| Recently, with the tendency of broadbandlization, personalization and mobilelization in wireless communications, a series of new techniques, such as Smart Antenna, Software Defined Radio, MIMO space-time code, will be employed in future wireless communications systems. Baseband process, which is one of the key technologies of modern wireless communication systems, is regarded as a great challenge for its realization and manufacture. A baseband adaptive coding and modulation system based on FPGA is designed and realized in this thesis. It is featured with high data rate, modularization and open architecture, and can meet the requirement of the link adaptation of MIMO-OFDM system.Adaptive transmission is a technique which could increase transmission quality and rate efficiently. And in the adaptive transmission system, Adaptive Modulation and Coding (AMC) is the techniques that interest people a lot. The main concept of AMC is that high order modulation and low coding rate can be used to boost up the average spectral efficiency when the channel state is perfect. And low modulation order and high coding rate can be used to enhance the error protection when the channel state is bad. In this paper, with the constraint of customer's SIINR which leads to different bit error rate (BER), we choose different order of modulation depend on the basis of IEEE802.16e PHY, a link adaptive algorithm based on gliding window is proposed. The simulation results show that the BER and spectral efficiency can be much better compared with fixed modulation and coding.We suggest a simplified algorithm for FPGA implementation based on the AMC, and the test of our system is independent with the other parts of the communication system due to the imbedded processor, NIOS II. The last test result shows that our system can give right response to different channel state information. In our algorithm, we divide the decoding block into many sub-blocks, which can save the hardware resources. |
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