Early experiences with WiFi 802.11ac will likely prove disappointing for those expecting a significant boost over existing 11n wireless, industry experts warn, with the soon-to-be-ratified standard taking a further generation before it lights up properly. “The new standard will be evolutionary, with two waves involved” Cisco’s Chris Spain tells Network Computing. “Out of the gate, the increases in performance over 11n will not be tremendously impressive. The second wave – which will require a hardware refresh – gets far more interesting.”
Although initial suggestions around 802.11ac indicated throughput rates of up to 6.9Gbps, the initial products are more likely to top out at 1.3Gbps at most. “First-generation 802.11ac products will achieve up to 1.3 Gbps through the use of three spatial streams,” Aerohive Networks’ Andrew vonNagy explains, “80-MHz-wide channels (double the largest 40 MHz channel width with 802.11n), and use of better hardware components that allow higher levels of modulation and encoding (up to 256-QAM).”
In fact, it could be “another three years or so until 11ac becomes compelling” as a must-have upgrade to WiFi 11n systems, Spain suggests. Even then, rather than speed, it may be overall capacity that proves the biggest draw. All 802.11n hardware will have support for both the 2.4GHz and 5GHz bands, helping shift devices out of the congested 2.4GHz range.
“What’s not being talked about enough is that 11ac clients will free up more 2.4-GHz space for clients that can’t upgrade,” Spain says, “and that advanced features like multiuser MIMO will provide wireless performance that is more switch-like compared to the shared media nature of 11n.”
As Qualcomm explained to us back in February, when the 11ac ratification was still around a year away, co-existing 11ac and legacy WiFi networks will also introduce a hindrance on speed; the biggest advantages will of course be seen when the network is 11ac-only. Routers supporting the new standard but working with b/g/n hardware will use a “round robin” distribution method in that case, rapidly connecting and disconnecting with each client in turn; each connection will negotiate the fastest possible speeds supported by router and client.
In contrast, 11ac supports concurrent operations, with a resulting increase in throughput. Nonetheless, it’ll be some time – even with early hardware getting the jump on sales pre-ratification – before 11ac is the dominant wireless system, and perhaps longer still before we see the key benefits from its on-paper potential.