We assessed enterprise-grade 802.11n systems in terms of pure 802.11n throughput and latency; mixed-mode (802.11n plus both 802.11g and 802.11a clients) throughput and latency; "WiMix" traffic handling, which comprises a combination of common enterprise application types; power over Ethernet consumption; and features. A complete, more detailed version of this methodology is available here.

We asked participating vendors to supply eight dual-radio (2.4- and 5-GHz) access points and placed each access point inside its own shielded RF chamber. We attached the VeriWave WaveTest WT-90 test instrument to the chambers (and within the chambers, to the antenna connectors of each access point) using multiple cables, one for each spatial stream. This setup ensured repeatability and freedom from outside interference sources. The VeriWave WT-90 also offered gigabit Ethernet traffic from up to four ports.

To measure 802.11n throughput, we defined a single SSID on the 5GHz radio for each of eight access points. We also configured access points and tested instruments to use 40MHz of bandwidth and short (400-nanosec) guard intervals to obtain the highest possible rate.

We offered test traffic at varying loads to determine the throughput rate (the maximum rate at which the access points dropped none of the offered frames). We repeated these tests nine times: Three times each offering downstream, upstream and bidirectional traffic, using three different frame sizes, using 88-, 512- and 1,518-byte frames. We also measured average and maximum latency and jitter at the throughput rate. The test duration in all cases was 60 seconds.

In the mixed-mode (or "convergence") tests, the goal was to determine throughput and latency for an access point concurrently handling a mix of 802.11n, 802.11g and 802.11a clients. We enabled both 2.4- and 5-GHz radios on four access points for these tests and associated 16 802.11n clients and four 802.11a or 802.11g clients to each radio. We used standard (800-nanosec) guard intervals on the 2.4-GHz radios and short (400-nanosec) guard intervals on the 5-GHz radios.

As in the pure 802.11n tests, we used a binary search algorithm to determine the system's throughput rate. Once again we ran separate tests for downstream, upstream and bidirectional traffic, and again used the same three frame lengths. We also measured average and maximum latency and jitter.