The Study Of The Identification And Adaptive Modulation Techniques For OFDM Signal

In this paper, the techniques of the OFDM signal identification and adaptive OFDM scheme are studied. Firstly, principles of cognitive radio technology are introduced, including its background, development and key techniques. Secondly, discriminating OFDM from single-carrier modulations is studied and a new method, which can be applied to both AWGN channel and multipath Rayleigh fading channel, is proposed. Thirdly, the method of adaptive bit and power allocation in OFDM is introduced, and a novel algorithm, which is agile, low complexity and close to optimum performance is proposed. Finally a sub-optimum method of identifying the sub-carrier modulation type of the OFDM signal, which based on maximum-likelihood, is studied, and is implemented in cognitive radio software simulation platform.