Optimisation of power allocation for asymmetric relay placement in multi‐hop relay systems

Abstract

In this study, schemes for optimisation of power allocation (OPA) for asymmetric relay placement are presented for multi-hop communication in a Rayleigh-fading environment. For a decode-and-forward (DF) multi-hop communication system, expressions are derived for optimised power allocation based on symbol error probability (SEP) and global channel state information (GCSI). The analysis for OPA based on GCSI is extended to a hybrid combination of amplify-and-forward (AF) and DF relays. Analysis is done for two kinds of modulation schemes: M-ary phase-shift keying with coherent detection and orthogonal M-ary frequency-shift keying with non-coherent detection. Simulation results show that for a multi-hop system with asymmetric relay placement, power optimisation schemes perform better than the conventional equal power allocation scheme. In addition, power optimisation based on GCSI shows substantially improved performance compared with power allocation based on end-to-end SEP. Further, performance comparison is shown for increase in number of relay nodes in an AF and DF multi-hop system with and without power allocation. The performance of a DF system improves with increase in number of relay nodes whereas performance of an AF system degrades. Hybrid relaying provides an option to exercise switching between DF and AF so as to extract the maximum advantage of the two relaying schemes.

Joint Power Allocation and Path Selection for Multi-Hop Noncoherent Decode and Forward UWB Communications

“…It has to be noted that, although the JPAPS requires a much lower computational load (and the AJPAPS even less), it outperforms the DF-CR-EP by 1.5 dB (1 dB) for NC1 (NC2), and it incurs in a negligible 0.4 dB loss compared to the DF-CR-OP in which the PA coefficients are found by an exhaustive search, i.e., performing the transmission for each possible couple of power coefficients (with a fixed step size) and then selecting the one that minimizes the BER. In addition, remark that, even if in general the AF schemes amplify also the noise along with signal and, therefore, are outperformed by the DF relaying systems [30], the AF-CR-OP yields better results than the DF-NCR-EP and the DF-CR-EP due to its different encoding and power allocation strategy.…”

“…III-C, wherein the possible paths are the direct P(S, D) (P = 0) and the relayed one P(S, R, D) (P = 1). From ( 22) and ( 24), the metric (26) evaluated for the relayed path amounts to (30) whereas that for the direct one is…”

Optimization of Resource Allocation in Multihop HARQ Relay Networks with a Delay Constraint

“…In particular, the joint optimization of power allocation (OPA) and relay placement (ORP) is presented for multihop communication in a Rayleigh-fading environment in [1]. The distance-dependent route selection problem is approached from the viewpoint of energy efficiency in [2].…”

A Network Coding for Multi-Hop Ship-to-Ship Communications

“…-홉 해상 통신 시스템. (amplify-and-forward) 또는 복호-후-전달(decodeand-forward) 방식을 기반으로 한 단방향 통신에 집중 되었다 [6][7][8][9] . 그러나 이러한 단방향 다중-홉 릴레이 방 식은 릴레이 전송 시 시간 슬롯이 추가로 소요되기 때 문에 주파수 효율이 저하되는 문제가 발생한다.…”