Comparison of BCH and convolutional codes in ds-ss multiple access environment
The most significant indicator of the performance of a multiple access packet radio network is its packet error probability. Packet errors in a multiple access system are a result of noise at the receiver and interference between packet transmissions. In this thesis, we compute an upper bound on the packet error probability induced in a direct sequence spread spectrum (DS-SS) multiple access packet radio network when convolutional or BCH codes are used for the encoding of the packets. More specifically, an upper bound on the bit error probability is first developed. Then, this upper bound is used to calculate upper bounds on the packet error probability for BCH codes. For convolutional codes, the upper bound on the final packet error probability, is a result of an upper bound on the packet error probability, an upper bound on the first event error probability and an upper bound on the bit error probability taken in that order. Due to the multiple bounds (three) introduced to compute the upper bound on the packet error probability for convolutional codes compared to the single upper bound utilized to evaluate upper bounds on the packet error probability for the BCH code, it is evident, that the above analysis favors the BCH over the convolutional codes. To remedy this shortcoming, we built a simulator package that allows you to compute upper bound on the packet error probability induced by convolutional codes utilizing, as in the case of the BCH code, only the upper bound on the bit error probability. The simulator permits the user to enter such parameters as constraint length, bit error probability and decode depth of the utilized Viterbi decoder. At the end of each run the simulator produces the number and the specific positions of the bits that remained uncorrected by the Viterbi decoder from which the packet error probability can be determined. From our results, a fair comparison of the performance of the BCH and convolutional codes in DS-SS multiple access packet radio network.
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Master of Science (M.S.)
College of Engineering
Length of Campus-only Access
Masters Thesis (Open Access)
Dissertations, Academic -- Engineering; Engineering -- Dissertations, Academic
Smith, Bancroft O. B., "Comparison of BCH and convolutional codes in ds-ss multiple access environment" (1990). Retrospective Theses and Dissertations. 4081.