Performance Analysis of Bit Error Rate by using Different Fading Path Channels in LDPC based OFDM System
Abstract
The OFDM technique can be implemented using Low Density Parity Check (LDPC) Codes because of their ability to reaching near Shannon limit performance. In this work we are presenting the effect of Bit Error Rate (BER) with Signal to Noise Ratio (SNR) in OFDM system which is based on LDPC over Additive White Gaussian Noise (AWGN), Rician and Rayliegh Fading Channel using MATLAB. The results are then compared with Conventional based OFDM system. The OFDM communication is very much inspired from the channel frequencies over the network. In such a network some kind of orthogonal distortion occurs over the channel called Inter Carrier Interference.
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Introduction
Orthogonal frequency division multiplexing (OFDM) is a digital multicarrier modulation technique. It seems to be an attractive choice for fourth generation (4G) wireless communication systems. The multicarrier technique can be implemented in multiple ways, including vector coding and OFDM [1]. OFDM offers high spectral efficiency, immunity to the multipath delay; low inter symbol interference (ISI), immunity to frequency selective fading and high power efficiency. Due to these advantages OFDM is chosen in high data rate communication systems such as Digital Video Broadcasting (DVB) and based mobile worldwide interoperability for microwave access (mobile Wi-MAX). However OFDM system suffers from serious problem of high PAPR. In OFDM system output is superposition of multiple sub-carriers. In this case, some instantaneous power output may increase to a large extent and may become far higher than the mean power of the system. To transmit signals with such high PAPR, it requires power amplifiers with very high power scope. These kinds of amplifiers are very expensive and have low efficiency.
Conclusion
Using MATLAB Figure 1 shows the BER Vs SNR of the LDPC Based OFDM system in RICIAN channel using QAM modulation scheme. This figure shows the relationship between BER and SNR. The values of SNR are from – 30 db to 0 db and the scale of SNR is linear. The values of BER are from 0.1 to 0.5 and scale of BER is log