What is the Value of Joint Processing of Pilots and Data in Block-Fading Channels?

TL;DR

This paper compares joint processing of pilots and data in block-fading channels with separate processing, showing joint processing offers significant spectral efficiency gains, especially in fast fading scenarios, with minimal pilot symbols needed.

Contribution

It demonstrates the advantages of joint processing over separate processing in block-fading channels and quantifies the minimal pilot symbols required for optimal performance.

Findings

Joint processing yields higher spectral efficiency than separate processing.

Only one pilot per antenna per coherence interval suffices with joint processing.

The advantage of joint processing is more pronounced in fast fading conditions.

Abstract

The spectral efficiency achievable with joint processing of pilot and data symbol observations is compared with that achievable through the conventional (separate) approach of first estimating the channel on the basis of the pilot symbols alone, and subsequently detecting the data symbols. Studied on the basis of a mutual information lower bound, joint processing is found to provide a non-negligible advantage relative to separate processing, particularly for fast fading. It is shown that, regardless of the fading rate, only a very small number of pilot symbols (at most one per transmit antenna and per channel coherence interval) should be transmitted if joint processing is allowed.