An application method of fdma technology in cooperative retransmission with hidden nodes

Abstract

The invention provides an optimal cooperative retransmission node selection and conflict avoidance scheme based on FDMA (frequency division multiple accesses). In the scheme, a subcarrier which can be exactly divided by 8 in an OFDM (orthogonal frequency division multiplexing) symbol forms an FDMA address, and each cooperative node corresponds to one address; after the cooperative retransmission node receives an NACK frame transmitted by a target node, an FDMA competition frame is generated after the OFDM modulation, the time domain waveform compression and the adding of CP are carried out, and the FDMA competition frame is directly transmitted without resignation; in the OFDM symbol, 1 is filled in the subcarrier corresponding to the node address, and 0 is filled in other subcarriers; after the target node receives a synthesis signal transmitted simultaneously by a candidate node, and after the removal of the CP, the restoration of a compressed waveform and an FFT operation, the module value analysis is carried out on the subcarrier corresponding to the FDMA address, and the node corresponding to the maximal module value is the best cooperative retransmission node; the application is characterized in that the FDMA technology is applied to the competition frame, the cooperative node is unnecessary to withdraw, the time-domain waveform is symmetrically compressed by utilizing the signal, the time cost is small, and the retransmission success rate and the efficiency are high.

Description

Technical field [0001] The present invention relates to the technical field of mobile communication, in particular to an application field of frequency division multiple access (FDMA) technology in cooperative retransmission with hidden nodes. [0002] technical background [0003] When transmitting data in a mobile Ad Hoc network, limited transmission power, user mobility, fading characteristics of the wireless channel, and the presence of interference will cause a high frame error rate. When frame errors and packet loss occur, retransmission is usually used to meet the system's reliability requirements. The traditional retransmission idea is to use forward error correction (FEC) plus automatic retransmission request (ARQ) mechanism. The source node performs the retransmission operation, but when the destination node receives a burst frame error, the source and destination nodes Poor channel conditions may not be able to recover quickly in many cases. At this time, the general FE...

AI Technical Summary

Problems solved by technology

At present, cooperative retransmission is a research hotspot. How to choose the best cooperative retransmission node is the key to the problem. The existing schemes can be roughly divided into two categories: one is based on the idea of ​​time-sharing backoff, based on the fact that the destination node can only be correct at one time. Receive a conflict-free burst frame, so the candidate cooperative retransmission nodes use some backoff scheme and RTS / CTS mechanism to compete for the channel and then perform cooperative retransmission, so this scheme has a large time overhead, cannot solve the problem of hidden nodes, and channel utilization Second, the destination node uses space diversity or code division multiple access technology to separate the conflicting burst frames, and the candidate cooperative retransmission nodes can retransmit the burst frames at the same time without backing off the contention channel

However, in this type of scheme, each candidate cooperative retransmission node has to retransmit the entire burst frame, which consumes a lot of system energy, the algorithm is complex, and the implementation cost is high.

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