Clipping value estimate for iterative tree search detection

The clipping value, defined as the log-likelihood ratio (LLR) in the case wherein all the list of candidates have the same binary value, is investigated, and an effective method to estimate it is presented for iterative tree search detection. The basic principle behind the method is that the clipping value of a channel bit is equal to the LLR of the maximum probability of correct decision of the bit to the corresponding probability of erroneous decision. In conjunction with multilevel bit mappings, the clipping value can be calculated with the parameters of the number of transmit antennas, Nt; number of bits per constellation point, Mc; and variance of the channel noise, σ2, per real dimension in the Rayleigh fading channel. Analyses and simulations show that the bit error performance of the proposed method is better than that of the conventional fixed-value method.

[1]  R. Muirhead Aspects of Multivariate Statistical Theory , 1982, Wiley Series in Probability and Statistics.

[2]  Andrej Stefanov,et al.  Turbo-coded modulation for systems with transmit and receive antenna diversity over block fading channels: system model, decoding approaches, and practical considerations , 2001, IEEE J. Sel. Areas Commun..

[3]  Gerhard Fettweis,et al.  Optimal LLR Clipping Levels for Mixed Hard/Soft Output Detection , 2008, IEEE GLOBECOM 2008 - 2008 IEEE Global Telecommunications Conference.

[4]  Stephan ten Brink,et al.  Achieving near-capacity on a multiple-antenna channel , 2003, IEEE Trans. Commun..

[5]  Tricia J. Willink,et al.  Iterative tree search detection for MIMO wireless systems , 2005, IEEE Transactions on Communications.

[6]  J.E. Mazo,et al.  Digital communications , 1985, Proceedings of the IEEE.

[7]  Gerhard Fettweis,et al.  Channel state information based LLR clipping in list MIMO detection , 2008, 2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications.

[8]  Sirikiat Lek Ariyavisitakul,et al.  Turbo space-time processing to improve wireless channel capacity , 2000, IEEE Trans. Commun..