Resource allocation for cooperative transmission in wireless networks with orthogonal users

Abstract

Abstract-This paper investigates the problem of efficient power allocation in a wireless communication system with two cooperating sources and one destination. The sources in the system each transmit information to a single destination at a fixed SNR target and cooperate via an orthogonal amplify-andforward protocol with two timeslots. We develop a framework for power allocation in this scenario around the concept of "cooperation ratios" and derive expressions for the transmit power required by each source to achieve their SNR targets as a function of these cooperation ratios. Numerical examples are presented for time-invariant channels as well as Rayleigh fading channels. Our results show that cooperation does not reduce required transmit powers when both sources have symmetric time-invariant channels to the destination. When sources have asymmetric time-invariant channels to the destination, total power is minimized when only the source with the stronger channel cooperates. In the case of Rayleigh fading channels, we demonstrate that mutual cooperation can minimize the average total required transmit power and can also lead to a reduction in average required transmit power for both sources.

Distributed power allocation strategies for parallel relay networks

“…In the subsequent time slots following the first one, the relays that belong to the set of reliable relays, A R , can decode and forward the source data to the destination, each in its assigned time slot. Throughout this paper, we assume that the reliable relays simply regenerate the source data X o [4], [13], [15]. The signal received at the destination from the reliable relay i is…”

“…Optimum power allocation strategies for relay networks are studied up-todate for several structures and relay transmission schemes. Three-node models are discussed in [12] and [13], while multi-hop relay networks are studied in [14]- [16]. Relay forwarding strategies for both AF and DF parallel relay channels in wideband regime are proposed in [17].…”

Power Allocation and Hybrid Relaying Strategies for F/TDMA Ad Hoc Networks

“…• Regenerative Decode-and-Forward (RDF): When the transmission from the source node is received reliably at the relay node, the relay node decodes the signal, reencodes it with the same codebook used in the original source node's transmission and transmits the signal in the second channel of the source node [5], [9], [10].…”

“…Hence, power efficiency is a critical concern when designing relay transmission strategies. It has been shown that significant performance improvement is achieved by the optimum power allocation for various relay assisted networks with single source destination pair [7], [9]- [11].…”

“…In such a scenario, the total relay power should be allocated between the transmissions of information from the sources that relay over this node, in order to obtain the best performance. The optimum power allocation for the relay nodes is studied for single source-destination pair in [7], [9]. In [17], the power allocation problem for the relay nodes in F/TDMA ad hoc networks is investigated for the case when each relay node assists the sources via the same relaying strategy.…”