DESCRIPTION
Title of Invention
METHOD FOR PHICH RESOURCE ALLOCATION
Technical Field
[0001]
The present invention relates to a method for PHICH resource allocation.
Background Art
[0002]
The following abbreviations may be found herein:
3GPP THIRD GENERATION PARTNERSHIP PROJECT
ACK ACKNOWLEDGEMENT
BW BANDWIDTH
CCE CONTROL CHANNEL ELEMENT
CRS CELL-SPECIFIC REFERENCE SIGNAL
DL DOWNL I K
DM-RS DEMODULATION REFERENCE SIGNAL
eNB (OR eNodeB) LTE BASE STATION
ARQ (OR H-ARO) HYBRID AUTOMATIC REPEAT REQUEST
ICIC INTER-CELL INTERFERENCE COORDINATION
IE INFORMATION ELEMENT
LTE LONG TERM EVOLUTION
LTE-A LONG TERM EVOLUTION ADVANCED
M lB MASTER INFORMATION BLOCK
NAC NEGATIVE ACKNOWLEDGEMENT
OFDM ORTHOGONAL FREQUENCY DIVISION MULTIPLEX
OFDMA ORTHOGONAL FREQUENCY DIVISION MULTIPLE ACCESS
PBCH PHYSICAL BROADCAST CHANNEL
PCFICH PHYSICAL CONTROL FORMAT INDICATOR CHANNEL
PDCCH PHYSICAL DOWNLINK CONTROL CHANNEL
PDSCH PHYSICAL DOWNL I K SHARED CHANNEL
PHICH PHYSICAL HARQ INDICATOR CHANNEL
PRB PHYSICAL RESOURCE BLOCK
PUSCH PHYSICAL UPLINK SHARED CHANNEL
RE RESOURCE ELEMENT
REG RESOURCE ELEMENT GROUP
TDD TIME DIVISION DUPLEX
UE USER EQUIPMEMT
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, 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.
Table 4.2-2: Uplink-downlink configurations
[0004]
In the table above, "D" indicates a DL subframe, "U" indicates an UL subframe and "S"
indicates a special subframe. The different UL-DL configurations in the table provide between
40% and 90% DL subframes, and in conventional practice the UL-DL configuration in use at an
eNB 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 or 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 (Rel. 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 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 improving PHICH resource allocation and
maintaining backward compatibility may help in this regard.
[0007]
Fig.l shows UE ACK/NACK procedure 100 (PUSCH transmission and PHICH
reception) in TDD system. As an example of the LTE timing rules specified in Rel. 11 and
illustrated in Fig. 1, one DL subframe may have the responsibility to send HARQ-ACK bits for 0,
1 or 2 UL subframe(s), depending on the adopted TDD configuration and DL subframe index.
For instance:
• If TDD configuration #0 is used, DL subframe #0 (101) in radio frame n is
responsible for sending HARQ-ACK for two UL subframes (105), namely UL
subframes #3 and #4 in radio frame h-G , and DL subframe # 1 (102) in radio frame
n is responsible for sending HARQ-ACK for one UL subframe, namely subframe
#7 (106) in radio frame 'h-I ' .
• If TDD configuration #2 is used, then DL subframe #0 (103) has no responsibility
for sending HARQ-ACK feedback for any UL transmission and, as a result, there is
no PHICH resource allocation on this DL subframe (103).
• If TDD configuration #3 is used, then DL subframe #0 (104) is responsible for
sending HARQ-ACK feedback for one UL subframe, namely subframe #4 (107).
• etc
[0008]
The PHICH resource allocation on each DL/Special subframe for each TDD
configuration is further illustrated in Fig. 2. The factor n¾ (as given by individual entries in the
table) indicates how many copies of PHICH resource are assigned on a given DL subframe in the
TDD system.
[0009]
In Rel. 8, 9, 10 and 1, PDCCH is transmitted on CCE which is made up by REs (or
REGs) not occupied by CRS, PCFICH and PHICH. The antenna port for CRS can be determined
by blind decoding of PBCH and REs used for PCFICH are predefined. Although PHICH
configuration can be determined from PHICH-Config via PBCH/MIB decoding, nevertheless for
TDD systems it is still not sufficient to determine how many REs (or REGs) are used for PHICH.
For example, for a configured DL system BW of 10 MHz, assuming Ng = 1/6, then NpHicHGroup
= 2, it is still necessary to know the factor m which depends on eNB configured UL-DL
configuration in order to further determine the exact number of REs (or REGs) occupied by
PHICH resource.
[0010]
The value of m is related to TDD configuration and DL subframe index. As a result, in
order to figure out the REs used for PHICH and thus determine the REs (or REGs) that are
carrying PDCCH(s), the TDD configuration should be determined first. However, TDD
configuration is transmitted in SIB1 via PDCCH with an associated PDSCH and the problem
becomes tricky because the index of TDD configuration is needed in order to decode PDCCH
with an associated PDSCH which contains the index of TDD configuration. This is therefore a
"chicken-egg" problem. One way to solve this problem, as was agreed in the standardization
meeting, is that a UE should perform blind decoding by assuming on a particular subframe the
possible value of m, in order to get the TDD configuration, and start to use the detected TDD
configuration to decode other PDCCH.
[0011]
Fig.3 shows PDCCH blind decoding and PHICH resource assignment 300. As
illustrated in Fig. 3, for different TDD configurations/DL subframes, the REG available for
PDCCH transmission may be different, although PHICH configuration PHICH-Config stays the
same
• Case 1: No PHICH resource assignment, m = 0
4 REGs (301) are used for PCFICH transmission, all other REGs can be used for
PDCCH transmission
• Case 2: PHICH resource assignment for one UL subframe, m = 1
Beside the 4 REGs used for PCFICH transmission, another 6 REGs (302) are used
for PHICH transmission, and the remaining REGs can be used for PDCCH
transmission
• Case 3: PHICH resource assignment for two UL subframes, ¾= 2
6 additional REGs are used for PHICH transmission, and the remaining REGs can
be used for PDCCH transmission.
[0012]
From the above example, it can be appreciated that if a UE has an incorrect
understanding of the m, value (which is determined by TDD configuration and subframe index),
or PHICH resource is not assigned according to factor m, known by the UE, then the UE will
have an incorrect understanding of CCE to REG mapping and will fail to decode PDCCH.
Summary of Invention
Technical Problem
[0013]
In flexible-TDD systems, it is highly likely that the TDD configuration of legacy UEs
will not be the same as the TDD configuration used by flexible-TDD UEs. If PHICH resource
is assigned to flexible-TDD UEs by following factor ¾related to TDD configuration of
flexible-TDD UEs, then legacy UEs will have problem in decoding PDCCH. It would be
desirable to maintain backward compatibility in flexible-TDD systems while sending
HARQ-ACK for UL transmission.
[0014]
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.
Solution to Problem
[0015]
In one form, the present invention relates broadly to a method for PHICH resource
allocation (or a method for resource allocation for the transmission of PUSCH HARQ-ACK
feedback) in a wireless communication system that supports a flexible TDD UL-DL
configuration and in which different TDD UL-DL configurations are available and the TDD
UL-DL configuration used by first UEs which operate according to the flexible TDD
configuration can be different to the TDD UL-DL configuration used by second UEs which
operate according to a long term TDD UL-DL configuration, the method comprising allocating
PHICH resources for both first UEs and second UEs according to LTE timing rules applicable to
the TDD UL-DL configuration in use by second UEs. Generally, the first UEs will be
flexible-TDD UEs (e.g. Rel. 12 & beyond UEs) and the second UEs will be legacy UEs (e.g. Rel.
8, , 10 or 11 UEs), and the term 'first UEs' and 'second UEs' may be understood accordingly in
the following description.
[0016]
In the form of the invention described in the previous paragraph, the method may also
include, determining that PHICH resource is allocated for second UEs with factor m = 2,
determining that HARQ-ACK for only one UL subframe should be fed back for first UEs, and
allocating PHICH resource with IPHICH
= 1 for first UEs. The method may further include
determining that PHICH resource is assigned for second UEs with factor = , determining that
HARQ-ACK for two UL subframes should be fed back, and allocating the assigned PHICH
resource with IPHICH
= 1 for first UEs to accommodate PUSCH HARQ feedback for the second
subframe.
[0017]
In another form, the present invention relates broadly to a method for PHICH resource
allocation (or a method for resource allocation for the transmission of PUSCH HARQ-ACK
feedback) in a wireless communication system that supports a flexible TDD UL-DL
configuration and in which different TDD UL-DL configurations are available and the TDD
UL-DL configuration used by first UEs which operate according to the flexible TDD
configuration can be different to the TDD UL-DL configuration used by second UEs which
operate according to a long term TDD UL-DL configuration, the method involving, for a given
subframe of a radio frame:
determining that the subframe is not a DL subframe in both the TDD UL-DL
configuration in use by first UEs and the TDD UL-DL configuration in use by second UEs,
determining that the subframe is a DL subframe in the TDD UL-DL configuration in use
by first UEs but an UL subframe in the TDD UL-DL configuration in use second UEs, and
allocating PHICH resource according to LTE timing rules applicable to the TDD UL-DL
configuration in use by first UEs.
[0018]
In the form of the invention described in the previous paragraph, the method may also
include, determining that said given subframe is a DL subframe in the TDD UL-DL
configuration in use by first UEs and also in the TDD UL-DL configuration in use by second
UEs, determining that a PHICH resource is not required (in the TDD UL-DL configuration in
use) by second UEs for said subframe, and allocating no PHICH resource to the subframe. The
method may further include, for said subframe, determining that a PHICH resource is required
(in the TDD UL-DL configuration in use) by first UEs, calculating the PHICH resource required
for sending PUSCH HARQ-ACK or remaining PUSCH HARQ-ACK, and allocating the PHICH
resource for transmission thereof via ePHICH IE if available and enabled or via UL grant if
ePHICH IE is not available or not enabled.
[0019]
The method may further include determining that a PHICH resource is required (in the
TDD UL-DL configuration in use) by second UEs for said given subframe, determining that
PHICH resource is not required (in the TDD UL-DL configuration in use) by first UEs, and
allocating the PHICH resource according to the LTE timing rules applicable to the TDD UL-DL
configuration in use by second UEs.
[0020]
The method may further include determining that a PHICH resource is required (in the
TDD UL-DL configuration in use) by first UEs for said subframe, determining that the PHICH
resource required (in the TDD UL-DL configuration in use) by second UEs is not less than that
required (in the TDD UL-DL configuration in use) by first UEs, determining that the PHICH
resource required (in the TDD UL-DL configuration in use) by second UEs is not more than that
required (in the TDD UL-DL configuration in use) by first UEs, and allocating the PHICH
resource according to the LTE timing rules applicable to the TDD UL-DL configuration in use
by second UEs.
[0021]
The method may further include determining that the PHICH resource required (in the
TDD UL-DL configuration in use) by second UEs in said subframe is more than that required (in
the TDD UL-DL configuration in use) by first UEs for said given subframe, allocating PHICH
resource according to the LTE timing rules applicable to the TDD UL-DL configuration in use
by second UEs, and allocating PHICH resource with IPHICH
= 1 for first UEs.
[0022]
The method may further include determining that the PHICH resource required (in the
TDD UL-DL configuration in use) by second UEs in said subframe is less than that required (in
the TDD UL-DL configuration in use) by first UEs, allocating the PHICH resource according to
the LTEtiming rules applicable to the TDD UL-DL configuration in use by second UEs, and
allocating the PHICH resource for first UEs to accommodate HARQ-ACK for associated UL
subframe(s) that have PUSCH HARQ-ACK timing aligned with that of second UEs.
[0023]
The method may further include, for said given subframe, calculating the PHICH
resource required for sending PUSCH HARQ-ACK or remaining PUSCH HARQ-ACK of first
UEs, and allocating PHICH resource for transmission thereof via ePHICH IE if this is available
and enabled or via UL grant if ePHICH IE is not available or not enabled.
[0024]
In another form, the present invention relates broadly to a wireless communication
system including a base station, first UEs and second UEs, wherein the wireless communication
system supports a flexible TDD UL-DL configuration, different TDD UL-DL configurations are
available and the TDD UL-DL configuration used by the first UEs which operate according to
the flexible TDD configuration can be different to the TDD UL-DL configuration used by the
second UEs which operate according to a long term TDD UL-DL configuration, and wherein the
base station is operable to perform the method for PHICH resource allocation as described in the
various forms of the invention above.
[0025]
In another form, the present invention relates broadly to a base station operable for use
in a wireless communication system that supports a flexible TDD UL-DL configuration and in
which different TDD UL-DL configurations are available and the TDD UL-DL configuration
used by first UEs which operate according to the flexible TDD configuration can be different to
the TDD UL-DL configuration used by second UEs which operate according to a long term TDD
UL-DL configuration, and wherein the base station is operable to perform a method as described
in the various method forms of the invention above.
[0026]
In another form, the present invention relates broadly to a method for use by first UEs
for PUSCH HARQ-ACK and PHICH signalling (or a method for reception of PUSCH
HARQ-ACK for use by UEs) in a wireless communication system that supports flexible TDD
UL-DL configuration and in which different TDD UL-DL configurations are available and the
TDD UL-DL configuration used by the first UEs which operate according to the flexible TDD
configuration can be different to the TDD UL-DL configuration used by second UEs which
operate according to a long term TDD UL-DL configuration, the method involving, for a given
flexible DL subframe of a radio frame in the TDD UL-DL configuration in use by the first UEs:
determining that the corresponding subframe in the TDD UL-DL configuration in use
by the second UEs is not a DL subframe,
determining that the given DL subframe in the TDD UL-DL configuration in use by the
first UEs is to carry PUSCH HARQ-ACK, and
monitoring for PHICH allocation according to LTE timing rules applicable to the TDD
UL-DL configuration in use by first UEs.
[0027]
In the form of the invention described in the previous paragraph, the method may
further include, determining that the corresponding subframe in the TDD UL-DL configuration
in use by the second UEs is a DL subframe, determining that said corresponding subframe in the
TDD UL-DL configuration in use by the second UEs is not allocated PHICH resource according
to the LTE timing rules applicable to the TDD UL-DL configuration in use by the second UEs,
determining that the given DL subframe in the TDD UL-DL configuration in use by the first UEs
is to carry PUSCH HARQ-ACK, and performing the following on the subframe:
UL grant monitoring for HARQ-ACK corresponding to previously sent PUSCH, if
ePHICH is not configured;
ePHICH monitoring for HARQ-ACK corresponding to previously sent PUSCH, if
ePHICH is configured; and
PDCCH(s) monitoring taking into account the number of REs allocated for PHICH for
second UEs.
[0028]
The method may further include, for the given flexible DL subframe, determining that
said corresponding subframe in the TDD UL-DL configuration in use by the second UEs is
allocated PHICH resource according to the LTE timing rules applicable to the TDD UL-DL
configuration in use by the second UEs, determining that the PHICH resource required (in the
TDD UL-DL configuration in use) by second UEs is not less than that required (in the TDD
UL-DL configuration in use) by first UEs, determining that the PHICH resource required (in the
TDD UL-DL configuration in use) by second UEs is not more than that required (in the TDD
UL-DL configuration in use) by first UEs, and performing PHICH monitoring according to the
LTE timing rules applicable to the TDD UL-DL configuration in use by second UEs and
performing PDCCH(s) monitoring taking into account the number of REs allocated for PHICH
for second UEs.
[0029]
The method may further include, for the given flexible DL subfrarne, determining that
the PHICH resource required (in the TDD UL-DL configuration in use) by second UEs is more
than that required (in the TDD UL-DL configuration in use) by first UEs, and performing
PHICH monitoring with IPHICH
= 1 and performing PDCCH(s) monitoring taking into account the
number of REs allocated for PHICH for second UEs.
[0030]
The method may further include, for the given flexible DL subfrarne, determining that
the PHICH resource required (in the TDD UL-DL configuration in use) by second UEs is less
than that required (in the TDD UL-DL configuration in use) by first UEs, and performing on the
subfrarne:
PHICH monitoring for HARQ-ACK of associated UL subframe(s) having PUSCH
HARQ-ACK timing aligned with that of the TDD UL-DL configuration in use by second UEs,
UL grant monitoring for HARQ-ACK of associated UL subframe(s) that is/are not
included in the PHICH of second UEs, if ePHICH is not configured,
ePHICH monitoring for HARQ-ACK of associated UL subframe(s) that is/are not
included in the PHICH of second UEs, if ePHICH is configured,
PDCCH(s) monitoring taking into account the number of REs allocated for PHICH for
second UEs.
[0031]
In another form, the invention relates broadly to a mobile station operable for use as a
first UE in a wireless communication system that supports a flexible TDD UL-DL configuration
and in which different TDD UL-DL configurations are available and the TDD UL-DL
configuration used by first UEs which operate according to the flexible TDD configuration can
be different to the TDD UL-DL configuration used by second UEs which operate according to a
long term TDD UL-DL configuration, and wherein the mobile station is operable to perform the
method for PUSCH HARQ-ACK and PHICH signalling for use by first UEs as described above.
[0032]
In another form, the invention relates broadly to a method for use in ePHICH mapping
in a wireless communication system that supports a flexible TDD UL-DL configuration and in
which different TDD UL-DL configurations are available and the TDD UL-DL configuration
used by first UEs which operate according to the flexible TDD configuration can be different to
the TDD UL-DL configuration used by second UEs which operate according to a long term TDD
UL-DL configuration, the method comprising using a subset of spare bits out of a set of spare
bits in a master information block (MIB) for ePHICH configuration. Preferably, the method
comprises using three out of ten spare bits in a MIB for ePHICH configuration.
[0033]
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
[0034]
According to the present invention, it is possible to provide a flexible TDD wireless
communication systems.
Brief Description of Drawings
[0035]
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:
[Fig. l ]
Fig. 1 illustrates UE ACK ACK procedure (PUSCH transmission and PHICH
reception) in a TDD system. In other words, Fig. 1 helps to illustrate the operation of the LTE
timing rules for PUSCH HARQ-ACK feedback according to TDD UL-DL configuration and
subframe number.
[Fig. 2]
Fig. 2 contains a table with the factor h¾for different subframes in different UL-DL
configurations.
[Fig. 3]
Fig. 3 contains three illustrations corresponding to the example given with reference to
Case 1, Case 2 and Case 3 respectively in the Background section above.
[Fig. 4]
Fig. 4 is a schematic illustration of a flexible-TDD wireless communication system.
[Fig- 5]
Fig. 5 contains illustrations corresponding to different example situations which are
used to explain the operation of the invention (or at least embodiments of the invention) in such
situations.
[Fig. 6]
Fig. 6 contains illustrations corresponding to different example situations which are
used to explain the operation of the invention (or at least embodiments of the invention) in such
situations.
[Fig. 7]
Fig. 7 contains illustrations corresponding to different example situations which are
used to explain the operation of the invention (or at least embodiments of the invention) in such
situations.
[Fig. 8]
Fig. 8 contains illustrations corresponding to different example situations which are
used to explain the operation of the invention (or at least embodiments of the invention) in such
situations.
[Fig. 9]
Fig. 9 contains illustrations corresponding to different example situations which are
used to explain the operation of the invention (or at least embodiments of the invention) in such
situations.
[Fig. 10]
Fig. 10 contains illustrations corresponding to different example situations which are
used to explain the operation of the invention (or at least embodiments of the invention) in such
situations.
[Fig. 11]
Fig. 11 contains illustrations corresponding to different example situations which are
used to explain the operation of the invention (or at least embodiments of the invention) in such
situations.
[Fig. 12A]
Fig. 1 A contains a flow chart illustrating a method for resource allocation for the
transmission of PUSCH HARQ-ACK feedback according to an embodiment of the invention.
[Fig. 12B]
Fig. 12B contains the flow chart illustrating a method for resource allocation for the
transmission of PUSCH HARQ-ACK feedback according to an embodiment of the invention.
The method represented by the flow chart in Fig. 12A and Fig. 12B may be performed by a base
station/eNB.
[Fig. 13A]
Fig. 3A contains a flow chart illustrating a method for the reception of PUSCH
HARQ-ACK which may be used by UEs that operate according to the flexible TDD
configuration (i.e. by first UEs such as, e.g., Rel. 12 & beyond UEs) according to an embodiment
of the invention.
[Fig. 13B]
Fig. 13B contains the flow chart illustrating a method for the reception of PUSCH
HARQ-ACK which may be used by UEs that operate according to the flexible TDD
configuration (i.e. by first UEs such as, e.g., Rel. 12 & beyond UEs) according to an embodiment
of the invention.
[Fig. 14]
Fig. 1 helps to illustrate/explain a method for use in ePHICH mapping.
[Fig. 15]
Fig. 15 helps to illustrate/explain a method for use in ePHICH mapping.
[Fig. 16]
Fig. 16 helps to illustrate/explain a method for use in ePHICH mapping.
Description of Embodiments
[0036]
Explanations will hereafter be given with reference to, and in the context of, wireless
communication systems that support Flexible-TDD UL-DL configuration, an example of which
is shown schematically in Fig. 4. The wireless communication system (400) depicted in Fig. 4
consists of a Rel. 12 & beyond eNB (401) which is backward compatible with previous releases
such as Rel. 8, Rel. 9, Rel. 10 and Rel. 11. The eNB (401) provides wireless connectivity,
network access and coverage for second/legacy UE(s) (403) as well as Rel. 12 & and beyond (i.e.
"first") UE(s) (404). The eNB (401) further 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 UE(s) (403) and Rel. 12 & beyond
UE(s) (404) respectively, and a "PHICH resource mapping and HARQ feedback" function
(402BIS) which takes into consideration the existence of legacy UE(s) operating within eNB
(401) coverage and assigns PHICH resource that ensures no impact on legacy UE performance.
[0037]
The eNB (401 will broadcast long term "TDD UL-DL configuration" to both legacy
UE(s) (403) and Rel. 12 & beyond UE(s) using SIBl (System Information Block type 1) (406).
The TDD UL-DL configuration transmitted on SIBl is considered "long term" configuration as
the period for SIBl update is the order of 640ms. The eNB (401) will also communicate "short
term" TDD UL-DL configuration but only to Rel. 12 & beyond UE(s) (404) using a fast
signalling approach and the period for TDD UL-DL configuration update can be as little as 10ms
(i.e. radio frame basis). The eNB (401) will also transmit PHICHs on subframes that are
determined by the "PHICH resource mapping and HARQ feedback" function (402BIS).
[0038]
In addition to performing the reception and use of TDD UL-DL configuration
broadcasted on SIBl, a Rel. 12 & beyond UE(s) (404) that operates within coverage of Rel. 12 &
beyond eNB (401) will further comprise TDD reconfiguration processing function (405) which
detects short term UL-DL configuration information (407). This function (405) will also perform
PDSCH H-ARQ encoding and selection of the appropriate UL subframe(s) for sending PDSCH
H-ARQ feedback to eNB (401). This function (405) will also perform the determination of DL
subframe on which it will monitor for its UL grant for the transmission of UL-SCH. The function
(405) further includes function (405BIS) which determines the required PHICH resource and DL
subframe on which it will receive H-ARQ-ACK corresponding to UL-SCH that it sends in
previously granted UL-subframe(s) using configured PHICH resource or/and UL grant or
configured ePHICH resource.
[0039]
For legacy UE(s) (403) operating within the Rel. 12 & beyond eNB (401) range, it/these
shall use TDD UL-DL configuration broadcasted on SIBl and operate according to the legacy
specifications that it/they complies to. The eNB (401) may not schedule legacy UE(s) (403) to
perform reception of PDSCH(s) or transmission of PUSCH(s) on the "flexible subframes".
[0040]
Embodiments of the invention may concern, inter alia, one or more of a method for
PHICH/ePHICH resource allocation and in particular for determining appropriate physical
resources including PHICH, UL Grant, and ePHICH for sending of PUSCH HARQ-ACK (408),
a procedure that may be implemented as eNB's PHICH resource mapping and HARQ feedback
function (402BIS) for the correct selection of physical resources for the transmission of PUSCH
HARQ-ACK ensuring no impact on legacy UE operating within eNB (401) coverage, and a
procedure that may be implemented as the Rel. 12 & beyond UE PHICH information processing
function (405BIS) for the correct reception PUSCH HARQ-ACK and processing of PHICH.
Fig. 4 also shows PUCCH/ PUSCH carries HARQ-ACK feedback for PDSCH or PDCCH
indication SPS release (409).
[0041]
Reference configuration selection for UL-SCH HARQ timing
[0042]
As legacy UE(s) have no knowledge of the Flexible-TDD system in use, PHICH
resource assignment in embodiments of the invention will generally follow the TDD
configuration used by legacy UE(s), at least on fixed DL subframes. This may help to ensure that
there is no performance impact on legacy UE(s) with regard to the reception of PHICH(s) and
PDCCH(s) intended for it/them.
[0043]
For example, in Fig. 5 (Fig. 5 shows resource assignment 500), configuration #3 is
configured for legacy UE(s) and by following the LTE timing rules for configuration #3, the
HARQ-ACK bits for UL subframe #4 (501) in radio frame #n is transmitted on DL subframe #0
(502) in radio frame #(n+l). Simultaneously, there exists a flexible-TDD UE with configuration
#0. By following the Rel. 8 LTE timing rule for configuration #0, DL subframe #0 (502) in radio
frame #(n+l) is configured to transmit HARQ-ACK for two UL subframes, namely subframes
#3 (503) and #4 (504) in radio frame #n for flexible-TDD UE. If factor m = 2 is used for PHICH
resource assignment to accommodate HARQ-ACK for the two UL subframes (subframes #3 and
#4), then more REGs should be occupied by PHICH(s) and more importantly, this is unknown to
the legacy UE which is configured with UL-DL configuration #3. As a result, the legacy UE will
include REGs used for additional PHICH Group(s) in the PDCCH blind decoding process and
will never succeed in PDCCH blind decoding intended for it.
[0044]
Therefore, if the PHICH resource required for the legacy system (i.e. required by legacy
UEs) is less than that for the concurrent flexible-TDD system (flexible TDD UEs), no more
PHICH resource is assigned by the eNB, and the eNB should decide how the existing PHICH
resource can be used by flexible-TDD UE in the manner discussed below.
[0045]
Referring to Fig. 6 (Fig. 6 shows resource assignment 600), the legacy UE is configured
with configuration #5 and the flexible-TDD UE is configured with configuration #0. According
to the Rel. 8 LTEtiming rule for UL-DL configuration #5, for legacy UE, DL subframe #0 (603)
is not allocated for HARQ-ACK transmission for any UL transmission using PHICH resource.
For flexible-TDD UE though, if the LTE timing rule of UL-DL configuration #0 is followed,
then DL subframe #0 should be configured for sending HARQ-ACK for two UL subframes,
namely subframe #3 (601) and subframe #4 (602). This would cause the legacy UE to miss its
intended PDCCH(s) decoding because it understands that no PHICH RE(s) are allocated on the
current subframe. Therefore, in order to achieve backward compatibility, no PHICH resource is
assigned on PDCCH region for the flexible-TDD UE.
[0046]
Thus, there is no PHICH resource assignment even when flexible TDD UEs require it.
In this case, the eNB should send ACK NAC in the manner discussed below and the flexible
TDD UE should be aware of the method to be used.
[0047]
Referring now to Fig. 7 (Fig. 7 shows resource assignment 700), as another example,
the legacy UE is configured with TDD UL-DL configuration #0 and flexible-TDD UE is
configured with TDD UL-DL configuration #4. It is possible that the transmission direction of
subframe #4 (702) follows the direction of the flexible-TDD system and is used as DL subframe
(704), however, PHICH resource for subframe #4 (702) is still assigned in subframe #0 (705)
according to timing rule of UL-DL configuration #0 to guarantee no impact on legacy UE
PDCCH decoding (Subframe #3 (701) is same as subframe #3 (601).). Furthermore, since the
UL HARQ-ACK for UL transmission of the flexible-TDD UE in UL subframe #3 (703) is
transmitted in DL subframe #9 by following the timing rule defined for UL-DL configuration #4,
PHICH resource for UL subframe #3 in DL subframe #0 (705) is over allocated in order to
maintain backward compatibility i.e. allowing the legacy UE to correctly performing PDCCH(s)
intended for its use. Thus, the PHICH resource is reserved for the legacy system even when
there is no UL transmission on the associated subframe.
[0048]
PHICH resource selection for flexible-TDD UE with PHICH resource assigned
according to factor mi= 2
[0049]
In Fig. 8 (Fig. 8 shows resource assignment 800), the legacy UE is configured with
TDD UL-DL configuration #0 and the flexible-TDD UE is configured with UL-DL configuration
#6. By following the LTE timing rule defined for UL-DL configuration #0, the factor m,= 2 is
used for PHICH resource assignment and HARQ-ACK for UL subframe #3 (801) and UL
subframe #4 (802) in radio frame #n are send on DL subframe #0 (803) in radio frame # (n+1).
In this example, DL subframe #0 (803) in radio frame # (n+1) may also be responsible to send
HARQ-ACK for one UL subframe, namely #4 (804) in radio frame #n by following timing rule
defined for UL-DL configuration #6. As there are two copies of PHICH resource assigned by
factor mi= 2, which of the copies of PHICH resource is allocated and used by flexible-TDD UEs
should be decided and understood by flexible TDD UEs.
[0050]
The straight forward solution in this case is to use PHICH resource related to IPHICH= 0.
However, legacy UE on UL subframe #3 and flexible-TDD UE on UL subframe #4 both can
have the same first PRB (Physical Resource Block) for UL transmission and the probability of
PHICH collision may be increased. Instead of that, using PHICH resource related to IPHICH
= 1
for flexible TDD UE may be more promising since legacy UE and flexible-TDD UE on the same
UL subframe cannot use the same first PRB for UL transmission and thus PHICH collision can
be more controllable.
[0051]
In reference to Fig. 9 (Fig. 9 shows resource assignment 900) as another example, the
legacy UEs use the same configuration #0 and the same parameters for PHICH resource
assignment as in Fig. 8. Flexible-TDD UEs are configured with TDD configuration # 1 and
follow a reference configuration #0 for HARQ-ACK timing. As a result, the HARQ-ACK for
UL subframe #3 (904) in radio frame #n is sent on DL subframe #0 (903) in radio frame #(n+l)
rather than on DL subframe #9 (905) in radio frame #n. Similar to the example depicted in Fig. 8,
as there are two copies of PHICH resource assigned by factor n¾= 2, the copy of PHICH
resource allocated to and used by flexible-TDD UEs should be decided and understood by the
flexible TDD UEs.
[0052]
The first option is that PHICH resource related to IPHICH
= 0 should be used by
flexible-TDD UEs because the same first PRB index cannot be used by two UEs on the same UL
subframe. However, it is worth mentioning that , for example, subframe #4 (902) in radio
frame #n has higher chance than subframe #3 (901) in radio frame #n of being configured as a
DL subframe by flexible-TDD system and thus the PHICH resources assigned for IPHICH
= 1 are
never used by legacy UE. From the perspective of alleviating PHICH resource collision, it may
therefore be beneficial to map HARQ-ACK of UL subframe #3 (904) of flexible-TDD UE to
PHICH resource related to IPHICH= 1 (the second copy of PHICH resource, as illustrated in (303)
of Fig. 3). Fig. 9 also shows subframe #4 (906).
[0053]
Therefore, feedback HARQ-ACK on PHICH resource associated with IPHICH
= 1 can be
served as a unified solution for different cases. Otherwise, case specific solutions need to be
applied.
[0054]
HARQ-ACK transmission for UL transmission in DL subframe with PHICH
resource assigned according to factor mi=l and flexible-TDD UE HARQ-ACK feedback for
two UL subframes
[0055]
In reference to Fig. 10 (Fig. 10 shows resource assignment 1000), Flexible-TDD UE
should feedback HARQ-ACK for two UL subframes: subframe #3 (1001) and subframe #4
(1002) in radio frame #n, and PHICH resource is assigned according to factor m = 1 to ensure
backward compatibility. The HARQ-ACK of only one UL subframe is allowed for
transmission on PHICH, but there is a need for HARQ-ACK of two UL subframes to be
transmitted. It would be more promising to send HARQ-ACK for UL subframe #4 (1002) in
radio frame #n rather than UL subframe #3 (1001) in radio frame #n for the sake of not
increasing the probability of PHICH resource collision. The HARQ-ACK for the remaining UL
subframe that cannot be transmitted using the reference configuration (e.g. subframe #3 (1001)
in radio frame #n), can be transmitted via UL grant or ePHICH in the same subframe. The
HARQ-ACK for UL subframe #4 (1004) in radio frame #n is sent on DL subframe #0 (1003) in
radio frame #(n+ 1).
[0056]
UL-HARQ feedback in one DL subframe without PHICH resource for
flexible-TDD system
[0057]
In reference to Fig. 11 (Fig. 1 1 shows resource assignment 1100), there is no PHICH
resource assignment on DL subframe #0 (1103) in radio frame #(n+l) by following the timing
rule defined for UL-DL configuration # 1 configured for legacy UE, but flexible-TDD system
with the configured UL-DL configuration #0 needs to feedback HARQ-ACK for one/two UL
subframe(s). In this case, the HARQ-ACK can be sent via UL grant implicitly, or on ePHICH
explicitly. DL subframe #0 should be configured for sending HARQ-ACK for two UL
subframes, namely subframe #3 (1101) and subframe #4 (1102) in Fig. 11. Fig. 11 also shows
subframe #2 (1104).
[0058]
Thus, an illustration of the procedure which may be implemented within a base station
such as eNB (401) in Fig. 4 as "eNB's PHICH resource mapping and HARQ feedback" function
(402BIS) for the correct selection of physical resources for the transmission of PUSCH
HARQ-ACK ensuring no impact on legacy UE operating within eNB (401) coverage is given in
the flowchart in Fig. 12Aand Fig. 12B.
[0059]
Similarly, a corresponding procedure which may be implemented at/in a mobile station
(UE) such as Rel. 12 & beyond UE (404) in Fig. 4 as "Rel. 12 & beyond (i.e. first) UE PHICH
information processing function (405BIS) for the correct reception PUSCH HARQ-ACK and
processing of PHICH is given in the flowchart shown in Fig. 13A and Fig. 13B.
[0060]
Following on from the embodiments of the invention discussed above, a related issue
concerns the design of ePHICH resource mapping. In particular, it may be possible for
ePHICH to be implemented using a backward compatible carrier where PDCCH region/PHICH
is still reserved for legacy UE. In this regard, 3-bits in MIB may be used to indicate the
semi-static ePHICH configuration in Rel. 11. Hence, if ePHICH and PHICH can be configured
at the same time, 3-bits out of 10 spare bits in MIB can be used to indicate the ePHICH
configuration. The N(group, PHICH) calculation, modulation and coding method may be
reused.
[0061]
The mapping of ePHICH on PRB is unknown to the legacy UE, and therefore the legacy
UE should not be scheduled on PRB used for ePHICH transmission, otherwise, the performance
of PDSCH will degrade. Also, for the sake of reducing the scheduling limitation of legacy UE
and frequency domain ICIC, ePHICH should be assigned on a limited number of PRBs. On the
other hand, ePHICH should also be distributed across DL bandwidth in order to achieve
frequency diversity gain. Therefore a mapping method similar to Rel. 11 can be adopted.
[0062]
Described below are about 11 steps for ePHICH resource mapping. For the purposes
of explanation, let
(1) : w ( + 2),y M (4i +3)} (i=0,l,2)
denote symbol quadruplet i for antenna port p. Mapping to resource elements may be defined
in terms of symbol quadruplets according to the following steps:
[0063]
1. Mapping of REG
[0064]
Four consecutive REs in PRBs used for ePHICH but not used for DM-RS, CSI-RS or
CRS form one REG.
[0065]
In reference to Fig. 14 (Fig. 14 shows mapping 1400), CRS is configured, and
accordingly there are two REGs (1401) and (1402) in OFDM symbol #4, two REGs (1403) and
(1404) in OFDM symbol #7 and two REGs (1405) and (1406) in OFDM symbol #11. There are
therefore a total of 6 REGs in one PRJB for ePHICH (i.e. RBEREG = 6) with the presence of CRS.
[0066]
In reference to Fig. 15 (Fig. 5 shows mapping 1500), CRS is not configured, and
accordingly there are 3 REGs (1501), (1502) and (1503) in OFDM symbol #4, 3 REGs (1504),
(1505) and (1506) in OFDM symbol #7 and 3 REGs (1507), (1508) and (1509) in OFDM
symbol #11. There are therefore a total of 9 REGs in one PRB for ePHICH (i.e. NRBeREG )
without the presence of CRS.
[0067]
For special subframe, because of the limited number of DL symbols on DL subframe,
ePHICH is mapped to OFDMA symbol #4, #7, #8 rather than #4, #7, # 11 in normal DL subframe.
The mapping pattern is similar to OFDMA #4 and #7 (with only two REGs on one OFDMA
symbol of one PRB when CRS is configured), although CRS is not configured on OFDMA
symbol #8.
[0068]
2. Determine the PRBs used for ePHICH
[0069]
Based on PHICH configuration (and additional parameter m in TDD system) and the
value of NRB 6REG, the UE can determine the number of PRB used for PHICH, and the calculation
of PRB number for ePHICH can be expressed as follows:
[0070]
For example, assu on
(3) : group NPHICH ~
(In the equation (3), the upper is for normal cyclic prefix, and the lower is for extended cyclic
prefix.)
[0071]
One ePHICH group takes 12 RE = 3 REGs.
[0072]
If CRS is configured, one PRB can provide 6 eREG for ePHICH and eREG belongs to
the same PRB cannot be assigned to the same ePHICH group in order to achieve diversity gain.
As a result, at least 3 PRBs are heeded.
[0073]
3. Determine the location of PRBs for ePHICH
[0074]
As mentioned above, PRBs used for ePHICH should be distributed on DL bandwidth in
order to achieve frequency diversity gain. The location of PRB for ePHICH also depends on a
cell-specific value offset eii-x in order to achieve frequency domain ICIC. The index of PRB
used by cell-x for ePHICH can be determined by
[0075]
In reference to Fig. 16 (Fig. 16 shows mapping 1600), assuming ep cH = 3, NRBD =:
6 and offsetceii-x R = 0, then the PRB indexes for these 3 PRBs are {0 ( 1601), 2 ( 1602), 4
(1603)} respectively.
[0076]
4. Indexing REG for ePHICH
[0077]
Let denote the number of resource element groups for ePHICH in OFDM symbol .
[0078]
Number the resource-element groups not assigned to PCFICH in OFDM symbol from
0 to ni'-l, starting from the resource-element group with the lowest frequency-domain index.
[0079]
5. Initialize m'=0 (PHICH mapping unit number)
[0080]
6. For each value of i=0,l,2
[0081]
7. Symbol-quadruplet z p (i) from ePHICH mapping unit m' is mapped to
the resource-element group represented by (k',l')i where the indices k ' and
li' are given by steps 8 and 9 below:
[0082]
domain index ' is given by
(In the equation (6), when lj' equals 8 or 11, for special subframe lj' equals 8, and for normal
subframe lj' equals 11. In the equation (7), the upper is for normal PHICH duration , all
subframes, and the lower is for otherwise (Extended duration).
[0083]
and offsetCeii-xS is the time domain offset of ePHICH resource for cell-x.
[0084]
9. Set the frequency-domain index kj' to the resource-element
group assigned the number
in step 4 above, where the number (8) is given by
and, offsetceii-xS is the frequency domain offset of ePHICH resource
for cell-x.
[0085]
In reference to Fig. 16, assuming offsetcdi-xS m = 0 and offset Ceii-xfreq = 0
If normal duration is configured
REG #0 (1604), REG #2 (1610) and REG #4 (1616) in OFDMA symbol #4 are used for
ePHICH group #0.
REG #0 (1605), REG #2 (1611) and REG #4 (1617) in OFDMA symbol #7 are used for
ePHICH group #1.
Cell with
can use other REGs, for instance.
If offset Ceii-yS = 0 and offset ceii-yfreq = 1 is configured for cell-y
REG # 1 (1609), REG #3 (1615) and REG # 5 (1621) in OFDMA symbol #4 are used for
ePHICH group #0.
REG # 1 (1608), REG #3 (1614) and REG #5 (1620) in OFDMA symbol #7 are used for
ePHICH group #1.
If extended duration is configured
REG #0 (1604) in OFDMA symbol #4, REG #2 (161 1) in OFDMA symbol #7 and REG
#4 (1618) in OFDMA symbol #11 are used for ePHICH group #0.
REG #0 (1605) in OFDMA symbol #7, REG #2 (1612) in OFDMA symbol #11 and
REG #4 (1616) in OFDMA symbol #4 are used for ePHICH group #0.
Similarly, for Cell with
can used other REGs for ePHICH.
[0086]
Fig. 16 also shows REG #0 (1606), REG # 1 (1607), REG #3 (1613) and REG # 5
(1619).
[0087]
10. Increase m' by 1.
[0088]
11. Repeat from step 5 until a PHICH mapping units have been assigned.
[0089]
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.
[0090]
Reference throughout this specification to ne embodiment' or 'an embodiment' (or
ne aspect' or 'an aspect') means that a particular feature, function, structure, or characteristic
described in connection with the embodiment (or aspect) is included in at least one embodiment
(or aspects) of the present invention. Thus, for example, the appearance of the phrases 'in one
embodiment' or 'in an embodiment' in various places throughout this specification are not
necessarily all referring to the same embodiment. Furthermore, the particular features,
functions, structures, or characteristics may be combined in any suitable manner in one or more
combinations.
[0091]
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.
[0092]
The above-mentioned processing may be executed by a computer. Also, it is possible to
provide a computer program which causes a programmable computer device to execute the
above - mentioned processing. The program can be stored and provided to a computer using any
type of non-transitory computer readable media. Non-transitory computer readable media
include any type of tangible storage media. Examples of non-transitory computer readable media
include magnetic storage media (such as floppy disks, magnetic tapes, hard disk drives, etc.),
optical magnetic storage media (e.g. magneto-optical disks), CD-ROM, CD-R, CD-R/W, and
semiconductor memories (such as mask ROM, PROM (Programmable ROM), EPROM
(Erasable PROM), flash ROM, RAM (Random Access Memory), etc.). The software modules
may be provided to a computer using any type of transitory computer readable media. Examples
of transitory computer readable media include electric signals, optical signals, and
electromagnetic waves. Transitory computer readable media can provide the software modules to
a computer via a wired communication line (e.g. electric wires, and optical fibers) or a wireless
communication line.
[0093]
This application is based upon and claims the benefit of priority from Australian
provisional patent application No.2013900937, filed on March 18, 2013, the disclosure of which
is incorporated herein in its entirely by reference.
Reference Signs List
UE ACK/NACK PROCEDURE
DL SUBFRAME #0
DL SUBFRAME # 1
DL SUBFRAME #0
DL SUBFRAME #0
TWO UL SUBFRAMES
SUBFRAME #7
SUBFRAME #4
PHICH RESOURCE ASSIGNMENT
4 REGs
6 REGs
SECOND COPY OF PHICH RESOURCE
WIRELESS COMMUNICATION SYSTEM
eNB
"TDD RECONFIGURATION PROCESSING" FUNCTION
"PHICH RESOURCE MAPPING AND HARQ FEEDBACK" FUNCTION
LEGACY UE(S)
REL. 12 & BEYOND UE(S)
TDD RECONFIGURATION PROCESSING FUNCTION
PHICH INFORMATION PROCESSING FUNCTION
SIB1
UL-DL CONFIGURATION INFORMATION
PUSCH HARQ-ACK
409 HARQ-ACK FEEDBACK FOR PDSCH OR PDCCH INDICATION SPS
RELEASE
500 RESOURCE ASSIGNMENT
501 UL SUBFRAME #4
502 DL SUBFRAME #0
503 SUBFRAME #3
504 SUBFRAME #4
600 RESOURCE ASSIGNMENT
601 SUBFRAME #3
602 SUBFRAME #4
603 DL SUBFRAME #0
700 RESOURCE ASSIGNMENT
701 SUBFRAME #3
702 SUBFRAME #4
703 UL SUBFRAME #3
704 DL SUBFRAME
705 SUBFRAME #0
800 RESOURCE ASSIGNMENT
801 UL SUBFRAME #3
802 UL SUBFRAME #4
803 DL SUBFRAME #0
804 UL SUBFRAME #4
900 RESOURCE ASSIGNMENT
901 SUBFRAME #3
902 SUBFRAME #4
903 DL SUBFRAME #0
904 UL SUBFRAME #3
905 DL SUBFRAME #9
906 SUBFRAME #4
1000 RESOURCE ASSIGNMENT
1001 SUBFRAME #3
1002 SUBFRAME #4
1003 DL SUBFRAME #0
1004 UL SUBFRAME #4
1100 RESOURCE ASSIGNMENT
1101 SUBFRAME #3
1102 SUBFRAME #4
1103 DL SUBFRAME #0
1104 SUBFRAME #2
1400 MAPPING
1401 to 1406 TWO REGS
1500 MAPPING
1501 to 1509 3 REGS
1600 MAPPING
1601 to 1603 PRB INDEX
1604 to 1606 REG #0
1607 to 1609 REG # 1
1610 to 1612 REG #2
1613 to 1615 REG #3
1616 to 1618 REG #4
1619 to 1621 REG #5
CLAIMS
[Claim 1]
A method for PHICH (Physical H-ARQ Indicator Channel) resource allocation in a
wireless communication system that supports a flexible TDD UL-DL (Time Division Duplex
Uplink-Downlink) configuration and in which different TDD UL-DL configurations are
available and the TDD UL-DL configuration used by first UEs (User Equipments) which operate
according to the flexible TDD configuration can be different to the TDD UL-DL configuration
used by second UEs which operate according to a long term TDD UL-DL configuration, the
method comprising allocating a PHICH resource for both first UEs and second UEs according to
LTE timing rules applicable to the TDD UL-DL configuration in use by second UEs.
[Claim 2]
The method for PHICH resource allocation as claimed in claim 1 further including,
determining that a PHICH resource is allocated for second UEs with factor m, = 2,
determining that HARQ-ACK for only one UL subframe should be fed back for first
UEs, and
allocating PHICH resource with IPHICH= 1 for first UEs.
[Claim 3]
The method for PHICH resource allocation as claimed in claim 1 further including,
determining that a PHICH resource is assigned for second UEs with factor = 1,
determining that HARQ-ACK for two UL subframes should be fed back, and
allocating the assigned PHICH resource with IPHICH
= 1 for first UEs to accommodate
PUSCH HARQ feedback for the second subframe.
[Claim 4]
A method for PHICH (Physical H-ARQ Indicator Channel) resource allocation in a
wireless communication system that supports a flexible TDD UL-DL (Time Division Duplex
Uplink-Downlink) configuration and in which different TDD UL-DL configurations are
available and the TDD UL-DL configuration used by first UEs (User Equipments) which operate
according to the flexible TDD configuration can be different to the TDD UL-DL configuration
used by second UEs which operate according to a long term TDD UL-DL configuration, the
method involving, for a given subframe of a radio frame,
determining that the said subframe is not a DL subframe in the TDD UL-DL
configuration in use by first UEs and also in the TDD UL-DL configuration in use by second
UEs,
determining that the said subframe is a DL subframe in the TDD UL-DL configuration
in use by first UEs but an UL subframe in the TDD UL-DL configuration in use by second UEs,
and
allocating a PHICH resource according to LTEtiming rules applicable to the TDD
UL-DL configuration in use by first UEs.
[Claim 5]
The method for PHICH resource allocation as claimed in claim 4 further including,
determining that said given subframe is a DL subframe in the TDD UL-DL
configuration in use by first UEs and also in the TDD UL-DL configuration in use by second
UEs,
determining that a PHICH resource is not required by second UEs for said given
subframe, and
allocating no PHICH resource to the subframe.
[Claim 6]
The method for PHICH resource allocation as claimed in claim 5 further including, for
said given subframe,
determining that a PHICH resource is required by first UEs,
calculating the PHICH resource required for sending PUSCH HARQ-ACK or
remaining PUSCH HARQ-ACK, and
allocating the PHICH resource for transmission thereof via ePHICH IE if available and
enabled or via UL grant if ePHICH IE is not available or not enabled.
[Claim 7]
The method for PHICH resource allocation as claimed in claim 5 further including,
determining that a PHICH resource is required by second UEs for said given subframe,
determining that the PHICH resource is not required by first UEs, and
allocating the PHICH resource according to the LTEtiming rules applicable to the TDD
UL-DL configuration in use by second UEs.
[Claim 8]
The method for PHICH resource allocation as claimed in claim 7 further including,
determining that a PHICH resource is required by first UEs for said given subframe,
determining that the PHICH resource required by second UEs is not less than that
required by first UEs,
determining that the PHICH resource required by second UEs is not more than that
required by first UEs, and
allocating the PHICH resource according to the LTE timing rules applicable to the TDD
UL-DL configuration in use by second UEs.
[Claim 9]
The method for PHICH resource allocation as claimed in claim 8 further including,
determining that the PHICH resource required by second UEs is more than that required
by first UEs for said given subframe,
allocating the PHICH resource according to the LTE timing rules applicable to the TDD
UL-DL configuration in use by second UEs, and
allocating the PHICH resource with for first UEs.
[Claim 10]
The method for PHICH resource allocation as claimed in claim 8 further including,
determining that the PHICH resource required by second UEs is less than that required
by first UEs for said given subframe,
allocating the PHICH resource according to the LTEtiming rules applicable to the TDD
UL-DL configuration in use by second UEs, and
allocating the PHICH resource for first UEs to accommodate HARQ-ACK for (an)
associated UL subframe(s) that have PUSCH HARQ-ACK timing aligned with that of second
UEs.
[Claim 11]
The method for PHICH resource allocation as claimed in claim 0 further including, for
said given subframe
calculating the PHICH resource required for sending PUSCH HARQ-ACK or
remaining PUSCH HARQ-ACK of first UEs, and
allocating the PHICH resource for transmission thereof via ePHICH IE if this is
available and enabled or via UL grant if ePHICH IE is not available or not enabled.
[Claim 12]
Awireless communication system including a base station, and first UEs and second
UEs, wherein the wireless communication system supports a flexible TDD UL-DL configuration,
different TDD UL-DL configurations are available and the TDD UL-DL configuration used by
the first UEs which operate according to the flexible TDD configuration can be different to the
TDD UL-DL configuration used by the second UEs which operate according to a long term TDD
UL-DL configuration, and wherein the base station is operable to perform the method for PHICH
resource allocation as claimed in claim 4.
[Claim 13]
A base station operable for use in a wireless communication system that supports a
flexible TDD UL-DL configuration and in which different TDD UL-DL configurations are
available and the TDD UL-DL configuration used by first UEs which operate according to the
flexible TDD configuration can be different to the TDD UL-DL configuration used by second
UEs which operate according to a long term TDD UL-DL configuration, and wherein the base
station is operable to perform the method for PHICH resource allocation as claimed in claim 4.
[Claim 14]
A method for use by first UEs for PUSCH HARQ-ACK and PHICH signalling in a
wireless communication system that supports a flexible TDD UL-DL configuration and in which
different TDD UL-DL configurations are available and the TDD UL-DL configuration used by
the first UEs which operate according to the flexible TDD configuration can be different to the
TDD UL-DL configuration used by second UEs which operate according to a long term TDD
UL-DL configuration, the method involving, for a given flexible DL subframe of a radio frame
in the TDD UL-DL configuration in use by the first UEs:
determining that the corresponding subframe in the TDD UL-DL configuration in use
by the second UEs is not a DL subframe,
determining that the given DL subframe in the TDD UL-DL configuration in use by the
first UEs is to carry PUSCH HARQ-ACK for first UEs, and
monitoring for PHICH allocation according to LTE timing rules applicable to the TDD
UL-DL configuration in use by first UEs.
[Claim 15]
The method for use by first UEs as claimed in claim 14 further including, for the given
flexible DL subframe,
determining that the corresponding subframe in the TDD UL-DL configuration in use
by the second UEs is a DL subframe,
determining that said corresponding subframe in the TDD UL-DL configuration in use
by the second UEs is not allocated PHICH resources according to the LTE timing rules
applicable to the TDD UL-DL configuration in use by the second UEs,
determining that the given DL subframe in the TDD UL-DL configuration in use by the
first UEs is to carry PUSCH HARQ-ACK, and
performing the following on the subframe:
UL grant monitoring for HARQ-ACK corresponding to previously sent
PUSCH, if ePHICH is not configured;
ePHICH monitoring for HARQ-ACK corresponding to previously sent PUSCH,
if ePHICH is configured; and
PDCCH(s) monitoring taking into account the number of REs allocated for
PHICH for second UEs.
[Claim 16]
The method for use by first UEs as claimed in claim 15 further including, for the given
flexible DL subframe,
determining that said corresponding subframe in the TDD UL-DL configuration in use
by the second UEs is allocated PHICH resource according to the LTEtiming rules applicable to
the TDD UL-DL configuration in use by the second UEs,
determining that the PHICH resource required by second UEs is not less than that
required by first UEs,
determining that the PHICH resource required by second UEs is not more than that
required by first UEs, and
performing PHICH monitoring according to the LTE timing rules applicable to the TDD
UL-DL configuration in use by second UEs and performing PDCCH(s) monitoring taking into
account the number of REs allocated for PHICH for second UEs.
[Claim 17]
The method for use by first UEs as claimed in claim 16 further including, for the given
flexible DL subframe,
determining that the PHICH resource required by second UEs is more than that required
by first UEs, and
performing PHICH monitoring with IPHICH
= 1 d performing PDCCH(s) monitoring
taking into account the number of REs allocated for PHICH for second UEs.
[Claim 18]
The method for use by first UEs as claimed in claim 16 further including, for the given
flexible DL subframe,
determining that the PHICH resource required by second UEs is less than that required
by first UEs, and
performing the following on the subframe:
PHICH monitoring for HARQ-ACK of associated UL subframe(s) having
PUSCH HARQ-ACK timing aligned with that of the TDD UL-DL configuration in use
by second UEs,
UL grant monitoring for HARQ-ACK of associated UL subframe(s) that is not
included in the PHICH of second UEs, if ePHICH is not configured,
ePHICH monitoring for HARQ-ACK of associated UL subframe(s) that is not included
in the PHICH of second UEs, if ePHICH is configured,
PDCCH(s) monitoring taking into account the number of REs allocated for
PHICH for second UEs.
[Claim 19]
A mobile station operable for use as a first UE in a wireless communication system that
supports a flexible TDD UL-DL configuration and in which different TDD UL-DL
configurations are available and the TDD UL-DL configuration used by first UEs which operate
according to the flexible TDD configuration can be different to the TDD UL-DL configuration
used by second UEs which operate according to a long term TDD UL-DL configuration, and
wherein the mobile station is operable to perform the method as claimed in claim 14.
[Claim 20]
A method for use in ePHICH mapping in a wireless communication system that
supports a flexible TDD UL-DL configuration and in which different TDD UL-DL
configurations are available and the TDD UL-DL configuration used by first UEs which operate
according to the flexible TDD configuration can be different to the TDD UL-DL configuration
used by second UEs which operate according to a long term TDD UL-DL configuration, the
method comprising using a subset of spare bits out of a set of spare bits in a master information
block (MIB) for ePHICH configuration.
[Claim 21]
A method for use in ePHICH mapping as claimed in claim 20 comprising using three
out often spare bits in a MIB for ePHICH configuration.