On the optimal feedback rate in interference-limited multi-antenna cellular systems

Jeonghun Park, Namyoon Lee, Jeffrey G. Andrews, Robert W. Heath

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)


We consider a downlink cellular network where multi-antenna base stations (BSs) transmit data to single-antenna users by using one of two linear precoding methods with limited feedback: 1) maximum ratio transmission (MRT) for serving a single user or 2) zero forcing (ZF) for serving multiple users. The BS and user locations are drawn from a Poisson point process, allowing expressions for the signal-to-interference coverage probability and the ergodic spectral efficiency to be derived as a function of system parameters, such as the number of BS antennas and feedback bits, and the pathloss exponent. We find a tight lower bound on the optimum number of feedback bits to maximize the net spectral efficiency, which captures the overall system gain by considering both of downlink and uplink spectral efficiency using limited feedback. Our main finding is that, when using MRT, the optimum number of feedback bits scales linearly with the number of antennas, and logarithmically with the channel coherence time. When using ZF, the feedback scales in the same ways as MRT, but also linearly with the pathloss exponent. The derived results provide system-level insights into the preferred channel codebook size by averaging the effects of short-term fading and long-term pathloss.

Original languageEnglish
Article number7470522
Pages (from-to)5748-5762
Number of pages15
JournalIEEE Transactions on Wireless Communications
Issue number8
Publication statusPublished - 2016 Aug

Bibliographical note

Publisher Copyright:
© 2002-2012 IEEE.

All Science Journal Classification (ASJC) codes

  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Applied Mathematics


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