EVM based AMC for an OFDM system

Abstract

A conventional OFDM system often poses a stringent linearity requirement to the transmitter, especially the radio-frequency power amplifier (RFPA), to maintain its bit error rate (BER). As a result, the output power from a RFPA is often limited, thus, the communication distance is compromised. With the deployment of WiMAX (IEEE 802.16), which is targeting at the mobile market, the communication distance is a concern. In this project, we propose to use Adaptive Modulation and Coding (AMC) to adaptively control the digital modulation and the output power of a RFPA. When the AMC selects the modulation order with the coding rate to achieve the targeted BER, the output power of a RFPA can be increased as long as its Error Vector Magnitude (EVM) is less than the required. Therefore, the communication distance of an OFDM system could be intelligently extended.