDD configuration #3 (510) is used by legacy the UE
and HARQ-ACK bits for DL subframe # 1 (511), #5 (512), #6 (513) are fed back on UL subframe
#2 (514) in radio Frame #n+l. The PUCCH resource (531) for the legacy UE is reserved
according to the DL association set indicated as item (125) of table (120) in Fig. 1.
[0039]
A second important aspect of at least some embodiments of the present invention relates
to alleviating the influence of ambiguity due to fast TDD configuration between UE and eNB.
In a Flexible-TDD system, then maybe ambiguity between UE and eNB in terms of what fast
TDD configuration is used for one radio frame. For instance, consider that in Radio Frame #n,
the eNB may send a Flexible-TDD configuration of #3 but the UE may somehow interpret this
indication as Flexible-TDD configuration #5. This ambiguity may influence the HARQ-ACK
even for a subframe which is a DL subframe in both configurations. It should be noted that
PUCCH resource reservation for Flexible-TDD systems may not (and preferably is not) related
to actual Flexible-TDD configuration detected by a Flexible-TDD UE, but follows the
predetermined reference configuration.
[0040]
Athird important aspect of at least some embodiments of the present invention relates to
achieving higher efficiency for PUCCH resource reservation. This aspect is addressed by the
embodiments described as Option-X and Option-Y below.
Option-X
[0041]
In order to avoid reserving two copies of PUCCH resource for the same subframe,
subframes which are included in the DL association set of legacy UE will not be included in the
DL association set of Flexible-TDD UE.
[0042]
For the convenience of description:
- let the DL association set of a legacy UE be referred to as the "DL association set 1" or "set
1",
- let the DL association set of the reference configuration used by a Flexible-TDD UE be
referred to as the "DL association set 2" or "set 2", and
- let the DL association set of a Flexible-TDD UE for PUCCH resource reservation be referred
to as the "DL association set 3" or "set 3".
[0043]
As depicted in Figs. 5 and 6, assuming UL-DL TDD configuration #3 (510) is used by
legacy UEs and either UL-DL TDD configuration #3,#4 or #5 (520) is used by flexible-TDD
UEs, DL/special subframes # 1 (511), #5 (512) and #6 (513) are included in set 1 (602) for TDD
configuration #3 as specified in Fig. 1 (125). Subframes #9 (521), #0 (522), #1, #3 (523), #4
(524), #5, #6, #7 (525) and #8 (526) are included in set 2 (601) for reference configuration #5. In
order to achieve higher PUCCH efficiency and avoid reserving redundant PUCCH resource for
subframes #1, #5 and #6 (602), DL association set of Flexible-TDD UE, set 3 (603), includes
subframes #9 (521),#0 (522), #7 (525), #8 (526), #4 (524) and #3 (523) only.
[0044]
Resource mapping for the DL association set 1 (602) is straightforward and follows the
Rel. 10 specification.
[0045]
DL association set 3 (603), on the other hand, can be further divided into two subsets;
subset 3A and subset 3B. Subset 3A contains fixed DL/Special subframes (i.e. subframe #9, #0,
#7, and #8) in subset 3A and subset 3B contains flexible subframes (i.e. subframe #3 and #4) in
set 3. The PUCCH resource mapping for these two subsets are carried out independently in
order to improve PUCCH efficiency. PUCCH reservation for flexible subframes (523,524) in
Fig. 5 needs special treatment because PUCCH resource reserved for a flexible subframe which
is used as an UL subframe will never be used for HARQ-ACK transmission. As mentioned in
the Background section above, contiguous PUCCH resource which is not used for HARQ-ACK
feedback can be reused for PUSCH transmission. Thus it may be reasonable to reserve one
block of PUCCH resource for flexible subframe rather than interleaving with fixed DL/special
subframe in the DL association set of Flexible-TDD UE.
[0046]
As illustrated in Fig. 5, in Option 1 (530) of Option-X, PUCCH resource for fixed
DL/special subframes #9 (521), #0 (522), #7 (525) and #8 (526) in the DL association set of the
Flexible-TDD UE is interleaved and reserved in PUCCH region as (532) according to the Rel. 10
specification. In relation to the flexible subframes, compared to flexible subframe #4 (524),
flexible subframe #3 (523) has a larger possibility of being used as an UL subframe and, as a
result, it would be better to reserve PUCCH resource (533) for flexible subframe #4 first,
followed by PUCCH resource (534) for flexible subframe #3.
[0047]
In Rel. 11, EPDCCH is defined for DCI transmission and UE-specific PUCCH offset is
indicated by RRC-signalling. As one way to improve PUCCH efficiency, EPDCCH can be
configured for DL transmission in flexible subframe for Flexible-TDD UE. As depicted in Fig.
5, in Option 2 (540) of Option-X, UE specific offset (543) is RRC-signalled and PUCCH
associated with two EPDCCH set is reserved for flexible subframe #4, followed by PUCCH
related to flexible subframe #3.
[0048]
If a UE is configured to receive EPDCCH on some fixed DL subframes and flexible
subframes, then the PUCCH resource is reserved in the order of fixed DL subframe first and
flexible later, and flexible subframe with higher probability of being used as DL subframe
mapped earlier than those with lower probability.
Option-Y
[0049]
For some DL subframes of a legacy UE which are used as UL subframes by
Flexible-TDD UE, the related PUCCH reserved can be used as PUCCH for fixed DL subframe
of Flexible-TDD UE and the subframe index could be different.
[0050]
As depicted with reference to example system (700) in Fig. 7, subframe #4 is used as a
DL subframe (71 1) by the legacy UE and is used as an UL subframe (725) by the Flexible-TDD
UE. Assume that collision of transmission is avoided by following the transmission direction
of the Flexible-TDD UE such that the PUCCH reserved for the legacy UE is neither used by the
legacy UE because no DL transmission to the legacy UE occurs in subframe #4, nor is it used by
the Flexible-TDD UE because it is an UL subframe. As a result, it would be reasonable to use
these PUCCH resources in order to achieve higher PUCCH resource efficiency. One way of
achieving this is to assign unused PUCCH resource of legacy UEs to fixed DL subframes of
Flexible-TDD UEs and schedule only legacy UEs on Fixed DL subframes.
[0051]
For the convenience of description, the above definitions of DL association sets are
reused.
- the DL association set of a legacy UE is referred to as the "DL association set 1" or "set 1",
- the DL association set of the reference configuration used by a Flexible-TDD UE is referred
to as the "DL association set 2" or "set 2", and
- the DL association set of a Flexible-TDD UE for PUCCH resource reservation is referred to
as the "DL association set 3" or "set 3".
[0052]
As depicted in Figs. 7 and 8, DL/special subframes #4 (711), #5 (712), #8 (714) and #6
(713) are included in set 1 (802) for TDD configuration #2 as specified in table (120) of Fig. 1.
Subframe #9 (721), #0 (722), # 1 (723), #3 (724), #4 (725), #5, #6, #7 (726), #8 (727) are
included in set 2 (801) for reference configuration #5. Subframe #0 (722), # 1 (723), #5 and #6
are fixed DL subframes and subframe #9 (721), #3 (724), #4 (725), #7 (726) and #8 (727) are
flexible subframes that form set 3 (803). In order to reuse legacy PUCCH resource, fixed DL
subframe #5 and #6 will map to PUCCH resource of subframe #5 (712) and #6 (713) for legacy
UE, and fixed DL subframe #0 (722) and # 1 (723) will map to PUCCH resource of subframe #4
and #8 of legacy UE.
[0053]
On the other hand, DL association set 3 can be further divided into three subsets, subset
3A, subset 3B and subset 3C. Subset 3A contains part of fixed DL/Special subframes in set 3,
and the size of subset 3A depends on the number of subframes in set 1 which are used as flexible
subframes in the Flexible-TDD system. Subset 3B contains the remaining fixed DL/Special
subframes in set 3, and subset 3C contains the flexible subframes in set 3. The PUCCH
resource mapping for these three subsets are carried out independently in order to improve the
PUCCH efficiency further.
[0054]
As depicted in Fig. 7, subframes # 0 and # 1 of Flexible-TDD UE share the same
PUCCH resource with subframes #4 and #8 of legacy UE respectively, and no PUCCH resource
collision occurs since legacy UE can only be scheduled on fixed DL/special subframe. The size
of subset 3B is zero in this example; otherwise a PUCCH interleaving method as specified in
legacy system is used. PUCCH resource mapping for subset 3C is the same as
above-mentioned method in Option-X. PUCCH is not interleaved and the PUCCH region
either follows the PUCCH for subset 3B or uses a UE specified PUCCH offset because ePDCCH
in used in flexible subframe by Flexible-TDD UE. The order of PUCCH resource allocation for
fixed DL subframe and flexible are the same as Option-X.
[0055]
Compared to Option-X, Option-Y can achieve higher PUCCH efficiency but at a cost of
restricted scheduling of legacy UEs; e.g. it is only possible to schedule legacy UEs for DL
transmission on fixed subframes.
[0056]
A fourth important aspect of at least some embodiments of the present invention relates
to achieving a higher coding gain for HARQ-ACK. Initial explanations relating to this (fourth)
aspect will be given with reference to the situation where PUCCH format la/lb is configured for
Flexible-TDD UE and HARQ-ACK bits are transmitted on PUSCH.
[0057]
As specified in section 7.3 of 3GPP TS 36.213, for TDD HARQ-ACK multiplexing and
a subframe n with > spatial HARQ-ACK bundling across multiple codewords within a DL
subframe is performed by a logical AND operation of all the corresponding individual
HARQ-ACKs. Where a UE is transmitting on PUSCH, the UE determines the number of
HARQ-ACK feedback bits C (i.e. the number of bits in the HARQ-ACK feedback bit set)
and the HARQ-ACK feedback bits " ' ~ ' ' to be transmitted in subframe n.
[0058]
If the PUSCH transmission is not adjusted based on a detected PDCCH with DCI
ACK, O format 0/4 intended for the UE, = and ' is associated with the spatially bundled
HARQ-ACK for DL subframe n~k ' , where k> K and HARQ-ACK feedback bits without
any detected PDSCH transmission or without detected PDCCH indicating downlink SPS release
are set to NACK.
[0059]
For a Flexible-TDD UE, the reference configuration should also be followed in
determining the number of HARQ-ACK feedback bits 0 ( the HARQ-ACK feedback
n A n = 0 ) C _ 1 bits ' ,., ., to be transmitted in subframe n.
[0060]
For instance, as depicted in Fig. 9, one Flexible-TDD UE mistakenly detects fast TDD
configuration as configuration # 1 (920 ) while configuration # 2 (910) is used by eNB. The
number of HARQ-ACK bits = , and M is the size of DL association set determined
according to the reference configuration (and is unrelated with the actual configuration used by
the Flexible-TDD UE).
[0061]
The HARQ-ACK feedback bits set (930) in Fig. 9 is divided into two parts. The first
part (931) is determined according to the reference configuration, and the second part (932) is
the last HARQ-ACK bit for SPS (Semi-Persistent Scheduling) PDSCH. Let it be assumed that
all PDSCH/PDCCH are successfully decoded, except PDSCH/PDCCH in subframe #8 (911) due
to the misinterpretation of the UL-DL configuration by the UE. Accordingly, a dummy
HARQ-ACK bit will be fed back for subframes #9 (921), #3 (922), #7 (923) and #8 (924)
without any detected PDSCH transmission or without detected PDCCH indicating DL SPS
release, as long as this subframe is used as DL subframe in reference configuration. The
problem with this scheme is that the percentage of dummy HARQ-ACK bits in the HARQ-ACK
feedback bits set is high meaning that coding gain is low. Further coding gain may be achieved
by reducing the number of dummy HARQ-ACK bits.
[0062]
Two possible options for achieving this, referred to as Option A and Option B, are
discussed below.
Option A
[0063]
In Option A, the HARQ-ACK feedback bits set is divided into 3 parts - see (1010),
(1011) and (1012) in Fig. 10. The first part (1010) is based on the value of the DL DAI
(Downlink Assignment Index) which is last detected. The second part ( 1011) is generated by
following the reference configuration. And the third part (1012) is a HARQ-ACK bit for SPS
PDSCH.
[0064]
As illustrated in Fig. 10, since the last detected DL DAI value is 4 (1013), there are at
least 4 dynamic PDSCH or PDCCH for DL SPS release. HARQ-ACK for dynamic PDSCH or
PDCCH for DL SPS release will be set to ACK/NACK depending on the detection result. If
there is no dynamic PDSCH or PDCCH for DL SPS release for one DL DAI value, then the
HARQ-ACK feedback will be set to NACK. In Fig. 10, the dynamic PDSCH or PDCCH for
DL SPS release associated with DAI values 1, 2, 3 and 4 are all successfully decoded and thus
the first part (1010) of the HARQ-ACK bits is set to {ACK, ACK, ACK, ACK}.
[0065]
The second part (1011) of the HARQ-ACK bits is set according to the reference
configuration. Since subframes #7 and #8 are used as DL subframes in reference configuration
and included in the DL association set, then two dummy HARQ-ACK bits for these two
subframes are set to NACK.
[0066]
The last part (1012) of HARQ-ACK bits is associated with SPS PDSCH. There is at
most one subframe within the DL association set used for DL SPS PDSCH, and the last
HARQ-ACK bit is set to ACK since this DL SPS PDSCH is correctly detected.
[0067]
Compared to the HARQ-ACK codebook size (M) specified in Rel. 10, Option A (which
is illustrated by example with reference to Fig. 10) drops two dummy HARQ-ACK bits and thus
higher coding gain is achieved.
[0068]
Fig. 11 is another example relating to Option A. Compared to the example in Fig. 10,
the difference in Fig. 11 is that UE missed the dynamic PDSCH or PDCCH for DL SPS release
in subframe #5 and only dynamic PDSCH or PDCCH for DL SPS release with DL DAI value of
1, 2, and 4 are detected. Accordingly, in the example in Fig. 11, HARQ-ACK feedback for DL
DAI value of 3 is set to NACK and thus {ACK, ACK, NACK, ACK} is assigned for the first part
(1110) of the HARQ-ACK feedback bits set. The second part ( 1) stays the same with two
dummy HARQ-ACK bits with value of NACK. And the third part ( 1112) is the last bit in
HARQ-ACK bits and related to the decoding result of DL SPS PDSCH.
[0069]
The first bit (1210) of the HARQ-ACK feedback bits set is dedicated to SPS PDSCH
HARQ-ACK, no matter whether SPS is activated or not. And HARQ-ACK bit is associated
with DAI value rather than subframe in the DL association set.
[0070]
From the examples relating to Option A above, it can be seen that dummy HARQ-ACK
bits are still padded in order to feedback the HARQ-ACK bits for DL SPS PDSCH correctly.
During the process of Rel. 8 standardization, it was proposed that the first HARQ-ACK bit be
used as the HARQ-ACK feedback for DL SPS PDSCH if there is one in the DL association set.
The problem with this method is that the DL SPS activation command may not be detected by
the UE. It is possible that the first HARQ-ACK bit might be used for dynamic PDSCH at the
UE side but interpreted as the HARQ-ACK bit of SPS PDSCH and HARQ-ACK bits for
dynamic PDSCH or PDCCH for DL SPS release may be started from the second bits. This
would disorder the HARQ-ACK feedback for all dynamic PDSCH and lead to incorrect
interpretation at the eNB side.
[0071]
In order to avoid the above problem, it is possible to dedicate the first HARQ-ACK bit
(1210) for SPS PDSCH no matter whether DL SPS PDSCH is activated or not. So the
HARQ-ACK bit set can be divided into two parts, the first part (1210) includes one HARQ-ACK
bit for SPS PDSCH, and the second part (121 1) is for dynamic PDSCH or PDCCH for DL SPS
release.
[0072]
As illustrated in Fig. 12, dynamic PDSCH or PDCCH for DL SPS release with DL DAI
value of 0 (1212) and 3 (1213) are detected and DL transmissions in subframe #4 and #5 are
missed. The first HARQ-ACK bit is assigned with the result of SPS PDSCH detection and if
no SPS PDSCH is detected then it is set to NACK. The HARQ-ACK bits concatenation is
based on the DL DAI value and the same as the first part in Option A.
[0073]
Compared to OptionA, each HARQ-ACK bit sent by Option 2 is useful and no dummy
HARQ-ACK bit is transmitted as thus the maximum coding gain can be achieved.
[0074]
The explanations relating to the fourth aspect given above refer to the situation where
PUCCH format la/lb is configured for Flexible-TDD UE and HARQ-ACK bits are transmitted
on PUSCH. The following refers to the situation where PUCCH format 3 is configured for
Flexible-TDD UE and HARQ-ACK bits are transmitted on PUCCH format 3 or PUSCH for
retransmission.
[0075]
The method specified in Rel. 10 for format 3 is similar to method for PUCCH format
la/lb when PUSCH for retransmission is used to feedback HARQ-ACK bits. Accordingly,
Option A and Option B can be used to concatenate HARQ-ACK bits in order to achieve higher
coding gain.
[0076]
In the present specification and claims (if any), the word 'comprising' and its derivatives
including 'comprises' and 'comprise' include each of the stated integers but does not exclude the
inclusion of one or more further integers.
[0077]
Reference throughout this specification to ne embodiment' or 'an embodiment' means
that a particular feature, structure, or characteristic described in connection with the embodiment
is included in at least one embodiment of the present invention. Thus, the appearance of the
phrases 'in one embodiment' or 'in an embodiment' in various places throughout this
specification are riot necessarily all referring to the same embodiment. Furthermore, the
particular features, structures, or characteristics may be combined in any suitable manner in one
or more combinations.
[0078]
In compliance with the statute, the invention has been described in language more or
less specific to structural or methodical features. It is to be understood that the invention is not
limited to specific features shown or described since the means herein described comprises
preferred forms of putting the invention into effect. The invention is, therefore, claimed in any
of its forms or modifications within the proper scope of the appended claims (if any)
appropriately interpreted by those skilled in the art.
[0079]
The whole or part of the exemplary embodiments disclosed above can be described as,
but not limited to, the following supplementary notes.
(Supplementary note 1) A method for concatenation of a HARQ-ACK bit set used for
HARQ-ACK (hybrid automatic repeat request-acknowledgement) feedback in a wireless
communication system that supports flexible-TDD (flexible-time division duplex) UL-DL
(uplink-downlink) configuration, wherein the HARQ-ACK bit set is divided into 3 parts:
the first part is based on the value of a DL assignment index which is last detected,
the second part is generated by following a reference configuration, and
the third part is a HARQ-ACK bit for SPS (semi-persistent scheduling) PDSCH
(physical downlink shared channel).
(Supplementary note 2) A method for concatenation of a HARQ-ACK bit set as claimed in
Supplementary note 1 wherein HARQ-ACK for dynamic PDSCH or PDCCH (physical downlink
control channel) for DL SPS release is set to either ACK (acknowledgement) or NACK
(negative acknowledgement) depending on the detection result, and if there is no dynamic
PDSCH or PDCCH for DL SPS release for one DL DAI (downlink assignment index) value then
the HARQ-ACK feedback is set to NACK.
(Supplementary note 3) A method for concatenation of a HARQ-ACK bit set used for
HARQ-ACK feedback in a wireless communication system that supports flexible-TDD UL-DL
configuration, wherein the first bit of the HARQ-ACK feedback bits set is dedicated to SPS
PDSCH HARQ-ACK no matter whether SPS is activated or not, and the HARQ-ACK bit set is
divided into two parts:
the first part including one HARQ-ACK bit for SPS PDSCH, and
the second part is for dynamic PDSCH or PDCCH for DL SPS release.
(Supplementary note 4) A wireless communication system that supports flexible-TDD UL-DL
configuration and which operates according to the method in any one of the preceding
Supplementary notes.
(Supplementary note 5) A method for PUCCH resource allocation in a wireless communication
system that supports flexible-TDD UL-DL configuration, wherein:
different UL-DL TDD configurations are provided and the UL-DL TDD configuration
used for flexible-TDD configuration can be different to the UL-DL TDD configuration used for
long term UL-DL TDD configuration;
for a given UL-DL TDD configuration, an UL subframe carries HARQ-ACK feedback
of one or more DL and/or special subframes from a previous frame or current frame;
a first DL association set contains one or more DL and/or special subframes for which
HARQ-ACK feedback is carried in the UL subframe for the UL-DL TDD configuration in use
by a first type of UE;
a second DL association set contains one or more DL and/or special subframes for
which HARQ-ACK feedback is carried in the UL subframe for a reference UL-DL TDD
configuration in use by a second type of UE;
a third DL association set contains the subframes which are in the second DL
association set but excludes any of those subframes which are also in the first DL association set;
the method comprising:
performing PUCCH resource allocation for subframes in the first DL association set by
block interleaving and, for subframes in the third DL association set, performing PUCCH
resource allocation such that the PUCCH region either follows that of the first DL association set
or a specified PUCCH offset is used.
(Supplementary note 6) A method as claimed in Supplementary note 5 wherein the third DL
association set comprises:
a first subset containing fixed DL and/or special subframes, and
a second subset containing flexible subframes, and
the method comprises
performing PUCCH resource allocation for the first subset and the second subset
independently.
(Supplementary note 7) A method as claimed in Supplementary note 6 wherein PUCCH resource
allocation for subframes in the first subset is block interleaved.
(Supplementary note 8) A method as claimed in Supplementary note 6 or 7 wherein, for
subframes in the second subset, PUCCH resource is allocated to flexible subframes with a higher
probability of being used as DL subframes ahead of flexible subframes with lower probability of
being used as DL subframes.
(Supplementary note 9) A method as claimed in Supplementary note 6 wherein a UE-specific
PUCCH offset is indicated by RRC-signalling, and the method comprises configuring EPDCCH
for DL transmission in flexible subframe for the second type of UE wherein PUCCH associated
with the EPDCCH set is reserved for subframes with a higher probability of being used as DL
subframes, followed by PUCCH for subframes with lower probability of being used as DL
subframes.
(Supplementary note 10) A method as claimed in Supplementary note 5 wherein:
for one or more particular subframes which are DL subframes in the UL-DL TDD
configuration used by the first type of UE, the corresponding subframe(s) in the UL-DL TDD
configuration used by the second type of UE is/are UL subframe(s), and
the method includes assigning unused PUCCH resource associated with the UL-DL
TDD configuration used by the first type of UE to fixed DL subframe(s) in the UL-DL TDD
configuration used by the second type of UE and scheduling only the first type of UE on the
fixed DL subframe(s).
(Supplementary note 11) A method as claimed in Supplementary note 10, wherein collision of
transmission is avoided by following the transmission direction of the second type of UE such
that PUCCH reserved for the first type of UE is neither used by the first type of UE because no
DL transmission to the first type of UE occurs in the said particular subframe(s), nor is/are the
particular subframe(s) used by the second type of UE because it/they is/are UL subframe(s).
(Supplementary note 12) A method as claimed in Supplementary note 10 or 11, wherein the third
DL association set comprises:
a first subset the size of which is dependent on the number of subframes in the first DL
association set;
a second subset which contains the remaining fixed subframes in the third DL
association set, and
a third subset which contains flexible subframes in the third DL association set,
the method comprising
performing PUCCH resource allocation for the first, second and third subsets independently.
(Supplementary note 13) A method as claimed in Supplementary note 12 wherein PUCCH
allocation for any subframes in the second subset is block interleaved.
(Supplementary note 14) A method as claimed in Supplementary note 12 or 13 wherein, for
subframes in the third subset, PUCCH resource is allocated after the PUCCH allocation for
subframes in the second subset.
(Supplementary note 15) A method as claimed in Supplementary note 12, 13 or 14 wherein, for
subframes in the third subset, PUCCH resource is allocated to flexible subframes with a higher
probability of being used as DL subframes ahead of flexible subframes with lower probability of
being used as DL subframes.
(Supplementary note 16) A method as claimed in Supplementary note 12, 13 or 14 wherein a
UE-specific PUCCH offset is indicated by RRC-signalling, and the method comprises
configuring EPDCCH for DL transmission in flexible subframe for the second type of UE
wherein PUCCH associated with two EPDCCH set is reserved for subframes with a higher
probability of being used as DL subframes, followed by PUCCH for subframes with lower
probability of being used as DL subframes.
(Supplementary note 17) A wireless communication system that supports flexible-TDD UL-DL
configuration and which operates according to the method in any one of Supplementary notes
5-16.
(Supplementary note 18) A wireless communication system as claimed in Supplementary note
17, wherein the wireless communication system includes a wireless base station, one or more of
the first type of UE and one or more of the second type of UE, wherein
the wireless base station broadcasts the long-term TDD UL-DL configuration to the first
type of UE and the second type of UE using System Information Block Type 1, and
the wireless base station broadcasts the short-term TDD UL-DL configuration to only
the second type of UE in the form of Downlink Control Information transmitted on PDCCH or
EPDCCH.
(Supplementary note 19) A wireless communication system as claimed in Supplementary note
18, wherein the second type of UE has a TDD reconfiguration processing function which
performs blind detection of the Downlink Control Information and also performs PDSCH HARQ
encoding and selects the appropriate UL subframe(s) for sending PDSCH HARQ feedback to the
base station.
(Supplementary note 20) A method substantially as hereinbefore described with reference to any
one or more of Figs. 5-8 or 10-12.
[0080]
This application is based upon and claims the benefit of priority from Australian Patent
Application No. 2013900058, filed on January 8, 2013, the disclosure of which is incorporated
herein in its entirety by reference.
Reference Signs List
[0081]
310 Flexible-TDD system
312 legacy UEs
313 Flexible-TDD UEs
400 wireless communication system cell
401 eNB
402, 405 TDD reconfiguration processing function
403 legacy UEs
404 Rel. 1 1 & beyond UEs
CLAIMS
[Claim 1]
A method implemented in a base station used in a wireless communications system that
supports flexible-TDD (flexible-time division duplex) UL-DL (uplink-downlink) configuration,
the method comprising:
configuring a first type of user equipment (UE) with a first type of configuration;
configuring a second type of UE with a second type of configuration; and
receiving from a user equipment a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal according to a DL association set,
wherein the DL association set comprises:
a first DL association set for a UL-DL TDD configuration used by the first type
of UE; and
a second DL association set for a reference UL-DL TDD configuration
including a third DL association set for PUCCH resource mapping used by the second type of
UE.
[Claim 2]
The method as in claim 1,
wherein the first type of UE comprises a legacy UE or a 3GPP Release 8, 9, and 10 UE,
wherein the second type of UE comprises a flexible-TDD UE,
wherein the first type of configuration comprises a long term UL-DL TDD
configuration, and
wherein the second type of configuration comprises a flexible-TDD configuration.
[Claim 3]
The method as in claim 1,
wherein the first DL association set indicates one or more subframes including at least
one of a DL subframe and a special subframe for which a HARQ-ACK feedback is sent to the
base station according to the UL-DL TDD configuration,
wherein the second DL association set indicates one or more subframes including at
least one of a DL subframe and a special subframe for which a HARQ-ACK feedback is sent to
the base station according to the reference UL-DL TDD configuration, and
wherein the third DL association set indicates one or more subframes excluding said one
or more subframes indicated by the first DL association set.
[Claim 4]
The method as in claim 3, further comprising:
for said one or more subframes indicated by the first DL association set, performing
PUCCH resource allocation by block interleaving;
for said one or more subframes indicated by the third DL association set, performing
PUCCH resource allocation such that a PUCCH region either follows a PUCCH region of the
first DL association set or a specified PUCCH offset is used.
[Claim 5]
The method as in claim 1,
wherein the third DL association set comprises:
a first subset indicating one or more subframes including at least one of a fixed
DL subframe and a special subframe; and
a second subset indicating one or more flexible subframes, and
the method further comprises:
performing PUCCH resource allocation independently for said one or more
subframes indicated by the first subset and for said one or more subframes indicated by the
second subset.
[Claim 6]
The method as in claim 5,
wherein PUCCH resource allocation for said one or more subframes indicated by the
first subset is block interleaved.
[Claim 7]
The method as in claim 5, further comprising:
allocating PUCCH resources for said one or more subframes indicated by the second
subset to a first flexible subframe with a higher probability of being used as a DL subframe
ahead of a second flexible subframe with lower probability of being used as a DL subframe.
[Claim 8]
The method as in claim 5,
wherein a UE-specific PUCCH offset is indicated by radio resource control
(RRC)-signalling,
wherein the method comprises:
configuring an enhanced physical downlink control channel (EPDCCH) for DL
transmission in a flexible subframe for the second type of UE, and
wherein a PUCCH associated with the EPDCCH is reserved for a subframe with a
higher probability of being used as a DL subframe, followed by a PUCCH for a subframe with a
lower probability of being used as a DL subframe.
[Claim 9]
The method as in claim 1,
wherein one or more DL subframes according to the UL-DL TDD configuration
comprise one or more UL subframes according to the reference UL-DL TDD configuration, and
wherein the method comprises:
assigning unused PUCCH resources associated with the UL-DL TDD
configuration to a fixed DL subframe in the reference UL-DL TDD configuration; and
scheduling the first type of UE on the fixed DL subframe.
[Claim 10]
. The method as in claim 1,
wherein the third DL association set comprises:
a first subset the size of which is dependent on the number of subframes in the
first DL association set;
a second subset which contains remaining fixed subframes in the third DL
association set; and
a third subset which contains flexible subframes in the third DL association set,
and
wherein the method comprises:
performing PUCCH resource allocation for the first, second and third subsets
independently.
[Claim 11]
The method as in claim 10,
wherein PUCCH allocation for one or more subframes indicated by the second subset is
block interleaved.
[Claim 12]
The method as in claim 10, further comprising:
allocating PUCCH resources for one or more subframes indicated by the third subset
after the PUCCH allocation for subframes in the second subset.
[Claim 13]
The method as in claim 10, further comprising:
allocating PUCCH resources for one or more subframes indicated by the third subset to
a flexible subframe with a higher probability of being used as a DL subframe ahead of a flexible
subframe with a lower probability of being used as a DL subframe.
[Claim 14]
The method as in claim 10,
wherein a UE-specific PUCCH offset is indicated by radio resource control
(RRC)-signalling, and
wherein the method comprises:
configuring an enhanced physical downlink control channel (EPDCCH) for DL
transmission in a flexible subframe for the second type of UE, and
wherein a PUCCH associated with an EPDCCH set of two is reserved for a subframe
with a higher probability of being used as a DL subframe, followed by a PUCCH for a subframe
with a lower probability of being used as a DL subframe.
[Claim 15]
In a wireless communications system that supports flexible-TDD (flexible-time division
duplex) UL-DL (uplink-downlink) configuration, the wireless communications system including
a first type of user equipment (UE) and a second type of UE, a method implemented in the
second type of UE, comprising:
transmitting to a base station a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal according to a DL association set,
wherein the DL association set comprises:
a first DL association set for a UL-DL TDD configuration used by the first type
of UE; and
a second DL association set for a reference UL-DL TDD configuration
including a third DL association set for PUCCH resource mapping used by the second type of
UE, and
wherein the first type of UE is configured with a first type of configuration and the
second type of UE is configured with a second type of configuration.
[Claim 16]
A method implemented in a wireless communications system that supports
flexible-TDD (flexible-time division duplex) UL-DL (uplink-downlink) configuration, the
method comprising:
configuring a first type of user equipment (UE) with a first type of configuration;
configuring a second type of UE with a second type of configuration; and
transmitting from a user equipment to a base station a HARQ-ACK (hybrid automatic
repeat request-acknowledgement) signal according to a DL association set,
wherein the DL association set comprises:
a first DL association set for a UL-DL TDD configuration used by the first type
of UE; and
a second DL association set for a reference UL-DL TDD configuration
including a third DL association set for PUCCH resource mapping used by the second type of
UE.
[Claim 17]
A base station used in a wireless communications system that supports flexible-TDD
(flexible-time division duplex) UL-DL (uplink-downlink) configuration, the base station
comprising:
a controller to configure a first type of user equipment (UE) with a first type of
configuration and a second type of UE with a second type of configuration; and
a receiver to receive from a user equipment a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal according to a DL association set,
wherein the DL association set comprises:
a first DL association set for a UL-DL TDD configuration used by the first type
of UE; and
a second DL association set for a reference UL-DL TDD configuration
including a third DL association set for PUCCH resource mapping used by the second type of
UE.
[Claim 18]
In a wireless communications system that supports flexible-TDD (flexible-time division
duplex) UL-DL (uplink-downlink) configuration, the wireless communications system including
a first type of user equipment (UE) and a second type of UE, the second type of UE comprising:
transmitter to transmit to a base station a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal according to a DL association set,
wherein the DL association set comprises:
a first DL association set for a UL-DL TDD configuration used by the first type
of UE; and
a second DL association set for a reference UL-DL TDD configuration
including a third DL association set for PUCCH resource mapping used by the second type of
UE, and
wherein the first type of UE is configured with a first type of configuration and the
second type of UE is configured with a second type of configuration.
[Claim 19]
A wireless communications system that supports flexible-TDD (flexible-time division
duplex) UL-DL (uplink-downlink) configuration, the wireless communications system
comprising:
a base station to configure a first type of user equipment (UE) with a first type of
configuration and a second type of UE with a second type of configuration; and
a user equipment to transmit to the base station a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal according to a DL association set,
wherein the DL association set comprises:
a first DL association set for a UL-DL TDD configuration used by the first type
of UE; and
a second DL association set for a reference UL-DL TDD configuration
including a third DL association set for PUCCH resource mapping used by the second type of
UE.
[Claim 20]
A method implemented in a base station used in a wireless communications system that
supports flexible-TDD (flexible-time division duplex) UL-DL (uplink-downlink) configuration,
the method comprising:
receiving from a user equipment a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal,
wherein a HARQ-ACK bit set in the HARQ-ACK signal comprises:
a first part based on a last detected DL assignment index;
a second part generated by following a reference configuration; and
a third part for a semi-persistent scheduling (SPS) physical downlink shared
channel (PDSCH).
[Claim 21]
A method implemented in a user equipment used in a wireless communications system
that supports flexible-TDD (flexible-time division duplex) UL-DL (uplink-downlink)
configuration, the method comprising:
transmitting to a base station a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal,
wherein a HARQ-ACK bit set in the HARQ-ACK signal comprises:
a first part based on a last detected DL assignment index;
a second part generated by following a reference configuration; and
a third part for a semi-persistent scheduling (SPS) physical downlink shared
channel (PDSCH).
[Claim 22]
A method implemented in a wireless communications system that supports
flexible-TDD (flexible-time division duplex) UL-DL (uplink-downlink) configuration, the
method comprising:
transmitting from a user equipment to a base station a HARQ-ACK (hybrid automatic
repeat request-acknowledgement) signal,
wherein a HARQ-ACK bit set in the HARQ-ACK signal comprises:
a first part based on a last detected DL assignment index;
a second part generated by following a reference configuration; and
a third part for a semi-persistent scheduling (SPS) physical downlink shared
channel (PDSCH).
[Claim 23]
The method as in any of claims 20 to 22,
wherein the HARQ-ACK signal for dynamic PDSCH or physical downlink control
channel (PDCCH) for DL SPS release is set to either ACK (acknowledgement) or NACK
(negative acknowledgement) depending on a detection result, and
wherein, if there is no dynamic PDSCH or PDCCH for DL SPS release for one DL
downlink assignment index (DAI) value, the HARQ-ACK feedback is set to NACK.
[Claim 24]
A base station used in a wireless communications system that supports flexible-TDD
(flexible-time division duplex) UL-DL (uplink-downlink) configuration, the base station
comprising:
receiver to receive from a user equipment a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal,
wherein a HARQ-ACK bit set in the HARQ-ACK signal comprises:
a first part based on a last detected DL assignment index;
a second part generated by following a reference configuration; and
a third part for a semi-persistent scheduling (SPS) physical downlink shared
channel (PDSCH).
[Claim 25]
A user equipment used in a wireless communications system that supports flexible-TDD
(flexible-time division duplex) UL-DL (uplink-downlink) configuration, the user equipment
comprising:
a transmitter to transmit to a base station a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal,
wherein a HARQ-ACK bit set in the HARQ-ACK signal comprises:
a first part based on a last detected DL assignment index;
a second part generated by following a reference configuration; and
a third part for a semi-persistent scheduling (SPS) physical downlink shared
channel (PDSCH).
[Claim 26]
A wireless communications system that supports flexible-TDD (flexible-time division
duplex) UL-DL (uplink-downlink) configuration, the wireless communications system
comprising:
a base station; and
a user equipment to transmit to the base station a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal,
wherein a HARQ-ACK bit set in the HARQ-ACK signal comprises:
a first part based on a last detected DL assignment index;
a second part generated by following a reference configuration; and
a third part for a semi-persistent scheduling (SPS) physical downlink shared
channel (PDSCH).
[Claim 27]
A method implemented in a base station used in a wireless communications system that
supports flexible-TDD (flexible-time division duplex) UL-DL (uplink-downlink) configuration,
the method comprising:
receiving from a user equipment a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal,
wherein a first bit of a HARQ-ACK bit set in the HARQ-ACK signal is dedicated to
semi-persistent scheduling (SPS) physical downlink shared channel (PDSCH) HARQ-ACK not
depending on whether SPS is activated or not, and
wherein the HARQ-ACK bit set comprises:
a first part including one HARQ-ACK bit for SPS PDSCH; and
a second part for dynamic PDSCH or physical downlink control channel
(PDCCH) for DL SPS release.
[Claim 28]
A method implemented in a user equipment used in a wireless communications system
that supports flexible-TDD (flexible-time division duplex) UL-DL (uplink-downlink)
configuration, the method comprising:
transmitting to a base station a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal,
wherein a first bit of a HARQ-ACK bit set in the HARQ-ACK signal is dedicated to
semi-persistent scheduling (SPS) physical downlink shared channel (PDSCH) HARQ-ACK not
depending on whether SPS is activated or not, and
wherein the HARQ-ACK bit set comprises:
a first part including one HARQ-ACK bit for SPS PDSCH; and
a second part for dynamic PDSCH or physical downlink control channel
(PDCCH) for DL SPS release.
[Claim 29]
A method implemented in a wireless communications system that supports
flexible-TDD (flexible-time division duplex) UL-DL (uplink-downlink) configuration, the
method comprising:
transmitting from a user equipment to a base station a HARQ-ACK (hybrid automatic
repeat request-acknowledgement) signal,
wherein a first bit of a HARQ-ACK bit set in the HARQ-ACK signal is dedicated to
semi-persistent scheduling (SPS) physical downlink shared channel (PDSCH) HARQ-ACK not
depending on whether SPS is activated or not, and
wherein the HARQ-ACK bit set comprises:
a first part including one HARQ-ACK bit for SPS PDSCH; and
a second part for dynamic PDSCH or physical downlink control channel
(PDCCH) for DL SPS release.
[Claim 30]
A base station used in a wireless communications system that supports flexible-TDD
(flexible-time division duplex) UL-DL (uplink-downlink) configuration, the base station
comprising:
receiver to receive from a user equipment a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal,
wherein a first bit of a HARQ-ACK bit set in the HARQ-ACK signal is dedicated to
semi-persistent scheduling (SPS) physical downlink shared channel (PDSCH) HARQ-ACK not
depending on whether SPS is activated or not, and
wherein the HARQ-ACK bit set comprises:
a first part including one HARQ-ACK bit for SPS PDSCH; and
a second part for dynamic PDSCH or physical downlink control channel
(PDCCH) for DL SPS release.
[Claim 31]
A user equipment used in a wireless communications system that supports flexible-TDD
(flexible-time division duplex) UL-DL (uplink-downlink) configuration, the user equipment
comprising:
a transmitter to transmit to a base station a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal,
wherein a first bit of a HARQ-ACK bit set in the HARQ-ACK signal is dedicated to
semi-persistent scheduling (SPS) physical downlink shared channel (PDSCH) HARQ-ACK not
depending on whether SPS is activated or not, and
wherein the HARQ-ACK bit set comprises:
a first part including one HARQ-ACK bit for SPS PDSCH; and
a second part for dynamic PDSCH or physical downlink control channel
(PDCCH) for DL SPS release.
[Claim 32]
A wireless communications system that supports flexible-TDD (flexible-time division
duplex) UL-DL (uplink-downlink) configuration, the wireless communications system
comprising:
a base station; and
a user equipment to transmit to the base station a HARQ-ACK (hybrid automatic repeat
request-acknowledgement) signal,
wherein a first bit of a HARQ-ACK bit set in the HARQ-ACK signal is dedicated to
semi-persistent scheduling (SPS) physical downlink shared channel (PDSCH) HARQ-ACK not
depending on whether SPS is activated or not, and
wherein the HARQ-ACK bit set comprises:
a first part including one HARQ-ACK bit for SPS PDSCH; and
a second part for dynamic PDSCH or physical downlink control channel
(PDCCH) for DL SPS release.