Interleaving Differential MMSE Multiuser Detection Based on Cyclic-stationary Period

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1 JOURNAL OF APPLIED SCIENCES Electronics and Information Engineering Vol. 30 No. 5 Sept DOI: /j.issn (wide code division multiple access, WCDMA) (interleaving differential minimum mean square error, IDMMSE). WCDMA (differential minimum mean square error, IDMMSE).. DMMSE. IDMMSE MMSE. TN (2012) Interleaving Differential MMSE Multiuser Detection Based on Cyclic-stationary Period FENG Xing-le, LI Wei, JIANG Yun-guo School of Information Engineering, Chang an University, Xi an , China Abstract: To suppress multiple access interference (MAI) in wide code division multiple access (WCDMA) systems in a fast fading channel, an interleaving differential MMSE multiuser detection method based on the cyclo-stationary period is proposed. According to typical characteristics of two-layered spreading modulation in WCDMA, the update criterion of coefficients is based on the cyclo-stationary period, instead of the spread factor. As the proposed method can characterize the pattern of MAI properly, improved performance can be achieved. Moreover, interleaving is involved to let the symbols with the same comprehensive spread sequence be transmitted consecutively to ensure that the channel gains of successive symbols keep constant in the fast fading channel. Simulation results show the performance is improved without increasing the system complexity, and Doppler shift is better dealt with. Keywords: wide code division multiple access (WCDMA), multiuser detection, differential minimum mean square error (IDMMSE), cyclo-stationary period, interleave (code division multiple access, CDMA) [1]. (minimum mean square error MMSE). (wide code division multiple access WCDMA). WCDMA MMSE. [2] (No ) (No.IRT0951) (No.2011K06-28) (No ) (No.CHD2012JC069, No.CHD2012TD011) MIMO xlfeng@chd.edu.cn

2 5 467 MMSE. [3] (high speed downlink packet access, HSDPA) (least mean square, LMS). [4] MMSE. [5] (direct sequencecode division multiple access, DS-CDMA) (differential minimum mean square error, DMMSE). [6] MMSE. MMSE [5] DMMSE DS- CDMA WCDMA WCDMA DMMSE DMMSE. DMMSE DMMSE. DMMSE WCDMA WCDMA (dedicated physical data channel, DPDCH) (dedicated physical control channel, DPCCH). WCDMA 1 (orthogonal variable spreading factor, OVSF) DPDCH DPCCH 2. WCDMA 1. 1 k. K v k (i) = K d k (i τ k )S k (mod (i/(p/g))) k=1 + n(i) (1) 1 Figure 1 System model

3 d k (i) = f k (i) [β I x k (i)c k,i + jβ Q y k (i)c Q,k ] (2) 1 (1) (2) k. 1 DPDCH DPCCH i x k (i) y k (i) OVSF C k,i C k,q β I β Q d k (i). x k (i) y k (i) C k,i C k,q OVSF C k,i C k,q x k (i) y k (i) f k (i) k i j. 2 1 d k (i) k S(2) S k S k (mod (i/(p/g))) u k (i) mod( ). S(2) S k OVSF C k,i. d k (i) G G S k P S k P/G S k (mod (i/(p/g))) k i G d k (i) n(i). u k (i) v k (i). u k (i) Jake [7]. 6 ( ) ( ) m m h [m] = h = h f s 4f d = f ( ) d 3 m Γ 2π 4 4πfd 2 14 J 1 4 ( π 2 m ) (3) f d f s = 4f d Γ (γ) = 1 (1+1/λ) z γ 1+γ/λ J 1 (γ) = 4 λ=1 λ=0 ( γ ) λ [7]. ( 1) λ λ!γ(1/4+λ+1) 1.3 WCDMA v k (i) û k (i) k [S k (mod (i/(p/g)))] H d k (i) G 1 ẑ k (i) G. k. k DPDCH DPDCH DPCCH.. ẑ k (i) G 1 ẑ k (i) G 1 w k (i) i x k (i) = w k (i) H ẑ k (i) (4) ẑ k (i) G x k (i) x k (i). w k (i). 2 IDMMSE 2.1 DMMSE DMMSE DS-CDMA [8] arg min{e[ x k (i 1) w k (i), ẑ k (i) w k x k (i) w k (i 1), ẑ k (i 1) 2 ]} (5) s.t. E[ w k (i), ẑ k (i) 2 ] = w H k Rw k = 1 (6) E [ ] w k (i), ẑ k (i) = wk H(i) ẑ k(i) R = E[ẑ k (i)ẑk H (i)]. (5). (5) (6). DMMSE.

4 DS-CDMA. G OVSF G. WCDMA G P. WCDMA OVSF S(2) 2. i G C k,i S k S k (mod (i/(p/g))). DMMSE ( G ) C k,i S(2) S k (mod (i/(p/g))) DMMSE WCDMA. 2 x k (i) x k (i (P/G)) x k (i (P/G)) x k (i) [9] DMMSE argmin{e[ x k (i (P/G)) w k (i), ẑ k (i) w x k (i) w k (i (P/G)), ẑ k (i (P/G)) 2 ]} (7) 2 Figure 2 Comprehensive spread sequence DMMSE (5) DMMSE (7) w k (i P/G) w k (i 1) w k (i). 2.2 IDMMSE DMMSE. w k (i (P/G)) w k (i) P/G DMMSE. u k (i) u k (i (P/G)) MMSE (interleave differential minimum mean square error, IDMMSE) u k (i) u k (i P/G), DMMSE. 3. u k (i) N (P/G) u k (i) G. P /G 1 2 N N.. u k (i) u k (i (P/G)). DMMSE. (7) x k (i) x k (i (P/G)).

5 Figure 3 Interleaving register matrix x k (i) x k (i (P/G)). NP /G x k (i) x k (i P/G). 2.3 (7) [10] LMS (normalized least mean squares, NLMS) DMMSE NLMS e k (i) = x k (i)w k (i (P/G)) H ẑ k (i (P/G)) x k (i (P/G))w k (i (P/G)) H ẑ k (i) (8) M(i) = ηm(i (P/G)) + (1 η)ẑ k (i) H ẑ k (i) (9) w k (i) = (w k (i (P/G)) + µ M(i)ẑk(i)ẑ k (i)x (i (P/G))e k (i)) w k (i (P/G)) H ẑ k (i (P/G)) (10) η M(i) * sgn () T. 4 4 IDMMSE Figure 4 Flow diagram of IDMMSE GPP [11] MATLAB WCDMA. Walsh 256 S(2) 32 8 DPDCH 1/32 DPCCH / ) [2] MMSE MMSE. 2) DMMSE_NLMS (7) w k (i (P/G)) w k (i) P/G, DMMSE. 3) IDMMSE_NLMS DMMSE_NLMS x k (i) x k (i (P/G)), IDMMSE.

6 5 471 DMMSE IDMMSE M(i)=0.1 η=0.5 µ= G 3 (symbol error ratio, SER). 900 MHz 30 km/h f d =25 Hz G=32. 5 DMMSE SER MMSE IDMMSE SER DMMSE. DMMSE IDMMSE x k (i) x k (i (P/G)) DMMSE. 6 Figure 6 Effect of Doppler shift on the performance 5 3 Figure 5 SER comparasion of three algrithms 2 3. E b /N o =10 db K=4 G= SER. MMSE DMMSE SER 0.5 IDMMSE x k (i) x k (i P/G) SER. 3, 3. E b /N o =10 db K=4 f d =30 Hz. 7 G x k (i) x k (i (P/G)) x k (i) x k (i (P/G)) SER. 7 Figure 7 Effect of spread factor on the performance 3.2 DMMSE MMSE DMMSE MMSE. 1 DMMSE MMSE. 1 Table 1 Complexity comparasion of two algorithms MMSE 3 G 2 G DMMSE 7 G 2 3 G IDMMSE N (P/G). (P/G)

7 WCDMA /s. DPDCH G x k (i) x k (i (P/G)) x k (i) x k (i (P/G)) IDMMSE. DPDCH x k (i) x k (i (P/G)) IDMMSE. 4 IDMMSE NLMS 1) DMMSE NLMS DS-CDMA WCDMA WCDMA DMMSE.. 2) x k (i) x k (i (P/G)) x k (i) x k (i (P/G)). IDMMSE [2] MMSE. IDMMSE RAKE. : [1] Verdu S. Multiuser detection [M]. 2 ed. Cambridge, MA: Cambridge University Press, [2] Du Qinghe, Zhu Shihua, Ren Pinyi. An improved adaptive MMSE algorithm for multirate multiuser detection in WCDMA systems [C]//IEEE Circuits and Systems Symposium on Emerging Technologies, 2004: [3] Lui Tai, Lu E. MIMO NLMS-ZF data detection approach for WCDMA based HSDPA systems [C]//Sarnoff Symposium, [S.l.]: IEEE press, 2009: 1-5. [4] Sharma S K, Naseem A S. Suppression of multiple access interference (MAI) in wideband code division multiple access (WCDMA) [C]//International Conference on Wireless and Optical Communications Networks, 2007: 1-6. [5] Madhow U, Zhu L J, Galup L. Differential MMSE: new adaptive algorithms for equalization, interference suppression and beamforming [C]//32nd Asilomar Conf. Signals, Systems and Computers, 1998: [6]. MMSE [J]. 2005, 20(3): Zhang Hongtao, Lu Jiren, Jiang Weidong. Differential detection adaptive algorithm for MMSE receiver [J]. Journal of Data Acquisition and Processing, 2005, 20(3): (in Chinese) [7] Peter H. A statistical discrete-time model for the WSSUS multipath channel [J]. IEEE Transactions on Vehcular Technology, 1992, 41(4): [8]. DMMSE DS- CDMA [J]. 2002, 20(01): Wang Linlin, Chen Jian, Sun Xiaoying, Wang Shuxun. Application of DMMSE criterion to DS- CDMA systems [J]. Journal of Changchun Post and Telecommunication Institute, 2002, 20(1): (in Chinese) [9]. WCDMA [J]. 2008, 23(1): Feng Xingle, Sun Zhaoyun, Duan Zongtao. Improved constant modulus algorithm of multiuser detection in WCDMA systems [J]. Journal of Data Acquisition and Processing, 2008, 23(1): (in Chinese) [10] Madhow U, Zhu L J. Differential MMSE: a framework for robust adaptive interference suppression for DS-CDMA over fading channels [J]. IEEE Transactions on Communication, 2005, 53(8): [11] 3rd Generation Partnership Project. 3G TS ver , Technical specification group radio access networks: spreading and modulation (FDD) [S] ( : )

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