Title page for ETD etd-113317959711591

Type of Document

Master's Thesis

Author

Nicoloso, Steven P.

URN

etd-113317959711591

Title

An Investigation of Carrier Recovery Techniques for PSK Modulated Signals in CDMA and Mulipath Mobile Environments

Degree

Master of Science

Department

Electrical and Computer Engineering

Advisory Committee

Advisor Name	Title
Stutzman, Warren L.
Woerner, Brian D.
Reed, Jeffrey Hugh	Committee Chair

Keywords

none

Date of Defense

1997-05-27

Availability

unrestricted

Abstract

The challenge of carrier recovery for digitally phase

modulated, suppressed-carrier signals has been the

target of much attention in mobile radio system design for

many years. Code division multiple access (CDMA)

cellular systems are now being deployed in mobile

environments, and the performance of carrier recovery for

CDMA is much less well understood. CDMA systems

typically utilize lower bit energies, relying instead upon

coding gain for reliable performance. As an additional

challenge, the multiple access interference (MAI) inherent

to direct-sequence spread-spectrum (DSSS) signalling

further hampers many carrier recovery techniques.

This thesis first surveys general carrier recovery strategies,

conventional as well as new, and then applies them to the

particular task of recovering a suppressed carrier in

mobile CDMA systems. First some of the theory

surrounding conventional, closed-loop, carrier recovery

techniques and several newer open-loop estimation

structures, based on the maximum likelihood (ML)

principle is presented. A novel decision-feedback ML

phase estimator is proposed. The statistical behavior of

this new structure as well as the related squaring estimator

are examined and are shown to be equivalent to the

stochastic performance of classical closed-loop

techniques.

Candidate receivers based upon closed- and open-loop

carrier recovery structures are proposed and then

examined via simulation. Both forward and reverse

cellular links are examined under a variety of both of

single-path and multipath conditions. The notion of

exploiting cyclostationary MAI in CDMA systems by

applying adaptive receiver techniques is also

examined, especially as this scheme relies to some extent

upon coherent carrier recovery for its promising

performance enhancements. This work concludes with

recommendations of the best carrier recovery strategies

for the variety of environments examined and suggestions

for future research are made.

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