PERFORMANCE of MULTIUSER V-BLAST WITH LIMITED FEEDBACK for USER SCHEDULING over NAKAGAMI-m FADING CHANNELS

Abstract

In this paper, the performance of a downlink multiuser zero-forcing (ZF) Vertical Bell Laboratories Layered Space-Time (V-BLAST) with an ordering scheme over Nakagami-m fading channels is presented. A system with two transmit antennas while each user is equipped with r (r≥2) receiver antennas is considered. In every time slot, the base station schedules a single user out of U users and communicates with it by adopting a limited feedback (FB) technique for user scheduling. One user is chosen based on a set of bits each sent from a distinct user to the transmitter. The channel considered in this investigation is the fading channel with Nakagami-m distribution which covers a wide range of multipath fading patterns. The adopted FB scheme requires a threshold value which is attained through a numerical optimization process. For a given shape parameter, the optimum threshold value approaches to zero as SNR increases. The results of the outage probability of the investigated systems with varying m-parameter value of Nakagami-m fading channels are presented and compared with the no FB method. It is shown that the studied FB approach on multiuser ZF V-BLAST indeed outperforms the no FB technique. The shape parameter value clearly affects the performance of the FB system, whereas it seems have no significant effect on the random user scheduling (no FB) method.

Keywords

• Zero-Forcing
• V-BLAST
• User Scheduling
• Limited Feedback
• Multiuser System
• Nakagami-m Fading Channel

References

1. [1] Foschini, G.J., Golden, G.D., Valenzuela, R.A. and Wolniansky, P.W., (1999), Simplified processing for high spectral efficiency wireless communication employing multi-element arrays. IEEE Journal on Selected Areas in Communications, 17(11), 1841-1852.
2. [2] Loyka, S. and Gagnon, F., (2004), Performance analysis of the V-BLAST algorithm: an analytical approach. IEEE Transactions on Wireless Communications, 3(4), 1326-1337.
3. [3] Zhang, X., Lv, Z. and Wang, W., (2008), Performance analysis of multiuser diversity in MIMO systems with antenna selection. IEEE Transactions on Wireless Communications, 7(1), 15-21.
4. [4] Zhang, X., Chen, F., and Wang, W., (2007), Outage probability study of multiuser diversity in MIMO transmit antenna selection systems. IEEE Signal Processing Letters, 14(3), 161-164.
5. [5] Yu, X., Dang, X., Leung, S., Liu, Y. and Yin, X., (2014), Unified analysis of multiuser scheduling for downlink MIMO systems with imperfect CSI. IEEE Transactions on Wireless Communications, 13(3), 1344-1355.
6. [6] Gesbert, D. and Alouini, M.-S., (2004), How much feedback is multi-user diversity really worth?. 2004 IEEE International Conference on Communications (IEEE Cat. No.04CH37577), 234-238.
7. [7] Zhang, W. and Letaief, K.B., (2007), MIMO broadcast scheduling with limited feedback. IEEE Journal on Selected Areas in Communications, 25(7), 1457-1467.
8. [8] Amelia, K., Özyurt, S. and Namdar, M., (2022), Performance of multiuser zero-forcing V-BLAST under 1-bit feedback for user scheduling. 2. International Cappadocia Scientific Research Congress, 1617-1623.

9. [9] Özyurt, S. and Kucur, O., (2020), Performance of multiuser TAS/MRC with 1-bit feedback user scheduling over correlated fading channels. AEU - International Journal of Electronics and Communications, 121,153210, ISSN 1434-8411.
10. [10] Al-Ghadhban, S., (2014), Opportunistic round robin scheduling for V-BLAST systems over multiuser MIMO channels. J Wireless Com Network 2014, 128.
11. [11] Nakagami, N., (1960), The m-Distribution, a general formula for intensity distribution of rapid fading. Hoffman, W.G., Ed., Statistical Methods in Radio Wave Propagation, 3-35.
12. [12] Popovic, H., Stefanovic, D., Mitic, A., Stefanovic, I. and Stefanovic, D., (2007), Some statistical characteristics of Nakagami-m distribution. 2007 8th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services, 509-512.
13. [13] Turin, G.L., Clapp, F.D., Johnston, T.L., Fine, S.B. and Lavry, D., (1972), A statistical model of urban multipath propagation. IEEE Transactions on Vehicular Technology, 21(1), 1-9.
14. [14] Suzuki, H., (1977), A statistical model for urban radio propagation. IEEE Transactions on Communications, 25(7), 673-680.
15. [15] Reşat, M.A., Karakoç, M.C. and Özyurt, S., (2020), Enhancement of physical layer security in Alamouti OFDM systems over Nakagami-m fading channels. 2020 28th Signal Processing and Communications Applications Conference (SIU), 1-4.