By discussing the concept of system capacity, both in terms of bit per system use and codewords per system use, we investigate the performance of asynchronous DS-CDMA systems with classical as well as chaos-based spreading sequences. Ideal i.i.d. codes, Gold codes and maximum-length codes, are taken as classical cases. Two different approaches are pursued. By means of Montecarlo estimations we first verify that, independently of the capacity defi- nition we use, chaos-based spreading sequence always outperforms conventional ones. Then we concentrate on a system with two users and stochastic spreading sequence that can be investigated in analytical form when codewords per system use are considered. With this we have the opportunity to derive the optimum autocor- relation profile in terms of sequence autocorrelation, showing that it tends to an exponential shape, alternating in sign, characterized by the well-known rate -2+sqrt(3)
Comparison Between Shannon Capacities of Chaos-Based and Conventional Asynchronous DS-CDMA Systems
MAZZINI, Gianluca;SETTI, Gianluca
2002
Abstract
By discussing the concept of system capacity, both in terms of bit per system use and codewords per system use, we investigate the performance of asynchronous DS-CDMA systems with classical as well as chaos-based spreading sequences. Ideal i.i.d. codes, Gold codes and maximum-length codes, are taken as classical cases. Two different approaches are pursued. By means of Montecarlo estimations we first verify that, independently of the capacity defi- nition we use, chaos-based spreading sequence always outperforms conventional ones. Then we concentrate on a system with two users and stochastic spreading sequence that can be investigated in analytical form when codewords per system use are considered. With this we have the opportunity to derive the optimum autocor- relation profile in terms of sequence autocorrelation, showing that it tends to an exponential shape, alternating in sign, characterized by the well-known rate -2+sqrt(3)I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
