67 results about "Cooperative diversity" patented technology

A base station (BS) communicates with a mobile station (MS) through relay stations (RSs). In one exemplary reliable relay-associated transmission scheme, the BS transmits data to the RSs using multicast or unicast. From the received packets, each RS calculates its reliability value according to a reliability function, which it informs the MS. The BS then generates a reliability metric to identify the RSs that are considered reliable. The reliable RSs transmit their information to the MS under a cooperative multicast transmission mode. Meanwhile, the unreliable RSs overhear the transmissions between the reliable RSs and the target MS. If the MS is unable to receive information from reliable RSs, the unreliable RSs can join the cooperative transmission to provide a higher cooperative diversity gain to the target MS.

A communications system includes a source, a destination, and multiple relays. In a first time period, the source emits a first transmission and a first relay retransmits a prior source transmission. Then, in a second, subsequent time period, the source node emits a second transmission and a second relay transmits the source transmission from the first time period. Optionally, the transmission from the second relay also includes the message from the first relay during the first time period. Similarly, in a third time period, the first relay transmits a message that includes the second relay's transmission and the second source transmission from the second time period. Alternatively, the source node transmit in a first frequency band, the first and second relays receive only in the first frequency band, and retransmit in a second frequency band, and the destination receives in both the first and second frequency bands.

The present invention provides a broadcast information transmission method in 3GPP V2X communication. The method comprises: V2X broadcast business initiator sends control information in a control resource pool and sends data information in the data resource pool, wherein the control information carries dispatching information; and after the initiator sends the broadcast information, each relay node forwards the data broadcast information in the cooperative diversity mode and leads in the diversity gain for the system by using the random phase difference. The broadcast information transmission method in the 3GPP V2X communication realizes efficient, reliable and implement-easy business information broadcast flooding in the scene and requirement standard with high-density nodes, the low delay requirement and the information transmission reliability requirement.

Disclosed is a method of providing cooperative diversity in a Multiple Input Multiple-Output (MIMO) wireless network including a source station, a relay station, and a destination station each for transmitting a plurality of streams through multiple antennas, the method including: decoding, by a relay station, a plurality of streams received from the source station, checking for errors in the individual decoded streams, and transmitting error detection information to the source station and thereafter relaying streams having no errors to the destination station and retransmitting, by a source station, streams corresponding to streams which were previously found to include errors to the destination station based on the error detection information.

The invention discloses a preamble design-based cooperative diversity orthogonal frequency division multiplexing (OFDM) timing and frequency offset estimation method in the field of wireless communication, which aims to mainly solve the problems of low accuracy, high complexity and low transmission efficiency of timing and frequency offset estimation from relays to a destination in a conventional cooperative diversity OFDM system. The method is implemented by the following steps of: (1) designing training sequences of each relay; (2) simultaneously transmitting the training sequences to the destination by using each relay; (3) estimating rough timing offset between the relays and the destination; (4) estimating fine timing offset between each relay and the destination; (5) calculating estimation values of the timing offset between each relay and the destination; (6) estimating decimal frequency offset between each relay and the destination; (7) estimating integral frequency offset between each relay and the destination; and (8) calculating the estimation values of the frequency offset between each relay and the destination. By the method, the timing and frequency offset estimation performance can be improved, the operational complexity can be reduced and the transmission efficiency can be improved.

A wireless communication system and method of performing cooperative diversity using cyclic delay is provided. A transmitting terminal constituting the wireless communication system includes: a data transmitter configured to transmit data to each of at least one relay terminal and a receiving terminal; an error detection result receiver to receive an error detection result from a relay terminal that detects an error in the data among the at least one relay terminal; and a data retransmitter configured to retransmit data to the receiving terminal when it is determined each of the at least one relay terminal detects the error in the data based on the error detection result.

A cooperative diversity method and apparatus that can minimize interference and maximize an efficiency of a transmission channel between terminals of a cooperative diversity pair, the method including: determining a pair of terminals to be a cooperative diversity pair according to a spectrum sensing result of a cognitive radio (CR); selecting a subchannel through which data is exchanged between the pair of terminals; and transmitting the data between the pair of terminals through the selected subchannel.

The invention discloses a communication method of a multi-input multi-output system assisted by a relay. The multi-input multi-output system assisted by a relay in the communication method comprises a transmitting end with M antennas, a relay transferring station with L antennas and a mobile receiving end with N antennas, wherein K paths of data streams are transmitted by the multi-input multi-output system assisted by the relay every time, and K is the minimum value of M, L and N. The communication method of the multi-input multi-output system assisted by the relay can remarkably improve thereceiving end frequency spectrum efficiency by adaptively utilizing the cooperative diversity gain of a through chain under the premise of low complexity and low feedback cost; and compared with the limited feedback precoding technology of the common relay assisted communication system, the adaptive selection cooperative diversity scheme is optimal.

A method and system are provided in a wireless communications system comprising a plurality of nodes (users) working cooperatively. The system provides cooperative diversity by allowing nodes to actively share their antennas and other resources to obtain spatial diversity. The nodes receive the same message (information data) from a common source. Each node enhances the reliability of the message with a modern forward error correction (FEC) code, converts the FEC encoded message into an ensemble of symbols, divides the ensemble of symbols into packets, modulates, dithers and transmits the packets to a receiving node. The dithering process is performed by varying the signal amplitude, phase, frequency and / or symbol timing of the modulated packets. A unique dither pattern is assigned to each node. The receiving node captures a composite signal comprising the transmitted packets of all or most of the transmitting nodes in the cooperative communications system. Because the transmitted packets are dithered independently in phase and / or amplitude, spatial diversity is transformed into temporal diversity.

A full-rate distributed space-time (ST) code design is provided for amplify-and-forward cooperative wireless channels. A signal space diversity technique is employed at the source node and a unique signature vector at each relay node. The distributed space-time (ST) codes can achieve full cooperative diversity and full rate. The achievable diversity gain is M+1, where M is the number of relay nodes. Optimal power allocation can be used to maximize the coding gain under a total power constraint.

The wireless transmission of layered signals, in a described embodiment, uses multiple relay nodes (304) to implement cooperative diversity. The method includes: (i) receiving layered signals from a source node (300), (ii) receiving, from a destination node (302), a relay allocation parameter to implement a cooperative relay strategy with one or more other relay nodes (304), and (iii) relaying the layered signals to the destination node (302) using the cooperative relay strategy.

Disclosed is a new solution to maximize throughput in wireless networks even when unpredictable and time-varying error exist. The present invention adapts to take an advantage of a network coding at a symbol level in multi-channel wireless networks. By operating the network coding at the symbol level and using soft decision values, the present invention is able to exploit both time and cooperative diversity in realistic multi-channel wireless networks, to adapt to time-varying and bursty channel errors, and to efficiently collect as many correct symbols as possible at the receiver.