IEEE Military Communications Conference, 'Bridging the Gap. Interoperability, Survivability, Security'
In this paper, we discuss a class of codes that are useful for optical beam combining communicati... more In this paper, we discuss a class of codes that are useful for optical beam combining communications. The data modulation scheme of interest is primarily on-off keying (OOK). We will investigate various code properties and obtain bounds on the minimum alphabet size of the codes. A difference sequence construction method for the codes is presented, and optimal and suboptimal codes are given. System error probability performance is evaluated. 1. Introduction Recently, there have been increasing interest in optical communications with diode combining [3, 41. The idea is to superimpose the outputs of several noninterfering laser diodes into a single light beam and then send the combined light energy over an optical channel. The optical channel can either be a fibre glass optical network or a free space direct optical link. At the receiving end, the received light beam is split into the individual laser beams (with distinct noninterfering wavelengths) that contain modulated information. The transmitted message can be recovered by decoding the data transmitted by the different lasers. The optical combining and splitting can be accomplished by optical mirrors, optical diffraction gradings [9], or acousto-optic deflectors [ll]. By using properly designed beam combining techniques and modulation formats, the information transmission capacity of an existing optical link can be increased. Consider the optical communication system depicted in Figure 1. There are N laser diodes with distinct operating wavelengths hl, h2,h3,. .. . AN, respectively, and their outputs are assumed to be interference free from each other. The binary data stream is divided into blocks of m binary data bits so that each block constitutes a 2"-12.4.1.
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Papers by Alex Lam