Low Complexity Power Allocation Schemes in Regenerative Multi-user Relay Networks

TL;DR

This paper introduces low-complexity power allocation schemes for multi-user relay networks that achieve near-optimal rates using statistical-CSI, significantly reducing computational complexity compared to existing methods.

Contribution

The paper develops two low-complexity power allocation schemes with order O(M log M) complexity for M-1-1 relay systems, close to maximum achievable rate under statistical-CSI.

Findings

Proposed schemes achieve rates close to optimal with much lower complexity.

Complexity reduction from O(M^3) to O(M log M).

Suitable for real-time multi-user relay system implementation.

Abstract

In relay assisted wireless communications, the multi-source, single relay and single destination system (an $M$-1-1 system) is of growing importance, due to the increased demand for higher network throughput and connectivity. Previously, power allocation in $M$-1-1 systems have assumed availability of instantaneous channel state information (CSI), which is rather idealistic. In this paper we consider an $M$-1-1 Decode-and-Forward (DF), Full-Duplex, orthogonal frequencey division multiple access (OFDMA) based relay system with statistical-CSI and analyze the achievable rate $R$ of such a system. We show how $R$ can only be maximized by numerical power allocation schemes which has a high-complexity of order $\mathcal O(M^3)$. By introducing a rational approximation in the achievable rate analysis, we develop two low-complexity power allocation schemes that can obtain a system achievable rate very close to the maximum $R$. Most importantly, we show that the complexity of our power allocation schemes is of order $\mathcal O(M\log M)$. We then show how our power allocation schemes are suitable for a multi-user relay system, where either the priority is to maximize system throughput, or where lower computations in power allocation scheme are essential. The work we present in this paper will be of value to the design and implementation of real-time multi-user relay systems operating under realistic channel conditions.