Co k Tas Yayõlõ ú Sistemleri ú ¸in Yeni Bir Yayma Dizisi A New Spreading Code for Multi-carrier Spread Spectrum Systems

We present a new spreading code for wireless multi-carrier spread spectrum (MCSS) communication systems that is ro- bust to noise and intentional jammers. In wireless communica- tions, linear time-varying channel spreads the transmitted sig- nal in both time and frequency due to multi-path and Doppler effects. Thus, the modeling and estimation of the communica- tion channel is an important task at the received end. We show that time-frequency analysis can be used to model and estimate the channel of MCSS systems. Using the discrete evolutionary transform (DET) of the noisy channel output, we are able to es- timate the spreading function of the channel. Simulations show that the proposed complex and random spreading code helps to increase the channel estimation performance.