Orwell-D: medium access control for data, speech and two-layer video

A modified version of the Orwell protocol to support mixed data, speech and video services is introduced. The protocol through the introduction of surplus cells and a dynamic bandwidth allocation mechanism can increase the network throughput by more than 50%. Compared to the original protocol, the surplus cells replace the empty cells, and the bandwidth allocation to the second-class traffic is dynamically varied, rather than being fixed at one. Control of the network is distributed, where each node monitors the load to ensure that its high priority cells, have preference to transmission and that they suffer minimal delays. This is based on aperiodically resetting the network, thus setting up cycles whose period indicates the current total traffic levels. The protocol has incorporated in it two dynamic bandwidth allocation algorithms for nonguaranteed cells. These maximise utilisation of any free bandwidth left over after class-1 transmission for class-2. These algorithms do not jeopardise the delays or safe passage of the class-1 cells