Threshold-based substream selection for closed-loop spatial multiplexing

Youngwook Ko, Cihan Tepedelenlioglu

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

We propose a low-complexity closed-loop spatial multiplexing method with limited feedback over multi-input-multi-output (MIMO) fading channels. The transmit adaptation is simply performed by selecting transmit antennas (or substreams) by comparing their signal-to-noise ratios to a given threshold with a fixed nonadaptive constellation and fixed transmit power per substream. We analyze the performance of the proposed system by deriving closed-form expressions for spectral efficiency, average transmit power, and bit error rate (BER). Depending on practical system design constraints, the threshold is chosen to maximize the spectral efficiency (or minimize the average BER) subject to average transmit power and average BER (or spectral efficiency) constraints, respectively. We present numerical and Monte Carlo simulation results that validate our analysis. Compared to open-loop spatial multiplexing and other approaches that select the best antenna subset in spatial multiplexing, the numerical results illustrate that the proposed technique obtains significant power gains for the same BER and spectral efficiency. We also provide numerical results that show improvement over rate-adaptive orthogonal space-time block coding, which requires highly complex constellation adaptation. We analyze the impact of feedback delay using analytical and Monte Carlo approaches. The proposed approach is arguably the simplest possible adaptive spatial multiplexing system from an implementation point of view. However, our approach and analysis can be extended to other systems using multiple constellations and power levels.

Original languageEnglish (US)
Pages (from-to)215-226
Number of pages12
JournalIEEE Transactions on Vehicular Technology
Volume57
Issue number1
DOIs
StatePublished - Jan 2008

Fingerprint

Spatial multiplexing
Spectral Efficiency
Multiplexing
Bit error rate
Closed-loop
Error Rate
Antenna
Antennas
Feedback
Feedback Delay
Limited Feedback
Space-time block coding (STBC)
Numerical Results
Fading Channels
Fading channels
Low Complexity
System Design
Signal to noise ratio
Closed-form
Monte Carlo Simulation

Keywords

  • Adaptive modulation
  • Bit error rate (BER)
  • Feedback delay
  • Multi-input & multi-output (MIMO) systems
  • Multi-input multi-output systems
  • Spatial multiplexing
  • Spectral efficiency
  • Substream selection

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Computer Networks and Communications

Cite this

Threshold-based substream selection for closed-loop spatial multiplexing. / Ko, Youngwook; Tepedelenlioglu, Cihan.

In: IEEE Transactions on Vehicular Technology, Vol. 57, No. 1, 01.2008, p. 215-226.

Research output: Contribution to journalArticle

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