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A Simple Recursively Computable Lower Bound on the Noncoherent Capacity of Highly Underspread Fading Channels

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Peer-reviewed

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Article

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Abstract

Real-world wireless communication channels are typically highly underspread: their coherence time is much greater than their delay spread. In such situations it is common to assume that, with sufficiently high bandwidth, the capacity without Channel State Information (CSI) at the receiver (termed the noncoherent channel capacity) is approximately equal to the capacity with perfect CSI at the receiver (termed the coherent channel capacity). In this paper, we propose a lower bound on the noncoherent capacity of highly underspread fading channels, which assumes only that the delay spread and coherence time are known. Furthermore our lower bound can be calculated recursively, with each increment corresponding to a step increase in bandwidth. These properties, we contend, make our lower bound an excellent candidate as a simple method to verify that the noncoherent capacity is indeed approximately equal to the coherent capacity for typical wireless communication applications. We precede the derivation of the aforementioned lower bound on the information capacity with a rigorous justification of the mathematical representation of the channel. Furthermore, we also provide a numerical example for an actual wireless communication channel and demonstrate that our lower bound does indeed approximately equal the coherent channel capacity.

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Keywords

Gauss-Markov processes, Hidden Markov processes, Kalman filters, Noncoherent information capacity, Underspread channels, Vehicular communications

Journal Title

IEEE Transactions on Wireless Communications

Conference Name

Journal ISSN

1536-1276
1558-2248

Volume Title

15

Publisher

Institute of Electrical and Electronics Engineers (IEEE)
Sponsorship
The work of T. H. Loh was supported by the 2013 - 2017 Electromagnetics and Time Metrology Programme of the National Measurement Office, an Executive Agency of the U.K. Department for Business, Innovation and Skills, under Projects EMT13018