Designing DSSS Communication Systems

Abstract

The purpose of our project is to design DSSS communication systems, in which many users will communicate with each other in the same channel, without affecting each other. The main aim of the project was to design a system using various available code sequences, and analyse their performance. The present explosion in digital communications and multi-user wireless cellular networks has urged a demand for more effective modulation methods, utilizing the available frequency spectrum more efficiently. To accommodate a large number of users sharing the same available frequency band, our requirement is the availability of large families of spreading sequences with excellent Autocorrelation and Cross-Correlation properties. These spreading sequences also pose the property of orthogonality. And hence these sets of orthogonal basis functions can be used to extend capacity by exploiting all available degrees of freedom (e.g. temporal, frequency and spatial dimensions) or can be used to employ orthogonal multi-code operation in parallel, such as used in the latest Wide-band Code Division Multiple Access modulation standards by employing sets of orthogonal codes to improve the overall data throughput capacity.