Power allocation and relay selection for AF two-path successive relaying networks

Abstract

Two‐path or successive relaying, which aims to establish two relay links transmitting different information symbols in adjacent time slots, has recently emerged as an attractive wireless communication protocol to improve the spectral efficiency in half‐duplex cooperative systems. In this paper, we investigate power allocation and relay selection techniques for amplify‐and‐forward two‐path successive relaying networks. Our approach is based on the maximization of the received SNR subject to a total power budget consumed by the source and the relay assisting this specific transmission. Two scenarios including with and without direct link are considered here. We show that the main problem has a closed‐form solution and only requires a few amounts of feedback bits to be broadcasted. Numerical results reveal that the proposed approaches are more insensitive to the inter‐relay interference and robust to channel estimation errors; meanwhile, they perform better than the existing schemes. Copyright © 2013 John Wiley & Sons, Ltd.

Rate Maximization Based Power Allocation and Relay Selection With IRI Consideration for Two-Path AF Relaying

“…Recent works in [16], [17] considered the IRI cancellation proposed in [14] in the two-path relay scheme and tried to further improve the performance by adopting power allocation or relay selection. Chu et al [16] proposed a power allocation method in order to minimize the symbol error rate with partial channel state information (CSI) at the source.…”

“…However, this approach may not be optimal in a typical/practical environment where the channel power gains of different links are often different. Meanwhile, in order to improve the achievable rate, Zhang et al [17] proposed a power allocation and relay selection algorithm for the two-path relay scheme when perfect CSI is available at the source. The authors in [17] considered the signal-tointerference-plus-noise ratio (SINR) of a single source-relaydestination path as their objective function while the amount of IRI is determined in the power allocation problem of previous time slot.…”

“…Meanwhile, in order to improve the achievable rate, Zhang et al [17] proposed a power allocation and relay selection algorithm for the two-path relay scheme when perfect CSI is available at the source. The authors in [17] considered the signal-tointerference-plus-noise ratio (SINR) of a single source-relaydestination path as their objective function while the amount of IRI is determined in the power allocation problem of previous time slot. As IRI cannot be controlled in this formulation, the corresponding results may be inefficient in the cases with nonnegligible IRI.…”

“…While individual power constraint represents the typical situation in practice, global power constraint can be used as a reference on the transmission power required per source-destination link for performance comparison of the two-path relay and direct point-to-point networks [18], [19]. Note that only global power constraint is considered in [16], [17].…”

“…1) Algorithm to find the global optimal solution: The problem (17) can be solved by a method similar to the one used to solve problem (11). Problem (17) is also non-convex [22].…”