Multipath Channels of Bounded Capacity

TL;DR

This paper investigates the capacity limits of non-coherent multipath fading channels, showing that with large delay spreads, the channel capacity remains bounded regardless of increasing signal-to-noise ratio.

Contribution

It establishes that for channels with large delay spreads and non-decaying path gain variances, the capacity does not grow unbounded with SNR, a novel insight into channel behavior.

Findings

Capacity is bounded when delay spread is large.

Path gain variances that decay no faster than geometrically lead to bounded capacity.

The result applies to non-coherent multipath channels with large delay spreads.

Abstract

The capacity of discrete-time, non-coherent, multipath fading channels is considered. It is shown that if the delay spread is large in the sense that the variances of the path gains do not decay faster than geometrically, then capacity is bounded in the signal-to-noise ratio.