Instantaneous Relaying: Optimal Strategies and Interference Neutralization

Abstract

In a multi-user wireless network equipped with multiple relay nodes, some relays are more intelligent than other relay nodes. The intelligent relays are able to gather channel state information, perform linear processing and forward signals whereas the dumb relays is only able to serve as amplifiers. As the dumb relays are oblivious to the source and destination nodes, the wireless network can be modeled as a relay network with smart instantaneous relay only: the signals of sourcedestination arrive at the same time as source-relay-destination. Recently, instantaneous relaying is shown to improve the degrees-of-freedom of the network as compared to classical cut-set bound.In this paper, we study an achievable rate region and its boundary of the instantaneous interference relay channel in the scenario of (a) uninformed non-cooperative source-destination nodes (source and destination nodes are not aware of the existence of the relay and are non-cooperative) and (b) informed and cooperative source-destination nodes. Further, we examine the performance of interference neutralization: a relay strategy which is able to cancel interference signals at each destination node in the air. We observe that interference neutralization, although promise to achieve desired degrees-of-freedom, may not be feasible if relay has limited power. Simulation results show that the optimal relay strategies improve the achievable rate region and provide better user-fairness in both uninformed non-cooperative and informed cooperative scenarios 1 . Index TermsThis work has been performed in the framework of the European research project SAPHYRE, which is partly funded by the European Union under its FP7 ICT Objective 1.1 -The Network of the Future.1 Part of this work is submitted to ISIT 2012 [1].

Instantaneous Relaying: Feasibility Conditions for Interference Neutralization

“…The practical motivation of the instantaneous relay can be found in [5]. In [6], the authors considered a SISO interference relay channel (IRC) and derived the achievable rate region. But the DoF gain in a MIMO IRC with arbitrary number of antennas at the relay remains unknown.…”

Interference Neutralization and Alignment in Cognitive Relay Assisted 3-User Interference Channels

“…In [7], relay is utilized to neutralize the interference and the achievable rate region is studied. However, interference alignment is not considered in [7].…”

“…In [7], relay is utilized to neutralize the interference and the achievable rate region is studied. However, interference alignment is not considered in [7]. [8] and [9] only study relay-aided single input single output (SISO) system.…”

Efficient information leakage neutralization on a relay-assisted multi-carrier interference channel

“…This method is adopted from a technique on relay networks, termed as interference neutralization (IN). IN has been applied to eliminate interference in various systems [13,18,19] including instantaneous relay channels [20]. Our prior work shows that IN is effective in improving secrecy rates in a two-hop wiretap channel [21].…”