Research On Single Carrier Frequency Domain Equalization System Based On Adaptive Transmission

The transmission rate in communication system becomes more and more higher with the needs of multi-media service. But because of the multi-path propagation caused by scattering, reflection and refraction in wireless channel, it proposes a great challenge to the design of broadband communication system. When the signal with different delays and attenuation coefficients arrived at the receiver, because of the multi-path effects, it will generate series ISI (Inter-Symbol Interference) interference. In OFDM (Frequency Division Multiplexing) system, multi-carrier transmission technology can divide the signal stream to some carriers in parallel; the channel in each carrier can be similar to flat-fading channel, so it can counteract the interference of ISI. But the system cost is much higher when the needs of linear range of amplifier are strict which is mainly caused by the faults of OFDM with higher PAR (Peak-to-Average Ratio). In contrast, the SC-FDE (Single Carrier Frequency Domain Equalization) system doesn't have such default, and it has the same complexity with OFDM system, Recenttly, much more attention has focused on it.In conventional wireless communication systems, the transmission parameters of receivers and transmitters, such as, modulation scheme, coding scheme, filtering roll-off factor, launching power, the length of frame, transmission rate are all fixed. So, when designing such a system, the worse condition of channel has to be considerated, which cause much lower utilization of bandwidth. Today, we are in a period with much scarcer frequency spectrum resources available. Such a bad design idea must be changed. With the unceasing explore, research of researchers and continuous improving of hardware condition, the idea of"adaptive transmission"gradually get researchers'heart. Its main idea is monitoring the change of channel and changing the parameters of receivers in real-time based on the quality information of channel, such as SNR (channel signal-to-noise ratio), SINR (Signal to Interference plus Noise Ratio), power consumption, BER (bit error rate). It can improve utilization of bandwidth and increase the robustness and average throughput of system at the same time.Firstly, the characters of Rayleigh channel, description parameters, modeling ways are studed and the channel model used are simulated. Secondly, the ASC- FDE system is studed which is generated by introducing the adaptive transmission technology into SC-FDE system. The key technology in this system is analized, including channel estimation techniques, SNR estimation techiniques, frequency domain equalization techiniques, adaptive transmission techiniques and the design of frame structure, the different algorithms of different key technology are simulated and analized. The suitable algorithms in the ASC-FDE system are chosen based the compromise consideration between the performance of algorithms and the ability of practical application and finish the design of system. Finnaly, dynamic simulation running result of ASC-FDE are given analysis and testify.