Cellular IS-95 CDMA Forward Link Simulation

Student: Frankie Mak

Supervisor: John Homer

Category: Engineering Thesis Project - Communications

This thesis describes the design and implementation of a Matlab simulated IS-95 CDMA Forward Link system. As cellular wireless communication becomes a worldwide communication standard, it is important in studying how data communications happen in a cellular system.

The result is an IS-95 CDMA Forward Link simulation software, which mimics real-time data communications from a basestation to a cellular unit. The software simulated cellular system structure consists of 3 major components: Transmitter, Communication Channel and Receiver.

The transmitter first codes and pre-processes the user signal prior to transmission. Its interoperations comprise of convolution encoding and repetition, block interleaving, long PN sequence, data scrambling, Walsh coding and quadrature modulation. Then, the transmitting signal goes through the Communication Channel. It is a medium which is between the transmitter and receiver, and is modelled by the impulse response of a multipath fading channel and consists of Addictive White Gaussian Noise (AWGN). Finally, the receiver equalizes, filters, and decodes the received signal to suppress the multipath and noise effects to reproduce the original user signal; by performing processing "complementary to those of the transmitter's modulation processes", the use of a Rake receiver for receiving multipath signals, and a Viterbi decoder for final decoding.

This simulation software allows studies on noise and multipath fading effects in a normal cellular system, and understanding on how interferences can greatly affect the quality of received signal. As a result, the simulation software provides a great tool for investigating techniques on how these effects can be suppressed and will be discussed in the thesis.

With the upcoming of 3rd Generation CDMA cellular systems, the developed simulation model further provides a framework for the study of systems such as CDMA2000 and WCDMA by future thesis students.

Thesis Document (PDF)

Poster Presentation (PDF)