| In cooperative systems, a collection of simple, single-antenna, nodes transmit jointly as a virtual antenna array to obtain the diversity benefits of a complex antenna array without adding more antennas at individual nodes. Several relay management strategies have been proposed in the past few years with most of the effort focused on evaluating decode-and-forward strategies using distributed space-time block codes. To achieve full spatial diversity, these schemes have generally required some global information and some communications among the potential relay nodes, such as the assignment of the antenna index (i.e., the column of the code matrix), as well as the number of nodes that will actually relay the source information.
In this paper, we evaluate the performance of several schemes which require minimal amounts of communication among relaying nodes and no global channel state information. In particular, we consider a distributed space-time block code with several approaches for assigning the appropriate antenna index to individual nodes for transmission. In the first approach, a unique antenna index is assigned to each node in the network at deployment. In an alternative approach, proposed by Luo, et al, each cooperating node randomly, and independently of other nodes, selects one column of the preselected code; this is termed the m-group relay strategy. Finally, in a generalization of m-group, proposed by Sirkeci-Mergen and Scaglione, individual relaying nodes use a random linear combination of the columns of the preselected code. Here, the probability of outage and the link-failure probability of each of these strategies is evaluated and compared under realistic conditions that include path loss and shadow fading, as well as Rayleigh fading.
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| Lu Zhang was born in Sichuan, China. He received the B.E. and M.E. degrees in 1999 and 2002, respectively, from the Department of Electronic Engineering, Beijing Institute of Technology, Beijing, China.
From April 2002 to January 2004, he was a R&D Engineer of HuaWei Technologies Limited Company. He joined Siemens Ltd. China in January 2004 and was a R&D Engineer of Info.& Comm. Mobile Networks Department until August 2004.
Since September 2004, He has been working as a Research Assistant and pursuing the PhD degree at University of Delaware. His research interests include distributed STBC technique, power control, energy efficient strategy, multi-hop routing, multi-source communication etc. in wireless cooperative relay network. |