Abstract-We investigate the impact of time diversity and space-time diversity schemes on the traffic capacity of large-scale wireless networks with low-cost radios. Especially, we analyze the tradeoff between relaying gain and increased interference due to additional traffic. The results of a simulation-based study imply that cooperative relaying with selection combining shows benefits for low interference scenarios. For high traffic, however, higher-order modulation schemes outperform the investigated cooperative relaying scenario due to lower interference. Index Terms-Cooperative relaying, interference, network capacity, Rayleigh fading. Cooperative relaying is a promising technique to mitigate the negative effects of multipath propagation. It can be applied to both relay-enhanced cellular systems and infrastructureless ad hoc networks. Although the past years have seen a tremendous amount of research in this area [1], the majority of work was limited to scenarios with at most four nodes. Questions regarding impact and requirements of cooperative relaying in large networks have not been addressed sufficiently. Our goal is to evaluate cooperative relaying from a networking perspective and address questions such as: What is the impact of cooperative relaying on the overall network performance? From a physical layer perspective, cooperative relaying can increase the point-to-point throughput between two nodes. If we consider, however, a network of many nodes, these gains do not come for free. From a network perspective, the relay transmissions cause additional interference to adjacent nodes. Assuming low-cost radios, which have neither MIMO nor sophisticated combining techniques, this additional interference reduces the spatial reuse of radio resources in interferencelimited networks. The goal of this paper is to analyze the network traffic capacity (in terms of subsequent transmissions) if cooperative relaying is used and the node density is high. We compare conventional direct transmission, time-diversity direct transmission, and cooperative relaying by simulations in a Rayleigh block fading channel. In particular, we investigate the tradeoff between exploiting diversity and additional interference caused by this diversity. The paper is structured as follows: Section II defines the modeling assumptions and explains the transmission methods. Section III contains the setup and the results of the performance evaluation. Next, Section IV covers related work. Finally, Section V concludes.
Reference REF investigates the impact of time diversity and space-time diversity schemes on the traffic capacity of large-scale wireless networks with low-cost radios and analyzes the tradeoff between relaying gain and increased interference due to additional traffic.
Diversity schemes in interference-limited wireless networks with low-cost radios
2011 IEEE Wireless Communications and Networking Conference
2011 IEEE Wireless Communications and Networking Conference
Computer Science