Capacity scaling laws in asynchronous relay networks

Authors

Rohit U. Nabar and Helmut Bölcskei

Reference

Allerton Conference on Communication, Control, and Computing, Monticello, IL, pp. 502-511, Oct. 2004, (invited paper).

[BibTeX, LaTeX, and HTML Reference]

Abstract

This paper examines capacity scaling in asynchronous relay networks, where L single-antenna source-destination terminal pairs communicate concurrently through a common set of K single-antenna relay terminals using one-hop relaying. In the perfectly synchronized case, assuming perfect channel state information (CSI) at the relays, the network capacity is known [1] to scale (asymptotically in K for fixed L) as C = (L/2)log(K) + O(1). In the absence of CSI at the relay terminals, it was shown in [1] that a simple amplify-and-forward architecture, asymptotically in K for fixed L, turns the network into a point-to-point multiple-input multiple-output (MIMO) link with high-SNR capacity C = (L/2)log(SNR)+O(1). In this paper, we demonstrate that lack of synchronization in the network, under quite general conditions on the synchronization error characteristics, leaves the capacity scaling laws for both scenarios fundamentally unchanged. However, synchronization errors do result in a reduction of the spatial multiplexing gain (pre-log in the capacity expression) and the effective signal-to-noise ratio at the destination terminals. Quantitative results for these losses, as a function of the synchronization error characteristics, are provided.

Keywords

Wireless networks, relay networks, capacity scaling

Download this document:

This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.