Wireless communications has been so far largely based on centralized control, which in effect has limited its deployment, coverage and application scenarios. The paradigm of peer-to-peer wireless communications is fundamentally to remove this bottleneck and to further expand wireless communications into new applications. The technical and design challenges in implementing these networks are however plenty and exist in all the layers of the OSI protocol stack. In this thesis, we only consider the physical layer model of these networks. We identify multiple antenna systems as a vital component of physical layer solutions. We first investigate the case of multiple antenna space-time coding techniques to achieve spatial diversity. We observe that when correlation between the antennas in a local antenna array becomes high due to space constraints in a terminal, current performance achieving strategies do not actually deliver good results. Moreover, most mobile terminals are currently equipped with only one antenna. In view of this limitation, we study the recently proposed user cooperation techniques for exploiting spatial diversity with user power constraints for a simple three terminal network. We find that these systems are beneficial even with relatively simple protocols such as selection relaying. Finally, with simulation results, we demonstrate that the system performance can be improved significantly via near-to optimal selection relaying.
| Identifer | oai:union.ndltd.org:ADTP/256623 |
| Date | January 2006 |
| Creators | Venkatasubramanian, Venkatkumar |
| Source Sets | Australiasian Digital Theses Program |
| Detected Language | English |
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