tailieunhanh - Ultra Wideband Communications Novel Trends System, Architecture and Implementation Part 4

Tham khảo tài liệu 'ultra wideband communications novel trends system, architecture and implementation part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 5 Low Complexity Phase-Unaware Detectors Based on Estimator-Correlator Concept Antti Anttonen1 Aarne Mammela1 and Subbarayan Pasupathy2 1VTT Technical Research Centre of Finland University of Toronto Finland 2Canada 1. Introduction Our goal is to present an overview of a class of low complexity detectors working in linear fading multipath channels. In addition we present briefly a unified theory based on the optimal maximum a posteriori probability MAP receiver concept Woodward Davies 1952 which in additive Gaussian noise leads to the estimator-correlator receiver Price 1956 Middleton 1957 Kailath 1960 Kailath 1969 . The terms receiver and detector are interchangeable. Detectors are estimators where the parameter or symbol set to be estimated is discrete Kay 1993 Kay 1998 . We consider phase-unaware detectors PUDs such as differentially coherent detector DD noncoherent detector ND and energy detector ED . The term PUD is used to emphasize that the receiver does not have any knowledge of the absolute phase of the received signal although it may have some knowledge of the internal phase structure. We use the term noncoherent to represent a special case of PUD system and this will be clarified later. PUD detectors are more robust than coherent detectors in a fading multipath channel since the carrier phase of a signal with a wide bandwidth or high carrier frequency may be difficult to estimate with a low complexity. Earlier extensive reviews include Schwarz et al. 1966 Van Trees 1971 and more recently Garth Poor 1994 McDonough Whalen 1995 Proakis 2001 Mammela et al. 2002 Simon Alouini 2005 Witrisal et al. 2009 . A summary of the estimator-correlator receiver is presented in Kay 1998 . Unless stated otherwise we exclude equalizers which increase the complexity of the receiver significantly Lodge Moher 1990 Colavolpe Raheli 1999 . Thus we avoid intersymbol interference ISI by signal design and concentrate on the reception of a single symbol which may include several .