U.S. patent application number 15/176294 was filed with the patent office on 2016-09-29 for methods for enhanced harq mechanism.
The applicant listed for this patent is MEDIATEK Singapore Pte. Ltd.. Invention is credited to Hua-Min Chen, Feifei Sun, Xiangyang Zhuang.
Application Number | 20160285595 15/176294 |
Document ID | / |
Family ID | 53756109 |
Filed Date | 2016-09-29 |
United States Patent
Application |
20160285595 |
Kind Code |
A1 |
Chen; Hua-Min ; et
al. |
September 29, 2016 |
Methods for Enhanced HARQ Mechanism
Abstract
Apparatus and methods are provided to enhance HARQ mechanism.
The UE repeatedly transmits a data block with a first repetition
number and retransmits the data block with a second repetition
number. In one embodiment, the first and the second repetition
number value are explicitly included in an uplink grant message. In
another embodiment, the UE obtains a repetition number value by
looking up a repetition number table indexed by the repetition
number indicator, which is included in an uplink grant message for
the first repetition number and included in a HARQ message for the
second repetition number. In yet another embodiment, the UE
determines a coverage enhancement degree value, a data block size
value and an available transport resource block size. The UE
obtains a repetition number by table-look-up based on the
coverage-enhancement degree value, the data block size, and the
transport resource block size.
Inventors: |
Chen; Hua-Min; (Beijing,
CN) ; Sun; Feifei; (Beijing, CN) ; Zhuang;
Xiangyang; (Lake Zurich, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MEDIATEK Singapore Pte. Ltd. |
Singapore |
|
SG |
|
|
Family ID: |
53756109 |
Appl. No.: |
15/176294 |
Filed: |
June 8, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/CN2015/071757 |
Jan 28, 2015 |
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15176294 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 72/042 20130101;
H04W 72/0413 20130101; H04L 1/1864 20130101; H04W 72/14 20130101;
H04L 5/0055 20130101; H04L 1/1607 20130101; H04L 1/189
20130101 |
International
Class: |
H04L 1/18 20060101
H04L001/18; H04W 72/04 20060101 H04W072/04; H04W 72/14 20060101
H04W072/14; H04L 5/00 20060101 H04L005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 28, 2014 |
CN |
PCT/CN2014/071684 |
Claims
1. A method comprising: determining a first repetition number by a
user equipment (UE) in a wireless system; repeatedly transmitting a
data block by the first repetition number; receiving a HARQ message
that indicates a negative acknowledgement; determining a second
repetition number for a data retransmission of the data block,
wherein the second repetition number is different from the first
repetition number; and repeatedly retransmitting the data block by
the second repetition number.
2. The method of claim 1, wherein the first repetition number is
greater than the second repetition number.
3. The method of claim 1, wherein the first repetition number value
is explicitly included in an uplink grant message for the data
transmission.
4. The method of claim 1, wherein the second repetition number
value is explicitly included in an uplink grant message for the
data retransmission.
5. The method of claim 1, wherein the determining of the first
repetition number involves: receiving an uplink grant message for
the data transmission, wherein the uplink grant message contains a
repetition number indicator; obtaining the first repetition number
value by looking up a repetition number table indexed by the
repetition number indicator.
6. The method of claim 1, wherein the determining of the second
repetition number involves: retrieving a repetition number
indicator from the HARQ message; and obtaining the second
repetition number value by looking up a repetition number table
indexed by the retrieved repetition number indicator.
7. The method of claim 1, further comprising a repetition number
lookup procedure involves: determining a coverage enhancement
degree value; determining a data block size; obtaining an available
transport resource block size; and obtaining a repetition number
based on the coverage enhancement degree value, the data block
size, and the transport resource block size.
8. The method of claim 7, wherein the first repetition number is
determined using the repetition number lookup procedure.
9. The method of claim 7, wherein the second repetition number is
determined using the repetition number lookup procedure.
10. A method, comprising: determining a first repetition number by
a base station for a user equipment (UE) in a wireless network;
sending first repetition number information to the UE; and
receiving a data transmission from the UE, wherein a data block is
repeatedly transmitted by the first repetition number.
11. The method of claim 10, wherein the first repetition number
value is explicitly included in an uplink grant for the data
transmission.
12. The method of claim 10, wherein a repetition number indicator
for the first repetition number value is included in an uplink
grant message for the data transmission.
13. The method of claim 10, further comprising: sending a HARQ NACK
message to the UE upon an unsuccessful decoding of the received
data transmission; sending a second repetition number information
to the UE, wherein the second repetition number is different from
the first repetition number; receiving a data retransmission from
the UE, wherein the data block is repeatedly retransmitted by the
second repetition number.
14. The method of claim 13, wherein the second repetition number
value is explicitly included in an uplink grant for the data
retransmission.
15. The method of claim 13, wherein a repetition number indicator
for the second repetition number value is included in the HARQ
message.
16. An user equipment (UE) comprising: a transceiver that transmits
an uplink data transmission to a base station and receives a
downlink data transmission from the base station; a HARQ handler
that determines a HARQ acknowledgment status for the uplink data
transmission based on the detection of the HARQ indicator; and a
repetition number handler that determines a first repetition number
for the uplink transmission of a data block, wherein the data block
is repeatedly transmitted by the first repetition number, and
determines a second repetition number for a data retransmission
upon detecting a NACK from a HARQ message, wherein the first
repetition number and the second repetition number are
different.
17. The UE of claim 16, wherein the first repetition number is
greater than the second repetition number.
18. The UE of claim 16, the first repetition number value is
explicitly included in an uplink grant message for the data
transmission.
19. The UE of claim 16, the second repetition number value is
explicitly included in an uplink grant message for the data
retransmission.
20. The UE of claim 16, the second repetition number value is
explicitly included in a HARQ message for the data
retransmission.
21. The UE of claim 16, wherein the repetition number handler
receives a repetition number indicator from an uplink grant message
for the data transmission, and determines the first repetition
number by looking up a repetition number table indexed by the
repetition number indicator.
22. The UE of claim 16, wherein the repetition number handler
receives a repetition number indicator from the HARQ message, and
determines the second repetition number by looking up a repetition
number table indexed by the repetition number indicator.
23. The UE of claim 16, wherein the repetition number handler
determines the first repetition number using a lookup procedure
involving: determining a coverage enhancement degree value for the
data transmission; determining a data block size for the data
transmission; obtaining an available transport resource block size
allocated for the data transmission; and obtaining the first
repetition number based on the coverage enhancement degree value,
the data block size, and the transport resource block size.
24. The UE of claim 16, wherein the repetition number handler
determines the second repetition number using a lookup procedure
involving: determining a coverage enhancement degree value for the
data retransmission; determining a data block size for the data
retransmission; obtaining an available transport resource block
size allocated for the data retransmission; and obtaining the
second repetition number based on the coverage enhancement degree
value, the data block size, and the transport resource block size.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is filed under 35 U.S.C. .sctn.111(a) and
is based on and hereby claims priority under 35 U.S.C. .sctn.120
and .sctn.365(c) from International Application No.
PCT/CN2015/071757, with an international filing date of Jan. 28,
2015, which in turn claims priority from International Application
Number PCT/CN/2014/071684 filed on Jan. 28, 2014. This application
is a continuation of International Application No.
PCT/CN2015/071757, which claims priority from International
Application Number PCT/CN/2014/071684. International Application
No. PCT/CN2015/071757 is pending as of the filing date of this
application, and the United States is a designated state in
International Application No. PCT/CN2015/071757. This application
claims priority under 35 U.S.C. .sctn.120 and .sctn.365(c) from
International Application Number PCT/2014/071684 filed on Jan. 28,
2014. The disclosure of each of the foregoing documents is
incorporated herein by reference.
TECHNICAL FIELD
[0002] The disclosed embodiments relate generally to wireless
communication, and, more particularly, to enhanced HARQ
mechanism.
BACKGROUND
[0003] Third generation partnership project (3GPP) and Long Term
Evolution (LTE) mobile telecommunication systems provide high data
rate, lower latency and improved system performances. Such systems
are optimized for regular data communications, wherein there is no
need for repeatedly (re)transmissions. However, in some situations,
repeatedly (re)transmissions are needed. For example, some UEs, in
the basements of residential buildings or locations shielded by
foil-backed insulation, metalized windows or traditional
thick-walled building construction, may experience significantly
larger penetration losses on the radio interface than normal LTE
devices. Repetition has been identified as a common technique to
bridge the additional penetration losses than normal LTE devices.
More resources/power is needed to support these UEs in the extreme
coverage scenario. In order to transmit/retransmit the data
efficiently, different repetition numbers can be applied to improve
the power consumption at the UE side, then a new mechanism for
repeated transmissions or retransmissions with different repetition
numbers is needed
SUMMARY
[0004] Apparatus and methods are provided to enhance HARQ
mechanism. In one novel aspect, the UE determines a first
repetition number and repeatedly transmits a data block by the
first repetition number. The UE receives a HARQ message that
indicates a negative acknowledgement. The UE determines a second
repetition number for a data retransmission of the data block,
wherein the second repetition number is different from the first
repetition number. The UE retransmits the data block by the second
repetition number. In one embodiment, the first repetition number
value is explicitly included in an uplink grant message for the
data transmission. In another embodiment, the second repetition
number value is explicitly included in an uplink grant message for
the data retransmission. In one embodiment, a repetition number
indicator is received from an uplink grant message for the data
transmission. The UE obtains the first repetition number value by
looking up a repetition number table indexed by the repetition
number indicator. In another embodiment, a repetition number
indicator is received from a HARQ message. The UE obtains the
second repetition number value by looking up a repetition number
table indexed by the retrieved repetition number indicator. In yet
another embodiment, the UE determines a coverage enhancement degree
value, a data block size value and an available transport resource
block size. The UE obtains a repetition number based on the
coverage enhancement degree value, the data block size, and the
transport resource block size.
[0005] Other embodiments and advantages are described in the
detailed description below. This summary does not purport to define
the invention. The invention is defined by the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The accompanying drawings, where like numerals indicate like
components, illustrate embodiments of the invention.
[0007] FIG. 1 is an exemplary block diagram illustrating a
schematic diagram of a wireless communications system according to
one embodiment of the present invention.
[0008] FIG. 2 shows exemplary diagrams of the single-state
indicator of ACK/NACK signal.
[0009] FIG. 3 shows exemplary flow diagram of determining a HARQ
NACK state upon detecting the HARQ indicator.
[0010] FIG. 4 shows exemplary flow diagram of determining a HARQ
ACK state upon detecting the HARQ indicator.
[0011] FIG. 5 shows an exemplary diagram of reusing a HARQ
indicator channel with ACK for data transmission.
[0012] FIG. 6 shows an exemplary diagram of reusing a HARQ
indicator channel with NACK for data transmission.
[0013] FIG. 7 shows and exemplary diagram of an UE-specific EPHICH
resource allocation.
[0014] FIG. 8 shows and exemplary diagram of a group-specific
EPHICH resource allocation.
[0015] FIG. 9 shows and exemplary diagram of a cell-specific EPHICH
resource allocation.
[0016] FIG. 10 shows and exemplary diagram for a data block
transmission/retransmission with different repetition levels where
different frequency resources are used.
[0017] FIG. 11 shows and exemplary diagram for a data block
transmission/retransmission with different repetition levels where
the same frequency resources are used.
[0018] FIG. 12 shows an exemplary diagram of the first repetition
number value indicated in an uplink grant message.
[0019] FIG. 13 shows an exemplary diagram of the first repetition
number index indicated in an uplink grant message.
[0020] FIG. 14 illustrates an exemplary diagram of using the
predefined rule to determine the first repetition number.
[0021] FIG. 15 shows an exemplary diagram of the second repetition
number index indicated in an uplink grant message.
[0022] FIG. 16 shows an exemplary diagram of the second repetition
number value indicated in an uplink grant message.
[0023] FIG. 17 illustrates an exemplary diagram of using the
predefined rule to determine the second repetition number.
[0024] FIG. 18 is an exemplary flow chart of a HARQ receiving
procedure where the UE terminates the procedure upon a maximum
number of decoding is reached.
[0025] FIG. 19 is an exemplary flow chart of a HARQ receiving
procedure where the UE terminates the procedure upon a maximum
number of NACK is reached or upon an ACK is determined.
[0026] FIG. 20 is an exemplary flow chart of a HARQ receiving
procedure where the UE terminates the procedure upon a maximum
number of HARQ reached and an ACK is determined.
[0027] FIG. 21 illustrates an exemplary flow chart of the UE
terminating the data transmission upon detecting maximum number of
repetition transmission is reached.
[0028] FIG. 22 illustrates an exemplary flow chart of the UE
terminating the data transmission upon detecting maximum number of
repetition transmission is reached or the maximum numbers of HARQ
indicators are received.
[0029] FIG. 23 is an exemplary flow chart for the UE to decode and
handle the single-state HARQ in accordance with embodiments of the
current invention.
DETAILED DESCRIPTION
[0030] Reference will now be made in detail to some embodiments of
the invention, examples of which are illustrated in the
accompanying drawings.
[0031] Repetition has been identified as a common technique to
bridge the additional penetration losses than normal LTE devices.
In order to transmit/retransmit the data efficiently, different
repetition numbers can be applied to improve the power consumption
at the UE side. Further, how to send feedback for a data reception
the kind of ACK/NACK determination rules are important issues for
the repeatedly transmitted data communication. For normal LTE UEs,
ACK or NACK can be received from the physical hybrid-ARQ indicator
channel (PHICH). Combined with the received control signaling, UEs
can determine to generate a new transmission or a retransmission by
an adaptive/non-adaptive mechanism. For UEs in a coverage hole, the
latency will be quite large to receive ACK/NACK feedback. To solve
the problem, using a control signaling to determine whether data is
received correctly based on a simplified rule is used for a robust
data transmission. Further, for some new carrier types or carrier
segmentations, legacy channels for acknowledgement feedback are not
supported. How to feedback ACK/NACK for the received data in such
legacy carriers is another issue needs to be addressed.
[0032] FIG. 1 is an exemplary block diagram illustrating a
schematic diagram of a wireless communications system according to
one embodiment of the present invention. A wireless communications
system 100 includes one or more fixed base infrastructure units 101
and 102, forming one or more access networks 110 and 120
distributed over a geographical region. The access network 120 and
110 may be a Universal Terrestrial Radio Access Network (UTRAN) in
the WCDMA technology or an E-UTRAN in the Long Term Evolution
(LTE)/LTE-A technology. The base unit may also be referred to an
access point, base station, Node-B, eNode-B, or other terminologies
used in the art. In some systems, one or more base stations are
communicably coupled to a controller forming an access network that
is commnacating with one or more core networks.
[0033] In FIG. 1, one or more mobile stations 103 and 104 are
coupled wirelessly to base stations 101 and 102 for wireless
service within a serving area, for example, a cell or within a cell
sector. The mobile station may also be called as user equipment
(UE), a wireless communication device, terminal or some other
terminologies. Mobile station 103 sends uplink data to base
stations 101 via uplink channel 111 in the time and/or frequency
domain. Mobile station 104 sends uplink data to base stations 102
via uplink channel 113 in the time and/or frequency domain. The
serving base stations 101 and 102 transmit downlink signals via a
downlink channel 112 and 114 to mobile stations 103 and 104,
respectively. In one embodiment, the communication system utilizes
Orthogonal Frequency Division Multiplexing Access (OFDMA) or a
multi-carrier based architecture including Adaptive Modulation and
Coding (AMC) on the downlink and next generation single-carrier
(SC) based FDMA architecture for uplink transmissions. SC based
FDMA architectures include Interleaved FDMA (IFDMA), Localized FDMA
(LFDMA), DFT-spread OFDM (DFT-SOFDM) with IFDMA or LFDMA. In OFDMA
based systems, remote units are served by assigning downlink or
uplink radio resources that typically comprises a set of
sub-carriers over one or more OFDM symbols. Exemplary OFDMA based
protocols include the developing LTE/LTE-A of the 3GPP standard and
IEEE 802.16 standard. The architecture may also include the use of
spreading techniques such as multi-carrier CDMA (MC-CDMA),
multi-carrier direct sequence CDMA (MC-DS-CDMA), Orthogonal
Frequency and Code Division Multiplexing (OFCDM) with one or two
dimensional spreading, or may be based on simpler time and/or
frequency division multiplexing/multiple access techniques, or a
combination of these various techniques. In alternate embodiments,
the communication system may utilize other cellular communication
system protocols including, but not limited to, TDMA or direct
sequence CDMA. The disclosure, however, is not intended to be
limited to any particular wireless communication system.
[0034] In FIG. 1, wireless communication network 100 is an
OFDM/OFDMA system comprising a base station eNB 101 and eNB 102,
and a plurality of mobile station 103 and mobile station 104. When
there is at least one downlink data block to be sent from base
station to mobile station, each mobile station gets a downlink
assignment, e.g., a set of radio resources in a physical downlink
shared channel (PDSCH). When a UE needs to send at least one uplink
data block to base station, the mobile station gets a grant from
the base station that assigns a set of uplink radio resources. In
3GPP LTE system based on OFDMA downlink, the radio resource is
partitioned into subframes each of which is comprised of two slots
and each slot has seven OFDMA symbols in the case of normal Cyclic
Prefix (CP). Each OFDMA symbol further consists of a number of
OFDMA subcarriers depending on the system bandwidth. The basic unit
of the radio resource grid is called Resource Element (RE), which
spans an OFDMA subcarrier over one OFDMA symbol. One type of the
basic block of the radio resources for scheduling in LTE is called
physical resource block (PRB), each of which contains several
consecutive OFDM symbols in one subframe and several consecutive
subcarriers in frequency domain. Virtual resource blocks (VRB) is
another type of the basic block of the radio resources definition
in LTE system, which have two types: localized type and distributed
type. For each virtual resource pair, a pair of virtual resource
blocks over two slots in a subframe are assigned together by a
single virtual resource block number. One downlink assignment or an
uplink grant comprises one or multiple basic blocks of the radio
resources, e.g., a set of PRBs.
[0035] Due to the variation of wireless channel or coverage
problem, the transmitted data may not be received correctly at the
reception end. Then, one or multiple retransmission(s) for a date
transmission will be required if the transmitter end receives a
negative acknowledgement (NACK) feedback from the reception end. If
a positive acknowledgement, i.e., an ACK, is received, UEs may
assume that the data is received correctly. Many specifications for
wireless communications specify such mechanism to guarantee data to
be transmitted correctly, and there are many designs to feedback
ACK/NACK. Taking the normal UEs in LTE/LTE-A system, physical
hybrid automatic repeat request (HARQ) indicator channel (PHICH)
transmitted by the base station is designed to feedback ACK/NACK
for uplink data transmission from mobile stations. However, there
is no consensus how to feedback an acknowledgement of a data
transmission for UEs in a coverage hole, such as the working item
"Low cost and enhanced coverage MTC UEs for LTE with a 15 dB
coverage improvement" in LTE. Further, there is some discussion to
introduce a new type of carrier or carrier segmentation for traffic
offloading, wherein the demodulation reference signals will be
redesigned or there is no common cell-specific signal for legacy
ACK/NACK feedback. Then, this invention proposes a new HARQ
indicator channel to feedback ACK/NACK.
[0036] Further, a new HARQ mechanism is proposed, especially
considering UEs with bad coverage. To improve the reliability of
the transmission for these UEs, multiple subframes may be bundled
for one block transmission, where the same set of radio resources
over these bundled subframes is allocated. Under these cases,
repetition number or subframe number is an important factor for a
correct data transmission. Then, How to transmit or retransmit with
a proper repetition number is an open issue.
[0037] For convenience, the new HARQ indicator channel is named as
enhanced PHICH (EPHICH), considering the function of this new
channel is quite similar to that of legacy PHICH, which informs UEs
the acknowledgement state of an uplink data reception. The signal
transmitted in EPHICH is named as a HARQ indicator, indicating the
acknowledgement state. The terminology used throughout this
invention is an example to describe the proposed concepts and
methods clearly, and does not limit its application in other
systems.
[0038] For an acknowledgement state feedback, this invention
proposes that a signal for ACK/NACK transmitted in EPHICH is
generated from a UE identity. Then, a UE can perform the signal
detection to check whether the received HARQ indicator contains the
UE identity and determine whether the detected signal is the
ACK/NACK signal for itself. In one embodiment, such UE identity is
Cell Radio Network Temporary Identity (C-RNTI) or C-RNTI sequence.
In another embodiment, the UE identity is a UE ID at MME, like SAE
Temporary Mobile Subscriber Identity (S-TMSI). In a third
embodiment, the UE identity is a configuration from a higher layer
and varies with time semi-statically. In these embodiments of the
present invention, the UE identity can be UE-specific or
group-specific.
[0039] According to the embodiments of the present invention, the
signal generated from the UE identity is a subset or an extension
of a UE identity sequence in one embodiment. For example, the
signal for ACK is a subset of C-RNTI sequence and a UE can
determine that the data is received correctly if such signal
containing a UE identity is detected.
[0040] In another embodiment, an ACK/NACK signal is a sequence of
coded CRC bits, where the CRC bits are generated from a common
signal for ACK/NACK and scrambled with a subset of UE-identity
sequence. Here, the common signal for ACK or NACK is predefined.
For example, "0" stands for an ACK and "1" represents a NACK. So
the common signal for ACK or NACK is called single-state HARQ
indicator for ACK or NACK. It measns one state of the common signal
is only for ACK or NACK, and the other state of the signal could be
reused as other signaling. So the single-state HARQ indicator could
be one state of the common signal, for example, the common signal
could be a combination of at least one bit, and only one state of
the common signal is used as the single-state HARQ indicator.
[0041] In a third embodiment, a HARQ indicator is a sequence of
coded common signals for ACK/NACK and a CRC sequence, scrambled
with a UE identity sequence. Here, the UE identity is group
specific and multiple UEs decode such indicator channel to obtain
the acknowledgement. Further, a UE grouping is performed since one
HARQ indicator comprises multiple ACK/NACK signals. After receiving
the HARQ indicator channel, a UE obtains its own ACK/NACK signal by
checking a HARQ index, where the HARQ index is configured by a
higher layer, or based on a function of a UE-specific identity.
[0042] In a fourth embodiment, a NACK signal is generated by
encoding a block of bits and a CRC sequence, where the CRC sequence
is generated from the block of bits and scrambled by a subset of UE
identity sequence. Here, the block of bits for NACK is a signal
comprising NACK at least. Further, a second repetition number for a
retransmission is also contained in such signal for NACK.
[0043] FIG. 1 further shows a simplified block diagram of base
station 101 in accordance to the current invention. Base station
101 has an antenna 155, which transmits and receives radio signals.
A RF transceiver module 153, coupled with the antenna, receives RF
signals from antenna 155, converts them to baseband signals and
sends them to processor 152. RF transceiver 153 also converts
received baseband signals from processor 152, converts them to RF
signals, and sends out to antenna 155. Processor 152 processes the
received baseband signals and invokes different functional modules
to perform features in base station 101. Memory 151 stores program
instructions and data 154 to control the operations of base station
101.
[0044] Base station 101 also includes a HARQ encoder 161, a HARQ
channel handler 162 and a repetition number module 163 in
accordance to embodiments of the current invention. In one example,
HARQ encoder 161 detects a NACK/ACK condition of the received
transmission from UE, encodes the NACK/ACK in a single-state
indication to the HARQ channel via processors 163 through a control
module. HARQ channel handler 162 generates HARQ channel information
based on the output from the HARQ encoder 161 and sends the HARQ
signal to the UE. Repetition number module 163 determines different
repetition number for the initial transmission and
retransmission.
[0045] FIG. 1 also shows a simplified block diagram of mobile
station 103 in accordance to the current invention. Mobile station
103 has an antenna 135, which transmits and receives radio signals.
An RF transceiver module 133, coupled with the antenna, receives RF
signals from antenna 135, converts them to baseband signals and
sends them to processor 132. RF transceiver 133 also converts
received baseband signals from processor 132, converts them to RF
signals, and sends out to antenna 135. Processor 132 processes the
received baseband signals and invokes different functional modules
to perform features in mobile station 103. Memory 131 stores
program instructions and data 134 to control the operations of
mobile station 103.
[0046] Mobile station 103 includes several modules that carry out
different tasks in accordance with embodiments of the current
invention. A HARQ decoder 141, a HARQ detector 142, a HARQ channel
handler 143 and a repetition number module 144. HARQ decoder 141
decodes the single-state HARQ indicator received from the base
station for mobile station 103. HARQ detector 142 detects a HARQ
signal channel. HARQ channel handler 143 obtains the HARQ indicator
received and processes the HARQ information. Repetition number
module 144 determines the repetition number for the initial
transmission and the retransmission for mobile station 103.
Single-State HARQ Indicator
[0047] FIG. 2 shows exemplary diagrams of the single-state
indicator of ACK/NACK signal. In Example #1, sequence 200 is a
C-RNTI sequence with a size 201. Sequence 220 is the transmitted
UE-specific single-state ACK/NACK signal with size 221. Sequence
220 is a subset of sequence 200. Different from Example #1, the
UE-specific single-state ACK/NACK signal in Example #2 is a
transformation of the UE-specific sequence. A sequence 240 is a
C-RNTI sequence with a size 241. A sequence 260 with size 261 is a
subset of sequence 240. According to a predefined signal generation
function 290, a UE-specific ACK/NACK signal 280 with a size 281 is
generated from sequence 260. Within the signal generation function
290, a CRC sequence with size 281 is generated from a common NACK
signal first. Then, the CRC sequence is scrambled with sequence
260.
[0048] After receiving a HARQ indicator channel, UEs will determine
the acknowledgement state on a predefined mapping way from the
result of signal detection. In one novel aspect, only one state of
HARQ signal is transmitted in a HARQ indicator channel. In one
embodiment, only a signal for the negative acknowledgement state is
transmitted by a HARQ indicator. If a UE detects the single-state
indicator in the HARQ signal, the UE determines that the data block
is not received correctly. OR if the single-state indicator is
detected in the HARQ indicator within a set of resources, the UE
determines that the data block is received correctly. Such rule can
be predefined. In another embodiment, a HARQ indicator comprising
only a signal for the positive acknowledgement is transmitted. A UE
can determine the transmitted data block is received correctly if
the signal is detected in the received HARQ indicator channel.
Otherwise, the UE can assume that the data block is not received
correctly. Note that the unused resources for the HARQ indicator
can be reallocated to other signals or channels, since only one
acknowledgement state is transmitted in the HARQ indicator
channel.
[0049] FIG. 3 shows exemplary flow diagram of determining a HARQ
NACK state upon detecting the HARQ indicator. After receiving a
HARQ indicator channel (Step 300), UEs further check whether CRC
passes (Step 340) from the result of decoded signal in Step 320.
Here, the HARQ signal is a block of coded bits containing a CRC
sequence, which is scrambled with C-RNTI. If CRC check passes, the
acknowledgement state is determined as negative (NACK) (Step 340).
Otherwise, a positive acknowledgement is determined (Step 380).
[0050] FIG. 4 shows exemplary flow diagram of determining a HARQ
ACK state upon detecting the HARQ indicator. Different from Example
#1 in FIG. 3, UEs determine the acknowledgement is positive (Step
470) if the UE identity is contained from the detected signal in
Example #2 shown in FIG. 4. Otherwise, a negative acknowledgement
is assumed. In this example, the HARQ signal is a C-RNTI
sequence.
[0051] In one novel aspect, one signal for one HARQ state, either
ACK or NACK, is transmitted to improve resource efficiency. In the
traditional two-state indicator, where "0" and "1" are used to
represent the NACK and ACK, respectively, the HARQ indicator is
transmitted for every transmission. In one embodiment, the
single-state HARQ indicator is transmitted only when the
transmission is successful and an ACK is needed. In another
embodiment, the single-state HARQ indicator is transmitted only
when the transmission is unsuccessful and a NACK is needed. The
unused states or resources for the HARQ indicator channel will be
allocated for other signals or channels, if there is no HARQ signal
to be transmitted. In one embodiment, only a signal for NACK is
transmitted. Alternatively, only a signal for ACK is transmitted.
Some examples are shown in FIG. 5 and FIG. 6.
[0052] FIG. 5 shows an exemplary diagram of reusing a HARQ
indicator channel with ACK for data transmission. A set of
frequency-time radio resources 500, spanning from subframe 50 to
subframe 54, are allocated for a HARQ indicator channel for UE#1,
UE#2 and UE#3. In one embodiment, only a signal for the negative
acknowledgement (NACK) is transmitted in the HARQ indicator
channel. For UE#1 and UE#2, HARQ indicators containing a negative
acknowledgement are transmitted within the resources 520 and 540,
respectively. Resources 560, which are allocated to transmit HARQ
information for UE#3 is not used for HARQ indicator because
transmission from UE#3 is successful. Instead of having to transmit
an ACK for UE#3, there is no HARQ indicator needed for UE#3 using
the single-state HARQ indicator method. In one embodiment,
resources 560 allocated for UE#3 HARQ are allocated and reused for
the downlink data transmission to UE#4. Upon decoding the HARQ
signal channels, UE#1 and UE#2 determine that the previously
transmitted/retransmitted data block is not received correctly at
the base station, while UE#3 can assume that the
transmitted/retransmitted data block is transmitted successfully,
since no NACK signal is detected from the EPHICH resources 560.
[0053] FIG. 6 shows an exemplary diagram of reusing a HARQ
indicator channel with NACK for data transmission. Different from
the example in FIG. 5, only ACK signal is transmitted in a HARQ
indicator channel in FIG. 6. There are also three UEs expecting to
receive ACK feedback from the base station. A set of resources 620
and 640 are used for ACK feedback to UE#1 and UE#2, respectively.
UE#1 and UE#2 determine that the transmitted or retransmitted data
block is received correctly at the base station when receiving ACK
feedback. For UE#3, it can be assumed that the transmitted or
retransmitted data is not received correctly, due to the absence of
ACK signal in resource block 660, which is allocated to UE#3 as its
HARQ signal channel. In one embodiment, resources 560 allocated for
UE#3 HARQ are allocated and reused for the downlink data
transmission to UE#4.
[0054] In one novel aspect, if there is no ACK or NACK signal to be
transmitted, the unused resources can be used for other signals or
data channels. As shown in FIG. 5 and FIG. 6, because the HARQ
indicator resources are only used for a single-state (ACK or NACK),
the resources are not needed for each transmission. The unused HARQ
resources can be reused for other UEs and/or for other channels.
The efficiency of the use of HARQ resources is improved.
[0055] In another novel aspect, the EPHICH can be a UE-specific
channel, a group-specific channel or a cell-specific channel. In
one embodiment, a set of UE-specific resources is allocated to one
UE only. The allocated set of resources is orthogonal to, or
overlaps partially with the EPHICH resources for other UEs. A
predefined rule based on some UE-specific identities is designed
for UEs to determine the resources. Alternatively, the UE-specific
resources are configured or reconfigured by a higher layer.
[0056] In another embodiment, a set of group-specific resources is
allocated to multiple UEs if EPHICH is group-specific. The
group-specific resources are separated into multiple subsets of
resources. One subset of resources is allocated for one UE. Each
subset of resources is orthogonal to, or overlaps fully or
partially with other subsets of resources. UE grouping is required.
For each group of UEs, one dedicated set of resources for the HARQ
indicator channel are allocated. Multiple HARQ indicators are
transmitted within the allocated resources. Within a cell, multiple
group-specific HARQ indicator channels can be transmitted
simultaneously. The allocated resources to these channels can be
separate from each other, or overlap partially/fully. A predefined
rule based on some group-specific parameter is designed for UEs to
determine the allocation of resources. Alternatively, the
group-specific resources are configured or reconfigured by a higher
layer.
[0057] In yet another embodiment, a cell-specific set of resources
is assigned to all UEs within the cell. Within the set of
resources, a HARQ indicator for one UE occupies a subset of
resources. Further, different subsets of resources are orthogonal,
or overlap partially/fully. The resources for the HARQ indicator
channel are broadcasted to all UEs, or determined by a predefined
rule based on some cell-specific parameters, such as a cell ID.
[0058] FIG. 7 shows and exemplary diagram of a UE-specific EPHICH
resource allocation. Three HARQ indicator channels 700, 730 and 740
are configured. HARQ indicator channels 700, 730 and 740 are
configured for UE#1, UE#2 and UE#3, respectively. Each HARQ
indicator channel occupies a different set of radio resources. The
resources for the HARQ indicator channel 700 start from subframe 70
to subframe 73. The radio resources for HARQ indicator channel 740
span over subframes from 71 to 75. The resources for channels 700
and 740 are orthogonal to each other. The resources for HARQ
indicator channel 730 start from subframe 72 to subframe 74. There
is a resource overlap 703 between the resources for the HARQ
indicator channel 700 and channel 730.
[0059] FIG. 8 shows and exemplary diagram of a group-specific
EPHICH resource allocation. Two sets of radio resources 800 and 840
are allocated to two sets HARQ indicator channels. The two sets of
radio resources are orthogonal to each other. Within the set of
resources 800, which spans over subframe 80 to subframe 84, two
HARQ indicators are transmitted, occupying a subset of radio
resources 810 and 820. Resources 810 and 820 overlap partially.
HARQ indicator channel 810 and 820 overlap at resource 821. In
another set of radio resources 840, the whole set of resources is
separated into two orthogonal subsets 850 and 860 for two HARQ
indicators.
[0060] FIG. 9 shows and exemplary diagram of a cell-specific EPHICH
resource allocation. Only one set of radio resources 900 is
allocated for a cell-specific HARQ indicator channel. In this
example, three HARQ indicators are transmitted within three subsets
of radio resources 910, 920 and 930. Radio resource 910 is
orthogonal to radio resource 930. Radio resource 930 is orthogonal
to radio resource 920. Radio resources 910 overlap with radio
resource 920 at resource 921.
Repetition Number Handling
[0061] To improve the spectrum efficiency and UE power consumption,
a new transmission/retransmission mechanism with multiple
repetition levels is proposed. The repetition number during the
retransmissions can be different from the repetition number for the
first or the initial transmission. In one embodiment, a data block
is transmitted repeatedly by a first repetition number after an
uplink message is given for the first or the initial transmission.
If feedback indicating the NACK is received, the UE transmits the
data block with a second repetition number during following
retransmissions. In one embodiment, the second repetition number is
smaller than the first repetition number. The first repetition
number for the initial transmission is noted as N.sub.initial, and
the second repetition number for kth retransmission is
N.sub.retrans.sup.k, where k=1, 2, . . . . In one embodiment,
N.sub.initial>(N.sub.retrans.sup.k=N.sub.retrans.sup.l) where
k.noteq.l, (k,l=1, 2 . . . ).
[0062] In another embodiment, a first repetition number for the
initial transmission is applied for the repetition of the initial
transmission of a data block. If a NACK is received, a second
repetition number, smaller than the first repetition number, is
applied during a retransmission of the data block. Further, a
second repetition number for each repetition number is different.
In one embodiment, the repetition number reduces each time, i.e.,
N.sub.initial>N.sub.retrans.sup.k>N.sub.retrans.sup.l, where
1.ltoreq.k<l.
[0063] FIG. 10 shows and exemplary diagram for a data block
transmission/retransmission with different repetition levels where
different frequency resources are used. A data block is transmitted
repeatedly with a repetition number 1010 from subframe 1001, for
the first time. During the first and the second retransmission, the
data block is transmitted with a second repetition number 1030 and
1050, where 1030 is equal to 1050. Further, 1030 and 1050 are
smaller than 1010. The starting subframe for the first and the
second retransmission is different, noted as 1002 and 1003. A set
of radio resources 1011, 1031 and 1051 is allocated for the initial
data transmission and the data retransmissions. The three sets of
radio resources, 1010, 1030, and 1050 are orthogonal in frequency
domain.
[0064] FIG. 11 shows and exemplary diagram for a data block
transmission/retransmission with different repetition levels where
the same frequency resources are used. In the initial transmission,
the first and the second retransmissions, a data block is
transmitted by a repetition number 1110, 1130 and 1150, where the
repetition number 1110>the repetition number 1130>repetition
number 1150. In this example, the data block is transmitted at
three different starting subframes 1101, 1102 and 1103,
respectively. The same set of resources for the transmission in the
frequency domain is used. For example, resources used during
retransmission are the resources allocated for the initial
transmission.
[0065] In one novel aspect, the first repetition number can be
indicated by an uplink grant message for a data block, or
determined by a predefined rule. In one embodiment, an indicator
within an uplink grant indicates the value of a first repetition
number by a value index. Subsequently, values for the first
repetition number are indexed in a predefined table. The index is
transmitted within the uplink grant message by a DCI format to
inform UEs the first repetition number for the initial
transmission. In another embodiment, the value of a first
repetition number is given by an indicator in an uplink grant
message directly. In a third embodiment, a first repetition number
is determined according to a predefined rule. The predefined rule
for the first repetition number is based on the amount of allocated
resources for a data block transmission and the size of the
transmitted data block. Further, a reported channel state indicator
is also a parameter to determine the first repetition number. A
coverage gap to be met is another parameter to determine the first
repetition number.
[0066] FIG. 12 shows an exemplary diagram of the first repetition
number value indicated in an uplink grant message. An uplink grant
message 1200 with a length of 1201 contains a repetition number
value. An indicator 1210 with a length of 1221 is contained in
uplink grant message 1200. Indicator 1210 represents the repetition
number upon decoding.
[0067] FIG. 13 shows an exemplary diagram of the first repetition
number index indicated in an uplink grant message. An uplink grant
message 1300 with a length of 1301 contains a repetition number
index. An indicator 1310 with a length of 1311 is contained in
uplink grant message 1300. Indicator 1310 represents the repetition
number index upon decoding. A repetition number table 1320 converts
the received repetition number index to a repetition number value.
By looking up the predefined table 1320, the UE obtains value of
the first repetition number based on the received repetition number
index 1310.
[0068] FIG. 14 illustrates an exemplary diagram of using the
predefined rule to determine the first repetition number. Different
values for a coverage enhancement degree are 1400 and 1450. A set
of value 1410 presents the amount of allocated radio resources for
a data block transmission. The set of value 1410 comprises multiple
values, such as 1411, 1412. Another set of value 1420 is a
transport block size (TBS), listing all values of block size such
as 1421 and 1422. Correspondingly, different value sets for the
first repetition number can be obtained and expressed as block 1401
and 1402. In one embodiment, the UE obtains the resource amount
value and TBS from a received uplink grant message. The UE
determines an explicit value for the first repetition number, by
looking up the table based on the resource amount value and TBS
value.
[0069] In another novel aspect, the second repetition number for
retransmission can be indicated by an indicator in an uplink grant
message in one embodiment. One example is a value index for the
second repetition is transmitted in the uplink grant message. The
second repetition number is determined by checking the value index
from a predefined value set or predefined value table. In another
embodiment, the second repetition number is an explicit value
indicated by an indicator in the uplink grant message. In yet
another embodiment, the second repetition number is obtained from a
feedback NACK signal, which comprises a NACK signal, and a second
repetition number. Except for a dedicated HARQ channel, such
feedback NACK signal can also be transmitted by a compact DCI
format transmitted in a control region. In one embodiment, the
second repetition number is selected from a value set for the
second repetition number, according to the determination rule for
the second repetition number. The determination rule is based on
the first repetition number, the amount of resources for a
retransmission and the index of a retransmission. In addition, the
size of the transmitted data block, or a coverage enhancement gap
is also considered to determine the second repetition number.
[0070] FIG. 15 shows an exemplary diagram of the second repetition
number index indicated in an uplink grant message. An uplink grant
message 1500 with the size of 1501 comprises an indicator 1510 with
the size of 1511. Indicator 1510 indicates a value index for the
second repetition number. The UE determines the value of the second
repetition number by checking a predefined value table for the
second repetition number N.sub.retrans.
[0071] FIG. 16 shows an exemplary diagram of the second repetition
number value indicated in an uplink grant message. An uplink grant
message 1600 with the size of 1601 comprises an indicator 1610 with
the size of 1611. Indicator 1610 indicates the second repetition
number value. The UE obtains the second repetition number
N.sub.retrans upon decoding indicator 1610.
[0072] FIG. 17 illustrates an exemplary diagram of using the
predefined rule to determine the second repetition number. Entries
1710 and 1750 are two different values for the first repetition
number. Under a certain value of the first repetition number, by
checking the amount of allocated radio resources (1711, 1712, etc.)
from a value set 1710 and the data block size (1721, 1722, etc.)
from a value set 1720, the value of the second repetition number
can be obtained explicitly from the value set 1701 and 1751.
[0073] As shown in FIG. 10 and FIG. 11, the resources for a data
block transmission/retransmission in the frequency domain can be
different or identical. In one embodiment, the resources for the
retransmission can be specified as the resources for the initial
transmission in one embodiment. In another embodiment, the
resources for retransmissions are determined according to a
predefined rule. The predefined rule specifies the set of resources
for a retransmission is obtained by adding an offset to the
resources for the initial transmission. The resource offset is a
function of a retransmission index, a starting subframe or frame
index of a retransmission, or a combination of these parameters. As
a result, the resources for the initial transmission and each
retransmission can be orthogonal to each other, or overlap
partially/fully in frequency domain.
[0074] One exemplary expression to determine the resources for a
kth retransmission I.sub.RB.sup.k is defined as:
I.sub.RB.sup.k=(I.sub.RB.sup.init+k)mod N.sub.RB.sup.UL,k=1,2, . .
. (1)
where I.sub.RB.sup.k is an index of allocated PRBs for kth
retransmission over the channel bandwidth, I.sub.RB.sup.init is an
index of allocated PRBs for the initial transmission over the
channel bandwidth, and N.sub.RB.sup.UL is the channel bandwidth
expressed as PRB number.
[0075] Another exemplary expression to determine the resources for
kth retransmission I.sub.RB.sup.k is defined as:
I.sub.RB.sup.k=(I.sub.RB.sup.init+S.sub.k mod 1024)mod
N.sub.RB.sup.UL, k=1,2, . . . (2)
where I.sub.RB.sup.k is an index of allocated PRBs for kth
retransmission over the channel bandwidth, I.sub.RB.sup.init is an
index of allocated PRBs for the initial transmission over the
channel bandwidth, S.sub.k is the starting frame index of kth
retransmission, and N.sub.RB.sup.UL is the channel bandwidth
expressed as PRB number.
Multiple HARQ Indicators Handling
[0076] To guarantee a robust transmission of ACK/NACK signal and
improve the resource/power efficiency, a mechanism of multiple HARQ
indicators feedback to one uplink data block is supported in this
invention, and a UE is required to receive multiple HARQ
indicators. In one embodiment, a maximal number for HARQ indicators
transmission is specified, and expressed as N.sub.HARQ.sup.max. A
UE should determine whether to receive another HARQ indicator after
a transmission or a retransmission if a NACK is received previously
or after receiving an ACK. If the cumulated number of received HARQ
indicators is smaller than the threshold, the UE will try to
receive another HARQ indicator regardless of the previously
received acknowledgement state.
[0077] In another embodiment, a maximal number for HARQ indicators
transmission is specified, and expressed as N.sub.HARQ.sup.max. A
UE should determine whether to receive another HARQ indicator after
a (re)transmission. If the cumulated number of received HARQ
indicators does not exceed the maximal number, the UE will try to
receive another HARQ indicator for this transmission. In case a
positive acknowledgement is assumed at UE side, the UE will stop
transmission and will not receive another HARQ indicator.
[0078] In a third embodiment, a maximum number of HARQ indicators
indicating ACK is specified and expressed as N.sub.ACK.sup.max. A
UE should determines whether to receive another HARQ indicator
after a HARQ indicator indicating ACK is received previously.
[0079] FIG. 18 is an exemplary flow chart of a HARQ receiving
procedure where the UE terminates the procedure upon a maximum
number of decoding is reached. The UE receives a HARQ indicator
channel (Step 1810) after an initial transmission (Step 1800) and
updates the HARQ indicator number counter by adding one.
Subsequently, an ACK/NACK determination (Step 1820) is performed.
If Step 1820 determines that a NACK is indicated by the received
HARQ indicator, the UE moves to Step 1821 and retransmits the data
block with a second repetition number. After the retransmission, a
further check for a cumulated number of received HARQ indicators is
performed (Step 1840). If the cumulated number of received HARQ
indicators is not larger than the specified threshold, the UE will
continue to receive another HARQ indicator for this retransmission
at Step 1841. Otherwise, this transmission of the data block
finishes. If Step 1820 determines that NACK is not received, no
retransmission is performed at Step 1825. The UE moves to Step 1880
and checks whether to receive another HARQ indicator. If the
threshold for the HARQ indicator is not reached, the UE moves back
to 1810 to wait for another HARQ indicator, otherwise this
transmission of the data block finishes.
[0080] FIG. 19 is an exemplary flow chart of a HARQ receiving
procedure where the UE terminates the procedure upon a maximum
number of NACK is reached or upon an ACK is determined. The UE
receives a HARQ indicator channel (Step 1910) after a data block
transmission with a first repetition number (Step 1900) and
performs an ACK/NACK determination (Step 1920). During Step 1910,
the counter for the HARQ indicator is updated by adding one every
time a HARQ indicator is received. Step 1921 means a NACK is
indicated by the received HARQ indicator, and a retransmission with
a second repetition number is performed correspondingly. After the
retransmission, a further check for a cumulated number of received
HARQ indicators is performed (Step 1930). If the cumulated number
of received HARQ indicators is not larger than the specified
maximum number for HARQ indicator, the UE will continue to receive
another HARQ indicator for this retransmission, as expressed by
Step 1931, otherwise the process of the data block transmission
ends (Step 1935). Different from the example in FIG. 18, the UE
will finish this transmission of the data block if a positive
acknowledgement state is determined (Step 1925).
[0081] FIG. 20 is an exemplary flow chart of a HARQ receiving
procedure where the UE terminates the procedure upon a maximum
number of HARQ reached and an ACK is determined. After an initial
transmission of a data block by repeated transmission with a first
repetition number (Step 2000), a UE will try to receive and decode
a HARQ indicator (Step 2010). Subsequently, a determination of the
acknowledgement state is performed, as expressed as Step 2020. If a
negative state is determined, a UE will start a retransmission of
the data block with a second repetition number (Step 2021). If a
positive state is determined, no retransmission is performed (Step
2025). Note that the counter for the HARQ indicator is updated once
a received HARQ indicator indicates a positive acknowledgement in
Step 2025. However, a UE will further check to receive another HARQ
indicator by checking the cumulated number of received positive
acknowledgements (Step 2030). If the number of the positive
acknowledgements reaches the threshold, the process of this data
block transmission ends (Step 2035). Otherwise, the UE will try to
receive another HARQ indicator for the transmitted data block.
[0082] To further reduce the power consumption at UE side and
improve the resource efficiency, a threshold for a repetition
number for a data block transmission is specified as
N.sub.data.sup.max, which is a maximal repetition number. In one
embodiment, the UE should judge whether the maximum repetition
number of the data block is reached before starting a new
retransmission when an NACK is detected. If the cumulated
repetition number, which is the sum of the repetition number for
the initial transmission and the repetition number in each
retransmission, exceeds the maximum repetition number, the UE will
stop retransmitting the data block. Otherwise a new retransmission
with a new repetition number will be performed.
[0083] FIG. 21 illustrates an exemplary flow chart for the UE to
terminate the data transmission upon detecting maximum number of
repetition transmission is reached. a UE performs an initial
transmission repeatedly and updates the counter for the data block
repetition number, after an uplink grant message (Step 2100). Then,
the UE will determine the acknowledgement state (Step 2120) from
the decoded HARQ indicator (Step 2110). If an ACK is determined,
the data block transmission ends. If a NACK is determined, the UE
will further check whether the cumulated repetition number of the
data block achieves the specified maximal number (Step 2130). If
not, a UE will try to receive and decode another HARQ indicator,
after performing a retransmission and updating the counter for the
data block repetition number (Step 2135). If the cumulated
repetition number of the data block is larger than the maximal
number, the transmission of this data block finishes and a UE will
wait for another uplink grant message (Step 2131).
[0084] FIG. 22 illustrates an exemplary flow chart for the UE to
terminate the data transmission upon detecting maximum number of
repetition transmission is reached or the maximum numbers of HARQ
indicators are received. At Step 2200, the UE performs an initial
transmission of a data block repeatedly after receiving an uplink
grant message and updates the counter for the data block repetition
number correspondingly. Subsequently, a HARQ indicator is received
(Step 2210), where the counter for the HARQ indicator number is
updated. An ACK/NACK determination is performed (Step 2220). If an
ACK is determined, the process of this data block transmission
terminates. If a NACK is determined, a comparison between the
cumulated repetition number and a maximal number for the data block
transmission is performed (Step 2230). The UE will terminate the
process of the data block transmission if the cumulated repetition
number reaches the maximum number (Step 2231). Otherwise, a
retransmission of the data block is performed and the counter for
the data block repetition number is updated (Step 2235. The UE will
further check whether the cumulated number of HARQ indicator is
larger than a threshold number for HARQ indicator (Step 2240). If
not, another HARQ indicator will be received and decoded, and the
counter for the HARQ indicator is also updated when a HARQ
indicator is received (Step 2241). If the cumulated number of HARQ
indicator reaches the specified value, the process of this data
block transmission terminates.
[0085] FIG. 23 is an exemplary flow chart for the UE to decode and
handle the single-state HARQ in accordance with embodiments of the
current invention. At Step 2301, the UE decodes one or more
resource blocks in a HARQ indicator channel. At Step 2302, the UE
detects a hybrid automatic repeat request (HARQ) indicator for a
data transmission, wherein the HARQ indicator is a single-state
indicator encoded with a UE identity (ID) of the UE, and wherein
the HARQ indicator is encoded in one of resource blocks of the HARQ
indicator channel. At Step 2303, the UE determines a HARQ
acknowledgment status for the data transmission based on the
detection of the HARQ indicator. At Step 2304, the UE increases a
HARQ count upon decoding the HARQ indicator channel. At Step 2305,
the UE retransmits the data transmission if the HARQ count is
smaller than a predefined maximum HARQ count and the HARQ
acknowledgement status is determined to be negative. At Step 2306,
the UE stops decoding the HARQ indicator channel if the HARQ count
is greater than a predefined maximum HARQ count. At Step 2307, the
UE increases a data transmission count by a repetition number for
data transmission of a data block and stops retransmitting the data
block if the data transmission count is greater than a redefined
maximum transmission number.
[0086] Although the present invention has been described in
connection with certain specific embodiments for instructional
purposes, the present invention is not limited thereto.
Accordingly, various modifications, adaptations, and combinations
of various features of the described embodiments can be practiced
without departing from the scope of the invention as set forth in
the claims.
* * * * *