Hybrid Amplification: An Efficient Scheme for Energy Saving in MIMO Systems

Gwenael Poitau, Ammar B. Kouki

.

DOI: 10.4236/wet.2012.31006                

Abstract

In this paper, a new amplification scheme for adaptive MIMO systems is proposed and tested. In this ‘hybrid amplification’ configuration, different amplifiers with different peak powers are used. In this way, each transmitter RF chain has a different DC-power consumption behavior. The adaptation algorithm, which chooses power and rate for each transmitter, uses these different amplifier behaviors to minimize the overall consumed energy. Several MIMO configurations designed for constant capacity applications have been simulated with different amplification schemes. Realistic amplifier models based on measured data are used. The difference between the amplifiers’ RF powers is set in order to keep optimal system performances. Then, it is shown that energy savings higher than 10% can be obtained with the hybrid amplification. The different tests are done for MQAM constellations in uncorrelated Rayleigh fading channels detected with a VBLAST ZF-SIC algorithm but can easily be extended to other correlated channels, detection algorithms or constellations.

Keywords

MIMO; VBLAST; Power Amplifiers; Power Efficiency; Hybrid Amplification

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	E. Telatar, “Capacity of Multi-Antenna Gaussian Channels,” European Transactions on Telecommunications, Vol. 10, No. 6, 1995, pp. 585-595. doi:10.1023/A:1008889222784
[2]	G. J. Foschini and M. J. Gans, “On Limits of Wireless Communications in a Fading Environment When Using Multiple Antennas,” Wireless Personal Communications, Vol. 6, No. 3, 1998, pp. 311-335.
[3]	P. W. Wolniansky, G. J. Foschini, G. D. Golden and R. A Valuenza, “V-BLAST: An Architecture for Realizing Very High Data Rates over the Rich-Scattering Wireless Channel,” 1998 URSI International Symposium on Signals, Systems and Electronics, Pisa , 29 September-2 October 1998, pp. 295-300. doi:10.1109/ISSSE.1998.738086
[4]	S. H. Nam and K. B. Lee, “Transmit Power Allocation for an Extended V-BLAST System,” 13th International IEEE Symposium on Personal, Indoor and Mobile Radio Communications, Vol. 2, 2002, pp. 843-848.
[5]	S. T. Chung, A. Lozano and H. C. Huang, “Approaching Eigenmode BLAST Channel Capacity Using V-BLAST with Rate and Power Feedback,” Vehicular Technology Conference Fall, Vol. 2, 15-18 September 2002, pp. 915-919.
[6]	S. T. Chung and A. Sutivong, “Practical Considerations for Extended V-BLAST: Quantized Parameters and Imperfect Channel Estimation,” 2002 IEEE Wireless Comunications and Networking Conference, Vol. 2, March 2002, pp. 682-686.
[7]	P. Ivanis and D. Drajic, “Combined Optimal Power Allocation and Adaptive Modulation for MIMO Systems with Imperfect CSI,” 6th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Service, Nis, 1-3 October 2003, pp. 167-170.
[8]	A. Milani, V. Tralli and M. Zorzi, “Improving Protocol Performance in BLAST-Based Wireless Systems Using Channel Adaptive Antenna Selection,” IEEE 55th Vehicular Technology Conference Spring, Vol. 1, 2002, pp. 409-413.
[9]	A. Milani, V. Tralli and M. Zorzi, “On the Use of Per-Antenna Rate and Power Adaptation in V-BLAST Systems for Protocol Performance Improvement,” Vehicular Technology Conference Fall, Vol. 4, 2002, pp. 2126-2130.
[10]	H. R. Zhuang, L. Dai, S. D. Zhou and Y. Yao, “Low Complexity Per-Antenna Rate and Power Control Approach for Closed Loop V-BLAST,” IEEE Transactions on Communications, Vol. 51, No. 11, 2003, pp. 1783-1787. doi:10.1109/TCOMM.2003.819227
[11]	N. Ka-Wai, R. S. Cheng and R. D. Murch, “Iterative Bit & Power Allocation for V-BLAST-Based OFDM MIMO System in Frequency Selective Fading Channels,” Wireless Comunications and Networking Conference, Vol. 1, 17-21 March 2002, pp. 271-275.
[12]	J. G. Proakis, “Digital Communications,” MacGraw Hill, Boston, 2001.
[13]	A. J. Goldsmith and C. Soon-Ghee, “Variable-Rate Variable-Power MQAM for Fading Channels,” IEEE Transactions on Communications, Vol. 45, No. 10, 1997, pp. 1218-1230. doi:10.1109/26.634685
[14]	S. Boumaiza and F. M. Ghannouchi, “Realistic Power Amplifier Characterization with Application to Baseband Digital Predistortion for 3G Base Stations,” IEEE Transactions on Microwave Theory and Techniques, Vol. 50, No. 12, 2002, pp. 3016-3021. doi:10.1109/TMTT.2002.805139
[15]	G. D. Durgin, “Space-Time Wireless Channels,” Prentice Hall, Upper Saddle River, 2003.
[16]	K. Young-Doo, K. Inhyoung, C. Jihoon, A. Jae-Young and Y. H. Lee, “Adaptive Modulation for MIMO Systems with V-BLAST Detection,” Vehicular Technology Conference Spring, Vol. 2, 2003, pp.1074-1078.
[17]	G. Poitau and A. Kouki, “Impact of Realistic Amplification Models on Dynamic VBLAST Amplification,” Proceedings of IEEE Vehicular Technology Conference, Vol. 2, 2004, pp 894-897.