automatic gain control for interoperability in ofdm systems
This paper presents interoperable Automatic Gain Control (AGC) algorithm in wireless Orthogonal Frequency Division Multiplexing (OFDM) system such as WLAN, WMAN, 3G-LTE [1]. We first analyze the method of AGC using received power in general OFDM systems. The analysis will show that the gain value largely fluctuates with presence or structure of signals. This fluctuation of gain is generated by the variation of received signal power that varies with presence of packet. We show how proposed algorithm can reduce the fluctuation of gain value. Results of simulation show that the utilization of proposed algorithm can reduce the fluctuation of gain value considerably. As a result, proposed AGC algorithm that can be used various communication systems can increase bit resolution of received signal because of reduction of gain fluctuation. Especially, OFDM system with high Peak to Average Power Ratio (PAPR) or 16-QAM and 64-QAM modulation schemes for high data rate transmission is sensitive to bit resolution, therefore proposed AGC algorithm supports to keep system performance stable in various communication systems.
interoperability ofdm agc gain fluctuation papr envelope distribution