초록 ▼

The specification relates to a method and apparatus supporting multiple access, bi-directional data and multimedia transfer described over a hybrid fiber/coax (HFC) network, though applicable to transmissions over other media as well. The protocol associated with the present invention supports downs

The specification relates to a method and apparatus supporting multiple access, bi-directional data and multimedia transfer described over a hybrid fiber/coax (HFC) network, though applicable to transmissions over other media as well. The protocol associated with the present invention supports downstream broadcast transmission from headend to cable modem, and also provides for allocation of bandwidth for cable modems to transmit back to the headend. The protocol supports different access modes such as STM, ATM, and VL; within each subframe of a subframe/frame/masterframe structure. The protocol is utilized over a system which provides for forward error correction (FEC) and scrambling/descrambling, while eliminating the deleterious effects on the error correcting capability of the FEC due to the bit error spreading associated with a scrambling/descrambling function. The protocol adapts to changing demands for a mix of circuit and packet mode applications and allocates upstream and downstream bandwidth in response to the a variety of bursty and isochronous traffic sources.

대표청구항 ▼

1. A method for transmission of scrambled and forward error corrected data from a transmitter to a receiver over a transmission medium, said method comprising the steps of:(A) scrambling data to be transmitted to produce scrambled data, wherein said scrambled data has a given number of bit transitio

1. A method for transmission of scrambled and forward error corrected data from a transmitter to a receiver over a transmission medium, said method comprising the steps of:(A) scrambling data to be transmitted to produce scrambled data, wherein said scrambled data has a given number of bit transitions to maintain synchronization between said transmitter and said receiver; (B) applying a forward error correction (FEC) scheme to said scrambled data, said scheme determining an FEC syndrome; said step of applying an FEC scheme to said scrambled data further comprising: classifying each byte of said scrambled data into a first group and a second group, said first group corresponding to said scrambled data being odd numbered bytes, said second group corresponding to said scrambled data being even numbered bytes; computing a first FEC number from said scrambled data of said first group; computing a second FEC number from said scrambled data of said second group; byte-wise interleaving said first FEC number and said second FEC number; and appending said first FEC number and said second FEC number to said scrambled data, said scrambled data order remaining undisturbed by application of said FEC scheme; and (C) transmitting said scrambled data and said FEC syndrome to said receiver for application at said receiver, wherein the order of applying said FEC scheme subsequent to scrambling said data to be transmitted prevents bit error spreading.