BER and PAPR Reduction of IEEE 802.11a Using RS Coding and SLM Technique

Abstract

The IEEE 802.11a Wireless Networks gains its popularity and fame by providing the users with several advantages in accessing information. This standard provides higher throughput on satisfactory distances using the 5 GHz frequency band. The band has up to 24 non-overlapping channels (depending on the country’s spectrum regulative) which is an advantage over existing 2.4 GHz band where it has only 3 such channels. Hence, the IEEE 802.11a has less Co-Channel Interference than its concurrent systems. Also the numbers of electronic devices operating in this band are very less. 802.11a uses Orthogonal Frequency Division Multiplexing (OFDM), a new encoding scheme that offers benefits over spread spectrum in channel availability and data rate by using multiband channel bandwidth for more number of users. Thus the channel availability becomes significant because more number of independent channels are available and makes the wireless network more scalable. Further the high data rate is accomplished by combining many lower-speed subcarriers to create one high-speed channel. As data spread over large number of subcarriers OFDM has large PAPR. This may saturate the power amplifier at the transmitter that means the maximum output power of the amplifier will limit the peak amplitude of the signal and this effect will produce interference both within the OFDM band and in adjacent frequency bands. Where in band interference will increase Inter Symbol Interference (ISI) while out band interference will result in high Adjacent Channel Interference (ACI). These are undesirable phenomena in communication system. In this thesis, the performance analysis of IEEE 802.11a has been carried out for different fading environments. Doppler shift, Cyclic Prefix (CP) and Forward Error Correction Code (FEC) are the other parameters which had been analysed in this thesis too. It has been observed that Reed Solomon code (RS) has gain of 1 dB over mandatory coding scheme (i.e. Convolution Code (CC)). Further the PAPR for IEEE 802.11a has been analysed and reduced using Selective Mapping technique (SLM).