Abstract
This research implements an estimation scheme for a Space-Time OFDM system over a fading channel and evaluates the performance of the receiver using this scheme. The channel estimation problem for ST-OFDM is complex as the receiver sees a superposition of distorted signals from each transmit antenna. The Expectation Maximization (EM) algorithm is used for estimation as it provides an iterative solution with less computational complexity compared to known schemes for similar performance levels and is robust over many different channel profiles. The system is implemented on Starcore's SC140 fixed point DSP core. The aim of this research is to study the fixed point implementation of this algorithm on a general purpose DSP, comment on the performance and existing functionality and suggest more functions if found to be required or desirable from the communications point of view. Another important part of this research is to take apart each block and analyze the fixed point effects occurring due to finite precision arithmetic. The aim is to identify finite precision system specific behavior, identify sources of quantization error and use this information to design a better system. We also aim to find out by analysis and simulations the best suited precision format (8-bit, 12-bit, 16-bit etc.) for the system. This analysis is expected to be applicable to iterative schemes in general.
Gopalan, Preeti (2002). A channel estimation algorithm for Space Time OFDM systems on the Starcore SC140 DSP. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2002 -THESIS -G6692.