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Research On Beamforming Related Technologies For Multi-Source Multi-Destination System

Posted on:2016-07-05Degree:DoctorType:Dissertation
Country:ChinaCandidate:W P JiangFull Text:PDF
GTID:1108330482957838Subject:Signal and Information Processing
Abstract/Summary:PDF Full Text Request
In modern communication scenario, information exchange happens in multiple communication standards, multiple cells and multiple users simultaneously. With the emergence of new technology, the system transmission model has changed from single source single destination (such as point-to-point transmission), single source multiple destinations (such as broad cast and multicast transmission) to coordinated transmission like multiple sources single destination (such as coordinated relay communication, where relay is treated as a forward source), and multiple sources multiple destinations (such as multiple cells multiple users communication and communication of X channel). Therefore, research on beamforming related technologies for multi-source multi-destination system needs to be studied. In this paper, we investigate the communication scenarios of multiple sources single destination and multiple sources multiple destinations. In multiple sources single destination system, we focus on coordinated relay communication, while in multiple sources multiple destinations system, the study is based on interference alignment technology. The main contribution of this paper can be summarized as follows:(1) We jointly optimize the source transmitting matrix, the relay precoding matrix and the receive matrix for two-hop MIMO relay systems with the direct source destination link and imperfect CSI. We have developed two iterative algorithms to design the statistically robust source and relay matrices for the commonly used MMSE criterion. We obtain locally optimal solutions to the original optimization problem by converting it to an equivalent nonrobust MIMO relay design problem with equivalent channel, source, relay, and receiver matrices. Simulation results show an improved robustness of the proposed algorithms against CSI mismatch compared with existing approaches.(2) We investigate the optimal source, relay, and receiver matrices design for AF multiuser MIMO relay communication systems when the source-destination links are considered. The evolved Tri-Step method and Bi-Step method are derived for the new system model to exploit the spatial diversity gain brought by the source-destination links. The optimal source, relay and receiver matrices taking into consideration of the direct links are obtained. From the theoretical derivation of MSE of the signal waveform estimation at the destination node, we show that the existence of the source-destination links bring benefits no matter how weak they are. Numerical examples demonstrate that the proposed algorithms perform much better than the existing ones in terms of both MSE and BER.(3) We propose an opportunistic scheduling method to achieve DoF gain by user and channel resource scheduling to form a 2-user 2×1 BIA in the setting of two-source two-destination X channel. The feasibility of our optimistic scheduling method found according to the analytical solution of a linear integer program problem is proved. All the users can form a 2-user 2×1 complete or partial BIA pair. With all the user pairs round-robin scheduled, each user has the same opportunity for transmitting. The achieved DoF expectation using our scheduling method is given, which shows that when K≥10, it can be very close to 4/3 in a setting K-user 2×1 broadcast or X channel.(4) We propose an iterative transceiver design and user scheduling algorithm which further digs into the multiuser diversity. The proposed algorithm is a SLNR-SINR bi-criteria combined iteration algorithm, which jointly optimizes the transmit beamforming vectors, the receive matrices and the user selection set. Although iteration is needed between the users and the BSs, no extra processing delay is introduced. The optimization results in each iteration can be used for the transmission of the next iteration, which is important for practical applications. Simulation results show performance gains to the conventional algorithms.
Keywords/Search Tags:multi-source multi-destination, beamforming, amplify and forward, relay, multiple users, blind interference alignment, opportunistic interference alignment, user scheduling
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