Study On Application Of Adaptive OFDM Over Wireless And Low Voltage Power Line

As a promising candidate technology of the physical layer for future wide band high-data-rate wireless and wire communications, OFDM has invoked a popular research interest in recent years. The adaptive OFDM technology can enhance the performance and can conquer the technology vulnerability. The successful application of the adaptive OFDM technology is to be supported from two research aspects: to provide channel estimation nicely and in time and to give the algorithm with which power and modulation can be adaptively allocated. Those are the two technological channels we follow in this paper.For the former, in this paper we studied the character of low voltage power line. We discussed the model of this channel. And we built the channel mode for emulation approximately. Form those we brought forward three channel estimation algorithms. One is the algorithm containing channel monitor has the best identification. The other is the algorithm based on blind channel has the least spending. The last one is the algorithm containing pilot tone has the character of the other two.For the later, in this paper we study in the services of fixed rated and variable rated. For the fixed rated service, we studied two kinds of adaptive allocating algorithms. Modulation mode and transmitting power can be adaptively allocated to minimize the total transmitting power for a fixed total bits number to be transmitted and with a given QoS (BER) being satisfied. For the variable rated we studied one kind of algorithm. And transmitting power can be adaptively allocated to maximize the total transmitted bits number (data throughput) with the total transmitting power constraint and a given QoS (BER) satisfied.