A Review on BER Performance Analysis and PAPR Mitigation in MIMO OFDM Systems

Abstract

New Technologies and thereby new applications are emerging not just in wired environment but also in the wireless arena. The next generation mobile systems are expected to provide a substantially high data rate to meet the requirements of future high performance multimedia applications. The minimum target data rate for the 4G system is expected to be at 10-20 Mbps and at least 2 Mbps in the moving vehicles. To provide such a high data rate with high spectral efficiency, a new modulation scheme is to be used. A promising modulation technique that is increasingly being considered for adoption by 4G community is a multi-carrier system. Existing 3G systems uses single carrier modulation technique whereas a multicarrier system which is otherwise known as Multicarrier Modulation (MCM) / Discrete Multi-tone Technique (DMT) sends a high speed data stream by splitting it up to multiple lower speed stream and transmitting it over a lower bandwidth subcarriers in parallel. Multi-Carrier system is a multiple access scheme used in OFDM-based telecommunication systems, allowing the system to support multiple users at the same time. Generally in a multi carrier system utilizes each user symbol in the frequency domain. That is, each user symbol is carried over multiple parallel subcarriers, but it is phase shifted (typically 0 or 180 degrees) according to a carrier value. The values differ per subcarrier and per user. The receiver combines all subcarrier signals, by weighing these to compensate varying signal strengths and undo the code shift. The receiver can separate signals of different users, because these have different (e.g. orthogonal) code values. Since each data symbol occupies a much wider bandwidth (in hertz) than the data rate (in bit/s), a signal-to-noise-plus-interference ratio (if defined as signal power divided by total noise plus interference power in the entire transmission band) of less than 0 dB is feasible. High peak to average power ratio (PAPR) is the major drawback of multicarrier transmission. Various approaches were had been proposed previously to reduce this factor. Though the main problem associated with these conventional approaches is they concentrated on reducing the number of carriers to reduce this PAPR but it increased the total amount the power required to transmit the power and also increased the complexity as well as loss of bit error rate. In this paper literature survey is carried out for BER Performance Analysis and PAPR reduction techniques.