Based On The Key Technologies Of The Dc-ofdm Ultra-wideband Technology

Orthogonal frequency division multiplexing(OFDM) is a promising technique for achieving high bit rates and high reliabilities required for wireless communication. This new technique has gained increased interest for its high bandwidth efficiency and robust performance in multipath dispersive environment. DC-OFDM based UWB technique has been selected as the standard of Information technology—Telecommunications and information exchange between systems of China, it could achieve up to 480Mbps data rates with small transmitting power. However due to the impact of wireless channel, the received signals will be attenuated, in order to demodulate the signals correctly channel estimation must be implemented; besides UWB is very sensitive to frequency offest, since this offest will greatly destory the orthogonality of sub carriers and result in decoder error, thus frequency offest estimation and compensation must be done.Firstly, this paper introduces LS, MMSE algorithm for premables and pilots, and introduces linear, spline, cubic interpolation algorithm for other sub carriers. This paper proposes a joint channel estimation algorithm based on premables and pilot sub carriers, simulation result shows this algorithm could achieve lOdB MSE gain than LS algorithm while the complexity is almost the same as LS.Secondly, this paper introduces the impacts of front-end non-ideal effects and then proposes a pilots based estimation algorithm for residual carrier frequency offest and sampling frequency offest, simulation result shows the MSE could be less than 10-8 when the CFO is 20ppm, SFO is 50ppm and SNR is 10dB.Finally, this paper implements the algorithms mentioned above on Xilinx Virtex-5 LX330FPGA, the synthesis result shows this module could achieve up to 132M clock frequency which is required by UWB systems.