148 results about "Relay channel" patented technology

Method and apparatus for determining a downlink channel response in an orthogonal frequency division multiplexing access (OFDMA) system. The method and apparatus uses the uplink quality indication channel for determining the downlink channel response, or uses round trip pilot relay channel sounding. The uplink quality indication channel may comprise modified mini-tiles. The subscriber station using round trip pilot relay channel sounding sends composite transponder pilots after receiving the DL pilots.

A system and method for relaying data communications in a Hybrid Automatic Repeat Request (HARQ) network. The system and method operable to receive a data communication packet from a base station during a first transmission time interval and simultaneously receive an acknowledgement signal from a subscriber station; and transmit a data communication packet to a subscriber station during a second transmission time interval and simultaneously transmit an acknowledgement signal to a base station.

A system and method of relay code design and factor graph decoding using a forward and a backward decoding scheme. The backward decoding scheme exploits the idea of the analytical decode-and-forward coding protocol and hence has good performance when the relay node is located relatively close to the source node. The forward decoding scheme exploits the idea of the analytical estimate-and-forward protocol and hence has good performance when the relay node is located relatively far from the source node. The optimal decoding factor graph is first broken into partial factor graphs and then solved iteratively using either the forward or backward decoding schemes.

The invention provides a method for realizing partner selection and cooperative transmission combining with position information. The method is to obtain the position information of each node by directly using a cooperative positioning technology of a cooperative communication system and provide a partner selection strategy according to the large-scale fading condition of information transmission: an information source firstly calculates a distance between the information source and each candidate trunk node; the information source adds the distance between the information source and each trunk node and the distance between each trunk node and a base station by combining the obtained position information of each candidate trunk node and the distance information between the candidate trunk node and the base station; the information source selects a trunk node with the minimum total distance value of a trunk information channel as a cooperative partner of the information source to help the information source transmit information, after the total distance value of the trunk information channel of each trunk node is known, thereby realizing gain of space diversity reception, reducing path loss, and achieving the aims of reducing the bit error probability during transmitting, improving the signal quality and expanding the network coverage.

A method for selecting a high-speed mobile user relay node in the coordination communication of a cellular system relates to a selection method of a relay node, which solves the problems that the selection success rate of a relay user is low, after the selection is realized, the duration is short, and the frequent handover is required in the selection method of the high-speed mobile user relay node currently. The method comprises the following steps: a base station groups each node entering a cell; a source node sends out a coordination communication request; the base station sends out communicable confirmation information to the source node, and the node which is positioned in the same group as the source node sends out a request which can carry out the coordination communication and the channel quality between the node and the source node to the base station simultaneously; the base station selects the node with the best channel quality as the relay node, and allocates a relay channel; and when the channel quality between the relay node and the source node or the channel quality between the relay node and the base station is lower than the threshold value, the base station re-selects a new relay node, and is used for stopping the relay through sending out an instruction or responding a request directly communicating with the source node.

This invention relates to a coordinate transmission based on joint network- channel coding utilizing the maximum system transmission rate to structure an odd-even check matrix, which includes coding odd-even check matrixes of a source channel, a relay channel and a network channel, and the source node codes the source information with the source channel odd-even check matrix and broadcasts it to the relay and the destination nodes, the relay node uses the relay channel matrix to code its own information and send it to the destination node and uses the network code matrix to code the source coded and relay coded information to get network coded information to pick up extra information and carry out low density odd-even check coding it to be sent to the destination node, which decodes the information sent by the source node and the relay node jointly.

A method of controlling an operation of a mobile base station that is linked to a mobile communication system via a wireless relay channel includes an information acquiring step of acquiring estimation-purpose base information for estimating a condition of radio interference between the mobile base station and one or more other base stations, the acquisition of the estimation-purpose base information being made by the mobile base station and involving measurement of a physical property responsive to a current position of the mobile base station, an estimation step of estimating the condition of radio interference based on the acquired estimation-purpose base information, and a control step of controlling an operation of the mobile base station based on the estimated condition of radio interference.

Disclosed herein are a method of communicating and establishing a relay channel between a base station and a non-line-of-sight channel terminal in a next generation cellular communication system. The method of communicating between a base station and a non-line-of-sight channel terminal includes a first step of the base station receiving channel state information from the non-line-of-sight channel terminal; a second step of the base station collecting channel state information between the non-line-of-sight channel terminal and adjacent terminals; a third step of, if there is a relay channel terminal that belongs to the adjacent terminals and that can ensure line-of-sight channels to the base station and the non-line-of-sight channel terminal, the base station and the non-line-of-sight channel terminal performing high frequency cellular communication via the relay channel terminal; and a fourth step of, otherwise, the base station and the non-line-of-sight channel terminal performing low frequency cellular communication.

Digital communication coding methods resulting in rate-compatible low density parity-check (LDPC) codes built from protographs. Described digital coding methods start with a desired code rate and a selection of the numbers of variable nodes and check nodes to be used in the protograph. Constraints may be set to satisfy a linear minimum distance growth property for the protograph. All possible edges in the graph are searched for the minimum iterative decoding threshold and the protograph with the lowest iterative decoding threshold is selected. Protographs designed in this manner may be used in decode and forward relay channels.

A relay node selection method in cooperative communication, relates to a selection method of the relay nodes, which solves the problems that relay users are not generated caused by severe collision when a plurality of relay applications are present in the relay node selection method of the cooperative communication. Nodes around source nodes transmit cooperative communication request to a base station, and leisure nodes ignore the cooperative communication request; the base station selects the nodes with better communication quality as the relay nodes, and distributes relay signals to the relay node; the relay nodes transmit the information of the resource nodes to the base station, selects the nodes which match with quality request as standby relay nodes; when the relay nodes detect that quality of the resource node descends, the relay nodes are exchanged; the base station devices to continue relaying or stop relaying according to the receiving quality. According to the invention, the nodes communicating with the base station around the resource nodes are selected as the relay nodes, without quantity of free users to generate relay request, thereby avoiding the generation of the collision, to successfully complete the relay process.

The invention provides a multithread bidirectional relay transmission method based on amplification forwarding. The method comprises the following steps: (1) a relay antenna selection phase: two source nodes sends a training signal sequence to a relay node respectively, according to the received training signal sequence, the relay node estimates channel information between the relay node and the two source nodes respectively, two corresponding channel matrixes are obtained, according to the two channel matrixes, an antenna subset involving two users interaction communication is selected, complexity and forwarding energy consumption of a relay node processing signal is reduced, a diversity gain is obtained, and error code performance of a system is raised; (2) a bidirectional relay transmission phase: according to the selected antenna subset, the relay node carries out bidirectional relay transmission, and information interaction is completed. According to the invention, a high efficiency bidirectional communication strategy based on ANC (analog network coding) is employed, with regard to multithread transmission, an antenna selection scheme and a linear decoupling technique of a receiving signal are made, sending energy consumption and operation complexity are reduced, and a degree of freedom of a multiple-input-multiple-output bidirectional relay channel is effectively utilized.

A scheduling system and method for use with relay-assisted wireless networks includes accessing feedback from mobile stations in a network and arranging users associated with a relay station in a list in accordance with marginal utilities. A determination of whether the users in the list can be eliminated from feedback overhead by testing conditions for feedback reduction is made. A diversity schedule is generated by employing a weighted bipartite graph with relay channels and access channels and performing a matching method. A transmission schedule is generated for channel usage in accordance with multi-user and channel diversity for mobile users and spatial reuse of channels across relay and access hops by incorporating rate feedback and interference for the mobile stations and the relay stations based upon the matching method applied to a new weighted graph which accounts for traffic loads and fairness as well.

The invention relates to a packet forwarding method in a cooperative network implementing a source terminal, a destination terminal, and at least one relay terminal. In case of a packet decoding error in a node of the network, this method, depending on the outage state of a direct or relayed channel between two nodes of the network, enables a determination of the node(s) having to perform retransmission of the packet and if applicable, the transmission resource(s) to be used.

The invention discloses a complete UAV (unmanned aerial vehicle) relay model which comprises two types of links, wherein one type of the links is a ground-air link from a ground station to a UAV, and a channel under the link is regarded as a Rician channel; and the other type of the links is an air-air link from a UAV to a UAV, and a channel under the link is regarded as a Rayleigh channel. Although the analysis is complicated, the relay model and a channel model can well conform to actual situations. Based on the channel model, the invention also provides a method for solving the interruption probability, and the method cannot be influenced by the channel model and is suitable for any channel model with a precondition that a channel matrix of the channel model must be known. By virtue of MATLAB (matrix laboratory) simulation, a curve of characteristic values of a channel matrix H can be obtained, then by virtue of curve fitting, a mathematical expression of the characteristic values can be obtained, and then a cumulative distribution function of the characteristic values is obtained, which is much simpler. By use of the method provided by the invention, the overall interruption probability of the two sections of the links is obtained, and the interruption probability under an actual situation is well reflected.

The invention discloses a transmission control method, a base station, a relay node and a communication system for a relay link. The transmission control method comprises the steps that: one pair or two pairs in the uplink/downlink sub-frame pairs is/are selected for the relay link transmission; configuration information including the selection result is generated and is then sent to a relay node; after receiving the configuration information, the relay node adjusts the access link timing of the user equipment (UE) attached to the relay node according to the receiving-to-transmission switch time (R-to-T switchtime) so as to make the access downlink timing hysteretic and the access uplink timing ahead. According to the technical scheme, the design complexity of a relay link channel is reduced and the resource utilization rate is improved.

The invention is a method for optimizing a downlink OFDMA cellular system, belonging to the technical field of wireless communication and comprising the steps as follows: respectively collecting direct channel gain and relay channel gain; distributing subcarriers to all users equally, determining a direct mode or a relay mode corresponding to each subcarrier, and determining the relay number of the corresponding subcarrier when the subcarrier adopts the relay mode; and distributing downlink transmitted power to all users respectively and distributing transmitted power for each subcarrier. The invention takes that the minimum velocity of all users is maximized by a base station as an aim, and distributes subcarriers to all users; each subcarrier distributed to a user preferentially selects a relay link according to the channel gains and is compared with a direct link to determine which transmission mode is adopted. Finally, total transmission power is distributed to relay and all subcarriers according to a certain way to improve the throughput of the system.

The invention discloses a transmission method for improving the safety achievable speed rate of an analog network coding two-way relay channel. The transmission method comprises the following steps that: an active interference node is injected, wherein the active interference node is used for transmitting an interference signal to prevent an eavesdropper from eavesdropping on a signal, and influence of the interference signal on a legal receiver can be eliminated; in a first time slot, when legal communication nodes transmit respective signals to a relay node, the interference node broadcasts the interference signal at the same time to interfere with eavesdropping of an illegal receiving node; and in a second time slot, the relay node amplifies and forwards superposed signals from the communication nodes and the interface node, the communication nodes eliminate two signals according to the known respective signals and the interference signal which is received in the first time slot to obtain the signal of an opposite side, and the eavesdropper cannot eliminate the interference signal completely. The method has the advantage that: by injecting the active coordinated interference node, the aims of preventing the eavesdropper from eavesdropping on the signal and effectively improving the safety achievable speed rate of a system are fulfilled.

An OFDM-based relay-assisted channel estimation method enables a composite channel (source-relay-destination) to be disintegrated into a source-to-relay channel and a relay-to-destination channel and separately estimated at the destination node in a relay-assisted way. A relay-amble signal is added to a sub-frame when the relay node is forwarding the amplified signals from the source node. Through the relay-amble signal, the second channel estimation from the relay node to the destination node is performed to obtain a second channel coefficient, and then uses an ML (Maximum Likelihood Estimator) algorithm to estimate a first channel coefficient from the source node to the relay node. After having estimated the coefficients of the two channels, the optimum diversity combining is performed at the destination node to improve accuracy of received data.

A method for selective routing of data transmission between clients is provided to select a better communication channel from a direct P2P channel and a relay channel according to routing hop counts of the pats. The method obtains a first routing hop count from a first client to a second client assuming a direct P2P channel therebetween, a second routing hop count from the first client to a relay server assuming a relay channel through the relay server, and a third routing hop count from the relay server two the second client assuming the relay channel through the relay server, and compares the sum of the second routing hop count and the third routing hop count with the first routing hop count. The method then selects a better data transmission channel from the direct P2P channel and the relay channel between the first client and the second client based on a comparison result. Also disclosed is a system using the method for selective routing.

The invention provides a multi-antenna two-way relaying compressing-forwarding method based on joint eigen-decomposition. A Lagrange optimization method is adopted. Firstly, a Lagrange function is written, and then a KKT (Karush Kuhn-Tucker) condition is used for performing resolution. The method is based on energy concentration and optimal characteristics of KKT transform, and joint approximate eigenvalue diversity is adopted. The aim is to decompose a plurality of matrixes at the same time with the same unitary matrix. A relay node is used for performing KLT transform on a received signal firstly, and performing vector quantization. The basic thought is to integrally quantize a vector consisting of a plurality of scalar data in a vector space, so that data is compressed, and information loss is reduced as much as possible. Through adoption of the Lagrange optimization method, an optimal compression noise vector, increase and rate are obtained. The invention substantially aims to allocate low-power quantization noise to channels with good channel conditions. Through adoption of an improved compressing-forwarding method, the system rate performance can be improved. In an asymmetrical two-way relaying channel, the advantage of enhancing the rate performance becomes more outstanding.