Mitigation of Loopback Self-Interference in Full-Duplex MIMO Relays
Mitigation of Loopback Self-Interference in Full-Duplex MIMO Relays
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DOI：
10.1109/tsp.2011.2164910
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发表时间：
2011-12
影响因子：
5.4
通讯作者：
T. Riihonen;S. Werner;R. Wichman
中科院分区：
文献类型：
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作者：
T. Riihonen;S. Werner;R. Wichman
全双工中继比半双工中继在频谱上更有效，因为每两跳仅需要使用一个信道。然而，最小化中继自干扰以使全双工可行至关重要。为此，我们分析了广泛的多输入多输出（MIMO）缓解方案：自然隔离，时域消除和空间抑制。消除从中继输入中减去复制的干扰信号，而抑制保留用于接收和发送滤波的空间维度。空间抑制可以通过天线子集选择、零空间投影，即，在正交子空间中接收和发送，或者通过选择重叠子空间的最小本征模来进行联合发送和接收波束选择以支持更多的空间流。此外，可以采用最小均方误差（MMSE）滤波来保持期望的信号质量，这对于消除是固有的，并且时域和空域处理的组合可以比单独的任一个更好。以干扰功率最小为目标，分别求解了联合设计、分离设计和独立设计三种情况下每种方案的最优滤波器。通过仿真对各种减缓方案的性能进行了评价和比较。结果表明，自干扰也可以有效地减轻存在不完美的边信息。
Full-duplex relaying is more spectrally efficient than half-duplex relaying as only one channel use is needed per two hops. However, it is crucial to minimize relay self-interference to render full duplex feasible. For this purpose, we analyze a broad range of multiple-input multiple-output (MIMO) mitigation schemes: natural isolation, time-domain cancellation, and spatial suppression. Cancellation subtracts replicated interference signal from the relay input while suppression reserves spatial dimensions for receive and transmit filtering. Spatial suppression can be achieved by antenna subset selection, null-space projection, i.e., receiving and transmitting in orthogonal subspaces, or joint transmit and receive beam selection to support more spatial streams by choosing the minimum eigenmodes for overlapping subspaces. In addition, minimum mean square error (MMSE) filtering can be employed to maintain the desired signal quality, which is inherent for cancellation, and the combination of time- and spatial-domain processing may be better than either alone. Targeting at minimal interference power, we solve optimal filters for each scheme in the cases of joint, separate and independent design. The performance of mitigation schemes is evaluated and compared by simulations. The results confirm that self-interference can be mitigated effectively also in the presence of imperfect side information.