Orthogonal or Superimposed Pilots? A Rate-Efficient Channel Estimation Strategy for Stationary MIMO Fading Channels

A. Taufiq Asyhari, Stephan Ten Brink

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)
64 Downloads (Pure)


This paper considers channel estimation for multiple-input multiple-output (MIMO) channels and revisits two competing concepts of including training data into the transmit signal, namely, orthogonal pilot (OP) that periodically transmits alternating pilot-data symbols, and superimposed pilot (SP) that overlays pilot-data symbols over time. We investigate rates achievable by both schemes when the channel undergoes time-selective bandlimited fading and analyze their behaviors with respect to the MIMO dimension and fading speed. By incorporating the multiple-antenna factors, we demonstrate that the widely known trend in which the OP is superior to the SP in the regimes of high signal-to-noise ratio (SNR) and slow fading, and vice versa, does not hold in general. As the number of transmit antennas (nt) increases, the range of operable fading speeds for the OP is significantly narrowed due to limited time resources for channel estimation and insufficient fading samples, which results in the SP being competitive in wider speed and SNR ranges. For a sufficiently small nt, we demonstrate that as the fading variation becomes slower, the estimation quality for the SP can be superior to that for the OP. In this case, the SP outperforms the OP in the slow-fading regime due to full utilization of time for data transmission.

Original languageEnglish
Article number7880605
Pages (from-to)2776-2789
Number of pages14
JournalIEEE Transactions on Wireless Communications
Issue number5
Early online date17 Mar 2017
Publication statusPublished - 1 May 2017
Externally publishedYes

Bibliographical note

Open Access . This work is licensed under a Creative Commons Attribution 3.0 License.


  • Achievable rates
  • Doppler frequency
  • generalized mutual information
  • MIMO
  • multiple antennas
  • orthogonal pilots
  • pilot-aided channel estimation
  • superimposed pilots

ASJC Scopus subject areas

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


Dive into the research topics of 'Orthogonal or Superimposed Pilots? A Rate-Efficient Channel Estimation Strategy for Stationary MIMO Fading Channels'. Together they form a unique fingerprint.

Cite this