RTL Implementation Of OFDM System

In wireless OFDM applications, since the radio channel is frequency selective and time-varying, a dynamic estimation of channel must be achieved before the demodulation of the received OFDM signals. As an effective approach for solving the channel estimation problems, the pilot-assisted channel estimation technique has received considerable attention in recent years. A channel estimation method based on comb type pilot arrangement is studied through different algorithms for both estimating channel at pilot frequencies and interpolating the channel. The estimation of channel at pilot frequencies is based on LS and LMS while the channel interpolation is accomplished by linear interpolation, second order interpolation, time domain interpolation and etc. Generally speaking, the more effective channel interpolation algorithm, the more complex hardware implementation. In this thesis, two novel channel interpolation methods based on angle interpolation are presented. Linear angle interpolation gains better performance than linear interpolation, also, second order angle interpolation is more outstanding than second order interpolation. Besides, these two algorithms are easy to be realized by hardware.FFT processor is another key component in the implementation of wideband OFDM systems. The design of complex multiplier is crucial to meet the fast, real-time processing demand in a mobile environment. The structure of complex multiplier derived from CODIC algorithm just satisfies the requirements. In this thesis, an improved structure of complex multiplier is proposed and implemented by FPGA. This new method saves more hardware resources than CORDIC in some applications such as WLAN 802.11.