Distributed Antenna Channels with Regenerative Relaying: Relay Selection and Asymptotic Capacity
- PDF / 540,767 Bytes
- 12 Pages / 600.05 x 792 pts Page_size
- 64 Downloads / 166 Views
Research Article Distributed Antenna Channels with Regenerative Relaying: Relay Selection and Asymptotic Capacity Aitor del Coso and Christian Ibars Centre Tecnol`ogic de Telecomunicacions de Catalunya (CTTC), Av. Canal Ol`ımpic, Castelldefels, Spain Received 15 November 2006; Accepted 3 September 2007 Recommended by Monica Navarro Multiple-input-multiple-output (MIMO) techniques have been widely proposed as a means to improve capacity and reliability of wireless channels, and have become the most promising technology for next generation networks. However, their practical deployment in current wireless devices is severely affected by antenna correlation, which reduces their impact on performance. One approach to solve this limitation is relaying diversity. In relay channels, a set of N wireless nodes aids a source-destination communication by relaying the source data, thus creating a distributed antenna array with uncorrelated path gains. In this paper, we study this multiple relay channel (MRC) following a decode-and-forward (D&F) strategy (i.e., regenerative forwarding), and derive its achievable rate under AWGN. A half-duplex constraint on relays is assumed, as well as distributed channel knowledge at both transmitter and receiver sides of the communication. For this channel, we obtain the optimum relay selection algorithm and the optimum power allocation within the network so that the transmission rate is maximized. Likewise, we bound the ergodic performance of the achievable rate and derive its asymptotic behavior in the number of relays. Results show that the achievable rate of regenerative MRC grows as the logarithm of the Lambert W function of the total number of relays, that is, C = log2 (W0 (N)). Therefore, D&F relaying, cannot achieve the capacity of actual MISO channels. Copyright © 2007 A. del Coso and C. Ibars. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1.
INTRODUCTION
Current wireless applications demand an ever-increasing transmission capacity and highly reliable communications. Voice transmission, video broadcasting, and web browsing require wire-like channel conditions that the wireless medium still cannot support. In particular, channel impairments, namely, path loss and multipath fading do not allow wireless channels to reach the necessary rate and robustness expected for next generation systems. Recently, a wide range of multiple antenna techniques have been proposed to overcome these channel limitations [1–4]; however, the deployment of multiple transmit and/or receive antennas on the wireless nodes is not always possible or worthwhile. For these cases, the most suitable technique to take advantage of spatial diversity is node cooperation and relay channels [5, 6]. Relay channels consist of single source-destination pairs aided in their communications by a set of wireless relay nodes that creates a distributed antenna arra
Data Loading...
