Coherent detection of orthogonal frequency division multiplexed signals in a fading channel / Selaka Bandara Bulumulla.

Format:

Book

Manuscript

Microformat

Thesis/Dissertation

Author/Creator:

Bulumulla, Selaka Bandara.

Contributor:

Venkatesh, Santosh S., 1959- advisor.

Laker, Ken, advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Penn dissertations--Electrical engineering.

Electrical engineering--Penn dissertations.

Local Subjects:

Penn dissertations--Electrical engineering.

Electrical engineering--Penn dissertations.

Physical Description:

xvi, 120 pages : illustrations ; 29 cm

Production:

1998.

Summary:

We consider the coherent detection of phase modulated orthogonal frequency division multiplexed (OFDM) signals in a fading channel. We model the fading channel as a vector auto-regressive process and derive the maximum a posteriori probability (MAP) receiver. The MAP receiver has a Kalman filter front end which estimates the channel state and a recursive algorithm which computes the a posteriori probability. The complexity of this receiver grows exponentially fast in the product of the number of sub-channels in the OFDM system and the length of transmission.

As the MAP receiver has high complexity, we consider two low complexity receivers. The first receiver uses Kalman filtering with decision feedback to estimate the channel state. As the feedback errors have a significant impact on the estimation, we place known symbols (pilot symbols) to arrest catastrophic error propagation. The second receiver uses pilot symbols directly in the channel estimation. We use a weighted sum of pilot positions, where the weights are selected according to the minimum mean squared error criterion, to estimate the channel states. We compare the performance of these receivers with two benchmarks--performance of an ideal receiver that has perfect knowledge of the channel state and a DPSK receiver. We show that the performance of the two low complexity receivers is better than the performance of the DPSK receiver and compare favorably with the performance of the ideal receiver.

Notes:

Supervisors: Santosh S. Venkatesh; Ken Laker.

Thesis (Ph.D. in Electrical Engineering) -- University of Pennsylvania, 1998.

Includes bibliographical references and index.

Local Notes:

University Microfilms order no.: 98-40176.

OCLC:

187472859