910 results about "Automatic repeat request" patented technology

A method for controlling errors in a wireless link layer using a simultaneous multiple copy scheme and an adaptive forward error correction (FEC) scheme in a wideband wireless communication is provided. The method for controlling errors in a link layer in wideband wireless communication using an automatic repeat request (ARQ) scheme, in which a wideband wireless channel is used for communication between a first node and a second node, includes the steps of (a) estimating the error ratio of a forward (a direction in which a cell is transmitted from the first node to the second node) channel using the state of a backward (a direction in which a cell is transmitted from the second node to the first node) channel, and transmitting a cell, in which a forward error correction (FEC) code having an encoding ratio that varies depending on the estimated error ratio is included in a protocol data unit (PDU) of a wireless link layer, through the forward channel and (b) re-transmitting the copy of a cell transmitted in the step (a), when feedback information that indicates that an error exists in the cell transmitted in the step (a) is received through the backward channel. It is possible to reduce the number of times of re-transmission by improving the probability of correcting forward errors using more error controlling bits as the state of the channel is worse and to minimize the waste of resources using less error controlling bits as the state of the channel is better, to thus obtain the optimal performance and guarantee the minimum delay time.

The present invention relates to a link control automatic repeat request (ARQ) operation in a wireless communication environment. When a terminal sends an original request for communication resources, the request includes not only payload size, but preferably quality of service parameters associated with the data to be transmitted. During uplink communications, the base station performs the link control based ARQ for lost or corrupt packets. When lost or corrupt packets are identified, a link control entity at the base station determines the appropriate retransmission parameters and contacts the uplink scheduler, if necessary, to obtain the corresponding communication resources for retransmission. The additional communication resources for retransmission are provided in a message, such as a negative acknowledgement message, which is sent to the mobile terminal to trigger retransmission of the lost or corrupted data.

An Automatic Repeat reQuest (ARQ) error correction method optimized for protecting real-time audio-video streams for transmission over packet-switched networks. Embodiments of this invention provide bandwidth-efficient and low-latency ARQ for both variable and constant bit-rate audio and video streams. Embodiments of this invention use timing constraints to limit ARQ latency and thereby facilitate the use of ARQ packet recovery for the transport of both constant bit rate and variable bit rate media streams.

A method for controlling the transmission of data in a radio communications system transmits response signals from a receiver which includes information that reflects received signal quality, as well as information indicating whether an error has occurred in the data transmission. In one case, acknowledgment signals or negative acknowledgment signals may be regarded as no reply and not forwarded to a transmitter. In another case, the signals could be recognized as an acknowledgment or retransmission request by a receiver. Preferably, the signals transmitted from the receiver to the transmitter are composed of more than 2-bit multiplexed information. By transmitting response signals of this type, the transmission efficiency of packet data may be increased, and the automatic repeat request (ARQ) performance by the system may be greatly improved.

A method for mapping a physical hybrid automatic repeat request indicator channel (PHICH) is described. The method for mapping a PHICH includes determining an index of a resource element group transmitting a repetitive pattern of the PHICH, according to a ratio of the number of available resource element groups in a symbol in which the PHICH is transmitted and the number of available resource element groups in a first or second OFDM symbol, and mapping the PHICH to the symbol according to the determined index. In transmitting the PHICH, since efficient mapping is performed considering available resource elements varying with OFDM symbols, repetition of the PHICH does not generate interference between neighbor cell IDs and performance is improved.

Devices and methods of reducing overall Hybrid Automatic Repeat Request-Acknowledgment (HARQ-ACK) of user equipment (UE) using a large amount of carrier aggregation are generally described. The UE may receive a subframe from an enhanced NodeB (eNB). The subframe may contain a physical downlink control channel (PDCCH) formed in accordance with a Downlink Control information (DCI) format. The DCI format may comprise a Downlink Assignment Index (DAI) for Time Division Duplexed (TDD) and Frequency Division Duplexed (FDD) operation. The UE may determine, dependent on the DAI, a number and ordering of Hybrid Automatic Repeat Request-Acknowledgment (HARQ-ACK) bits to be transmitted on a Physical Uplink Shared Channel (PUSCH) and subsequently transmit the HARQ-ACK bits.

A system and method for random access channel (RACH) capture, where user equipment (UE) transmits a series of time-spaced access preambles each having an increasing power level to Node B and terminates access preamble transmission in response to an acquisition indicator (AI) signal returned from Node B and transmits its RACH message part. A collision detection preamble (CDP) is sent immediately after the message or embedded with the message. A collision detection indicator (CDI) signal matching the CDP is transmitted from Node B to the UE identified as having the failed RACH message requesting retransmission of the message. Optionally, the relative retransmission power level is also specified to the UE along with the CDI signal.

A method for requesting retransmission of high-speed packet data in a receiving Automatic Retransmission reQuest (ARQ) entity of a mobile communication system that simultaneously performs Hybrid Automatic Retransmission reQuest (HARQ) and ARQ. The method includes, upon receipt of a packet, determining a sequence number of the received packet, and determining if there is at least one missing packet preceding the received packet; if there is at least one missing packet, driving a first timer which is set to a time required when a number of retransmission attempts reaches a predetermined maximum number of HARQ retransmissions, and monitoring receipt of the missing packet; and upon expiration of the timer, sending to a transmitting ARQ entity an Acknowledgement (ACK) including a last sequence number among sequence numbers of normally received consecutive ARQ packets.

An apparatus and method for re-transmitting data in a wireless access communication system are disclosed. The data retransmission method in a wireless access communication system performing a data transmission / reception operation between a terminal and a base station using ARQ (Automatic Repeat Request) includes the step of transmitting allocation information for bandwidth for data retransmission with respect to data received by the base station and ARQ feedback information according to an error which is included in the received data from the base station to the terminal, and re-transmitting the data in which the error had occurred through the allocated bandwidth based on the allocation information of the bandwidth for the data retransmission from the terminal to the base station.

An automatic retransmission request control system in OFDM-MIMO communication system. In this system, an ACK / NACK output part (320) of a receiver transmits, to a transmitter, a feedback information of positive or negative response based on the result of a cyclic redundancy check. An error data stream decision part (310) of the transmitter determines, based on the feedback information, a data stream that need be retransmitted, and a retransmission mode selection part (312) selects a retransmission mode from among (a) a mode in which to transmit the data, which are to be retransmitted, via the same antenna as in the previous transmission, while transmitting, at the same time, new data by use of an antenna via which no data retransmission is requested; (b) a mode in which to transmit the data, which are to be retransmitted, via an antenna via which no retransmission is requested, while transmitting new data via another antenna at the same time; (c) a mode in which to use STBC to retransmit the data via an antenna via which no retransmission is requested; and (d) a mode in which to use STBC to retransmit the data via all the available antennas.

Method and apparatus for image transmission using arithmetic coding, based on continuous error detection uses a controlled amount of added redundancy. A continuous error detection scheme is provided, wherein there is a trade-off between the amount of added redundancy and the time needed to detect an error once it occurs. Herein, there is no need for the cyclic redundancy check (CRC) to wait until an entire block of data has been received and processed before an error can be detected. The invention can be used to great advantage both in the automatic repeat request (ARQ) and other concatenated coding schemes. Errors in the received bit stream are detected by introducing added redundancy, e.g., a forbidden symbol, in the arithmetic coding operation. The forbidden symbol is never intended to be encoded. The redundancy error causes loss of synchronization, which is used to detect errors. If a forbidden symbol gets decoded, it means that an error has occurred. In this invention, there is direct control over the amount of redundancy added vs. the amount of time it takes to detect an error. For image compression systems, by using the invention and ARQ, only one device would suffice both for source compression and channel coding.

The present invention relates to a hybrid automatic repeat request (HARQ) method for transmitting data packets from a transmitting entity to a receiving entity via a data channel. Further, the present invention is related to mobile stations, base stations, radio network controllers and communication systems performing in the HARQ method. To overcome problems resulting from asynchronous retransmissions, the present invention provides a HARQ method sending retransmissions synchronous. According to the method, a feedback message is received from the receiving entity at the transmitting entity and, in case the feedback message indicates that the data packet has not been received successfully, a retransmission data packet is transmitted to the receiving entity after a predetermined time span upon having received said feedback message. The receiving entity soft combines the retransmission data packet with the previously received data packet.

Systems and methods for retransmitting unsuccessfully transmitted data across a communication link. The retransmission mechanism may be applied to point to multipoint networks including wireless networks. Each packet is encapsulated in an ARQ frame and assigned a sequence number for the purpose of coordinating acknowledgments and retransmissions. Information as to which packets require retransmission is communicated in the form of a bitmap where each bit indicates an acknowledgment status for a given packet. Any missing packets in the received sequence are assumed to require retransmission.

In a data communication system, the function of automatic repeat request is provided for transmission of packets based on a data communication protocol such as the Real-Time Transport Protocol or the User Datagram Protocol. Lost packets are detected at various timings, for example, when the beginning packet of each frame is received, the final frame of each frame is received, at a time limit of processing, and at a regular interval, and retransmission requests are issued accordingly. A data reception terminal does not issue a retransmission request if associated retransmission data will not be in time for playing with consideration of processing time and roundtrip time, thereby avoiding the transmission of useless retransmission request packets and retransmission packets.

An automatic repeat request mechanism (such as Type II / III hybrid ARQ) which includes (soft or hard) combining of initially transmitted and retransmitted versions of a packet, is provided for retransmission of erroneous packets. According to the present invention, in association with each retransmission, there is outband signaling from a transmitter to a receiver that unambiguously indicates when, e.g. the exact time or physical location, the first transmission of the packet was carried out, so that it is possible to combine the retransmitted version with the previous version(s) of the packet. Soft combining requires that the initial packet and the retransmitted packet be identical. In an embodiment of the invention, in order to overcome this problem, the information that needs to be changed between the initial transmission and the retransmission(s) of a packet is sent outband with other outband signaling information. Thus, the retransmitted packet can be maintained unchanged and the requirement for identical packets in soft combining is met.

A communication system and method includes the steps of: a) transmitting an ACK signal indicating a received packet includes no error or a NACK signal indicating the received packet includes error from a reception end to a transmission end, and performing automatic repeat request; b) obtaining reliability of the received packet when demodulating it at the reception end; and c) reporting from the reception end to the transmission end the reliability of the received packet utilizing the ACK / NACK signal by using not less than three levels.

Disclosed is a mobile communication systems, and more particularly a method of retransmitting data through a reverse link in a packet data, system, using ARQ (automatic repeat request) The present invention discloses a method for retransmitting data through a reverse link in Packet Data communication system using automatic repeat request(ARQ) adjusting data retransmission energy to be reduced at a predetermined ratio of one receiving energy for an initial data transmission to other receiving energy for a data retransmission.

Disclosed are a system and method for transmitting / receiving an ARQ for correcting errors in an OFDM / TDMA terminal, and generating high-rate frames. The ARQ transmitting / receiving system of an OFDM / TDMA terminal comprises a CPU transmitting / receiving a data packet to / from an upper block in a software manner; an ARQ transmitting / receiving unit receiving the data packet, dividing the data packet into fragments each having a predetermined size, storing the fragments, generating a frame at the moment of generating a frame based on the stored fragment information, checking whether ARQ is retried or not, and transmitting / receiving the ARQ in a hardware manner; an interface buffer storing data transmitted between the CPU and the ARQ transmitting / receiving unit; and a fragment buffer storing fragments generated by the ARQ transmitting / receiving unit.

A method of providing an automatic repeat request (ARQ) that employs a selective repeat, enabling a transmitting medium access control (MAC) entity at a transmitting station to retransmit those MAC data whose previous transmissions have failed is described. The MAC data is organized into fixed-sized ARQ blocks, with said ARQ blocks being the building blocks of MAC service data units (MSDUs) or MSDU fragments; The transmitting MAC entity assigns a local number and a global number to each ARQ block to be transmitted and identifies ARQ blocks contained in a transmitted MAC protocol data unit (MPDU) by including into the MPDU the local and global numbers of the first ARQ block in that MPDU. A receiving MAC entity at a receiving station determines and acknowledges the reception status of the ARQ blocks received or anticipated.

An apparatus and method for changing a signal mapping rule in an hybrid automatic repeat request (HARQ) system are provided. In a transmitter in an automatic repeat request (ARQ) system according to the present invention, a memory stores different signal constellations for a predetermined modulation scheme according to retransmission numbers (k). A modulator reads a signal constellation according to a current retransmission number from the memory, upon receipt of a retransmission request signal from a receiver, and modulates transmission data to complex symbols on the signal constellation.

Methods and apparatus are provided for modulating ACK / NACK persistence to improve data traffic performance. In one implementation, a method for control of automatic repeat requests between a transmitting terminal (102) and a receiving terminal (104) comprises: defining (1404) a buffer window of a buffer, the window to buffer multiple higher layer data blocks each segmented into multiple physical layer data blocks, the window beginning at a current higher layer block in which at least one physical layer block has not been received; obtaining (1406) an indication of whether physical layer blocks are completely received; determining (1408), based on the obtaining step, that a subsequent higher layer block within the window has been completely received; and discarding (1410) the current higher layer block when a time delay of the current higher layer block exceeds an estimate of a delay tolerance corresponding to a higher layer application.

<heading lvl="0">Abstract of Disclosure< / heading> An embodiment of the invention includes an efficient error-control system and method for recovering packet losses, especially losses in distributing multicast video over broadband residential networks. Preferably, unlike most existing error-control algorithms designed for Internet multicast, the system and method does not employ substantial feedback suppression. Preferably, the system and method does not employ substantial multicasted retransmission. Preferably, the system and method does not employ substantial parity retransmission. Preferably, the system and method does not employ substantial local loss recovery. The system and method integrates two existing classes of error-control algorithms: Automatic Repeat Request (ARQ) and Forward Error Correction (FEC), to reduce traffic overhead and achieve scalability.

A method and system for controlling discontinuous reception (DRX) in a mobile device in a wireless communications network that supports voice-over-internet-protocol (VoIP) and that uses an automatic repeat-request (ARQ) method, like a hybrid automatic repeat-request (HARQ) method, uses autonomous DRX control after initial VoIP traffic setup. If the mobile device transmits a negative-acknowledgement signal (NACK) indicating unsuccessful receipt of a VoIP packet, then it autonomously turns on a predetermined delay time later to receive the retransmission of the VoIP packet, where the predetermined delay time is related to the time for the base station to process the NACK and prepare the VoIP packet for retransmission. When the mobile device transmits or retransmits a VoIP packet, reception is deactivated, but is autonomously activated the predetermined delay time later to receive an acknowledgement signal (ACK) or NACK. VoIP packets may be transmitted from the mobile device the predetermined delay time before VoIP packets are transmitted from the base station. This alignment allows an ACK or NACK to be transmitted from the base station in the same transmission time interval (TTI) as a VoIP packet.

The present invention relates to a method and an arrangement for obtaining efficient radio resource utilization over a radio interface in a communication network comprising a transmitting entity (18) transmitting data over said radio interface to a receiving entity (15), said transmitting entity (18) comprising at least an upper layer utilizing an automatic repeat request (ARQ) protocol on top of a lower layer utilizing a hybrid automatic repeat request (HARQ) protocol, whereby a timer in said upper layer is arranged to supervise operation of said upper layer. Said timer is set based on an indication of receipt status of the transmitted data in said receiving entity (15) according to said lower layer hybrid automatic repeat request protocol.

A method for handling segmentation and numbering of protocol data units (PDUs) in a radio link control (RLC) entity of a wireless communications system includes handling a plurality of service data units (SDUs), an SDU of the plurality of SDUs comprising at least a first sequence number (SN) field and a first data field, a PDU of the RLC entity comprising a second data field storing all or segmented data of the first data field, the PDU further comprising a second SN field at least storing a value of the first SN field, and the RLC entity using the second SN field for performing an automatic repeat request, duplicate detection, a sequence number check, in-sequence delivery, etc.

An Automatic Repeat reQuest (ARQ) error correction transmitting apparatus and method in a multiple antenna system are provided. In the ARQ error correction apparatus, a serial-to-parallel converter converts serial input data to parallel data, a retransmission processor determines a permutation transmission mode with respect to an initial transmission mode, in response to a retransmission request fed back from a receiver, and an STBC encoder STBC-encodes the parallel data and transmits the STBC-coded data through the transmit antennas according to the permutation transmission mode.

Methods and apparatus are provided for modulating ACK / NACK persistence to improve data traffic performance. In one implementation, a method for control of automatic repeat requests between a transmitting terminal (102) and a receiving terminal (104) comprises: defining (1404) a buffer window of a buffer, the window to buffer multiple higher layer data blocks each segmented into multiple physical layer data blocks, the window beginning at a current higher layer block in which at least one physical layer block has not been received; obtaining (1406) an indication of whether physical layer blocks are completely received; determining (1408), based on the obtaining step, that a subsequent higher layer block within the window has been completely received; and discarding (1410) the current higher layer block when a time delay of the current higher layer block exceeds an estimate of a delay tolerance corresponding to a higher layer application.

A hybrid ARQ retransmission method involves encoding data packets with a forward error correction (FEC) technique prior to transmission. The data packets are retransmitted based on an automatic repeat request and subsequently soft-combined with previously received erroneous data packets either on a symbol-by-symbol or a bit-by-bit basis. The symbols of the erroneous data packets are modulated by employing a first signal constellation. The symbols of the retransmitted data packets are modulated by employing at least a second signal constellation. Each symbol bit has a mean bit reliability defined by the individual bit reliabilities over all symbols of the predetermined signal constellation. The first constellation and the at least second signal constellation are selected such that the combined mean bit reliabilities for the respective bits of all transmissions are averaged out.

In a communication where a retransmission is attained based on a Hybrid-ARQ (Automatic repeat ReQuest) system, retransmission having no gain is reduced, and improvement of the transmission efficiency is intended. A mode determining unit 111 of a base station carries out calculation to obtain a received signal quality difference information indicative of a difference between a received signal quality at the current stage and that of a past stage at a terminal, and supplies to a control unit 112. The control unit 112 controls a power setting unit 113 based on the received signal quality difference information supplied from the mode determining unit 111, and thus a transmission power of a signal transmitted from an adaptive coding and modulation unit 13 can be controlled. The present invention can be applied to a base station of a portable telephone communication network, for example.