Interference and SIR in DS-CDMA networks : a simulation study, 1999

Item — Call Number: MU Thesis Sha

Identifier: b2159654

Staff Only

Scope and Contents

From the Collection:

The collection consists of theses written by students enrolled in the Monmouth College and Monmouth University graduate Electronic Engineering programs. The holdings are bound print documents that were submitted in partial fulfillment of requirements for the Master of Science degree.

Dates

Creation: 1999

Creator

Shah, Manan (Author, Person)
Prabhakar, Nannimanglam (Thesis advisor, Person)

Conditions Governing Access

All analog collection holdings are limited to library use only.

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Extent

1 Items (print book) : 44 pages ; 8.5 x 11.0 inches (28 cm).

Language of Materials

English

Additional Description

Abstract

Code division multiple access (CDMA) is a "spread spectrum" technology, which means that it spreads the information contained in a particular signal of interest over a much greater bandwidth than the original signal. In a CDMA spread spectrum system, simultaneous reception of multiple signals is possible through the use of orthogonal codes. This significantly increases the system performance in addition to providing security for the user data.

The objective of this simulation project is to characterize the multiple-access inteference in Direct Sequence CDMA (DS-CDMA). We approach the problem by proposing a general multiple signal communication modes where N users transmit and receive data on the same frequency range thus saving bandwidth. We study the protocol for multiple signal transmission by use of orthogonal codes to code the data. Concentration is made on forward channel (from Base station to Mobile station). We attempt to study the effect of user load on the system performance and probability of error. We also attempt to study the effect of phase errors that might occur due to multiple path transmission of data and the effect of additive noise on the modulated signal during transmission. The amplitude of the interfering signal is changed and its effect on the output is studied. We use Walsh Hadamard sequences to generate the pseudo-noise (PN) code; these have the advantage of being orthogonal, thereby eliminating any multi-access interference.

An analysis of the simulation shows that as we increase the phase delay, signal to Interference ratio (SIR) decreases rapidly. As the number of users increases, SIR ratio decreases; but it does not decrease very rapidly if synchronization is maintained. In order to get better SIR ratio we have to use larger pseudo-noise sequence.

Partial Contents

1. Abstract -- 2. Introduction -- 3. Multiple access -- 4. Spread spectrum -- 5. Pseudo-noise generator -- 6. Orthogonal function -- 7. Simulation -- 8. Conclusion -- Appendix A. Graphs -- Appendix B. Simulation code -- References.