Rate control of channels on a time division multiplex bus

A method for transmitting at least a first channel of digital data in a first direction over a bidirectional time division multiplex bus and controlling transmission of at least a second channel of digital data in the opposite direction, where each of said channels comprises a sequence of data bytes, in each direction of transmission said bus carries a bit stream comprising sequential digital frames, each of said frames is divided into a plurality of sequential time slots, each of said time slots comprises a sequence of data byte transfer opportunities each of which is interleaved with respective data byte transfer opportunities of the remaining time slots, each of said time slots has the same predetermined bandwidth b.sub.t, the bandwidth of each of said channels may be other than n times b.sub.t, and n is a positive integer, said method comprising the steps of:

• assigning said first channel to a selected number m of said time slots in said first direction, where m=n, b.sub.c is the bandwidth of said first channel, and the relationship between b.sub.c and b.sub.t is given by the expression (n-1)b.sub.t <b.sub.c .mu.nb.sub.t ;
• generating a validity identification signal for each data byte transfer opportunity in said selected time slots in said first direction;
• transmitting sequential bytes of digital data from said channel over said bus during data byte transfer opportunities in said selected m time slots in said first direction;
• transmitting a first digital state as said validity identification signal substantially simultaneously with each data byte from said channel carried during data byte transfer opportunities by said bus in said selected m time slots in said first direction;
• transmitting a second digital state as said validity identification signal substantially simultaneously with each remaining data byte transfer opportunities in said bus in said selected m time slots in said first direction;
• generating a bandwidth request signal for each data byte transfer opportunity in time slots in said first direction;
• transmitting a first digital state as said bandwidth request signal substantially simultaneously with enough data byte transfer opportunities in said bus in said selected m time slots in said first direction so that sufficient bandwidth is provided in said opposite direction to accommodate said second channel;
• and
• transmitting a second digital state as said bandwidth request signal substantially simultaneously with each remaining data byte transfer opportunity in said bus in said selected m time slots in said first direction.

A terminal for transmitting at least one channel of digital data over a time division multiplex bus, where said channel comprises a sequence of data bytes, said bus carries a bit stream comprising sequential digital frames, each of said frames is divided into a plurality of sequential time slots, each of said time slots comprises a sequence of data byte transfer opportunities each of which is interleaved with respective data byte transfer opportunities of the remaining time slots, each of said time slots has the same predetermined bandwidth b.sub.t, the bandwidth of said channel may be other than n times b.sub.t, and n is a positive integer, said terminal comprising:

• means for assigning said channel to a selected number m of said time slots, where m=n, b.sub.c is the bandwidth of said channel, and the relationship between b.sub.c and b.sub.t is given by the expression (n-1)b.sub.t <b.sub.c .mu.nb.sub.t ;
• means for generating a validity identification signal for each data byte transfer opportunity in said selected time slots;
• means for transmitting sequential bytes of digital data from said channel over said bus during data byte transfer opportunities in said selected m time slots;
• means for transmitting a first digital state as said validity identification signal substantially simultaneously with each data byte from said channel carried during data byte transfer opportunities by said bus in said selected m time slots;
• and
• means for transmitting a second digital state as said validity identification signal substantially simultaneously with each remaining data byte transfer opportunities in said bus in said selected m time slots.

A system for transmitting at least a first channel of digital data in a first direction over a bidirectional time division multiplex bus and controlling transmission of at least a second channel of digital data in the opposite direction, where each of said channels comprises a sequence of data bytes, in each direction of transmission said bus carries a bit stream comprising sequential digital frames, each of said frames is divided into a plurality of sequential time slots, each of said time slots comprises a sequence of data byte transfer opportunities each of which is interleaved with respective data byte transfer opportunities of the remaining time slots, each of said time slots has the same predetermined bandwidth b.sub.t, the bandwidth of each of said channels may be other than n times b.sub.t, and n is a positive integer, said method comprising the steps of:

• means for assigning said first channel to a selected number m of said time slots in said first direction, where m=n, b.sub.c is the bandwidth of said first channel and the relationship between b.sub.c and b.sub.t is given by the expression (n-1)b.sub.t <b.sub.c .mu.nb.sub.t ;
• means for generating a validity identification signal for each data byte transfer opportunity in said selected time slots in said first direction;
• means for transmitting sequential bytes of digital data from said channel over said bus during data byte transfer opportunities in said selected m time slots in said first direction;
• means for transmitting a first digital state as said validity identification signal substantially simultaneously with each data byte from said channel carried during data byte transfer opportunities by said bus in said selected m time slots in said first direction;
• means for transmitting a second digital state as said validity identification signal substantially simultaneously with each remaining data byte transfer opportunities in said bus in said selected m time slots in said first direction;
• means for generating a bandwidth request signal for each data byte transfer opportunity in time slots in said first direction;
• means for transmitting a first digital state as said bandwidth request signal substantially simultaneously with enough data byte transfer opportunities in said bus in said selected m time slots in said first direction so that sufficient bandwidth is provided in said opposite direction to accommodate said second channel;
• and
• means for transmitting a second digital state as said bandwidth request signal substantially simultaneously with each remaining data byte transfer opportunity in said bus in said selected m time slots in said first direction.