An efficient technique for merging transmissions in a multicarrier context

A well-known allocation technique, called bit-loading, results in the creation of tone maps which define, for each subcarrier on a particular transmission path, the appropriate constellation that has to be applied based on a link quality criterion. If this technique allows to efficiently optimize point-to-point transmissions in the network, it poses several challenges when transmitting the same information to multiple stations, i.e. Multicast/Broadcast data streams. In this paper, an efficient algorithm that smartly merges similar tone maps is presented, in order to better handle Multicast/Broadcast data streams. The demonstration of its efficiency will be made placing ourselves in the context of power line communications networks following the HPAV specification. However, our merging principle itself remains applicable to any system associating multicarrier modulations and bit-loading algorithms, as it could be in an indoor wireless environment.