A NEW PROTOCOL TO DESIGN CELLULAR SYSTEMS WITH VARIABLE SPREADING FACTORS
Main Article Content
Abstract
The emerging M-commerce (mobile +e-commerce) needs more support in operating systems in order to be successful over a wireless environment. The system needs to support a seamlessintegrati n to support voice, audio and conventional data. It should also support many users with guaranteed quality. In this paper, a new effective design protocol for Code Division Multiple Access(CDMA) mobile systems with Variable Spreading Factor (VSF) is presented, such that various Quality of Service (QoS) based on different traffic types can be provided. Increasing spreading factors can benefit the system because it will increase the desired signal strength linearly. The measured Bit Error Rate (BER) can be reduced 75 times with a long spreading factor. By taking advantage of this benefit, switching the spreading factors dynamically is proposed, based on the current load with multimedia traffic.These proposals are implemented in mobile and base stations, and the system performance measured. The results indicated that the proposed system can always maintain a desired quality forall voice connections.
Article Details
How to Cite
Publication Dates
References
Adachi, F., Sawahashi, M., and Okawa, K.. (1997), Three structured generation of orthogonal spreading codes with different blength for forward link Ds-CDMA mobile, Elec. Lett. Vol. 33, no.1, pp 27-28, Jan.
Akyildiz, 1.. Levine, D., and Joe, I., (1999), A slotted CDMA protocol with BER scheduling for wireless multimedia networks, IEEE/ACM Transaction on networking. Vol. 7, no. 2, pp. 146- 157.
Choi. S. and Shin, K. Uplink CDMA systems with diverse QoS Guarantees for heterogeneous traffic. MOBICOM'97, Budapest. pp. 120-130.
Frenger, P. Orten, P. and Ottosson, T. (1999), Code-spread CDMA with interference cancellation,IEEE Journal on Selected areas in communications, vol.17, no12, pp.2090-2095.
Fukumasa, H., Kohno, R., and Imai. H., (1994), Design of PN sequences with good odd and even correlation properties for DS/CDMA, IEEE Journal on Selected areas in communications, vol.12.no 5, pp.828-836.
Lops, M.. Ricci, G., and Tulino, A., (1998), Narrow-band interference suppression in multiuser CDMA systems", IEEE Transaction on communications, vol.46, no9, pp.1163-1175.
Oh. S., and Wasserman, K., (1999), Dynemic spreading gain control in multimedia CDMA networks, IEEE Journal on Selected areas in communications, vol.17, no5. pp.918-927.
Stavroulakis, P., (2000), Third generation mobile telecommunication systems. Springer.
Technical specification Group, (1999). Spreading and modulation, 3G TS 25.223. V 3.1.0. Dec.