Conference Paper

Beamforming for Space Division Duplexing

Dept. of Electr. & Comput. Eng., Univ. of Alberta, Edmonton, AB, Canada
DOI: 10.1109/icc.2011.5962761 Conference: Communications (ICC), 2011 IEEE International Conference on
Source: IEEE Xplore


This paper examines space division duplexing (SDD) in multiple-input multiple-output (MIMO) systems. The antennas each full-duplex node has are partitioned to form two antenna banks - one for transmission, the other for reception. Self-interference is avoided at each full-duplex node by utilizing the nullspace (or the left nullspace) of corresponding self-interference channel for transmission (or reception). Simulation results are provided on the error performance. Useful insights are obtained on the effects finite precision arithmetic, and quantization errors have on the feasibility of SDD.

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    • "This progressive physical/linklayer frequency-reuse concept can render up to double spectral efficiency at system level at the cost of a significant technical challenge: self-interference mitigation [2]. In particular, this paper focuses on bidirectional links [3]–[5], where two full-duplex transceivers communicate with each other, and the numerical results assume a symmetric setup where the two transceivers are equivalent and channels are reciprocal. "
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    ABSTRACT: In this paper, the performance of cochannel full-duplex multiple-input multiple-output (MIMO) nodes is considered in the context of models for realistic hardware characteristics. Here, cochannel full-duplex relay indicates a node that transmits and receives simultaneously in the same frequency band. It is assumed that transmit and receive phase centers are physically distinct, enabling adaptive spatial transmit and receive processing to mitigate self-interference. The use of MIMO indicates a self-interference channel with spatially diverse inputs and outputs, although multiple modes are not employed in this paper. Rather, we focus on rank-1 transmit covariance matrices. In practice, the limiting issue for cochannel full-duplex nodes is the ability to mitigate self-interference. While theoretically a system with infinite dynamic range and exact channel estimation can mitigate the self-interference perfectly, in practice, transmitter and receiver dynamic range, nonlinearities, and noise, as well as channel dynamics, limit the practical performance. In this paper, we investigate self-interference mitigation limitations in the context of eigenvalue spread of spatial transmit and receive covariance matrices caused by realistic hardware models.
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