Resource Allocation Algorithm Research For Air-Ground OFDMA System And FPGA Implementation

The air-ground communication systems are some communications to the use ofhigh-altitude communications platform directly or relay forward communicationsystems. Such systems have important applications in some special circumstances orspecial areas. Orthogonal frequency division multiplexing （OFDM） technique hasmany advantages, such as high spectrum efficiency, resistance to multipathinterference and frequency selective fading, etc. Orthogonal frequency divisionmultiplexing multiple access（OFDMA） technology based on OFDM technology wasused in air-ground communication systems, it will greatly improve the system capacityand user quality of service. In addition, the application of OFDMA access technologycan be more flexible selection of the appropriate algorithm for the optimal allocation ofresources, enhancing the performance of the systems. Adaptive resource allocationalgorithms research for OFDMA systems has been a hot research topic in the field ofcommunication.First, channel characteristics of the air-ground communication system areintroduced; system resource allocation model has been constructed by a multi-usernetwork modeling and analysis. Two improved resource allocation schemes based ongenetic algorithm （GA） and water-filling algorithm have been proposed. The channelstate information （CSI） of the users based on the system model has considered beingresource allocation model inputs. The first algorithm based on the standard geneticalgorithm （SGA）, has been joined the elite individual retention policies for improvingthe convergence of the algorithm and the strategy of maintaining proportional fairnessfor proportional fairness among users. The second algorithm is based on water-fillingalgorithm, first, it has used the proportional fair strategy for subcarrier allocation, andthen it has used a separate water-filling algorithm for each user to power allocation.Finally, two algorithms simulation results was given with using MATLAB software,and compared with standard genetic algorithm simulation results.Next, the standard genetic algorithm （SGA） is designed use Field ProgrammableGate Array （FPGA） based on modular design. First, the FPGA’s internal structure andthe basic design process is introduced, to Altera Cyclone III series chips as an example.Secondly algorithm of hardware and software environment is introduced. The software is Altera’s integrated development software, the Quartus II; development board is SOC/family experiment KX₇C series of experimental development system. Then the SGAis divided some modules, such as fitness calculation module, control module,population initialization module, selection module, crossover and mutation module,data channel selection module, the random number generator module, and memorymodule, etc. Subsequently, the functional and timing simulation for each module isintroduced. Finally the top-level module is downloaded to the Altera Cyclone III-EP3C40Q240C8N chip, and program is run out and debugged on the developmentboard. Finally the results are analyzed.