Adaptive Filter is a part of Digital signal system which is widely used in the modern communication system. The basic application of adaptive filter such as adaptive noise cancellation, channel equalization, system identification and adaptive beam forming. So its implementation is a great deal and that much important field in digital system world. As we know intersymbol interference (ISI) caused by the multipath in band limit frequency selective time dispersion channel distort the transmitted signal. In this paper we are concentrated on modifying the algorithm for the adaptive filter and proposed Modified Variable Step Size Leaky LMS (MVSS-LLMS) which improves the channel estimation in the noisy environment. Here we compare the results of our proposed algorithm with the LMS, RLS and VLLMS and represent that it improves in computational complexity and Bit Error Rate (BER).
Keywords: FPGA, Adaptive Channel Estimation, Adaptive filter, LMS algorithm
In this modern world, communication is the heart of the world. In future, the wireless communication systems will require the high data rate technologies as the demanding of high data rate services such as multimedia, voice etc. There are various modulation techniques that are require for transferring the data. However, for transferring large amount of data some new modulation schemes are requires. One of these new modulation technique is Orthogonal Frequency Division Multiplexing (OFDM) . Therefore, to meet this enormous demand of higher data rate and better coverage of wireless network, one approach is to increase the channel bandwidth over which the radio signal is transmitted. But this approach is not practically possible as the frequency spectrum is very expensive even though by increasing the more complex modulation scheme for improving the throughput it is not used due to increase complexity of radio system and therefore its cost.
MIMO is a technology which improve the performance of the wireless system. MIMO is referred as Multiple Input and Multiple Output i.e a radio links with multiple transmitter antennas and multiple receiver antennas. While transmission of the radio signal from the transmitter antenna through space might be possibilities of signal path effected by reflection, diffraction which result in multipath signal at the receiver antenna which causes interferences and signal fading. MIMO technology multiplexing those multipath signal with advance DSP algorithm in order to improve the bandwidth efficiency and range .
MIMO and OFDM techniques are combined in an attractive method for wireless system, which is refer as MIMO-OFDM . The generalized block diagram of MIMO-OFDM system is shown in figure 1. Least mean square (LMS), Kalman filter, Normalized Least mean square (NLMS) and variable step size LMS (VSSLMS) are some of the numerical computational techniques that have been applied for Noise Cancellation in wireless communication. Along with it, soft...