Superimposed or time-division multiplexed pilots in time-varying channels: an informative consideration

ABSTRACT

Two major techniques are used to embed pilots into data, time-division multiplexed (TDM) and superimposed (SIP). In this paper, we compare these two techniques in an informative consideration under time varying fading channels. Besides the ordinary SIP without dealing with the interference, we also study two different kinds of performance improved iterative SIP: interference subtraction (IS) and interference exploitation (IE). Using Wiener filtering and accounting estimation error, the capacity lower bounds and BER expressions are derived. Numerical results show that great potential benefits are brought by SIP if the interference is utilized properly. With this potential exploited, SIP shows great superior to PSAM, especially in high speed environments.

REFERENCES

• 1: L. Tong, B. M. Sadler, and M. Dong, "Pilot-assisted wireless transmissions: general model, design criteria, and signal processing," IEEE Signal Processing Magazine, vol 21, pp. 12--25, Nov. 2004.
• 2: J. K. Cavers, "An analysis of pilot symbol assisted modulation for Rayleigh fading channels," IEEE Trans. Veh. Technol., vol. 40, pp. 686--693, Nov. 1991.
• 3: P. Hoeher and F. Tufvesson, "Channel estimation with superimposed pilot sequence," in GLOBECOM, vol. 4, Rio de Janeiro, Brazil, Dec. 1999, pp. 2162--2166.
• 4: M. Dong, L. Tong, and B. M. Sadler, "Optimal insertion of pilot symbols for transmissions over time-varying flat fading channels," IEEE Trans. Signal Process., vol. 52, no. 5, pp. 1403--1418, May 2004.
• 5: M. Tapio and P. Bohlin, "A capacity comparison between time multiplexed and superimposed pilots," in Proc. 38th Asilomar Conf. Signals, Syst., Comput., Pacific Grove, CA, Nov. 7--10, 2004, pp. 1049--1053.
• 6: S. He, J. K. Tugnait and X. Meng, "On superimposed training for MIMO channel estimation and symbol detection," IEEE Trans. Signal Processing, vol. 55, part 2, pp. 3007--3021, June 2007.
• 7: Ghogho, M., D. McLernon, et al. (2005). "Channel estimation and symbol detection for block transmission using data-dependent superimposed training." IEEE Signal Process. Lett., vol. 12, no. 13, pp. 226--229, Mar. 2005.
• 8: Heinrich Meyr , Marc Moeneclaey , Stefan Fechtel, Digital Communication Receivers: Synchronization, Channel Estimation, and Signal Processing, John Wiley & Sons, Inc., New York, NY, 1997
• 9: J. Baltersee, G. Fock, and H. Meyr, "An information theoretic foundation of synchronized detection," IEEE Trans. Commun., vol. 49, no. 12, pp. 2115--2123, 2001

INDEX TERMS

Primary Classification:
  H. Information Systems
  H.1 MODELS AND PRINCIPLES
      H.1.1 Systems and Information Theory
          Subjects: Information theory

General Terms:
Algorithms, Performance, Theory

Keywords:
achivable rates, pilot symbol assited modulation, superimposed training, time varying fading channels