1.  Throughput subject to packet size  High latency: 11 – 32 ms  Not flexible  Choose high throughput or low latency

2. packet size64 Bytes128 Bytes256 Bytes512Bytes1024 Bytes1280 Bytes1518Bytes1522 Bytes(Vlan tagged) UL %DL%Wi100T.....Wi100T.....Wi100T.....Wi100T.....Wi100T.....Wi100T.....Wi100T.....Wi100T..... 010041.70.0942.11.142.65.042.121.540.630.442.633.240.533.240.534.5 208043.90.0444.50.343.91.444.67.743.537.045.139.442.038.946.438.8 406045.80.0346.50.343.91.446.810.146.041.547.243.242.039.946.440.4 50 46.50.0347.10.343.91.447.39.546.542.847.243.142.044.846.444.6 604045.80.0346.50.343.91.446.810.146.041.547.243.242.039.946.440.4 802043.90.0444.50.343.91.444.67.743.537.045.139.442.038.946.438.8 100041.70.0942.11.142.65.042.121.540.630.442.633.240.533.240.534.5 Wi-Fi is extremely sensitive to packet size Max throughput can only be achieved when big packet sizes are transmitted.

3.  The small packet problem can be solved in Wi-Fi through concatenation.  Small packets are received in the radio and grouped into larger packets.  The end result is similar data throughput as with large packets. PROBLEM: Concatenation adds 10 – 14 ms Delay!

4.  The latency problem in Wi-Fi can be resolved by fragmenting packets so that smaller packets are sent on a fixed time interval.  This means that all packet sizes are fixed and at a smaller size.  As seen on the previous slides, Wi-Fi performance suffers when packet-sizes are small. PROBLEM: Fixed frames lower data throughput!

5.  Throughput subject to packet size  Concatenation solves problem  Adds significant delay (+10 – 14ms)  High latency: 11 – 18 ms (21 – 32ms w/concatenation)  Fixed frame sizes (fragmentation) solves latency  Turn-off concatenation  Choose latency or throughput  Wi-Fi based product can offer: 1. High Throughput with high latency 2. Low latency with low throughput at fixed frame rate