Title page for ETD etd-06062008-172207
|Type of Document
||Baker, Kenneth R.
||Importance sampling simulation of free-space optical APD pulse position modulation receivers
|Pratt, Timothy J.
|Bostian, Charles W.
|Graybeal, Jack D.
|Date of Defense
Free-space optical communication technology has many advantages over RF /microwave
in satellite and other spacecraft applications where reductions in size, weight and prime power
requirements are combined with increased data transfer capability over long distances.
Ultimately, the design and implementation of free-space optical communication systems is
dependent on suitable analysis of the link. The analysis of these systems is difficult due to the
complicated time-varying propagation of optical energy over the free-space channel. This
difficulty is combined with a shortage of suitable analytical expressions for adequately
determining the performance of free-space optical receivers. As the link must be modeled and
analyzed, simulation of the free-space optical communication link can initiate the process of
exploring the application of lightwave technology to the free-space channel. A prohibitive
amount of time is required to simulate receiver bit error rate (BER) performance at the low
error rates of interest. This dissertation presents the results achieved in reducing the amount of
time required to simulate, to a given accuracy, the bit error rate performance of an APD based
free-space optical receiver.
An improved technique for the importance sampling simulation of direct detection APD
receivers has been developed. Two methods for efficiently simulating and biasing the probability
distribution function of the APD process are presented and discussed. This is the first use the
Webb, Mcintyre, Conradi statistics in importance sampling simulation of an APD. The general
procedure for applying importance sampling to the optical communication system simulation
problem is presented in detail. The technique of importance sampling has been extended to
include the simulation of maximum likelihood optical M-ary PPM receivers, an optical receiver
relevant to free-space applications. The use of importance sampling is shown to reduce the time
required to simulate M-PPM APD receivers by several orders of magnitude, from 9000 years to
less than one hour in one example.
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