A novel Bit and Power allocation scheme for OFDM system over the low voltage power line

Bit and Power allocation in adaptive orthogonal frequency division multiplexing (OFDM) systems is a crucial technique to improve spectral efficiency. Bit and power allocation based on Water-filling algorithm can obtain optimal solution in theory. Due to the modulation manner and actual integer programming requirement, optimal results of bit and power allocation can not be obtained. Cloud Particle Swarm Optimization (CPSO) algorithm is proposed in this paper. A novel evolutionary mode is given using uncertain property of cloud model to improve diversity of population and overcome the shortcoming of running into local minimum in Particle Swarm Optimization (PSO) algorithm, which can realize the balance between exploration and exploitation in search space. Dynamic reducing search space in evolutional process can improve convergence speed of algorithm proposed, accordingly the problem of bit allocation maximizing data rate under the power and bit error rate constraints over the distribution network is solved in CPSO. Numeral results demonstrate the performance of proposed algorithm is the equivalence to bit adding algorithm, accompany with reducing calculation time. At the same transmission rate the savable power in CPSO algorithm is 4.7-14.8 dBm comparing with the Water-filling algorithm.