NSF Org:	CCF Division of Computing and Communication Foundations
Recipient:	WASHINGTON STATE UNIVERSITY
Initial Amendment Date:	February 9, 2001
Latest Amendment Date:	April 16, 2003
Award Number:	0098357
Award Instrument:	Continuing Grant
Program Manager:	Venugopal V. Veeravalli CCF  Division of Computing and Communication Foundations CSE  Directorate for Computer and Information Science and Engineering
Start Date:	May 15, 2001
End Date:	August 31, 2004 (Estimated)
Total Intended Award Amount:	$245,925.00
Total Awarded Amount to Date:	$252,175.00
Funds Obligated to Date:	FY 2001 = $80,528.00 FY 2002 = $81,099.00 FY 2003 = $90,548.00
History of Investigator:	Benjamin Belzer (Principal Investigator) belzer@eecs.wsu.edu
Recipient Sponsored Research Office:	Washington State University 240 FRENCH ADMINISTRATION BLDG PULLMAN WA  US  99164-0001 (509)335-9661
Sponsor Congressional District:	05
Primary Place of Performance:	Washington State University 240 FRENCH ADMINISTRATION BLDG PULLMAN WA  US  99164-0001
Primary Place of Performance Congressional District:	05
Unique Entity Identifier (UEI):	XRJSGX384TD6
Parent UEI:
NSF Program(s):	COMMUNICATIONS RESEARCH
Primary Program Source:	01000102DB NSF RESEARCH & RELATED ACTIVIT app-0102  app-0103
Program Reference Code(s):	9218, HPCC
Program Element Code(s):	409600
Award Agency Code:	4900
Fund Agency Code:	4900
Assistance Listing Number(s):	47.070

ABSTRACT

Abstract:

This research considers the design of bandwidth efficient coded modulation for partially coherent channels. Such channels occur in practice when coherent receivers are operated at low or moderate signal-to-noise ratios (SNRs), resulting in noisy phase estimates. This happens for example on wireless channels, where multipath fading causes fluctuations in received SNR. This research leverages a recent breakthrough known as turbo coding, wherein the outputs of two or more encoders at the transmitter are iteratively decoded at the receiver, resulting in reliable communication at SNRs within 1 dB of channel capacity. This research integrates phase-tracking error into all aspects of turbo coded modulation design, thereby reducing the required SNR for practical coherent communication systems. The new design techniques stemming
from this research will therefore interest not only communication and coding theorists, but also engineers designing practical communication systems.

The goal of this research is to develop theoretically based, practical design methods for parallel and serially concatenated turbo coded modulation over partially coherent (PC) channels, including PC additive white Gaussian noise (AWGN) channels, and PC fading channels with and without channel state information (CSI), with and without correlated fading, and with closed-loop and open-loop phase estimation. The investigators study the information capacity of PC channels, and determine capacity-achieving input probability density functions (PDFs) and capacity-optimal constellations for equiprobable and non-equiprobable signaling under average and peak power constraints. Distance metrics based on pairwise symbol error probabilities will be derived for PC fading channels, and iterative decoder performance prediction tools based on union bounds and convergence-region analysis will be developed. The investigators will then study set-partitioning, bits-to-symbol mapping, and code-search procedures for both linear and non-linear recursive convolutional encoders used as constituent codes in concatenated trellis-coded modulation schemes. Finally, shaping code design techniques for turbo coded modulation on power-constrained PC channels will be developed, based on the capacity-achieving PDFs of these channels, which are known to be non-Gaussian. These codes will shape the high-dimensional space of encoder output symbol sequences so that the induced two-dimensional PDF will
closely approximate the capacity-optimal input PDF.

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