Transparent inband feedback for training-based mimo systems

Oussama Souihli, Tomoaki Ohtsuki

Research output: Contribution to journalArticlepeer-review


Recently, Echo-MIMO, a delay-free feedback scheme has been proposed for Closed-Loop MIMO systems, where the receiver echoes the received signal on the fly to the transmitter without any processing. While this reduced feedback latency allows for more use of the channel's coherence time for data transmission, it comes at high power-and-bandwidth costs, as twoMIMO transmissions are required in the feedback phase. In this paper, we present a feedback scheme that preserves the advantages of Echo-MIMO while requiring only one feedback transmission. The echoed signals are judiciously combined with the receiver's signals such that their separation at the transmitter be lossless, and that no extra transmit power nor bandwidth be required. In addition, we highlight the estimation accuracy degradation in Echo-MIMO owing to the echoed noise, and analytically confirm the intuition that removing the noise prior to echoing the received signal provides better estimation than echoing the noisy received signal as is and later account for the noise effect upon echo reception. Simulation results show that the proposed scheme outperforms Echo-MIMO in terms of channel estimation accuracy and achievable capacity.

Original languageEnglish
Pages (from-to)587-599
Number of pages13
JournalWireless Personal Communications
Issue number3
Publication statusPublished - 2012 Apr


  • Channel estimation
  • Channel feedback
  • Closed-Loop MIMO
  • Rayleigh fading

ASJC Scopus subject areas

  • Computer Science Applications
  • Electrical and Electronic Engineering


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