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Cooperative transmission in MIMO relay broadcast channels

Summary

Wireless multiuser communications are suffering from problems of reliability, coverage and spectrum efficiency. Relay broadcast is one of the promising techniques to solve these problems by exploiting the distributed spatial diversity arising from the relay mechanism and the local spatial diversity introduced by the multiple antennas.

The channel capacity of relay broadcast channels has been investigated in literature, which shows a significant improvement over the classical broadcast channels without relay. However, a practical transmission scheme is yet to be invented.

In this project, we design a low-complexity beamforming, relaying and combining scheme for MIMO relay broadcast channels. In the preliminary study, we consider the scenario where one base station (BS) transmits to two mobile stations (MSs), where one of the MSs with strong signal reception and/or processing power can help the other besides receiving its own data. The transmission vector space is partitioned into subspaces to accommodate the transmission from the BS to both MSs and the relaying between MSs. The zero forcing (ZF) criterion is used to avoid interferences among these transmissions. With multiple antennas at both the BS and MSs, and the channel state information (CSI) available (fully or partially) to the relevant parties, the subspace partitioning can be adjusted to optimise the overall system performance. The power allocation between users and relay can also be optimised to improve the performance further. Different levels of CSI availability will be investigated and reduced CSI scheme will be proposed such that the scheme can fit into both TDD and FDD systems. When more than two MSs are involved in the communication scenario, a relay selection algorithm will be developed in such a way the most effective MS is selected to act as the relay.

Supervisor

Professor Branka Vucetic.

Research location

Electrical and Computer Engineering

Program type

PHD

Synopsis

Wireless multiuser communications are suffering from problems of reliability, coverage and spectrum efficiency. Relay broadcast is one of the promising techniques to solve these problems by exploiting the distributed spatial diversity arising from the relay mechanism and the local spatial diversity introduced by the multiple antennas.

The channel capacity of relay broadcast channels has been investigated in literature, which shows a significant improvement over the classical broadcast channels without relay. However, a practical transmission scheme is yet to be invented.

In this project, we design a low-complexity beamforming, relaying and combining scheme for MIMO relay broadcast channels. In the preliminary study, we consider the scenario where one base station (BS) transmits to two mobile stations (MSs), where one of the MSs with strong signal reception and/or processing power can help the other besides receiving its own data. The transmission vector space is partitioned into subspaces to accommodate the transmission from the BS to both MSs and the relaying between MSs. The zero forcing (ZF) criterion is used to avoid interferences among these transmissions. With multiple antennas at both the BS and MSs, and the channel state information (CSI) available (fully or partially) to the relevant parties, the subspace partitioning can be adjusted to optimise the overall system performance. The power allocation between users and relay can also be optimised to improve the performance further. Different levels of CSI availability will be investigated and reduced CSI scheme will be proposed such that the scheme can fit into both TDD and FDD systems. When more than two MSs are involved in the communication scenario, a relay selection algorithm will be developed in such a way the most effective MS is selected to act as the relay.

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Opportunity ID

The opportunity ID for this research opportunity is 648

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