Changes between Version 21 and Version 22 of 802.11/wlan_exp/app_notes/dcf_with_multiple_flows
- Timestamp:
- Apr 17, 2014, 9:47:39 AM (10 years ago)
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802.11/wlan_exp/app_notes/dcf_with_multiple_flows
v21 v22 61 61 Next, we use the WLAN Experiment Framework to enable all 4 flows simultaneously. 62 62 63 || Simultaneous || Throughput (Mbps)||64 || Flow 1|| 2.06 ||65 || Flow 2|| 2.06 ||66 || Flow 3|| 4.18 ||67 || Flow 4|| 4.47 ||68 || Sum Throughput|| 12.77 ||63 ||= Simultaneous =||= Throughput (Mbps) =|| 64 ||= Flow 1 =|| 2.06 || 65 ||= Flow 2 =|| 2.06 || 66 ||= Flow 3 =|| 4.18 || 67 ||= Flow 4 =|| 4.47 || 68 ||= Sum Throughput =|| 12.77 || 69 69 70 70 The first thing to notice is that the sum throughput achieved by all flows together is less than any one of the throughputs achieved by one of the flows on their own. The isolated throughputs in the [#Baseline:PerformanceofEachFlowinIsolation previous section] are upper bounds on perfomance because there are no losses due to collisions. When all four flows contend for the same medium, collisions are inevitable, yielding an overall reduction in network sum throughput. … … 103 103 Re-running the experiments with this change yields the following. 104 104 105 || || Isolated Throughput (Mbps) || Simultaneous Throughput (Mbps)||106 || Flow 1|| 14.84 || 3.7 ||107 || Flow 2|| 14.83 || 3.7 ||108 || Flow 3|| 14.07 || 2.72 ||109 || Flow 4|| 14.08 || 2.71 ||110 || Sum Throughput|| n/a || 12.83 ||105 || ||= Isolated Throughput (Mbps) =|| = Simultaneous Throughput (Mbps) =|| 106 ||= Flow 1 =|| 14.84 || 3.7 || 107 ||= Flow 2 =|| 14.83 || 3.7 || 108 ||= Flow 3 =|| 14.07 || 2.72 || 109 ||= Flow 4 =|| 14.08 || 2.71 || 110 ||= Sum Throughput =|| n/a || 12.83 || 111 111 112 112 When the flows are run separately, we can see that Flow 1 and Flow 2 achieve slightly higher throughputs than they used to because of the CW change. When each flow is run simultaneously, we can see that their relative share of the sum throughput is a very different story than what it used to be. … … 134 134 The per-flow isolated throughputs are identical to the first experiment, so they will not be re-presented here for brevity. Instead, we jump directly to the case where all four flows are activated simultaneously. 135 135 136 || Simultaneous || Throughput (Mbps)||137 || Flow 1|| 3.9 ||138 || Flow 2|| 3.9 ||139 || Flow 3|| 2.37 ||140 || Flow 4|| 2.25 ||141 || Sum Throughput|| 12.42 ||136 ||= Simultaneous =||= Throughput (Mbps) =|| 137 ||= Flow 1 =|| 3.9 || 138 ||= Flow 2 =|| 3.9 || 139 ||= Flow 3 =|| 2.37 || 140 ||= Flow 4 =|| 2.25 || 141 ||= Sum Throughput =|| 12.42 || 142 142 143 143
