Note: Descriptions are shown in the official language in which they were submitted.
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Express Mail Label No. EV748349925US
[0001] METHOD AND SYSTEM FOR IMPLEMENTING
H-ARQ-ASSISTED ARQ OPERATION
[0002] FIELD OF INVENTION
[0003] The present invention is related to wireless communication
systems. More particularly, the present invention is related to a method and
system for implementing hybrid automatic repeat request (H-ARQ)-assisted
automatic repeat request (ARQ) in a wireless communication system.
[0004] BACKGROUND
[0005] In conventional wireless communication systems, such as
wideband code division multiple access (WCDMA) Release 5/6, high speed
data transmission is,achieved by high speed downlink packet access (HSDPA)
and high speed uplink packet access (HSUPA) technologies. To improve
reliability of data transmission, H-ARQ and ARQ are implemented.
[0006] Figure 1 shows a conventional wireless communication system
100. The system 100 includes a user equipment (UE) 110, a Node-B 120 and a
radio network controller (RNC) 130. H-ARQ entities are located in a medium
access control (MAC) layer 112 of the UE 110 and a MAC layer 122 of the
Node-B 120. Packets are assigned transmission sequence numbers (TSNs) in
an H-ARQ transmitter. An H-ARQ receiver receives the packets and attempts
to decode the transmitted packets. If a packet is not decodable, the H-ARQ
receiver sends a negative acknowledgment (NACK) back to the H-ARQ
transmitter for retransmission of the failed packet. If a packet is correctly
decoded, the H-ARQ receiver sends a positive acknowledgment (ACK) for the
packet to the H-ARQ transmitter. Upon receiving a NACK, the H-ARQ
transmitter retransmits the packet if the number of retransmissions of the
failed packet is less than a predetermined maximum limit, and the allowed
transmission time for the failed packet has not expired. Otherwise, the failed
packet is discarded and recovered at an ARQ level.
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[0007] ARQ entities are located in a radio link control (RLC) layer 114 of
the UE 110 and an RLC layer 132 of the RNC 130. The ARQ entities handle
the retransmission of the failed packet. The ARQ entities recover packets that
are lost due to an NACK-to-ACK misinterpretation error at the H-ARQ level.
The ARQ process in an RLC layer is quite complex with many options to
perform status reporting.
[0008] An H-ARQ assisted ARQ operation may be considered when both
the H-ARQ and ARQ functions are co-located, such as in a universal mobile
telecommunication systems (UMTS) Node-B or a long term evolution (LTE)
evolved Node-B (eNode-B).
[0009] Figure 2 shows an example of an H-ARQ-assisted ARQ operation
proposed for third generation partnership project (3GPP) standards. A
transmitter 250 includes an ARQ transmitter 252 and an H-ARQ transmitter
254. A receiver 260 includes an ARQ receiver 262 and an H-ARQ receiver 264.
The H-ARQ transmitter 254 provides a local ACK or a local NACK to the ARQ
transmitter 252.
[0010] As shown in Figure 2, a local NACK is generated when the H-
AR.Q transmitter 254 fails the H-ARQ transmission, (e.g., due to maximum
retransmission limit). The ARQ transmitter 252 sends an ARQ protocol data
unit (PDU) x to the H-ARQ transmitter 254 (step 202). The H-ARQ
transmitter 254 sends the ARQ PDU x to the H-ARQ receiver 264 (step 204).
The ARQ PDU x is not decodable and the H-ARQ receiver 264 sends a NACK
to the H-ARQ transmitter 254 (step 206). The H-ARQ transmitter 254
retransmits the ARQ PDU x to the H-ARQ receiver 264 (step 208). The ARQ
PDU x is still not decodable and the H-ARQ, receiver 264 sends another NACK
to the H-ARQ transmitter 254 (step 210). At such a point, it is determined
that the number of retransmissions for the ARQ PDU x reaches a maxi
mum
retransmission limit (step 212). The H-ARQ transmitter 254 then sends a
local NACK for the ARQ PDU x to the ARQ transmitter 252 (step 214).
[0011] A local NACK may also be generated when an NACK-to-ACK
error is reported from the H-ARQ receiver 264 to the H-ARQ transmitter 254.
Still referring to Figure 2, the ARQ transmitter 252 sends an ARQ PDU y to
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the H-ARQ transmitter 254 (step 216). The H-ARQ transmitter 254 transmits
the ARQ PDU y to the H-ARQ receiver 264 (step 218). The ARQ PDU y is not
decodable and the H-ARQ receiver 264 sends a NACK to the H-ARQ
transmitter 254 (step 220). However, the NACK is misinterpreted as an ACK
by the H-ARQ transmitter 254 and the H-ARQ transmitter 254 treats the
ARQ PCU y as successfully transmitted. The H-ARQ receiver 264 detects an
NACK-to-ACK error, (e.g., when the H-ARQ receiver 264 receives a new PDU
via the same H-ARQ process while waiting for retransmission of the ARQ
PDU y), (step 222). The H-ARQ receiver 264 sends a NACK-to-ACK error
indicator to the H-ARQ transmitter 254 (step 224). Upon receipt of the
NACK-to-ACK error indicator, the H-ARQ transmitter 254 sends a local
NACK to the ARQ transmitter 252 and the ARQ PDU y is recovered at an
ARQ level (step 226).
[0012] As shown in Figure 2, a local ACK is generated when none of the
above two events for an ARQ packet occurs during a predefined time interval.
The ARQ transmitter 252 sends an ARQ PDU z to the H-ARQ transmitter 254
(step 228). The H-ARQ transmitter 254 transmits the ARQ PDU z to the H-
ARQ receiver 364 (step 230). The ARQ PDU z is successfully decoded and the
H-ARQ receiver 264 sends the ARQ PDU z to the ARQ receiver 262 (step 232),
and sends an ACK to the H-ARQ transmitter 254 (step 234). When it is
determined that a NACK-to-ACK error is not reported during a predetermined
time interval (step 236), the H-ARQ transmitter 254 sends a local ACK to the
ARQ transmitter 252 (step 238). The ARQ transmitter 252 will discard the
packet from a transmit buffer after receiving the local ACK from the H-ARQ
transmitter 254.
[0013] In the above example of an H-ARQ assisted ARQ system, a
complex layer 2 (L2) status reporting mechanism is removed under the
assumption that the NACK to-ACK error is the only significant source of
undetected packet loss. The ARQ transmitter will not be able to recover the
packet for cases where the NACK-to-ACK error indicator is lost or a shared
channel is lost due to a discontinuous transmission (DTX)/ACK error. Thus
lossless transmission cannot be guaranteed.
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[0014] Current downlink H-ARQ, (Release 5), does not specify the
maximum number of retransmissions for a packet. Thus, the H-ARQ
transmitter or receiver does not know the maximum num.ber of transmissions
for each packet. There is an assumption that the ARQ transmitter and the H-
ARQ transmitter have the same PDU size. The H-ARQ transmitter informs
the ARQ transmitter the segment that is lost, (not the ARQ PDU). If the ARQ
PDU is retransmitted, the H-ARQ transmitter will retransmit the complete
packet, not only the missing segment. It is also unclear how to recover the
last packet of the H-ARQ transmission.
[0015] SUMMARY
[0016] The present invention is related to a method and system for
implementing H-ARQ-assisted ARQ in a wireless communication system. An
H-ARQ receiver determines whether an H-ARQ NACK-to-ACK error occurs.
When an H-ARQ NACK-to-ACK error occurs, the H-ARQ receiver sends an H-
ARQ error indicator to the H-ARQ transmitter unless the number of
retransmissions of the failed packet has reached a maximum retransmission
limit, a maximum time for delivery of the failed packet has expired and/or a
lifespan of the failed packet has expired. The H-ARQ transmitter tries to
recover the failed packet. The H-ARQ transmitter sends a local NACK to the
ARQ transmitter if the maximum retransmission limit has been reached, the
maximum delivery time has expired or the lifespan of the failed packet has
expired, so that the failed packet can be recovered at an ARQ level. The H-
ARQ receiver sends a local NACK to the ARQ receiver if the H-ARQ receiver
does not receive the failed packet before certain conditions occur. Based on
reception of the local NAK, the ARQ receiver may send a status report to the
ARQ transmitter for recovery of the failed packet.
[0017] BRIEF DESCRIPTION OF THE DRAWINGS
[00181 A more detailed understanding of the invention may be had from
the following description of a preferred embodiment, given by way of example
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and to be understood in conjunction with the accompanying drawing(s)
wherein:
[0019] Figure 1 shows a conventional wireless communication system;
[0020] Figure 2 shows an example of an H-ARQ-assisted ARQ operation
proposed for third generation partnership project (3GPP) standards; and
[0021] Figure 3 is a signaling diagram of a process for implementing an
H-ARQ-assisted ARQ operation in accordance with the present invention.
[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] The features of the present invention may be incorporated into
an integrated circuit (IC) or be configured in a circuit comprising a
multitude
of interconnecting components.
[0024] Figure 3 is a signaling diagram of a process 400 for implementing
an H-ARQ-assisted ARQ operation in a wireless communication system 300 in
accordance with the present invention. The system 300 includes a transmitter
310 and a receiver 320. The transmitter 310 includes an ARQ transmitter 312
and an H-ARQ transmitter 314. The receiver 320 includes an ARQ receiver
322 and an H-ARQ receiver 324.
[0025] In order to support the H-ARQ-assisted AR~,I in accordance with
the present invention, the following parameters are defined:
= TErrorIndicator: H-ARQ error indication timer is defined as the
amount of time that an H-ARQ receiver should wait for a retransmission of
the failed packet before sending an HARQ error indicator. It is preferable to
keep the H-ARQ error indication timer constant for the whole system for
simple implementation. However, the H-ARQ error indication timer may be
adjusted based on the quality of service (QoS) requirements. For example, the
length of the H-ARQ error indication timer may be linked to the scheduling
priority.
= NlRetransmfssfon: Maximum number of retransmissions allowed for a
packet. The maximum number of retransmissions may be based on the QoS
requirements, and be configured per service type.
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= Tneii~sry: Maximum delivery time allowed for successful delivery of
the packet after the first transmission. The maximum delivery time may be
based on the QoS requirements, (e.g., a block error rate, latency, or the
like),
and be configured per service type.
= TR..,erysy.,,~: For synchronous H-ARQ, a time within which the H-
ARQ receiver expects to receive a failed packet after transmitting an H-ARQ
error indicator.
= Tae.eryAsy~,r: For asynchronous H-ARQ, a time within which the
H-ARQ receiver expects to receive a failed packet after transmitting an H-
ARQ error indicator. The timer may be associated with the QoS requirements,
and be configured per service type. For example, the length of the timer may
be linked to the scheduling priority.
= WHaR,q: A window, (i.e., the number of packets), within which a
failed packet should be received. If the failed packet is not received within
WxAxQ, it is assumed lost.
[0026] The transmitter 310 and the receiver 320 may also be given with
a parameter for a lifespan of a packet, (i.e., the maximum time to transmit
the
packet). The parameters may be provided by a central node to the H-ARQ
receiver 324 and the H-ARf~,1 transmitter 314. If the parameters are defined
per service type, the parameters may be given to the H-ARQ receiver 324 and
the H-ARQ transmitter 314 at the start of that service.
[0027] The maximum number of retransmissions and/or the lifespan of a
packet may be dynamically changed depending on the QoS requirements. The
maximum number of transmissions may be indicated by either explicitly
identifying the number of transmissions in the associated signaling or
identifying a MAC flow that is associated with a configured maximum number
of transmissions. In accordance with the first option, the number of
retransmissions per packet is indicated in the associated control signaling
for
the first transmission. In accordance with the second option, each MAC flow
may be associated with a certain number of retransmissions and by
identifying the MAC flow in the associated control signaling for the first
transmission, the maximum number of transmissions may be indicated. If the
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second option is used, the identified MAC flow is translated to the maximum
number of transmisisons configured by the receiver. The maximum number of
retransmissions may also be known by an H-ARQ process ID if specific H-ARQ
processes are dedicated to a MAC flow for a set of MAC flows. Alternatively, a
flag may be set in the associated signaling to indicate last transmission.
[0028] A process 400 for implementing an H-ARQ-assisted ARQ
operation in accordance with the present invention is explained hereafter with
reference to Figure 3. The H-ARQ transmitter 314 transmits a packet to the
H-ARQ receiver 324 (step 402). If the packet is successfully received, the H-
ARQ receiver 324 sends the packet to the ARQ receiver 322 (not shown in
Figure 3). If the packet is not successfully received, the H-ARQ receiver 324
sends a NACK to the H-ARQ transmitter 314 (step 404). After sending the
NACK in step 404, the H-ARQ receiver 324 determines whether an H-ARQ
NACK-to-ACK error occurs (step 406). Upon detection of the H-ARQ NACK-
to-ACK error, the H-ARQ receiver 324 generates, and sends, an H-ARQ
NACK-to-ACK error indicator to the H-AR(Q transmitter 314 (step 408).
[00291 For synchronous H-ARQ transmission, the time of a H-ARQ
retransmission is known to the receiver. If the H-ARQ receiver 324 receives a
new packet when expecting retransmission of the failed packet, the H-ARQ
receiver 324 determines that an H-ARQ NACK-to-ACK error occurs and sends
an H-ARQ NACK-to-ACK error indicator unless the failed packet has been
transmitted for the maximum number of retransmissions.
[0030] For asynchronous H-ARQ transmission, a timer TErrarInai'-.tor is set
at the H-ARQ receiver 324 when the maximum number of retransmission has
not been reached and the H-ARQ receiver 324 sends a NACK to the H-ARQ
transmitter 314 at step 404. If the failed packet is successfully received
before
the timer TErrorinaic8tor expires, the timer TErrarlnd;cator is reset to zero
and the H-
ARQ NACK-to-ACK error indicator is not generated. If the H-ARQ receiver
324 does not successfully receive the failed packet before the timer
TE~rznaiestor
expires, the H-ARQ receiver 324 determines that an H-ARQ NACK-to-ACK
error occurs and sends an H-ARQ NACK-to-ACK error indicator to the H-ARQ
transmitter 314 unless the number of transmissions of the failed packet has
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reached the maximum retransmission limit, the maximum delivery time for
the packet, (TDd1õery), has expired, and/or the lifespan of the failed packet
has
expired.
[0031] The H-ARQ NACK-to-ACK error indicator is sent from the H-
ARQ receiver 324 to the H-ARQ transmitter 314 to inform about a NACK-to-
ACK misinterpretation at the H-ARQ transmitter 314. The H-ARQ NACK-to-
ACK error indicator is associated with a particular H-ARQ process and a
particular packet in the H-ARQ process. The H-ARQ NACK-to-ACK error
indicator contains H-ARQ process identity (ID) and a TSN to identify the
packet ID in the H-ARQ process.
[0032] For synchronous H-ARQ, the H-ARQ process ID and the TSN
may be removed since a fixed timing relationship between the failed
transmission and the error report can be used to associate the H-ARQ NACK-
to-ACK error indicator with an H-ARQ process ID and a packet TSN. For
example, if there are four (4) synchronous H-ARQ processes, the H-ARQ
NACK-to-ACK error indicator may be sent after time t of receiving the packet
with a TSN n for which the NACK-to-ACK error happened.
[0033] An H-ARQ NACK-to-ACK error indicator packet may be
independent of the H-ARQ operation. This is achieved by sending the process
identity (if needed) and time offset to identify reception time of the
received
error. Alternatively, the H-ARQ NACK-to-ACK error indicator may be sent as
a physical layer signal at a fixed time offset after the reception of the
received
error packet .
[0034] If more than one packet may be sent simultaneously from the
transmitter 310 to the receiver 320, the packets have their own cyclic
redundancy check (CRC) and one H-ARQ NACK-to-ACK error indicator may
be used to send NACK-to-ACK error indications for several packets. Hence,
the H-ARQ NACK-to-ACK error indicator may contain multiple H-ARQ
process IDs, associated packet TSNs and/or timing offset.
[0035] The H-ARQ NACK-to-ACK error indicator may have its own CRC
to ensure reliable transmission. This allows MAC or RLC layer signaling for
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H-ARQ NACK-to-ACK error indication. The H-ARQ .NACK-to-ACK error
indicator packet may be created either at H-ARQ or ARQ level.
[0036] StiD. referring to Figure 3, to ensure receipt of the H-ARQ NACK-
to-ACK error indicator, the H-ARQ transmitter 314 may send an ACK to the
H-ARQ receiver 324 (step 410). The H-ARQ receiver 324 may repeatedly send
the H-ARQ NACK-to-ACK error indicator until the H-ARQ receiver 324
receives an ACK from the H-ARQ transmitter 314 or radio link fails.
[0037] After receiving the H-ARQ NACK-to-ACK error indicator at step
408, the H-ARQ transmitter 314 tries to recover the error at an H-ARQ level
by retransmitting the failed packet unless the maximum retransmission limit
has reached, the maximum delivery time has expired, and/or the lifespan of
the failed packet has expired (step 412). The H-ARQ transmitter 314 may
send a local NACK to the ARQ transmitter 312 so that the failed packet can
be recovered at an ARQ level (step 414). Preferably, the H-ARQ transmitter
314 sends the local NACK to the ARQ transmitter 312 only if the maximum
number of retransmissions has been reached, the maximum delivery time for
transmission of the failed packet has expired, or the lifespan of the failed
packet has expired.
[00381 In the prior art, upon successful delivery of a packet, the H-ARQ
receiver 324 sends an ACK to the H-ARQ'transmitter 314 and the H-ARQ
transmitter 314 sends a local ACK to the ARQ transmitter 312. In accordance
with the present invention, the H-ARQ transmitter 314 may or may not send a
local ACK to the ARQ transmitter 312 in such situation.
[0039] After sending the H-ARQ NACK-to-ACK error indicator at step
408, the H-ARQ receiver 324 determines at step 416 whether the H-ARQ
receiver 324 does not receive the failed packet successfully before at least
one
of the following conditions:
1) expiration of Tx,eco,erysyc (for synchronous H-ARQ transmission)
or Txeoõe,yAsyn~, (for asynchronous H-ARQ transmission);
2) receipt of a new H-ARQ packet with a sequence number which
is higher than the sequence number of the failed packet by WxARQ;
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3) reaching the maximum number of retransmissions of the failed
packet;
4) expiration of the timer Tneii~ery; and
5) expiration of the lifespan of the failed packet.
[0040] If at least one of the foregoing conditions occurs, the H-ARQ
receiver 324 sends a local NACK to the ARQ receiver 322 (step 418). Upon
reception of the local NACK, the ARQ receiver 322 may send a status report to
the ARQ transmitter 312 to recover the failed packet (step 420). The mapping
between an ARQ PDU and an H-ARQ PDU is not relevant as long as the H-
ARQ receiver 324 is able to identify the ARQ PDU that needs to be recovered.
[0041] The ARQ buffer at the ARQ transmitter 312 may be emptied
after receiving the status report from the ARQ receiver 322. The status report
for the failed packet contains the information about successfully received
packets. Alternatively, the ARQ receiver 322 may send a status report after
receiving N consecutive packets successfully or expiration of a timer.
Alternatively, the ARQ transmitter 312 may poll the ARQ receiver 322 after
transmitting the last packet in the buffer. The reason for polling is to
recover
early from the NACK-to-ACK error at an H-ARQ level for the last packet.
Setting the "Poll bit for the last packet" is a. configurable parameter for a
data
flow.
[0042] In order to improve the recovery of the last packet in H-ARQ
transmissions, a special small packet with a last packet indication may be
sent from the H-ARQ transmitter 314 after the H-ARQ buffer is empty. The
transmission of the special packet with a last packet indication ensures early
recovery of the loss of the last packet at the H-ARQ level. The H-ARQ receiver
324 sends a response back to the H-ARQ transmitter 314 upon receiving the
special packet. The response packet may be a new packet generated at an H--
ARQ level indicating the last TSN received. Alternatively, the response
packet may be sent by using an H-ARQ error indication packet indicating that
it is a response to the small packet.
[0043] Alternatively, in order to reduce the signaling overhead, a null
transmission may be sent after the last data packet in an H-ARQ
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transmission queue to invoke the ACK check on the previous transmission. A
null packet only includes control information (i.e., no payload). The H-ARQ
transmitter 314 transmits the null packet after reception of an H-ARQ ACK
for the last data packet in the H-ARQ transmission queue. Once the H-ARQ
receiver 324 receives a null packet, the H-ARQ receiver 324 confirms reception
of the last data packet as well as the null packet. If, at the H-ARQ receiver,
the last packet was not successfully received and therefore a NACK was sent
in response to the last packet and the maximum number of transmissions was
not reached, the reception of the null packet will allow the H-ARQ receiver
324 to detect the NACK-to-ACK error.
[0044] The transmitter 310 and the receiver 320 may be a WTRU, a
base station or any other network entity in a WCDMA, CDMA2000 or long
term evolution (LTE) of a third generation (3G) system. "WTRU" includes but
is not limited to a user equipment (UE), a mobile station, a fixed or mobile
subscriber unit, a pager, a cellular telephone, a personal data assistant
(PDA),
a computer, or any other type of user device capable of operating in a
wireless
environment. "Base station" includes but is not limited to a Node-B, a site
controller, an access point or any other type of interfacing device in a
wireless
environment.
[0045] Embodiments.
[0048] 1. A method for implementing H-ARQ-assisted ARQ in a
wireless communication system including a transmitter and a receiver, the
transmitter including an H-ARQ transmitter and an ARQ transmitter, the
receiver including an H-ARQ receiver and an ARQ receiver.
[0047] 2. The method of embodiment 1 comprising the step of an H-
ARQ receiver determining whether an H-ARQ NACK-to-ACK error occurs.
[0048] 3. The method of embodiment 2 comprising the step of the H-
ARQ receiver sending an H-ARQ NACK-to-ACK error indicator to the H-ARQ
transmitter when an H-ARQ NACK-to-ACK error occurs unless the number of
retransmissions of a failed packet has reached a maximum retransmission
limit, a maximum time for delivery of the failed packet has expired or a
lifespan of the failed packet has expired.
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[0049] 4. The method as in any of the embodiments 2-3, wherein the
H-ARQ NACK-to-ACK error indicator is associated with an H-ARQ process ID
and the failed packet at the H-ARQ transmitter.
[0050] 5. The method of embodiment 4, wherein the H-ARQ NACK-
to-ACK error indicator includes the H-ARQ process ID and a transmission
sequence number of the failed packet.
[0051] 6. The method of embodiment 4, wherein the H-ARQ NACK-
to-ACK error indicator is sent with a fixed timing offset with respect to
transmission of the failed packet.
[0052] 7. The method as in any of the embodiments 3-6, wherein
transmission of the H-ARQ NACK-to-ACK error indicator and transmission of
the failed packet are independent.
[0053] 8. The method as in any of the embodiments 3-7, wherein the
H-ARQ NACK-to-ACK error indicator is sent via at least one of physical layer
signaling, a MAC layer signaling and an RLC layer signaling.
[0054] 9. The method as in any of the embodiments 3-8, wherein
more than one packet is transmitted from the H-ARQ transmitter to the H-
ARQ receiver simultaneously and the H-ARQ NACK-to-ACK error indicator
indicates H-ARQ NACK-to-ACK errors of more than one packet.
[0055] 10. The method as in any of the embodiments 3-9, wherein the
H-ARQ NACK-to-ACK error indicator is sent along with a CRC.
[0056] 11. The method as in any of the embodiments 3-10, wherein
the H-ARQ NACK-to-ACK error indicator is generated by one of the H-ARQ
receiver and an ARQ receiver.
[0057] 12. The method as in any of the embodiments 3-11, further
comprising the step of the H-ARQ transmitter sending an ACK to the H-ARQ
receiver upon receipt of the H-ARQ NACK-to-ACK error indicator.
[0058] 13. The method of embodiment 12, wherein the H-ARQ
receiver sends the H-ARQ NACK-to-ACK error indicator repeatedly if the H-
ARQ receiver does not successfully receive the ACK for the H-ARQ NACK-to-
ACK error indicator and a radio link between the H-ARQ transmitter and the
H-ARQ receiver does not fail.
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[0059] 14. The method as in any of the embodiments 3-13, wherein
the H-ARQ receiver sends the H-ARQ NACK-to-ACK error indicator if the H-
ARQ receiver receives a new packet via the same H-ARQ process assigned for
the failed packet instead of retransmission of the failed packet.
[0060] 15. The method as in any of the embodiments 3-14, wherein
the H-ARQ receiver sends the H-ARQ NACK-to-ACK error indicator if the H-
ARQ receiver does not receive the failed packet until an error indication
timer
expires, the error indication timer being set when a NACK is sent to the H-
ARQ transmitter.
[0061] 16. The method as in any of the embodiments 3-15, further
comprising the step of the H-ARQ transmitter retransmitting the failed packet
until the failed packet is successfully delivered unless the maximum
retransmission limit has reached, the maximum delivery time has expired or
the lifespan of the failed packet has expired.
[0062] 17. The method of embodiment 16, further comprising the step
of the H-ARQ transmitter sending a local NACK to the ARQ transmitter if the
maximum retransmission limit has reached, the maximum delivery time has
expired or the lifespan of the failed packet has expired, so that the failed
packet is recovered at an ARQ level.
[0063] 18. The method as in any of the embodiments 3-17, further
comprising the step of the H-ARQ receiver setting a recovery timer when the
H-ARQ receiver sends the H-ARQ NACK-to-ACK error indicator.
[0064] 19. The method of embodiment 18 comprising the step of the
H-ARQ receiver sending a local NACK to the ARQ receiver if the H-ARQ
receiver does not receive the failed packet before the recovery timer expires.
[0065] 20. The method of embodiment 19, further comprising the step
of the ARQ receiver sending a status report to the ARQ transmitter for
recovery of the failed packet.
[0066] 21. The method as in any of the embodiments 3-20, further
comprising the step of the H-ARQ receiver sending a local NACK to the ARQ
receiver if the H-ARQ receiver does not receive the failed packet until the H-
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ARQ receiver receives a packet with a sequence number higher than a
sequence number of the failed packet by a predetermined number.
[0067] 22. The method of embodiment 21, further comprising the step
of the ARQ receiver sending a status report to the ARQ transmitter for
recovery of the failed packet.
[0068] 23. The method as in any of the embodiments 3-22, further
comprising the H-ARQ receiver sending a local NACK to the ARQ receiver if
the H-ARQ receiver does not receive the failed packet until the number of
retransmissions of the failed packet reaches a maximum retransmission limit
for the failed packet.
[0069] 24. The method of embodiment 23, further comprising the step
of the ARQ receiver sending. a status report to the ARQ transmitter for
recovery of the failed packet.
[00701 25. The method as in any of the embodiments 3-24, further
comprising the step of the H-ARQ receiver sending a local NACK to the ARQ
receiver .if -the H-ARQ receiver does not receive the failed packet until a
maximum time for delivery of the failed packet expires.
[0071] 26. The method of embodiment 25, further comprising the step
of the ARQ receiver sending a status report to the ARQ transmitter for
recovery of the failed packet.
[0072] 27. The method as in any of the embodiments 3-26, further
comprising the step of the ARQ receiver sending a status report when the
ARQ receiver receives a predetermined number of packets successfully.
[0073] 28. The method as in any of the embodiments 3-27, further
comprising the step of the ARQ receiver sending a status report when a status
reporting timer expires.
[0074] 29. The method as in any of the embodiments 3-28, further
comprising the step of the ARQ transmitter requesting a status report from
the ARQ receiver and the ARQ receiver sending a status report to the ARQ
transmitter.
[0075] 30. The method of embodiment 29, wherein the ARQ
transmitter requests the status report after transmitting a last packet.
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[0076] 31. The method as in any of the embodiments 3-30, further
comprising the step of the H-ARQ transmitter sending a small packet with a
last packet indication after sending a last packet in a buffer.
[0077] 32. The method of embodiment 31, comprising the step of the
H-ARQ receiver sending a response to the small packet, whereby a recovery of
the last packet is ensured by the small packet.
[0078] 33. The method as in any of the embodiments 31-32, wherein
the small packet is a null transmission.
[0079] 34. The method as in any of the embodiments 31-33, wherein
the response to the small packet is transmitted by using the H-ARQ NACK-to-
ACK error indicator.
[0080] 35. The method as in any of the embodiments 3-34, wherein
parameters for the maximum retransmission limit, the maximum time for
delivery of a packet and a lifespan of a packet are configured by a central
controlling entity.
[0081] 36. The method of embodiment 35, wherein the parameters
are configured when the transmitter is active.
[0082] 37. The method of embodiment 35, wherein the parameters
are configured at the start of a service.
[0083] 38. The method as in any of the embodiments 35-37, wherein
the parameters are configured dynamically depending on QoS requirement of
a packet.
[0084] 39. The method as in any of the embodiments 3-38, wherein
the maximum retransmission limit of a packet is indicated by identifying a
particular MAC flow associated with a specific maximum retransmission limit
in an associated control signaling for the first transmission.
[0085] 40. The method as in any of the embodiments 3-38, wherein
the maximum retransmission limit of a packet is explicitly indicated in an
associated control signaling for the first transmission.
[0086] 41. A wireless communication system for implementing H-
ARQ-assisted ARQ.
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[0087] 42. The system of embodiment 41 comprising a receiver
including an H-ARQ receiver and an ARQ receiver, the H-ARQ receiver being
configured to determine whether an H-ARQ'NACK to-ACK error occurs and
send an H-ARQ NACK-to-ACK error indicator to an H-ARQ transmitter
unless the number of retransmissions of a failed packet has reached a
maximum retransmission limit, a maximum time for delivery of the failed
packet has expired or a lifespan of the failed packet has expired.
[0088) 43. The system of embodiment 42 comprising a transmitter
including the H-ARQ transmitter and an ARQ transmitter.
[0089] 44. The system as in any of the embodiments 42-43, wherein
the H-ARQ NACK-to-ACK error indicator is associated with an H-ARQ
process ID and the failed packet at the H-ARQ transmitter.
[0090] 45. The system as in any of the embodiments 42-44, wherein
the H-ARQ NACK-to-ACK error indicator includes the H-ARQ process ID and
a transmission sequence number of the failed packet.
[0091] 46. The system as in any of the embodiments 42-45, wherein
the H-ARQ NACK-to-ACK error indicator is sent with a fixed timing offset
with respect to transmission of the failed packet.
[0092] 47. The system as in any of the embodiments 42-46, wherein
transmission of the H-ARQ NACK-to-ACK error indicator and transmission of
the failed packet are independent.
[0093] 48. The system as in any of the embodiments 42-47, wherein
the H-ARQ NACK-to-ACK error indicator is sent via at least one of physical
layer signaling, a MAC layer signaling and an RLC layer signaling.
[0094] 49. The system as in any of the embodiments 42-48, wherein
the H-ARQ transmitter and the H-ARQ receiver are configured to transmit
and receive more than one packet simultaneously and the H-ARQ transmitter
is configured to send the H-ARQ NACK-to-ACK error indicator indicating H-
ARQ NACK-to-ACK errors of more than one packet.
[0095] 50. The system as in any of the embodiments 42-49, wherein
the H-ARQ NACK-to-ACK error indicator is sent along with a CRC.
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[0096] 51. The system as in any of the embodiments 42-50, wherein
the H-ARQ NACK-to-ACK error indicator is generated by one of the H-ARQ
receiver and an ARQ receiver.
[0097] 52. The system as in any of the embodiments 43-51, wherein
the H-ARQ transmitter is configured to send an ACK to the 'H-ARQ receiver
upon receipt of the H-ARQ NACK-to-ACK error indicator.
[0098] 53. The system of embodiment 52, wherein the H-ARQ
receiver sends the H-ARQ NACK-to-ACK error indicator repeatedly until the
H-ARQ receiver successfully receives the ACK for the H-ARQ NACK-to-ACK
error indicator.
[0099] 54. The system as in any of the embodiments 42-53, wherein
the H-ARQ receiver sends the H-ARQ NACK-to-ACK error indicator if the H-
ARQ receiver receives a new packet via the same H-ARQ process assigned for
the failed packet instead of retransmission of the failed packet.
[00100] 55. The system as in any of the embodiments 42-54, wherein
the H-ARQ receiver sends the H-ARQ NACK-to-ACK error indicator if the H-
ARQ receiver does not receive the failed packet until an error indication
timer
expires, the error indication timer being set when a NACK is sent to the H-
ARQ transmitter.
[00101] 56. The system as in any of the embodiments 43-55, the H-
ARQ transmitter retransmits the failed packet until the failed packet is
successfully delivered unless the maximum retransmission limit has reached,
the maximum delivery time has expired or the lifespan of the failed packet has
expired.
[00102] 57. The system as in any of the embodiments 43-56, wherein
the H-ARQ transmitter sends a local NACK to the ARQ transmitter if the
maximum retransmission limit has reached, the maximum delivery time has
expired or the lifespan of the failed packet has expired, so that the failed
packet is recovered at an ARQ level.
[00103] 58. The system as in any of the embodiments 42-57, wherein
the H-ARQ receiver sets a recovery timer when the H-ARQ receiver sends the
H-ARQ NACK-to-ACK error indicator and sends a local NACK to the ARQ
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receiver if the H-ARQ receiver does not receive the failed packet before the
recovery timer expires.
[00104] ' 59. The system of embodiment 58, wherein the ARQ receiver
sends a status report to the ARQ transmitter for recovery of the failed
packet.
[00105] 60. The system as in any of the embodiments 42-59, wherein
the H-ARQ receiver sends a local NACK to the ARQ receiver if the H-ARQ
receiver does not receive the failed packet until the H-ARQ receiver receives
a
packet with a sequence number higher than a sequence number of the failed
packet by a predetermined number.
[00106] 61. The system of embodiment 60, wherein the ARQ receiver
sends a status report to the ARQ transmitter for recovery of the failed
packet.
[00107] 62. The system as in any of the embodiments 42-61, wherein
the H-ARQ receiver sends a local NACK to the ARQ receiver if the H-ARQ
receiver does not receive the failed packet until the number of
retransmissions
of the failed packet reaches a maximum retransmission limit for the failed
packet.
[00108] 63. The system of embodiment 62, wherein the ARQ receiver
sends a status report to the ARfq,l transmitter for recovery of the failed
packet.
[00109] 64. The system as in any of the embodiments 42-63, wherein
the H-ARQ receiver sends a local NACK to the ARQ receiver if the H-ARQ
receiver does not receive the failed packet until a maximum time for delivery
of the failed packet expires.
[00110] 65. The system of embodiment 64, wherein the ARQ receiver
sends a status report to the ARQ transmitter for recovery of the failed
packet.
[00111] 66. The system as in any of the embodiments 42-65, wherein
the ARQ receiver sends a status report when the ARQ receiver receives a
predetermined number of packets successfully.
[00112] 67. The system as in any of the embodiments 42-66, wherein
the ARQ receiver sends a status report when a status reporting timer expires.
[00113] 68. The system as in any of the embodiments 43-67, wherein
the ARQ transmitter requests a status report from the ARQ receiver and the
ARQ receiver sends a status report to the ARQ transmitter.
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[001141 69. The system of embodiment 68, wherein the ARQ
transmitter requests the status report after transmitting a last packet.
[00115] 70. The system as in any of the embodiments 43-69, wherein
the H-ARQ transmitter sends a small packet with a last packet indication
after sending a last packet in a buffer and the H-ARQ receiver sends a
response to the smaIl packet, whereby a recovery of the last packet is ensured
by the small packet.
[00116] 71. The system of embodiment 70, wherein the small packet is
a null transmission.
[00117] 72. The system as in any of the embodiments 70-71, wherein a
response to the small packet is transmitted by using the H-ARQ NACK-to-
ACK error indicator.
[001181 73. The system as in any of the embodiments 42-72, wherein
parameters for at least one of the maximum retransmission limit, the
maximum time for delivery of a packet and a lifespan of a packet are
configured by a central controlling entity.
[00119] 74. The system of embodiment 73, wherein the parameters are
configured when the receiver is active.
[00120) 75. The system of embodiment 73, wherein the parameters are
configured at the start of a service.
[00121] 76. The system as in any of the embodiments 73-75, wherein
the parameters are configured dynamically depending on QoS requirement of
a packet.
[00122) 77. The system as in any of the embodiments 42-76, wherein
the maximum retransmission limit of a packet is indicated by identifying a
particular MAC flow associated with a specific maximum retransmission limit
in an associated control signaling for the first transmission.
[00123] 78. The system as in any of the embodiments 42-76, wherein
the maximum retransmission limit of a packet is explicitly indicated in an
associated control signaling for the first transmission.
[00124] 79. A receiver for implementing H-ARQ-assisted ARQ.
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[00125] 80. The receiver of embodiment 79 comprising an ARQ
receiver and an H-ARQ receiver.
[00126] 81. The receiver of embodiment 80 wherein the H-ARQ
receiver is configured to determine whether an H-ARQ NACK-to-ACK error
occurs and send an H-ARQ NACK-to-ACK error indicator to an H-ARQ
transmitter unless at least one of the following has occurred: the number of
retransmissions of a failed packet has reached a maximwn retransmission
limit, a maximum time for delivery of the failed packet has expired and a
lifespan of the failed packet has expired.
[00127] 82. The receiver of embodiment 81, wherein the H-ARQ
NACK-to-ACK error indicator is associated with an H-ARQ process ID and the
'failed packet at the H-ARQ transmitter.
[00128] 83. The receiver of embodiment 81, wherein the H-ARQ
NACK to-ACK error indicator includes the H-ARQ process ID and a
transmission sequence number of the failed packet.
[00129] 84. The receiver as in any of the embodiments 81-83, wherein
the H-ARQ NACK-to-ACK error indicator is sent with a fixed timing offset
with respect to transmission of the failed packet.
[00130] 85. The receiver as in any of the embodiments 81-84, wherein
transmission of the H-ARQ NACK-to-ACK error indicator and transmission of
the failed packet are independent.
(00131] 86. The receiver as in any of the embodiments 81-85, wherein
the H-ARQ NACK-to-ACK error indicator is sent via at least one of physical
layer signaling, a MAC layer signaling and an RLC layer signaling. -
[00132] 87. The receiver as in any of the embodiments 81-86, wherein
the H-ARQ receiver is configured to receive more than one packet
simultaneously and send the H-ARQ NACK-to-ACK error indicator indicating
H-ARQ NACK-to-ACK errors of more than one packet.
[00133] 88. The receiver as in any of the embodiments 81-87, wherein
the H-ARQ NACK-to-ACK error indicator is sent along with a CRC.
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[001341 89. The receiver as in any of the embodiments 81-88, wherein
the H-ARQ NACK-to-ACK error indicator is generated by one of the H-ARQ
receiver and the ARQ receiver.
[001351 90. The receiver as in any of the embodiments 81-89, wherein
the H-ARQ receiver sends the H-ARQ NACK-to-ACK error indicator
repeatedly until the H-ARQ receiver successfully receives an ACK for the H-
ARQ NACK-to-ACK error indicator.
[00136] 91. The receiver as in any of the embodiments 81-90, wherein
the H-ARQ receiver sends the H-ARQ NACK-to-ACK error indicator if the H-
ARQ receiver receives a new packet via the same H-ARQ process assigned for
the failed packet instead of retransmission of the failed packet.
[00137] 92. The receiver as in any of the embodiments 81-91, wherein
the H-ARQ receiver sends the H-ARQ NACK-to-ACK error indicator if the H-
ARQ receiver does not receive the failed packet until an error indication
timer
expires, the error indication timer being set when a NACK is sent to the H-
ARQ transmitter.
[00138] 93. The receiver as in any of the embodiments 81-92, wherein
the H-ARQ receiver sets a recovery timer when the H-ARQ receiver sends the
H-ARQ NACK-to-ACK error indicator and sends a local NACK to the ARQ
receiver if the H-ARQ receiver does not receive the failed packet before the
recovery timer expires.
[00139] 94. The receiver as in any of the embodiments 81-93, wherein
the ARQ receiver sends a status report to the ARQ transmitter for recovery of
the failed packet.
[00140] 95. The receiver as in any of the embodiments 81-94, wherein
the H-ARQ receiver sends a local NACK to the ARQ receiver if the H-ARQ
receiver does not receive the failed packet until the H-ARQ receiver receives
a
packet with a sequence number higher than a sequence number of the failed
packet by a predetermined number.
[001411 96. The receiver as in any of the embodiments 81-95, wherein
the H-ARQ receiver sends a local NACK to the ARQ receiver if the H-ARQ
receiver does not receive the failed packet until the number of
retransmissions
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of the failed packet reaches a maximum retransmission limit for the failed
packet.
[00142] 97. The receiver as in any of the embodixnents 81-96, wherein
the H-ARQ receiver sends a local NACK to the ARQ receiver if the H-ARQ
receiver does not receive the failed packet until a maximum time for delivery
of the failed packet expires.
[00143] 98. The receiver as in any of the embodiments 81-97, wherein
the ARQ receiver sends a status report to the ARQ transmitter for recovery of
the failed packet.
[00144] 99. The receiver as in any of the embodiments 81-98, wherein
the ARQ receiver sends a status report when the ARQ receiver receives a
predetermined number of packets successfully.
[00145] 100. The receiver as in any of the embodiments 81-99, wherein
the ARQ receiver sends a status report when a status reporting timer expires.
[00146] 101. A transmitter for implementing H-ARQ-assisted ARQ.
[00147] 102. The transmitter of emb'odim.ent 101 comprising an ARQ
transmitter and an H-ARQ transmitter.
[00148] 103. The transmitter of embodiment 102 wherein the H-ARQ
transmitter is configured to receive an H-ARQ NACK-to-ACK error indicator,
and at least one of the ARQ transmitter and the H-ARQ transmitter is
configured to recover a failed packet corresponding to the H-ARQ NACK-to-
ACK error.
[00149] 104. The transmitter of embodiment 103, wherein the H-ARQ
transmitter is configured to send an ACK to the H-ARQ receiver upon receipt
of the H-ARQ NACK-to-ACK error indicator.
[00150] 105. The transmitter as in any of the embodiments 103-104,
wherein the H-ARQ transmitter retransmits the failed packet until the failed
packet is successfully delivered unless at least one of the following has
occurred: the maximum retransmission limit has reached, the maximum
delivery time has expired and the lifespan of the failed packet has expired.
[00151] 106. The transmitter as in any of the embodiments 103-105,
wherein the H-ARQ transmitter sends a local NACK to the ARQ transmitter if
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the maximum retransmission limit has reached, the maximum delivery time
has expired or the lifespan of the failed packet has expired, so that the
failed
packet is recovered at an ARQ level.
[00152] 107. The transmitter as in any of the embodiments 103-106,
wherein the ARQ transmitter requests a status report from the ARQ receiver.
[00153] 108. The transmitter of embodiment 107 wherein the ARQ
transmitter requests the status report after transmitting a last packet.
[00154] 109. The transmitter as in any of the embodiments 103-108,
wherein the H-ARQ transmitter sends a small packet with a last packet
indication after sending a last packet in a buffer, whereby a recovery of the
last packet is ensured by the small packet.
[001551 110. The transmitter of embodiment 109 wherein the small
packet is a null transmission.
[00156] 111. The transmitter as in any of the embodiments 109-110,
wherein a response to the small packet is.transmitted by using the H-ARQ
NACK-to-ACK error indicator.
[00157] Although the features and elements of the present invention are
described in the preferred embodiments in particular combinations, each
feature or element can be used alone without the other features and elements
of the preferred embodiments or in various combinations with or without other
features and elements of the present invention. The methods or flow charts
provided in the present invention may be implemented in a computer
program, software, or firmware tangibly embodied in a computer-readable
storage medium for execution by a general purpose computer or a processor.
Examples of computer-readable storage mediums include a read only memory
(ROM), a random access memory (RAM), a register, cache memory,
semiconductor memory devices, magnetic media such as internal hard disks
and removable disks, magneto-optical media, and optical media such as CD-
ROM disks, and digital versatile disks (DVDs).
[00158] Suitable processors include, by way of example, a general
purpose processor, a special purpose processor, a conventional processor,
adigital signal processor (DSP), a plurality of microprocessors, one or more
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microprocessors in association with a DSP core, a controller, a
mi.crocontroller,
Application Specific Integrated Circuits (ASICs), Field Programmable Gate
Arrays (FPGAs) circuits, any other type of integrated circuit (IC), and/or a
state machine.
[00159] A processor in association with software may be used to
implement a radio frequency transceiver for use in a wireless transmit receive
unit (WTRU), user equipment (UE), terminal, base station, radio network
controller (RNC), or any host computer. The WTRU may be used in
conjunction with modules, implemented in hardware and/or software, such as
a camera, a video camera module, a videophone, a speakerphone, a vibration
device, a speaker, a microphone, a television transceiver, a hands free
headset,
a keyboard, a Bluetooth module, a frequency modulated (FM) radio unit, a
liquid crystal display (LCD) display unit, an organic light-emitting diode
(OLED) display unit, a digital music player, a media player, a video game
player module, an Internet browser, and/or any wireless local area network
(WLAN) module.
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