Differential Unitary Space-Time Modulation


Bertrand M. Hochwald       Wim Sweldens


Abstract: We present a framework for differential modulation with multiple antennas across a continuously fading channel, where neither the transmitter nor the receiver knows the fading coefficients. The framework can be seen as a natural extension of standard differential phase shift keying (DPSK) commonly used in single-antenna unknown-channel systems. We show how our differential framework links the unknown-channel system with a known-channel system. As a special case, we introduce a class of diagonal signals where only one antenna is active at any time, and show how these signals may be used to achieve full transmitter diversity and low probability of error.

Status: IEEE Trans. Comm., Vol. 48, No 12, pp 2041-2052, Dec. 2000.

Dates:
June 2000: We made several matlab programs related to this paper available. (see below for download)
May 2000: The paper is accepted for publication in IEEE Trans. Comm. Some very minor changes were made.
February 2000: We posted a revised version of the paper based on referees comments. We use a slightly different normalization in Sections 2.2 and 2.3.
October 1999: We posted a revised version of the paper. The main difference is a revised definition of the diversity product ζ; the new definition is the square root of the old one. This way the diversity product is more amenable to interpretation in the known channel case.
July 1999:
Initial posting.
July 1999:
Submitted.

Download: PDF v3.0 (.pdf) (151K).

BiBTeX entry: 


   @article{dust00, 
     author = {B. Hochwald and W. Sweldens},
     title = {Differential Unitary Space-Time Modulation},
     journal = {IEEE Trans. Comm.},
     month = {December},
     year = {2000},
     pages = {2041-2052}
   }
Software: The following Matlab programs try to find the best Abelian groups either through random search (randsearch.m) or exhaustive search (exhsearch.m), listrelprime.m is an auxiliary program.
randsearch.m, exhsearch.m, listrelprime.m.

Note: This paper can be seen as a follow-up of an earlier paper on "Systematic Design of Unitary Space Time Constellations". There also is a follow-up paper called "Fast Multiple Antenna Differential Decoding ".