Optimal frame arrangement for multiplexing a plurality of subchannels onto a fixed rate channel

摘要

In order to multiplex a plurality of various rate subchannels onto a fixed rate channel, a frame structure is defined consisting of j tuples of bits. Some of the tuples are i bits long and some are less than i, the sum of the bits less than i in these tuples being equal to k where k is greater than or equal to zero. The total number of bits per frame is thus equal to ij-k where i, j and k are mathematically determined as a function of the rates of the subchannels and the rate of the fixed channel. In one tuple of i bits in each frame, all bits are set ZERO. In each other tuple, the last bit is set ONE. Framing is detected by monitoring for a ONE followed by i ZEROes a pattern which cannot occur elsewhere in the frame regardless of the data. This frame arrangement can yield shorter frames than the frame structure disclosed in U.S. Pat. No. 4,617,658, thus decreasing reframe time.