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Distributed Cooperative Spatial Multiplexing System

Xie, Nian (2014) Distributed Cooperative Spatial Multiplexing System. PhD thesis, University of York.

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Abstract

Multiple-Input-Multiple-Output (MIMO) spatial multiplexing systems can increase the spectral efficiency manyfold, without extra bandwidth or transmit power, however these advantages are based on the assumption that channels between different transmit antenna and receive antenna are independent which requires the elements in antenna array be separated by several wavelengths. For small mobile devices, the requirement is difficult to implement in practice. Cooperative spatial multiplexing (C-SM) system provides a solution: it organizes antennas on distributed mobile stations to form a virtual antenna array (VAA) to support spatial multiplexing. In this thesis, we propose a novel C-SM system design which includes a transmitter with two antennas, a single antenna receiver and a relay group with two single antenna relays. In this design, we assume that the transmitter tries to transmit two coded independent messages to the receiver simultaneously but the transmitter-receiver link is too weak to support the transmission. Thus a relay group is introduced to help with the transmission. After relays receive the messages from the transmitter via a $2\times 2$ MIMO link, they first detect and quantize the received messages, then compress them independently according to the Slepian and Wolf theorem, the compressed messages are sent to the receiver simultaneously where de-compression and de-quantization are performed on the received messages. After that the resulting messages are combined to estimate the original coded messages. The estimated coded messages are decoded to produce the original messages. The basic system structure is studied and an analytical bit error rate expression is derived. Several transmission protocols are also introduced to enhance the system BER performance. The merit of this design is focus on the relay destination link. Because the Slepian and Wolf theorem is applied on the relay-destination link, messages at the relays can be compressed independently and de-compressed jointly at the receiver with arbitrarily small error probability but still achieve the same compression rate as a joint compression scheme does. The Slepian and Wolf theorem is implemented by a joint source-channel code in this thesis. Several schemes are introduced and tested, the testing results and performance analysis are given in this thesis. According to the chief executive officer (CEO) problem in the network information theory, we discover an error floor in this design. An analytical expression for this error floor is derived. A feedback link is also introduced from the receiver to the relays to allow the relays to cooperatively adapt their compression rates to the qualities of the received messages. Two combination schemes at the receiver are introduced, their performances are examined from the information theory point of view, the results and performance analysis are given in this thesis. As we assume that the relay destination link is a multiple access channel (MAC) suffers from block Rayleigh fading and white Gaussian noise, the relationship between the MAC channel capacity and the Slepian and Wolf compression rate region is studied to analyse the system performance.

Item Type: Thesis (PhD)
Academic Units: The University of York > Electronics (York)
Identification Number/EthosID: uk.bl.ethos.632978
Depositing User: Mr Nian Xie
Date Deposited: 14 Jan 2015 12:40
Last Modified: 08 Sep 2016 13:32
URI: http://etheses.whiterose.ac.uk/id/eprint/7650

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