Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
  • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
  • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
  • H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
  • H04L1/0026—Transmission of channel quality indication
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
  • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
  • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
  • H04L1/1812—Hybrid protocols; Hybrid automatic repeat request [HARQ]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
  • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
  • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
  • H04L1/1829—Arrangements specially adapted for the receiver end
  • H04L1/1848—Time-out mechanisms
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
  • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
  • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
  • H04L1/1867—Arrangements specially adapted for the transmitter end
  • H04L1/1874—Buffer management
  • H04L1/1877—Buffer management for semi-reliable protocols, e.g. for less sensitive applications like streaming video
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
  • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
  • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
  • H04L1/1867—Arrangements specially adapted for the transmitter end
  • H04L1/188—Time-out mechanisms
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
  • H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
  • H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
  • H04L1/0009—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the channel coding
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
  • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
  • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
  • H04L1/1829—Arrangements specially adapted for the receiver end
  • H04L1/1835—Buffer management
  • H04L1/1841—Resequencing

Definitions

• the present invention generally relates to a wireless communication system employing retransmission with, a hybrid automatic repeat request (HARQ), and more particularly, to techniques for providing reliable packet delivery with a HARQ mechanism without complexity and unnecessary delay.
• HARQ hybrid automatic repeat request
• Figure 1 shows a retransmission protocol 100 for current
• the protocol 100 utilizes a user equipment (UE) 102, a Node B
• the UE 102 includes a physical (PHY) layer 110, a medium access control (MAC) layer 112, and a radio link control (RLC) layer 114.
• the Node B 104 includes a PHY layer 120 and a MAC layer 122.
• the RNC 106 includes a MAC layer 130 and an RLC layer 132.
• a HARQ process 140 runs in the MAC layers 112, 122 between the UE 102 and the Node B 104.
• the packets are assigned sequential transmission sequence numbers (TSNs) in a HARQ entity at the transmitter.
• TSNs sequential transmission sequence numbers
• a corresponding HARQ entity receives the packet transmissions and attempts to decode and recover each transmitted packet.
• the receiver HARQ entity is tasked with providing the recovered packets to higher layers in the proper order. Since individual packets may require a different number of retransmissions for successful delivery, a reordering entity is used at the receiver to buffer and reorder the packets.
• the receiver sends a negative acknowledgment (NACK) to the transmitter to initiate a retransmission of the packet. Otherwise, the receiver sends an acknowledgment (ACK) for the corresponding packet.
• NACK negative acknowledgment
• ACK acknowledgment
• the transmitter Upon receiving a NACK, the transmitter retransmits the corresponding packet if the number of allowed retransmissions for the HARQ packet is less than a predetermined maximum value. Otherwise, the packet is discarded by the HARQ process, and retransmission of the packet is handled by an ARQ process 142 in the RLC layers 114, 132 between the UE 102 and the RNC 106.
• the packet may not be correctly received in the RLC layer of the receiver side (i.e., the RLC layer of the UE 102 or the RNC 106) due to a decoding failure in the HARQ process or packet losses between the Node B 104 and the RNC 106.
• an ARQ process 142 is provided in the RLC layers 114, 132 between the UE 102 and the RNC 106.
• the packets are assigned sequence numbers (SNs) in the RLC entity at the transmitter similar to the TSNs and the packets are held in a retransmission buffer until the transmitter receives an ACK for the packets from the receiver.
• the RLC in the receiver generates status protocol data units
• PDUs containing an ACK or a NACK and sends the PDUs to the transmitter, so that the RLC in the transmitter can retransmit the missing packet or delete the correctly transmitted packet from the retransmit buffer.
• Some of the packets may not be received correctly after several retransmission attempts in the RLC layer or before a packet discard timer for the packets has expired.
• the RLC in the transmitter then discards the packets and informs the upper layer and the receiver.
• the receiver RLC layer reorders the received packets and initiates a procedure for a missing packet.
• the present invention relates to retransmission management applicable to future wireless communication systems, such as a system specified in the third generation partnership project (3GPP) long term evolution (LTE), but is also applicable to other kinds of wireless communication systems providing for reliable packet retransmission. More particularly, the present invention relates to retransmission management of a transmitter/receiver (e.g., wireless transmit/receive unit (WTRU) or base station) and agent (e.g., RNC) for reliable packet reception without loss or error.
• a transmitter/receiver e.g., wireless transmit/receive unit (WTRU) or base station
• agent e.g., RNC
• the present invention introduces a retransmission management technique to provide reliable data packet delivery with a simple retransmission scheme and to reduce the complexity, latency, and overhead of status reporting in the RLC layer in future communication systems (e.g., LTE).
• This retransmission scheme reduces packet latency by removing the delay in retransmitting packets from the RLC layer.
• Layer 2 (RLC and MAC) signaling overhead is also reduced by removing duplicate signaling between the MAC HARQ and RLC acknowledged mode (AM).
• the status PDUs sent between peer-to-peer RLC layers is also a factor, since it is a non-negligible burden in signaling and degrades spectral efficiencies.
• This scheme simplifies implementation by removing duplicate functionalities, such as a reordering buffer and a transmit buffer between the MAC layer and the RLC layer.
• a MAC+ layer is introduced, which incorporates RLC layer functionalities into the MAC layer. Only one set of sequence numbers is used to synchronize outstanding transmissions (i.e., the number of transmitted but not acknowledged transmissions).
• TTI transmission time interval
• the invention further proposes that transmission sequencing, multiplexing, segmentation, concatenation, and padding are performed at the time of LTE-TFC (transport format combination) selection, rather than in advance of TFC selection as in existing RLG AM operation.
• a method for transmitting a packet from a transmitter to a receiver in a wireless communication system begins by building a packet by a transport format combination (TFC) selection process, and the packet is transmitted from the transmitter to the receiver. If the HARQ entity at the transmitter receives an indication that the packet was not successfully received at the receiver, the packet is retransmitted via a HARQ procedure. If the HARQ procedure did not successfully transmit the packet, then the packet is retransmitted via a retransmission management (RM) procedure. If the RM procedure did not successfully transmit the packet, then the packet is discarded by the transmitter.
• TFC transport format combination
• a method for receiving a packet in a wireless communication system begins by successful reception of a packet by a HARQ entity at a receiver.
• the packet is forwarded to a reordering buffer and reassembly entity, where a TSN of the packet is examined.
• the packet is delivered to an upper layer if the TSN of the packet indicates that the packet was received in an expected order.
• the packet is also delivered to an upper layer if an out-of- sequence timer (T_deliver) expires.
• T_deliver out-of- sequence timer
• a system for retransmission management of packets in a wireless communication system includes a transmitter and a receiver.
• the transmitter includes a TFC selector having a segmentation/concatenation processor and a multiplexer, a transmit buffer connected to the multiplexer, an RM processor connected to the TFC selector, and a HARQ processor connected to the transmit buffer and the RM processor.
• the receiver includes a HARQ processor, a reordering buffer and reassembly entity connected to the HARQ processor, and an RM entity.
• a method for suspending data transmission from a transmitter to a receiver in a wireless communication system begins by determining at the transmitter if a suspend condition exists.
• a suspend condition can exist due to poor channel conditions or a handover, for example.
• Data transmission from the transmitter to the receiver is suspended if the suspend condition exists.
• a determination is made at the receiver if a resume condition exists, and data transmission from the transmitter to the receiver is resumed if the resume condition exists.
• Figure 1 is a diagram of a retransmission protocol for current
• Figure 2 is a diagram of a retransmission protocol for a MAC+ layer with a merged RLC layer
• Figure 3 is a block diagram of a MAC+ layer
• Figure 4 is a block diagram of a MAC+ layer with an RLC sublayer
• Figures 5A and 5B are flow diagrams of a transmitter and a receiver operating according to the retransmission scheme.
• Figure 6 is a flowchart of a method for suspending and restarting transmission to a receiver.
• a user equipment includes, but is not limited to, a wireless transmit/receive unit (WTRU), a mobile station, a fixed or mobile subscriber unit, a pager, or any other type of device capable of operating in a wireless environment.
• WTRU wireless transmit/receive unit
• a base station includes, but is not limited to, a Node B, an enhanced Node B (eNode B), a site controller, an access point, or any other type of interfacing device in a wireless environment.
• eNode B enhanced Node B
• the present invention introduces a protocol architecture containing a retransmission loop called "HARQ with retransmission management (RM)".
• HARQ with retransmission management HARQ with retransmission management
• the proposed radio interface is layered into two protocol layers for the user plane: the PHY layer, and the MAC layer between the WTRU and the base station.
• the present invention does not include an RLC layer, and the functionalities of the RLC layer in the RNC in 3GPP Release 5/6 are merged into the MAC layer, and is herein referred to as a "MAC+" layer.
• the MAC+ layer provides support for data transmission modes (e.g., transparent mode (TM), unacknowledged mode (UM), and acknowledged mode (AM)) similar to the existing RLC layer in 3GPP Release 5/6.
• Figure 2 shows a protocol structure 200 for the MAC+ layer; only the entities pertaining to retransmission are discussed herein.
• the structure 200 includes a UE 202 and a Node B 204.
• the UE 202 includes a PHY layer 210 and a MAC+ layer 212.
• the Node B includes a PHY layer 220 and a MAC+ layer 222.
• the MAC+ layers 212, 222 may include additional entities to handle functionalities other than retransmission.
• One difference between the structure 200 and 3GPP Release 5/6 is that the ARQ process in the RLC layer does not exist in the structure 200, and retransmission by the HARQ process is modified for reliable data delivery.
• an additional retransmission loop in the HARQ process is provided by the transmitter and is handled by retransmission management (RM) 224.
• RM retransmission management
• An inner-loop process dictates retransmission in the HARQ and an outer-loop process dictates retransmission handled by RM.
• Figure 3 is a block diagram of a system 300 including a transmitter 302 and a receiver 304 communicating according to a MAC+ layer protocol.
• the base station On downlink signals, the base station is the transmitter and the UE is the receiver.
• the UE For an uplink signal, the UE is the transmitter and the base station is the receiver.
• the transmitter 302 includes a TFC selector (packet size selector)
• the segmentation/concatenation processor 312 and the MUX 314 are located within the TFC selector 310.
• the receiver 304 includes a HARQ entity 330, a reordering buffer and reassembly entity 332, and an RM processor 334.
• the HARQ entities 320, 330 communicate with each other via a HARQ process 340 and the transmitter 302 and the receiver 304 communicate with each other via control signals 342.
• the TFC selector 310 decides the packet size and the data flows that are multiplexed in a TTI.
• a packet may consist of retransmitted data and/or new data.
• Each data flow has its own segmentation/concatenation processor 312, and there is only one MUX 314 per UE.
• the segmentation/concatenation processor 312 segments and concatenates the data from an upper layer as a unit specified by the TFC selector 310.
• the MUX 314 performs multiplexing of different flows of packets from an upper layer, as specified by the TFC selector 310.
• the transmit buffer 316 stores packets for less than a TTI before sending them to the HARQ entity 320. Packets which failed to transmit correctly by the HARQ process 340 may be retransmitted based on a decision from the RM processor 318, and may have a higher priority than new transmissions.
• Each packet is associated with a TSN.
• a TSN is created for new packets and a retransmitted packet may retain its original TSN.
• the TSN is the identity assigned to each packet by the transmitter 302 for transmissions and retransmissions and is used by the receiver 304 for reordering the packets.
• the TSN can be a combination of upper layer sequence number(s) and the sequence number of the multiplexed or segmented packet(s).
• the TSN can also be a combination of the upper layer sequence number(s) with the byte offset to identify each segment of the upper layer packet(s).
• the HARQ entity 320 handles the HARQ functionality in the transmitter 302. Multiple HARQ processes can be supported by the HARQ entity 320.
• the transmitter 302 waits for an ACK from the receiver 304 for the packet before retransmission.
• the maximum number of retransmissions by the HARQ process 340 is denoted as N_HARQ, which can be a predetermined value or a changeable value configured by an upper layer or by the RM processor 318.
• N_HARQ is based on the data flow (data that is multiplexed within a transmission) which is related to a specific quality of service (QoS) requirement for latency and a block error rate (BLER) target.
• QoS quality of service
• BLER block error rate
• the HARQ entity 320 informs the RM processor 318 whether or not a packet was sent successfully.
• the RM processor 318 manages outer-loop retransmission for packets that fail successful transmission by the HARQ process 340.
• the failed packets during a HARQ transmission can be held in the RM processor 318.
• the RM processor 318 sends an indication to the TFC selector 310, which uses this information to build a new packet.
• a number of maximum outer-loop retransmissions N_DAT can be configured and changed by the RM processor 318, by an upper layer, or be predetermined for each data type.
• the TFC selector 310 can control the selection of the adaptive modulation and coding scheme. Another possibility is for a central entity in the network to indicate an appropriate constellation and coding scheme that is selected according to channel conditions.
• a control signal 342 between the transmitter 302 and the receiver 304 contains status information.
• the transmitter 302 sends the status information (TSNs of discarded packets) when it discards packets, whereby the receiver 304 delivers the received packets to an upper layer without waiting to receive the discarded packets.
• a control signal sent by the receiver 304 sends the status of the received packets.
• the status generation signal may also be used to indicate reception of HARQ packets instead of sending immediate ACK/NACK feedback.
• Another possibility is to send the TSN as part of the control information over the air for each HARQ process. Hence, the HARQ transmitter identifies the packet in a HARQ process by the TSN.
• the HARQ receiver may use the TSN to identify lost HARQ packets and for ACK/NACK indication.
• the HARQ entity 330 receives the packets and forwards the packets to the reordering buffer and reassembly entity 332.
• the reordering buffer and reassembly entity 332 ensures that the packets are received and are in the proper order based on the TSN of each packet.
• the reordering buffer and reassembly entity 332 builds concatenated packets and reorders the packets. A packet is sent to the upper layer if it is received in the expected order or if an out-of-sequence timer expires.
• FIG. 4 is a block diagram of a protocol architecture 400 containing TFC selection in an RLC sublayer.
• the architecture 400 can be implemented in connection with a transmitter 402 and a receiver 404.
• the transmitter 402 includes a MAC sublayer 410 having a HARQ entity 412 and a transmit buffer 414, and an RLG sublayer 420 with TFC selection having a
• MUX 422 a segmentation/concatenation processor 424, and an RM processor
• the RLC sublayer 420 performs TFC selection every TTI and manages retransmission based on an indication from the MAC sublayer 410.
• the receiver 404 includes a MAC sublayer 430 having a HARQ entity 432, and an RLC sublayer 440 having a reordering buffer and reassembly entity
• the following RM timers can be implemented by the RLC sublayers 420, 440 or by the RM processors 426, 444.
• T_discard is a timer that counts the lifetime of a packet. The timer starts when a packet arrives at the transmitter 402, and can be incremented every TTI or decremented from a predetermined value
• T_discard_th (which is defined below).
• T__suspend is a timer that is incremented every TTI after the RM processor 426 suspends data transmission to the receiver 404.
• T__deliver is a timer present at the reordering buffer and reassembly entity 442 of the receiver 404 and starts after detecting a missing packet.
• RM parameters can be configured by the upper layer or by the RM processor 426, 444 depending on the data types or priorities.
• Time-sensitive data may have lower thresholds, for example in video telephony as compared to non-real time services.
• T_discard_th is a maximum time that a data packet is held in the transmitter 402. A data packet will be discarded once the T_discard timer exceeds T_discard_th.
• T_suspend_th is a maximum time duration of data suspension by the RM processor 426, which can suspend data transmission to a receiver 404 and resume transmissions when the timer Tjsuspend exceeds T_suspend_th.
• T_deliver_th is a maximum waiting time for a missing packet.
• the reordering buffer and reassembly entity 442 at the receiver 404 delivers the out of sequence received packet if the missing packet is not delivered within a T_deliver_th period of time.
• N_HARQ_RETX is a maximum number of retransmissions by the
• N_RM_RETX is a maximum number of retransmissions from the
• RM processor 426 (outer loop retransmission). A counter is incremented every time a packet is scheduled to be transmitted by the RM processor 426.
• T_stop is a time duration for suspending data transmission. If the number of failed packets during this duration is greater than a predetermined value, the RM processor 426 can suspend data transmission to the receiver 404.
• the transmitter 402 retransmits a failed packet of a previous HARQ transmission by RM or RLC without exchanging status PDUs
• the packets not correctly transmitted via HARQ transmissions are sent to the RLC sublayer 420 for retransmission.
• Retransmitted packets preferably have a higher priority than new packets that have not been previously scheduled.
• the retransmitted packets have the same priority as the new packets and will be buffered at the end of the transmission queue.
• the transmit buffer 414 removes the packet from the transmit queue even if it is not successfully transmitted by HARQ. All the packets are saved by the RM processor 426, and can be sent to the transmit buffer 414 for retransmission,
• the RM processor 426 or the RLC sublayer 420 has the capability of determining the number of outer-loop retransmissions for a packet depending on its required QoS.
• the RLC layer has different entities for the different modes: transparent mode (TM), unacknowledged mode (UM), and acknowledged mode (AM).
• TM transparent mode
• UM unacknowledged mode
• AM acknowledged mode
• the RLC sublayer 420 operates the HARQ process only for the data transmission in AM mode.
• the receiver's reordering buffer and reassembly entity 442 can deliver the packets to an upper layer without reordering and recovering or in sequential order.
• the reordering buffer and reassembly entity 442 sends the received packets to the upper layer instantaneously after reassembly.
• the reordering buffer and reassembly entity 442 reorders the received packets and waits until the missing packet can be received during T_deliver. After T_deliver expires, the missing packets can be discarded and the reordering buffer and reassembly entity 442 delivers the rest of the packets in sequence.
• the RLC sublayer 420 has the capability to control modulation and coding rates for data transmission to a particular receiver 404.
• the RLC sublayer 420 decides the constellation of modulation/coding rate with TFC selection based on the channel conditions, packet failure rate, MIMO technique, etc.
• Figures 5 A and 5B are flow diagrams of a retransmission method
• the method 500 begins with the transmitter 502 setting parameters (step 510).
• a packet arrives at the transmitter (step 512) and the transmitter starts the timer T_discard (step 514). Based on the TFC selection, a packet is built and a TSN is assigned to the packet (step 516). The packet is then sent to the receiver 504 (step 518).
• the timer T_discard is compared against the threshold T_discard_th to determine if the timer has expired (step 528). If the timer T_discard has expired, then the transmitter 502 discards the packet (step 530). A discard message is sent to the receiver 504 with the discarded packet's TSN (step 532). The discard message can contain the TSN of a discarded packet and/or the number of consecutive packets discarded following the discarded packet.
• the reordering buffer and reassembly entity in the receiver 504 Upon receiving the discard message, the reordering buffer and reassembly entity in the receiver 504 delivers the out of sequence packets to the upper layers (without the discarded packets; step 534), and the receiver 504 waits for the next packet (step 520). [0060] If the discard timer T_discard has not expired (step 528), then a determination is made whether to perform outer-loop (RM) retransmission (step 538). If the RM retransmission process is not to be performed, then the packet is discarded (step 530) and the method continues as described above.
• RM outer-loop
• N_RM_RETX the maximum number of allowed transmissions
• the RM processor may configure N_RM_RETX for the packets which were configured as the transparent mode (TM) or the unacknowledged mode (UM) in 3GPP Release 5/6.
• each data packet may have a different value of N_RM_RETX configured by the network. Typically, a lower value of N_RM_RETX is selected for time sensitive data.
• the packet is discarded (step 530) and the method continues as described above. If the current number of RM retransmissions is below the threshold (step 540), then the packet is resent via TFC selection (step 516) as described above.
• an ACK is sent to the transmitter 502 and the packet is forwarded to the reordering buffer and reassembly entity (step 542).
• the received packet is checked to determine if its TSN is the next expected TSN (i.e., the next sequential packet; step 544). If the TSN is the next expected TSN, then the timer T_deliver is reset to zero (step 546) and the reordering buffer and reassembly entity delivers all of the in-sequence packets to the upper layers (step 548) and the receiver 504 waits for the next packet (step 520).
• step 544 If the TSN is not the next expected TSN (step 544), a determination is made whether the TSN is less than the next expected TSN (step 550). If the TSN is less than the next expected TSN, then the packet is discarded (step 552) and the receiver 504 waits for the next packet (step 520). [0065] If the TSN is not less than the next expected TSN (step 550), a determination is made whether the timer T__deliver is set (step 554). If the timer T_deliver is not set, then the timer is started (step 556) and the receiver 504 waits for the next packet (step 520).
• step 554 If the timer T_deliver has already been started (step 554), then the timer T_deliver is checked to determine whether it has exceeded the maximum allowed delivery time, T_deliver_th (step 558). If the timer T_deliver has not expired, then the receiver 504 waits for the next packet
• step 558 If the timer T_deliver has expired (step 558), then the reordering buffer and reassembly entity delivers all of the sequential packets, except for the missing packet, to the upper layers and sets the next expected TSN accordingly (step 560).
• the timer T_deliver is reset to zero (step 562) and the receiver 504 waits for the next packet (step 520).
• the packet can be delivered to the upper layer depending on the implementation. If the packet is ignored, the receiver 504 transmits the TSN of the missing packet via control signaling when it delivers the packets (except the missing packet) so that the packet is discarded at the transmitter 502.
• the NACKed packet will be retransmitted until it has been successfully received by the receiver 504, and the steps 520-562 of the method 500 will not be performed.
• FIG. 6 is a flowchart of a method 600 for suspending and restarting transmission to a receiver.
• the RM processor can suspend data transmission to the receiver for the following conditions:
• the reported channel quality indicator (CQI) is lower than a predetermined value.
• the RM processor can save the CQI (referred to as a
• the transmitter does not receive an ACK for the transmitted packets after N_HARQ_RETX retransmissions.
• the transmitter does not receive an ACK for the transmitted packets after N_RM_RETX retransmissions in outer-loop RM.
• a predetermined number of consecutive packets transmitted to the receiver were not ACKed via HARQ transmission.
• the number of packets (may not be consecutive) which do not receive an ACK via HARQ transmission exceeds a predetermined value during the time duration T_stop.
• a handover process has started.
• step 604 If a suspend condition exists, then the RM processor notifies the upper layers (step 606) and notifies the HARQ entity to stop transmitting to the receiver (step 608). The RM processor then starts the timer T_suspend and saves the current CQI (step 610).
• Transmission to a suspended receiver can be resumed under one of two conditions.
• a determination is made whether the timer T_suspend has expired by comparing it to the threshold T_suspend_th (step 612). If the timer T_suspend has expired, then the RM processor notifies the HARQ entity to resume transmission to the receiver (step 614) and the method terminates (step 604). If the timer T_suspend has not expired (step 612), a determination is made whether the current CQI is greater than a predetermined value (step 616).
• the predetermined value can be either an absolute value or a relative value related to the suspended CQI.
• the RM processor notifies the HARQ entity to resume transmission to the receiver (step 614) and the method terminates (step 604). If the current CQI is less than the predetermined value (step 616), then the method continues with step 612 as described above.
• a method for transmitting a packet from a transmitter to a receiver in a wireless communication system comprising the steps of: building a packet by a transport format combination (TFC) selection process; transmitting the packet from the transmitter to the receiver; receiving an indication at the transmitter that the packet was not successfully received at the receiver; retransmitting the packet from the transmitter to the receiver via a hybrid automatic repeat request (HARQ) procedure; retransmitting the packet from the transmitter to the receiver via a retransmission management
• TFC transport format combination
• TSN is a combination of an upper layer sequence number and a sequence number of a multiplexed packet.
• TSN is a combination of an upper layer sequence number and a sequence number of a segmented packet.
• a method for receiving a packet in a wireless communication system comprising the steps of: receiving the packet at a receiver; forwarding the packet to a reordering buffer and reassembly entity; examining a transmission sequence number (TSN) of the packet; delivering the packet from the reordering buffer and reassembly entity to an upper layer if the TSN of the packet indicates that the packet was received in an expected order; determining whether the packet should be accepted if the TSN of the packet indicates that the packet was not received in the expected order; delivering the packet from the reordering buffer and reassembly entity to an upper layer if the packet is accepted; and discarding the packet by the reordering buffer and reassembly entity if the packet is not accepted.
• the determining step includes using a delivery timer associated with the packet to determine whether the packet was received within a predetermined period of time.
• [0104] 22 A system for retransmission management of packets in a wireless communication system, comprising a transmitter and a receiver.
• the transmitter includes: a transport format combination (TFC) selector; a transmit buffer connected to the TFC selector; a first retransmission management (RM) processor connected to the TFC selector and the transmit buffer; and a first hybrid automatic repeat request (HARQ) processor connected to the transmit buffer and the first RM processor.
• TFC transport format combination
• RM retransmission management
• HARQ hybrid automatic repeat request
• [0106] 24 The system according to embodiment 23, wherein the TFC selector includes a multiplexer and a segmentation and concatenation entity.
• the receiver includes: a second HARQ processor; a reordering buffer and reassembly entity connected to the second HARQ processor; and a second
• RM processor connected to the reordering buffer and reassembly entity.
• HARQ processor in the transmitter are part of a second communication sublayer.
• a method for suspending data transmission from a transmitter to a receiver in a wireless communication system comprising the steps of: determining at the transmitter if a suspend condition exists; suspending data transmission from the transmitter to the receiver if the suspend condition exists; determining at the receiver if a resume condition exists; and resuming data transmission from the transmitter to the receiver if the resume condition exists.
• the suspending step includes the steps of: notifying upper layers of the suspended transmission; and notifying a retransmission function to suspend data transmission to the receiver.
• a method for retransmission of data packets between a transmitter and a receiver in a wireless network comprising the steps of: sending a hybrid automatic request (HARQ) for retransmission and performing outer loop retransmission management, such that a failed data packet is resent according to a configurable number of outer loop retransmissions .
• HARQ hybrid automatic request
• a WTRU configured to perform the method according to one of embodiments 47-81.
• a WTRU configured as the transmitter according to one of embodiments 47-81.
• a WTRU configured as the receiver according to one of embodiments 47-81.
• a base station configured to perform the method according to one of embodiments 47-81.
• a base station configured as the transmitter according to one of embodiments 47-81.
• a base station configured as the receiver according to one of embodiments 47-81.
• a system comprising the WTRU and the base station according to one of embodiments 82-87.

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• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Quality & Reliability (AREA)
• Multimedia (AREA)
• Mobile Radio Communication Systems (AREA)
• Detection And Prevention Of Errors In Transmission (AREA)
• Communication Control (AREA)

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• 2006
  • 2006-09-28 KR KR1020087011607A patent/KR20080056307A/ko active IP Right Grant
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  • 2006-09-28 EP EP09170210.0A patent/EP2124373A3/en not_active Withdrawn
  • 2006-09-28 CN CN2011101137116A patent/CN102208970A/zh active Pending
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