Multiuser OFDM Adaptive Resource Allocation Scheme In Ka-band Satellite Communication Channel

In this paper, cooperation projects China Institute of Aerospace Technology Group 504 Fifth Institute in Ka-band satellite communication channel to study the multi-user OFDM adaptive power and bit allocation techniques.Compared to traditional satellite communications, Ka band satellite communication of this study have available a wide bandwidth communications capacity, strong anti-jamming capability, privacy is good. Therefore, military communications and commercial communications have been widely used. However, Ka-band mobile satellite communications due to the higher frequency band, so the band is susceptible to rain attenuation, atmospheric absorption, flicker and cloud attenuation factors such as weather, coupled with multi-path effects and shadowing satellite communications exist, must adopt the necessary measures to reduce the impact of these negative factors. OFDM technology because of its simple structure, high spectrum efficiency, the characteristics of the time and frequency selective channel anti-degeneration, with adaptive technology can change the modulation, transmit power and other parameters according to changes in the channel in order to maximize send information to improve communication resource utilization and system throughput of the system. Therefore, the combination of adaptive transmission technology and OFDM technology can effectively improve the transmission performance of the system.Firstiy,completed building Ka-band mobile satellite communication channel model to simulate the Ka-band transmission performance under different weather conditions, and carried out a computer simulation analysis. Secondly, the establishment of adaptive resource allocation for LDPC codes and Kite code multiuser OFDM systems under the channel for user data transmission rate and the target BER certain conditions, allowing the system to minimize the total transmit power of the principle of selecting the joint subcarrier, adaptive power and bit allocation algorithms. Performance simulation, and results in a slight shadow under conditions suitable for kite code under the shadow of moderate and severe conditions suitable for standard conclusion ccsds LDPC codes. Finally, the algorithm is added constraints, and compares the performance constraints and there are no constraints joint resource allocation scheme. Conclusion displayed in ensuring the transmission rate of each user premise, there is no constraint constraint performance and performance very close, this can ensure the transmission performance of the channel without the expense of an individual user to lower quality of service.Although the paper puts forward some conclusions, but there are still areas for improvement, future research can continue further work in this direction. In this article assumes a known sender channel information, so there is no consideration of channel estimation, the next step can be studied. Also in a multi-user resource allocation, we propose adding constraints, but constraints and no deeper study, the next step in this direction as research.