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Chapter 5Upstream channel capacity and characterisation pOn the other hand, a loss of 6% in terms of system throughput was seen with theexponential backoff algorithm for ‘MCI-2’, as depicted in Figure 5.17. The splitting treealgorithm did not provide a loss for ‘MCI-2’, because this algorithm resolves collisionsmore efficiently than the exponential backoff algorithm, regardless of the number ofMPEG2 frames (with MCI information) within the 3 ms period. This inefficiency of theexponential backoff algorithm results in a reduction in system throughput.System Throughput (%)66636057545148454239363330Backoff-MCI-1Backoff-MCI-2Tree-MCI-1Tree-MCI-23 Mbps Upstream32 Kbps kbps IPBackoff & Tree Algorithm30 33 36 39 42 45 48 51 54 57 60 63 66umber of Active StationsFigure 5.17 – System throughput vs. No. of active stations for different MCI values.5.4.7 Effects of packet size for single and multiple node scenariosAnother critical parameter in the performance of any computer network is the packetsize. From results in Section 4.5, packet size was proved by both analytical model andsimulation (Figure 4.18) to have a significant impact on system performance, especiallywhen small and large packets are considered for data transmissions.5-29