Hybrid Spread Spectrum Techniques for Cell Phone

In addition to frequency hopping and direct sequence, spread spectrum multiple access techniques, there are several other combinations of hybrids that offer advantages in the field of cellular mobile communication systems. The available broadband spectrum is divided into multiple sub-spectra with narrower bandwidth. Frequency hopping multiple access (FHMAT) consists of a direct sequence modulated signal whose center frequency periodically pseudo randomly hops. In this paper, we propose a hybrid spectrum spreading scheme using TDCDMA (Time Division Code Division Multiple Access) scheme which assign different spreading codes to different cells in eac.

The idea of ​​this project is to study a variety of spread spectrum techniques. These techniques include two processes: direct sequence spread spectrum and frequency hopping spread spectrum. Both technologies are simulated with software called MATLAB. In addition, we will briefly explain the multi-access possibility of spectrum spreading. In this project we will handle spread spectrum implementation using direct sequence spread spectrum and frequency hopping spread spectrum techniques. Spread spectrum is a new communication format. It provides a noninterfering network that prevents any interference. By not allowing interference and interference, it helps to make the channel resistant. Spectrum spreading and its techniques are described in detail in a later chapter.

Direct sequence spread spectrum (DSSS) is a modulation technique used in telecommunications. In this modulation technique, as with other spread spectrum techniques, the transmitted signal occupies a wider bandwidth than the modulated information signal. In spread spectrum modulation, the carrier signal appears in the full bandwidth (spectrum) of the transmit frequency of the device, this is a continuous string pseudo noise (PN) code symbol called "Spread Ø" in DSSS, the sine wave is pseudo randomly phase And modulated. "Each of these chips has a much shorter duration than the information bits, in fact the information signal is modulated by a faster chip sequence, so the chip rate is much higher than the bit rate of the information signal is.

Spread spectrum is a statistical modulation technique used to increase the available channel bandwidth. In this paper, we focus on the spread spectrum model. That is, two users use MATLAB for BPSK modulation of actual spread spectrum. In addition, simple studies on changes and interpretations of these observations are under way. Here we will change the SNR value of the AWGN module in the block diagram of the given spread spectrum model and observe and explain the change.