Blind array channel division multiple access (AChDMA) for mobile communications

The paper introduces array channel division multiple access (AChDMA), which is a new blind algorithm for advanced SDMA in mobile communications systems. As an SDMA technique, AChDMA increases the system capacity by improving its time and frequency reuse. Being a blind algorithm, it requires no training sequences, previously known directions of arrival, or user codes, AChDMA separates the moving sources by tracking their multipath configuration and resolving their distinct generalized steering vectors. It maximizes a finite mixture log-likelihood function, combining an efficient initialization procedure with an EM-based algorithm that provides fast convergence to the global maximum. AChDMA reconstructs the mobile data sequences using only internal variables of the EM algorithm. These characteristics and its parallel structure make AChDMA suitable for real-time mobile communications. We test AChDMA with synthetic data in a number of different scenarios, illustrating the ability of the blind algorithm to separate and track in time the moving sources, and showing its good performance in a variety of practical situations.

[1]  José M. F. Moura,et al.  Cramer-Rao bound for location systems in multipath environments , 1991, IEEE Trans. Signal Process..

[2]  Bjorn Ottersten,et al.  The spectrum efficiency of a base station antenna array system for spatially selective transmission , 1995 .

[3]  J. Capon.  High-resolution frequency-wavenumber spectrum analysis , 1969 .

[4]  R. Morgan.  Mobile radio communications. , 1982, Hospital engineering.

[5]  Victor Barroso,et al.  A Model Based Equalization Structure for Underwater Communications , 1993 .

[6]  G. Okamoto,et al.  Throughput multiplication of wireless LANs: spread spectrum with SDMA , 1996, Proceedings of Vehicular Technology Conference - VTC.

[7]  K. Anand,et al.  Blind separation of multiple co-channel BPSK signals arriving at an antenna array , 1995, IEEE Signal Processing Letters.

[8]  William C. Y. Lee,et al.  Mobile Cellular Telecommunications Systems , 1989 .

[9]  Hui Liu,et al.  Blind estimation of array responses for an asynchronous multiuser system , 1995, 1995 IEEE 45th Vehicular Technology Conference. Countdown to the Wireless Twenty-First Century.

[10]  S. Talwar,et al.  Blind estimation of multiple digital signals transmitted over FIR channels , 1995, IEEE Signal Processing Letters.

[11]  Björn E. Ottersten,et al.  The spectrum efficiency of a base station antenna array system for spatially selective transmission , 1994, Proceedings of IEEE Vehicular Technology Conference (VTC).

[12]  José M. F. Moura,et al.  L2 and L1 Beamformers: Recursive Implementation and Performance Analysis , 1994, IEEE Trans. Signal Process..

[13]  Robert J. Mailloux,et al.  Phased Array Antenna Handbook , 1993 .

[14]  C. R. Baker.  Stochastic processes in underwater acoustics , 1986 .

[15]  V.A.N. Barroso,et al.  Impact of array processing techniques on the design of mobile communication systems , 1994, Proceedings of MELECON '94. Mediterranean Electrotechnical Conference.

[16]  W. Kuperman,et al.  Matched field processing: source localization in correlated noise as an optimum parameter estimation problem , 1988 .

[17]  Victor Barroso,et al.  Beamforming with Correlated Arrivals in Mobile Communications1 , 1999 .

[18]  Arogyaswami Paulraj,et al.  Recursive adaptive beamforming for wireless CDMA , 1995, Proceedings IEEE International Conference on Communications ICC '95.

[19]  A. Paulraj,et al.  Blind estimation of multiple co-channel digital signals using an antenna array , 1994, IEEE Signal Processing Letters.

[20]  Harry L. Van Trees,et al.  Detection, Estimation, and Modulation Theory, Part I , 1968 .

[21]  J. P. McGeehan,et al.  The performance enhancement of multibeam adaptive base-station antennas for cellular land mobile radio systems , 1990 .

[22]  Hui Liu,et al.  A deterministic approach to blind symbol estimation , 1994, IEEE Signal Processing Letters.

[23]  A. F. Smith,et al.  Statistical analysis of finite mixture distributions , 1986 .

[24]  J. Kennedy,et al.  Direction finding and "smart antennas" using software radio architectures , 1995 .

[25]  Guanghan Xu,et al.  Throughput multiplication of wireless LANs for multimedia services: SDMA protocol design , 1994, 1994 IEEE GLOBECOM. Communications: The Global Bridge.

[26]  Babak Hossein Khalaj,et al.  Spatio-temporal channel estimation techniques for multiple access spread spectrum systems with antenna arrays , 1995, Proceedings IEEE International Conference on Communications ICC '95.

[27]  José M. F. Moura,et al.  Optimal filtering in the presence of multipath , 1986 .

[28]  Andreas F. Molisch,et al.  Capacity enhancement and BER in a combined SDMA/TDMA system , 1996, Proceedings of Vehicular Technology Conference - VTC.