A Stationary Converging Self Interference Mitigating Approach for Full-Duplex MIMO Relays

A Stationary Converging Self Interference Mitigating Approach for Full-Duplex MIMO Relays
Authors:REVATHI, V.UMA

Abstract: Relaying is used in wireless communication, relay nodes are using in relaying process. Relay node are receiving the information from source node while transmitting to destination node. Full-duplex relaying is more spectrally efficient than the half-duplex relaying. Multiple users can communicate each other by using MIMO. This work proposes an adaptive method to mitigate the self-interference signal for full-duplex decode-and-forward MIMO relays which is able to track temporal variations of the self-interference channel. This method makes use of signals available at the relay to estimate the self-interference channel in order to cancel it. Further it analyzes the behavior of the algorithm in terms of its stationary points and mean convergence. The proposed cancellation block can be added to a full-duplex relay, if the self-interference is too large in its current operation environment. 

Keywords: Full-Duplex, Regenerative Relaying, Self-Interference, MIMO, Adaptive Filtering. 

INTRODUCTION 

          Full duplex (FD) wireless systems have the potential to double the system spectral efficiency compared to half duplex(HD) systems [1]. The main difficulty in implementing a FD system is that the strong loop-back selfinterference exceeds the limited dynamic range at the receiver. This phenomenonis critical since it saturates the receiver which will not only prevent the correct reception of the desired signal but may also damage the device. Recently, several approaches have been proposed to implement SISO FD transceivers via self-interference cancellation. Most of them involve advanced concepts in both RF transceiver architecture and digital signal processing at the receiver. The simplest approach is to use directional transmit (Tx) and receive (Rx) antennas to decouple the Tx and Rx signals [2]. However, this approach is only suitable when the data source and the data sink are sufficiently separated spatially (probably different devices). In [3], an antenna cancellation approach was proposed, which requires two Tx antennas. By proper position adjustment, the signals of both Tx antennas overlap destructively at the Rx antenna, which leads to a certain degree of self-interference cancellation. This approach can be regarded as a static beam-forming approach and has the drawback that it is only suitable for narrow band transmissions and requires accurate manual tuning of antenna positions.

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