ABSTRACT
This chapter discusses how information is transmitted reliably and efficiently over an optical link through the application of modulation and error-correction coding. Statistical models of modulations commonly used in near-Earth laser communications are described. The limiting information rates of various modulations and models are provided. An example, the Poisson pulse-position modulation channel, is used to illustrate trade-offs commonly encountered in the design of a coded modulation. Methods to mitigate fading and jitter through coding and related signal processing techniques are described. Several classes of codes and trade-offs between them are discussed. Examples of gains achievable with the codes are provided.
