An Improved Low Complexity OFDM Adaptive Bit Power Allocation Method

Adaptive modulation technology can adaptively perform bit and power allocation of subcarriers based on channel state information to improve the transmission performance of the communication system. The traditional Greedy algorithm can achieve optimal bit and power allocation results, but requires a lot of search and sorting during the allocation process. When the number of subcarriers or average number of bits per subcarrier (BPS) is large, the algorithm has high complexity and poor real-time performance. This paper proposes a fast pre-allocation Greedy algorithm based on table lookup. The method establishes a Mapping table between bit allocation and channel gain, realizes bit fast pre-allocation by looking up the table, and then performs iterative optimization allocation based on the Greedy algorithm. The simulation results show that the improved algorithm complexity is greatly reduced, and its bit error performance is similar to the algorithm.