Relay assisted F/TDMA ad hoc networks: node classification, power allocation and relaying strategies

Abstract

This paper considers the design of relay assisted F/TDMA ad hoc networks with multiple relay nodes each of which assists the transmission of a predefined subset of source nodes to their respective destinations. Considering the sum capacity as the performance metric, we solve the problem of optimally allocating the total power of each relay node between the transmissions it is assisting. We consider four different relay transmission strategies, namely regenerative decode-and-forward (RDF), nonregenerative decode-and-forward (NDF), amplify-and-forward (AF) and compress-and-forward (CF). We first obtain the optimum power allocation policies for the relay nodes that employ a uniform relaying strategy for all nodes. We show that the optimum power allocation for the RDF and NDF cases are modified water-filling solutions. We observe that for a given relay transmit power, NDF always outperforms RDF whereas CF always provides higher sum capacity than AF. When CF and NDF are compared, it is observed that either of CF or NDF may outperform the other in different scenarios. This observation suggests that the sum capacity can be further improved by having each relay adopt its relaying strategy in helping different source nodes. We investigate this problem next and determine the optimum power allocation and relaying strategy for each source node that relay nodes assist. We observe that optimum power allocation for relay nodes with hybrid relaying strategies provides higher sum capacity than pure RDF, NDF, AF or CF relaying strategies. Index TermsRelay power allocation, Decode-and-Forward, Amplify/Compress-and-Forward, Sum capacity. † Semih Serbetli is with

Fading Multiple Access Relay Channels: Achievable Rates and Opportunistic Scheduling

“…Such models have been considered for the MARC in [10] and, in general, for multiterminal relay networks in [21] and [23].…”

“…Resource allocation in multi-user relay networks has been studied recently in [21]- [23]. The authors in [21] and [23] consider a specific orthogonal model in which the sources time-duplex their transmissions and are aided in their transmissions by a half-duplex relay, while in [22] the optimal multi-user scheduling policy is determined under the assumption of a nonfading backhaul channel between the relay and destination.…”

“…The authors in [21] and [23] consider a specific orthogonal model in which the sources time-duplex their transmissions and are aided in their transmissions by a half-duplex relay, while in [22] the optimal multi-user scheduling policy is determined under the assumption of a nonfading backhaul channel between the relay and destination. In contrast, in this paper, we consider a more general multi-access channel with a half-duplex (orthogonal) relay and model all internode wireless links as ergodic fading channels with perfect channel state information available at all nodes.…”

Joint bandwidth and power allocation in wireless multi-user decode-and-forward relay networks

“…Power allocation aiming at optimizing the sum capacity of multiple users for four different relay transmission strategies has been studied in [31], while an AF based strategy in which multiple sources share multiple relays using power control has been developed in [32], [33].…”

“…System throughput maximization and the worst user throughput maximization are studied using convex optimization in [15]. Sum capacity maximization is taken as an objective for power allocation in [31], while max-min SNR, power minimization, and throughput maximization are used as power allocation criteria in [32].…”