Design and Application of MIMO Relay Station in Broadcast Channel
Date Issued
2013
Date
2013
Author(s)
Chien, Chun-Che
Abstract
Nowadays, the demand for high throughput of wireless mobile communication systems has arouse widespread of multi-input-multi-output (MIMO) technologies. It is well known that with the deployment of multiple antennas at wireless terminals, capacity enhancement as well as robustness against channel fading or interference avoidance can be achieved. In the meanwhile, in order to enhance the cell-edge users'' throughput, the deployment of relay stations has been a promising scheme which can prevent the wired backhaul costs. Both techniques have been adopted in several wireless cellular standards such as 3GPP LTE or IEEE802.16 WMAN. In order to exploit the benefits of above two techniques, a compound scheme that incorporates MIMO technology into the relay architecture has been proposed and is the main focus of this thesis. The MIMO relay station could be two types, which are the fixed relay station placing at some specific location for filling in the coverage hole, and the mobile relay station which is also a function of users’ mobile device , it can support the receiving of other mobile stations. Both types of relay stations will be analyzed in the cellular systems in this dissertation.
For fixed MIMO relay station, a system design of MIMO broadcast relay channel based on individual signal-to-interference-plus-noise ratio (SINR) constraints at the mobile stations (MS) is considered. By exploring the structure of downlink-uplink duality at either the base station (BS) or the relay station (RS), we propose two schemes of joint power allocation and beamforming design at the BS and the RS. The problem of existence of feasible solutions under practical power constraints at the BS and the RS with given SINR targets is considered first. Then the problem of sum power minimization is considered. Each design problem can be solved efficiently using optimal joint power allocation and beamforming under the framework of convex optimization. We also show the benefit of subchannel pairing at the RS and generalize the problem to multi-hop scenario in order to further improve the power efficiency.
Different design strategy is adopted for the mobile MIMO relay system. The multi-hop relay links between each user pair form consecutive Device-to-Device (D2D) links, and this structure can be regarded as multiple D2D communications under the cellular system. Due to the flexibility of routing path selection in this D2D enabled system, two spectrally efficient as well as outage tolerant multi-hop protocols are proposed. In the first protocol, a user forwards its own data stream after decoding, then interference cancellation is performed at each receiving node to eliminate the interference from this user. In the second protocol, a user decodes and cancels its own signal from the received vector and forwards the remaining signal. The receiving nodes decode their own streams by jointly considering the previous received vectors. The receive diversity as well as selection diversity of each protocol is analyzed in each additional hop.
The background or preliminaries of associated technologies are provided before entering each research topic. Comparisons of proposed schemes in terms of performance evaluation and complexity calculation show the benefits over traditional schemes. Finally, some future research directions to complete or extend the research results are provided in the conclusion part.
Subjects
多輸入多輸出系統
中繼器
廣播通道
功率控制
波束合成
最佳化設計
裝置對裝置通訊
中斷機率
Type
thesis
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