ELECTRICA

A NEW SPREADING CODE FOR MULTI-USER MC-SS COMMUNICATION SYSTEMS

1.

Bahcesehir University, Department of Electrical and Electronics Engineering, Istanbul Turkey

2.

Yeditepe University, Department of Electrical and Electronics Engineering, Istanbul Turkey

3.

Istanbul University, Department of Electrical and Electronics Engineering, Istanbul Turkey

4.

University of Pittsburgh, Department of Electrical and Computer Engineering, Pittsburgh, PA 15261 USA

ELECTRICA 2005; 5: 1411-1417
Read: 730 Downloads: 540 Published: 28 December 2011

Multi-carrier spread spectrum (MCSS) communication systems are able to mitigate the effects of fading, interferences and Doppler frequency shifts as well as to support multiple access schemes. It is possible to get optimum performance from MCSS systems by carefully choosing the spreading sequences. However, due to inter-user interferences, performance degrades as the number of users increases unless the transmission channels are modeled and estimated. In this paper, we present a new spreading sequence obtained from a complex quadratic sequence multiplied by a pseudo random noise sequence, thus exploiting the properties of constant envelope and statistical independence. Our approach is based on the time-frequency characterization of the wireless communication channel by means of discrete evolutionary transform. The properties of the new spreading sequence enables us to estimate the parameters of multi-user channels, both for uplink and downlink transmission cases, and design a receiver that is robust to channel noise, inter-user interference and intentional jammers. The performance of the proposed system is illustrated by simulations.

 

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EISSN 2619-9831