基于梳状导频的OFDM分组自适应比特装载与功率控制

无线通信环境中信道信息(ChannelStateInformation,CSI)随时间变化明显,需要不断地更新自适应比特装载和功率控制的策略。现有的OFDM自适应比特装载方法需要大量的信令来传递当前比特装载的策略,不适用于无线通信的应用环境。为此,本文针对OFDM系统的特征提出了一种利用插入梳状导频的信道估计得到的带有误差的信道信息,来完成自适应比特装载的算法。首先把OFDM子载波进行分组,然后利用基于梳状导频的信道估计对信道时变进行跟踪,使用即时获得的CS完成自适应比特装载算法。仿真实验证明,在保证算法简单、实用及保证要求的误码率(BER)性能的情况下,信道信令的开销低于传统算法的10%。

Grouped Adaptive Bit Loading and Power Control Based on Comb-pilots in OFDM

In wireless communications, channel state information (CSI) is obviously time-varying and so the adaptive policy has to be updated continuously.The current OFDM adaptive bit loading methods which need massive signings to transfer the bit loading policy are not adaptive to the wireless communications. For OFDM systems, this paper proposes a method for adaptive bit loading under the imperfect CSI get by the channel estimation based on the comb-pilots insertion. The method firstly divides the subcarriers into a few groups and then gets CSI based on the channel estimations by comb-pilots to track the time-varying channel. Then,it implements the new adaptive bit loading algorithm using the instantaneous CSI in OFDM. Simulation result shows that the method just needs less 10% channel signings than current algorithms while guaranteeing the simplicity and practicality of algorithm and the required BER (Bit Error Rate).