Spectrally efficient noncoherent communication

This paper considers noncoherent communication over a frequency-nonselective channel in which the time-varying channel gain is unknown a priori, but is approximately constant over a coherence interval. Unless the coherence interval is large, coherent communication, which requires explicit channel estimation and tracking prior to detection, incurs training overhead which may be excessive, especially for multiple-antenna communication. In contrast, noncoherent detection may be viewed as a generalized likelihood ratio test (GLRT) which jointly estimates the channel and the data, and hence does not require separate training. The main results in this paper are as follows 1) We develop a "signal space" criterion for signal and code design for noncoherent communication, in terms of the distances of signal points from the decision boundaries. 2) The noncoherent metric thus obtained is used to guide the design of signals for noncoherent communication that are based on amplitude/phase ...

• Type: Journal
• Year: 2002
• Where: TIT
• Authors: Dilip Warrier, Upamanyu Madhow
• Keywords: Coherence Interval, Noncoherent Communication, Time-varying Channel Gain, TIT 2002