Izvorni znanstveni članak
https://doi.org/10.24138/jcomss.v7i2.178
Performance of Blind Turbo Equalizer in Indoor Channels
Mohamed Lassaad Ammari
; 6’Tel Research Unit, School of Communications of Tunis, University of Carthage, Tunisia
Sažetak
In this paper, we consider the transmission of turbo coded symbols in the indoor radio environment. The system is affected by the intersymbol interference (ISI) caused by the multipath time-delay spread of the transmission medium. To reduce the channel effect, we propose to use a blind turbo equalizer combining channel estimation, equalization and turbo decoding. The equalizer consists of an interference canceller (IC) and a MAP-BCJR decoder. To improve system performances, we redefine the channel reliability factor used by the MAP-BCJR decoding algorithm. We propose a new metric that takes into account the statistics of the signal at the equalizer output. The channel coefficient estimation is performed using a recursive least squares (RLS) algorithm. A blind receiver initialization technique is proposed. This technique is based on a soft decisiondirected least mean square algorithm (soft DD-LMS). For the proposed turbo detector, the ISI cancellation, channel estimation and decoding are jointly performed through an iterative process where modules exchange a soft information.
Ključne riječi
Indoor channel; MAP decoder; turbo processing; channel reliability; RLS channel estimation
Hrčak ID:
180260
URI
Datum izdavanja:
25.6.2011.
Posjeta: 807 *