Abstract

The next generation of mobile networks is anticipated to support real-

time multimedia applications with diverse classes of traffic and bandwidth necessities.

The present Wireless broadband (WIBRO) uses Orthogonal Frequency Division Multiple

Access system with time division duplex mode, employing asymmetric slot allocation

between uplink and downlink, is a fine solution for mixed realistic traffic. Further it has

fascinated broad attention amongst researcher community as a most promising candidate

for multiple access in 4G mobile communication systems. However due to increase in

growth of Internet, multimedia and broadband services and also iniquitous channel

environments, demands a highly proficient multiple access techniques. To support this

asymmetric traffic, WIBRO uses Time Division Duplexing (TDD) techniques which

dynamically varying the number of slots in uplink and downlink. However using of

IFFT/FFT in OFDMA results in poor signal to noise ratio in an additive white Gaussian

noise medium whose characteristics varies from time to time. To overcome this, a method

of implementing discrete wavelet transforms is used in place of FFT which improves the

overall performance of the system. The simulation result shows that a Signal to Noise

Ratio (SNR) is improved for a given AWGN channel and also it brings down the Bit Error

Rate (BER) to acceptable limit. We also analyze the effect of change in distance ratio on

BER.