902 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.

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.

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 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 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.

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.

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.

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.

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 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.