Patent ID: 7099268

Claim:
An orthogonal frequency division multiplex modem circuit which uses a plurality of subcarriers for communication, and transmits and receives a plurality of communication channels, each of said plurality of communication channels is capable of transmitting and receiving different types of communications from the other of said plurality of communication channels, where each type of communications has different bit rates, QoS (Quality of Service) and priorities which are caused by said different types of communications, said plurality of subcarriers are divided into groups and each of said groups are assigned one group per each of the plurality of communication channels, respectively, said orthogonal frequency division multiplex modem circuit includes in a transmitting side, means for randomizing alignment of the respective subcarriers on a frequency axis, and in a receiving side, means for de-randomizing a signal where the alignment is randomized, and wherein the processing for randomizing positions of the respective subcarriers is updated every symbol.