67 results about "Cooperative diversity" patented technology

The present invention discloses a self-adapting cooperative retransmission method based on the self-adapting coding modulation. The method selects an appropriate coding modulation plan grade and a largest retransmission number for transmitting the data package according to the channel state information of the direct transmission link from a source end to a target end and the service quality request of different services. Because of the broadcast characteristic of the radio channel, the target end and a relay node can receive the data simultaneously. If the target end does not decode correctly, the retransmission is actuated. The retransmission by the source end or the relay node is determined by the selected coding modulation plan and whether the relay node correctly receives the data package. The invention combines the self-adapting coding modulation technique, a hybrid automatic retransmission technique and cooperative diversity for consideration. The cooperation is selected to execute at the time when the cooperative gain is evident. The incorrect or no-gain cooperation is avoided thereby improving the transmission quality and effectively optimizing the whole capability of the system at the state that the spending of the cooperation signaling is reduced as possible.

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 device, method, and system for cooperative diversity wireless communication. The method includes detecting at least one relay wireless device (106). A wireless communication link is established with the at least one relay wireless device (106). Forward link address information of a target wireless device (104) is transmitted, via the wireless communication link (118) to the at least one relay wireless device (106) a forward link wireless communication data signal received by the at least one relay wireless device (106). An instruction to transmit to the target wireless device (104) the forward link wireless communication data signal received by the at least one relay wireless device (106) is also transmitted to the at least one relay wireless device (106), via the wireless communication link. The forward link wireless communication data signal being destined for reception by the target wireless device (104).

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.

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 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.

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 invention discloses a cooperative diversity scheme for wireless sensor networks based on the decoding and forwarding of distributed space-time codes, which comprises cluster head determination, cooperative establishment, time-slot planning and data transmission. The cooperative diversity scheme effectively solves the problems that a plurality of prior cooperative schemes such as amplify-and-forward, decode-and-forward, coded cooperation and so on have complicated design, difficult realization, low diversity efficiency, difficult cooperative synchronization and so on, effectively improves the frequency spectrum efficiency and the energy efficiency of the system, and greatly decreases the system energy consumption of the wireless sensor networks.

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.

The invention discloses a source end network coding and alternated transmission-based relay cooperation method, which is characterized in that: two relays are positioned outside the receiving radius of each other; a source end performs network coding on binary information sequences which are sent by the source end every three time slots; the two relays alternatively send the information in the adjacent time slots, the relay which sends the information in the last time slot receives the information in the present time slot, and the relay which receives the information in the last time slot sends the information in the present time slot; and when one relay receives the information sent by the source end in every time slot, the other relay forwards the information which is received and processed in the last time slot to a target end. Under the condition of not influencing cooperative diversity gain, the characteristics of two relay transmission models are fully utilized, more informationcan be transmitted within the same number of time slots, multiplexing loss in relay cooperative transmission is reduced, the transmission efficiency of the information is improved by 2 / 3, and both transmission performance and efficiency are considered in an actual relay cooperative communication system.

The invention discloses a method for selecting cooperative nodes in a wireless communication network, which can effectively improve cooperative diversity performance as well as the transmission capacity and reliability of the wireless communication system and ensure the requirement of the quality of service (QoS) of users. The method comprises the following steps: (1) an information source S sends relay requests to nodes around; (2) if the nodes are in leisure, a response signal is sent, and if no leisure node exists, the step (1) is continued; (3) if only one leisure node exists, the operation is switched into the step (6), and an AF or DF cooperative mode is directly adopted; (4) if a plurality of leisure nodes exist, the information source S calculates the distance L between the information source S and the leisure nodes according to the strength of a utilization signal, time difference, angle or GPS information, and then the leisure nodes send information to a target terminal, calculate the distance D between the leisure nodes and the target terminal according to the signal strength, the time difference, the angle or the GPS information and feed back the distance to the information source S; (5) the leisure node with the minimum product of the distance L and the distance D is selected as an optimum relay node; and (6) finally the system adopts the AF or DF cooperative mode.

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.

The invention provides a relaying method for uplink data retransmission and a mobile communication system. The transparent relaying method comprises the following steps: a base station receives uplink data, a first reference signal and control information embedded into the uplink data, which are retransmitted on a first resource by a user terminal based on a NACK (Negative Acknowledgement) signal; the base station receives the uplink data or the precoded uplink data and a second reference signal, which are transmitted on the first source by a relaying station based on the ANCK signal, wherein the second reference signal is different from the first reference signal; and the base station calculates channel response by utilizing the first reference signal, the second reference signal and the received signals and detects the control information and the uplink data by using the calculation result of channel response. According to the invention, cooperative diversity gain is obtained on the basis of correctly transmitting the control information and the uplink data.

The invention relates to a method for strengthening WiMAX uplink performance by using cooperative diversity, relating to a wireless communication system. By using the technology of cooperative diversity, users in the WiMAX system share resources with each other to form a virtual MIMO (Multiple-Input Multiple-Output) system. Each of mutually cooperative users transmits the own signals to a base station, and simultaneously receives the signals transmitted by the cooperative users. After the user receives the signals of the cooperative users, the own signals and the received signals of the cooperative users are transmitted with an antenna by using different subcarriers. The cost of the system is saved and the power consumption of the system is reduced. By applying the cooperative diversity, the WiMAX system obtains obvious diversity gain, and the system performance is enhanced. In addition, the technology of cooperative diversity is combined with the key technology OFDM (Orthogonal Frequency Division Multiplexing) of WiMAX physical layer, thereby forming cooperative diversity mechanism of frequency selective fading channel and solving the cooperative diversity problem of frequency selective fading channel.

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.

The invention discloses a cooperative diversity transmission method and device which is based on OFDM and applied to a narrow band low voltage power line communication network. The method comprises the steps that available subcarriers are divided into a plurality of channels based on an OFDM modulation system, idle nodes in a low voltage power line carrier communication network are used as relays, and all nodes in the network can be made to participate in work through the fact that different nodes send the same raw information on different channels. Further, due to the fact that working channels of different nodes can be selected freely, the effects that node sending power is fully used and frequency diversity is improved are achieved, and therefore the capability for confronting frequency selective fading and colored noise is improved. In addition, different interleaving codes or different channel codes are used by different channels, time diversity can be improved, and the capability for confronting time varying interference and pulse noise is enhanced. Through the OFDM cooperative diversity transmission method and device, the effect that reliable communication quality is supplied under the premise that communication frequency bands and the amount of nodes are used is achieved.

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.

There are provided a cooperative diversity method and a cooperative diversity system using opportunistic relaying. In cooperative diversity wireless communications, an optimum relay is selected considering an interference effect between adjacent cells, and the selected relay transmits a data signal received from a transmitter to a receiver. Accordingly, an optimum relay is selected considering interference between channels not only in a single cell environment but also a multi cell environment, and a signal is transmitted to a receiver through the selected relay, thereby increasing transmission efficiency and improving reliability.

The invention provides a cooperative diversity application method in 3GPP V2X. The cooperative diversity application method comprises the steps of transmitting control information by a V2X broadcast service initiator in a control resource pool, and then transmitting data information in the data resource pool; wherein the control information and the data information can be retransmitted, and the control information carries scheduling information for first transmission and possible retransmission of the data information; after the V2X broadcast service initiator transmits the data broadcast information, forwarding the data broadcast information by each relay node in a cooperative diversity manner with a random phase difference, wherein the forwarding manner comprises forwarding first transmission and forwarding retransmission of data and / or the control information. The cooperative diversity application method can improve QoS performance of service information under a precondition that parameters such as resource occupation and time delay are unchanged.

Diversity techniques are commonly used in wireless communications to combat multi-path fading. Recent interests in ultra -wideband technology focus on multi-band OFDM systems that can explore the high diversity due to the independent frequency bands. To achieve full diversity with high data rate, a system (800), apparatus (500) and method that uses coded modulation with spreading rotation of transmitted signals. A 2x2 integer rotation matrix for QAM signals, 3x3 and 4x4 integer rotation matrices for QAM signals are provided. Compared with the non -regular QAM shape for real rotation matrices, each of these integer rotation matrices makes the regular QAM shape after rotation. The systematic design of these spreading matrices can be used to simplify the receiver structure such as simplified ML, MMSE and ZF, and then reduce their decoding complexity. Further, the present invention achieves cooperative diversity not only from distributed users but also from the signal space diversity of each user. An embodiment is provided for a cooperative system (100) in which different rows of integer rotation matrices are used by a source and relays as a modulation scheme to increase cooperative diversity.

The invention provides a bandwidth-saving video transmission method. According to the method, video data are deconstructed into text semantic information at a sending terminal to realize textualized transmission of key information; and the text semantic information is constructed into a reconstructed image consistent with the semantic information of an original target image at a receiving terminalbased on an image generation technology. Therefore, different forms of computing capabilities are given to each part in the communication network structure; specifically, a mode of endowing a sendingterminal with a video data feature semantic computing capability and endowing a receiving terminal with a semantic generation image computing capability is adopted, and an original local centralizedcomputing communication mode is converted into a cooperative diversity computing communication mode, so that the bandwidth and storage resources are greatly reduced, and the transmission, storage andretrieval efficiency is improved.

The invention relates to a cooperative diversity positioning method based on a satellite positioning system. A space-time cooperative diversity positioning scheme based on an Alamouti code and MIMO-spread spectrum space diversity coding are designed according to the satellite positioning system. The method concretely comprises the steps that according to space-time cooperative diversity positioning based on the Alamouti code, adjacent satellites in the same track are grouped into satellite pairs so that adjacent satellite cooperative diversity is realized; and cooperative diversity MIMO-spread spectrum space diversity coding aiming at the satellite positioning system is designed based on an MIMO-direct sequence spread spectrum method multi-code model. Compared with methods in the prior art, the method has superiorities that signal gain is enhanced without increasing positioning signal transmitting power so that the service life of the satellites can be effectively prolonged under the premise of guaranteeing anti-interference capability; and cooperative diversity of the adjacent satellites closely combines the positioning satellite constellation characteristics, and robustness of positioning signals is enhanced without changing a space segment structure function or increasing extra burden of the satellites.

The invention provides a cooperative diversity transmission method of a radio base station and cellular communication base stations. The cooperative diversity transmission method comprises steps that the radio base station broadcasts and transmits original signals [X1 X2 X3 X4...]; and at the same time, a first cellular communication base station, in cooperation with the radio base station, transmits signals [-X2*X1* -X4*X3*...] to a subscriber, wherein X1, X2, X3 and X4 are data vectors with the identical length, and the symbol * represents the complex conjugation of signals; a second cooperative transmission cellular communication base station, in cooperation with the radio base station, transmits signals [X3 X4 X1 X2...] to the subscriber; and a third cooperative transmission cellular communication base station, in cooperation with the radio base station, transmits signals [-X4*X3* -X2*X1*...] to the subscriber. According to the cooperative diversity transmission method, no change on the radio transmission signals is needed, that is, on the condition of not influencing original radio reception, signals orthogonal to radio signals are transmitted by the cellular communication base stations, and thus cooperative diversity transmission is formed, and the network capacity and the coverage effect of the radio transmission in a hybrid network of radio and cellular communication are improved.