Concepts for DMT transmission systems with dynamic carrier allocation

Recently, multi-carrier modulation (MCM) systems have become quite popular due to many advantages. One of the most important features of discrete multi-tone (DMT) systems is rate adaptability, and the maximum data rate for an existing loop can be easily determined by means of adaptive loading algorithms. However, time-variant disturbers, e.g. narrow band interference, can lead to a significant performance loss which may be counteracted by decreasing the data rate. Yet dynamic rate adaption is difficult as higher protocol layers are concerned. In this paper we present system concepts for dynamic carrier allocation and seamless rate adaption to mitigate the introduced performance degradation. This includes strategies for bit swapping to maintain the current data rate as well as dynamic rate adaption. Protocols for robust and fast exchange of allocation tables between receiver and transmitter are presented.