Opportunistic Relaying in Wireless Networks

Abstract

Relay networks having $n$ source-to-destination pairs and $m$ half-duplex relays, all operating in the same frequency band in the presence of block fading, are analyzed. This setup has attracted significant attention and several relaying protocols have been reported in the literature. However, most of the proposed solutions require either centrally coordinated scheduling or detailed channel state information (CSI) at the transmitter side. Here, an opportunistic relaying scheme is proposed, which alleviates these limitations. The scheme entails a two-hop communication protocol, in which sources communicate with destinations only through half-duplex relays. The key idea is to schedule at each hop only a subset of nodes that can benefit from \emph{multiuser diversity}. To select the source and destination nodes for each hop, it requires only CSI at receivers (relays for the first hop, and destination nodes for the second hop) and an integer-value CSI feedback to the transmitters. For the case when $n$ is large and $m$ is fixed, it is shown that the proposed scheme achieves a system throughput of $m/2$ bits/s/Hz. In contrast, the information-theoretic upper bound of $(m/2)\log \log n$ bits/s/Hz is achievable only with more demanding CSI assumptions and cooperation between the relays. Furthermore, it is shown that, under the condition that the product of block duration and system bandwidth scales faster than $\log n$, the achievable throughput of the proposed scheme scales as $\Theta (\log n)$. Notably, this is proven to be the optimal throughput scaling even if centralized scheduling is allowed, thus proving the optimality of the proposed scheme in the scaling law sense.

17 pages, 8 figures, To appear in IEEE Transactions on Information Theory

References in corpus (3)

• A Simple Cooperative Diversity Method Based on Network Path Selection
• Crystallization in large wireless networks
• Throughput Scaling of Wireless Networks With Random Connections

Cited by in corpus (13)

• Opportunistic Interference Mitigation Achieves Optimal Degrees-of-Freedom in Wireless Multi-cell Uplink Networks
• Parallel Opportunistic Routing in Wireless Networks
• Achievable Rates for the Fading Half-Duplex Single Relay Selection Network Using Buffer-Aided Relaying
• Can One Achieve Multiuser Diversity in Uplink Multi-Cell Networks?
• Opportunistic Network Decoupling With Virtual Full-Duplex Operation in Multi-Source Interfering Relay Networks
• Throughput Scaling of Wireless Networks With Random Connections
• Throughput of Large One-hop Wireless Networks with General Fading
• On the Impact of Relay-side Channel State Information on Opportunistic Relaying
• Decentralized Two-Hop Opportunistic Relaying With Limited Channel State Information
• Power Allocation Strategies across N Orthogonal Channels at Both Source and Relay
• Caching Gain in Wireless Networks with Fading: A Multi-User Diversity Perspective
• Multi-Stream Opportunistic Network Decoupling: Relay Selection and Interference Management
• Analysis of Uncoordinated Opportunistic Two-Hop Wireless Ad Hoc Systems