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

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

 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!

 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!

 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