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How much training is needed in multiple-antenna wireless links?

Hassibi, Babak and Hochwald, Bertrand M. (2003) How much training is needed in multiple-antenna wireless links? IEEE Transactions on Information Theory, 49 (4). pp. 951-963. ISSN 0018-9448. doi:10.1109/TIT.2003.809594.

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Multiple-antenna wireless communication links promise very high data rates with low error probabilities, especially when the wireless channel response is known at the receiver. In practice, knowledge of the channel is often obtained by sending known training symbols to the receiver. We show how training affects the capacity of a fading channel-too little training and the channel is improperly learned, too much training and there is no time left for data transmission before the channel changes. We compute a lower bound on the capacity of a channel that is learned by training, and maximize the bound as a function of the received signal-to-noise ratio (SNR), fading coherence time, and number of transmitter antennas. When the training and data powers are allowed to vary, we show that the optimal number of training symbols is equal to the number of transmit antennas-this number is also the smallest training interval length that guarantees meaningful estimates of the channel matrix. When the training and data powers are instead required to be equal, the optimal number of symbols may be larger than the number of antennas. We show that training-based schemes can be optimal at high SNR, but suboptimal at low SNR.

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Additional Information:© Copyright 2003 IEEE. Reprinted with permission. Manuscript received May 18, 2000; revised February 9, 2002. [Posted online: 2003-04-15] The material in this paper was presented at the 34th Asilomar Conference on Signals, Systems and Computers, Asilomar, CA, October 2000.
Subject Keywords:BLAST, high-rate wireless communications, receive diversity, space–time coding, transmit diversity
Issue or Number:4
Record Number:CaltechAUTHORS:HASieeetit03
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6794
Deposited By: Archive Administrator
Deposited On:21 Dec 2006
Last Modified:08 Nov 2021 20:37

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