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Reserch under contract with Lucent Technologies
Multiple access and resource management in wireless systems using smart antennas

Wireless data services are expected to be a major player in the telecommunications market of the near future. High capacity and good performance are being sought when designing such systems. Adaptive antenna arrays (\u201csmart antennas\u201d) are gaining a lot of attention as a means to achieve large capacity and enhanced signal quality by using multiple antenna elements at the base stations together with adaptive signal processing algorithms. Previous work on systems with smart antennas has considered the performance enhancements afforded by this technology and the combining/equalization techniques to achieve them by reducing cochannel interference and compensating for multipath distortion. Also, application of the technology to increase the capacity of current systems has been investigated. Most of these works have considered cellular telephone systems, where operation of antenna arrays is facilitated by circuit-switching mode, whereby the whole connection history can be used in principle to estimate the propagation/interference environment. Of considerable interest, in view of data applications, is the consideration of packet-switching systems using smart antennas. Here, the packet-switched mode essentially requires that the antenna array be tuned slot-by-slot, as the set of users transmitting in a given slot is no longer determined in advance, but rather depends on the random traffic dynamics. This means that a fast and accurate mechanism must be provided to enable proper estimation of some channel and interference properties. For example, training fields may be included in the radio burst. Also, some means toidentify which users are active in a given slot might be necessary. Therefore, the classic problem of efficient design of Media Access Control (MAC) and Resource Management (RM) schemes must be revisited in the considered environment to take into account the new opportunities as well as the new constraints.

Our contribution to the research project is to explore the issues related to the design of MAC/RM protocols. The starting point, in addition to the scarce literature on the topic, will be our own recent research results on MAC efficiency of smart antenna systems. The expected results will be recommendations about efficient design criteria for MAC/RM schemes in systems using smart antennas as well as a thorough study of the interaction between data-link/network protocolsand space/time processing at the physical layer.




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