Communication over Wireless Fading Channels: A Modern View

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The design of efficient wireless communication systems relies on adeep understanding of the basic characteristics of the underlyingchannel. The most fundamental and unique characteristic of wirelesschannels is the random time-variation of the channel strengths, aphenomenon known as fading. Communication over fading channels hasbeen a topic of study since the 60's. A very different view of theproblem, however, emerges from recent research. The traditional viewof fading is that it is a source of unreliability that has to becompensated for by various diversity techniques. The modern view ismuch morepowerful and considers fading as a source of randomization from naturethat can be exploited to get very significant capacity boost.The research project addresses several key problems within thismodern paradigm. They will be centered around two areas: 1)opportunistic communication : the dynamic rate and power allocationover the dimensions of time, frequency, antennas and usersso that transmission is done when and where the channel is strong;2) multi-antenna communication: the use of multiple transmit andreceive antennas to increase the number of degrees of freedom availablefor communication in richly scattered fading environments. The issuesstudied are focused on how the random fading can be exploited even inthe face ofchannel uncertainty, and the interplay between the modern andtraditional views of channel fading.