Method and system for digital communications over a fragmented channel

A method of data transmission in a communication system with a transmission channel having transmission sub-channels for transmitting and receiving data, said method comprising:

• allocating two or more first sub-channels to a first terminal wherein one of the first sub-channels is a first primary sub-channel and another one of the first sub-channels is a first secondary sub-channel;
• allocating one or more second sub-channels to a second terminal wherein one of the second sub-channels is the same sub-channel as the first secondary sub-channel and none of the second sub-channels are the same sub-channel as the first primary sub-channel;
• determining if the first primary sub-channel is congested;
• transmitting the data from or receiving the data at the first terminal on the first primary sub-channel if the first primary sub-channel is not congested;
• requesting to send data on the first secondary sub-channel if the first primary sub-channel is congested;
• receiving confirmation that the data may be sent on the first secondary sub-channel;
• and
• transmitting the data from or receiving the data at the first terminal on the first secondary sub-channel.