Adaptive MIMO-MLSE Blind Detection in Heterogeneous Stream Transmission for Mobile Radio Communications

Issei KANNO  Hiroshi SUZUKI  Kazuhiko FUKAWA  

IEICE TRANSACTIONS on Communications   Vol.E91-B   No.7   pp.2346-2356
Publication Date: 2008/07/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e91-b.7.2346
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
mobile communications,  MIMO,  heterogeneous stream,  blind signal detection,  blind channel estimation,  adaptive MIMO-MLSE detector,  stream ambiguity,  

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This paper proposes a novel MIMO system that introduces a heterogeneous stream (HTS) scheme and a blind signal detection method for mobile radio communications. The HTS scheme utilizes different modulation or coding methods for different MIMO streams, and the blind detection method requires no training sequences for signal separation, detection, and channel estimation. The HTS scheme can remove the ambiguity in identifying separated streams without unique words that are necessary in conventional MIMO blind detection. More specifically, two examples of HTS are considered: modulation type HTS (MHTS) and timing-offset type HTS (THTS). MHTS, which utilizes different modulation constellations with the same bandwidth for different streams, has been previously investigated. This paper proposes THTS which utilizes different transmission timing with the same modulation. THTS can make the blind detection more robust and effective with fractional sampling. The blind joint processing of detection and channel estimation performs adaptive blind MIMO-MLSE and is derived from an adaptive blind MLSE equalizer that employs the recursive channel estimation with the Moore-Penrose generalized inverse. Computer simulations show that the proposed system can achieve superior BER performance with Eb/N0 degradation of 1 dB in THTS and 2.5 dB in MHTS compared with the ideal maximum likelihood detection.