| With the continuous development of power line communication, power line is as the most extensive transmission network, there is great market potential in broadband network access, audio signals and other high-speed data transmission. But the power line channel is severe frequency-selective fading characteristics, the orthogonal frequency division multiplexing (OFDM) can be to effectively suppress frequency selective fading in multi-path transmission of channel, so, OFDM has become the preferred program in the power line communication.bit-power can be allocated dynamically under the state of each subchannel for OFDM, namely, the dynamic allocation of subchannels. Adaptive bit-power allocation in OFDM is the key technology that improves the spectrum efficiency and reduces losses of power.For the analysis of the low voltage power line channel characteristic and the theory of OFDM, under the criteria to maximize rate, this studies dynamic allocation of subchannel for OFDM in low-voltage power line. Firstly, three kinds of typical allocation algorithm introduced, for their deficiencies in the simulation, the particle swarm algorithm applied to dynamic allocation of subchannel for OFDM in low-voltage power line, but it is easy to fall into local optimal solution in the allocation process, it is not easy to find the best solution. So, the simplified particle swarm optimization with a variation based on the cloud model proposed, the simulation shows that the improved particle swarm algorithm can save a lot of computing time, complexity is low, compared with the bit addition and the basic particle swarm distribution method. And adding up to the same transmission rate with the bit addition method. The transmission rate of this algorithm is superior with their distribution results in comparison with the other two algorithms.When the transmission rate is same,this algorithm compared with water-filling algorithm and bisection algorithm can save power.
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