802.11ac 'Gigabit Wi-Fi' Starts To Show Potential, Limits 101
alphadogg writes "Vendor tests and very early 802.11ac customers provide a reality check on 'gigabit Wi-Fi' but also confirm much of its promise. Vendors have been testing their 11ac products for months, yielding data that show how 11ac performs and what variables can affect performance. Some of the tests are under ideal laboratory-style conditions; others involve actual or simulated production networks. Among the results: consistent 400M to 800Mbps throughput for 11ac clients in best-case situations, higher throughput as range increases compared to 11n, more clients serviced by each access point, and a boost in performance for existing 11n clients."
Ideal situations (Score:2, Interesting)
"Among (sic) the results: consistent 400M (sic) to 800Mbps throughput for 11ac clients in best-case situations"
Best case being: the only device on the network; inside a Faraday cage; on the dark side of the Moon; 3 centimetres away from the antenna.
BTW: Google.... fuck your dictionary. It IS centimetres.
Now try it in urban neighborhood (Score:1, Interesting)
With 20+ APs contending for their own slice of half or third of 5 ghz band. 802.11ac took the best feature of the 5 Ghz band, plenty of non overlapping channels, then turned into back into the quagmire of the 2.4 Ghz band by allowing 80 and 160 Mhz spectrum usage. Of course, the router manufacturers are going to enable 160 Mhz by default even when everyone in the neighborhood is on a 25 Mbps cable modem connection.
Why not properly implement 802.11n first? (Score:5, Interesting)
Hardware manufacturers I'm pointing my my finger at you. The most powerful features of 802.11n are largely unimplemented. Laptop/tablet/phone Support for 3 spatial streams is about as rare and rocking horse shit. Support for even 5 ghz is spotty at best and its hard to find out if whatever piece of hardware you want to consider buying even supports it. Heck even 2 spatial streams at 2 ghz is something your lucky to get unless you spend more than $699 on a laptop. The lowest common denominator for 802.11n and what the "wireless n" wifi support really means for half the devices on the market is a single spatial stream 802.11n at 2 ghz, which is 65 Mbps max. I can buy a mid range smartphone with 4g support and the wifi is still single spatial stream at 2 ghz. Hardware manufacturers have no incentive to put better implementations of 802.11n in their because most customers aren't savvy enough to tell the difference and demand better from device manufacturers. 802.11n is on old specification. There's no excuse why 2 spatial streams can't be the minimum. The silicon to do this is cheap and has been refined for many years.
802.11ac will probably suffer the same fate. The minimum implementation to get the "wireless ac" sticker on the box is going to be what half to three quarters of the devices on the market will support, even 10 years from now.
Re:Now try it in urban neighborhood (Score:5, Interesting)
Fortunately 5GHz penetrates walls very poorly -- I have a 6cm thick concrete interior wall (I'm in Switzerland, after all, they love concrete) that separates too rooms. The 5GHz signal in the room without an AP is so bad that my network card (a PCI-Express card for a desktop with three external antennas) essentially refuses to connect. 2.4GHz works fine. This is in an area with exactly zero 5GHz Wi-Fi users within range, a noise floor of about -95dBm, and no other sources of interference.
Channel bonding on 5GHz makes a lot of sense due to its extremely short range.
Re: not exactly gigabit (Score:4, Interesting)
Reaching far back to my Cisco knowledge from 2003-ish, that's because 802.11 requires acknowledging every single packet, whereas wired Ethernet allows a larger window, so several packets get sent before an acknowledgement. I don't know if that's still the case (perhaps a modern network engineer will confirm, please), but that could be the reason for seeing just about double the transfer speed through a wire. On wireless, you're using almost twice as many packets to receive the same data.
Don't judge too much from early implementations (Score:4, Interesting)
Have they implemented the full 256QAM 5/6 rate yet with full 80+80MHZ bonding yet? (160 MHZ of channel bandwidth) using 8 transmit antennas and 8 receive antennas on both AP and wireless clients?
I expect early APs and early chipsets will not yet fully implement all the advantageous features 802.1AC has to offer
They'll have made compromises to save money.
Re:Why not properly implement 802.11n first? (Score:4, Interesting)
It's not quite that bad. The demand for low power devices that run a long time on batteries is actually reducing transmit power in many applications. It will take time for people to upgrade, and unfortunately certain devices like wifi routers will still be quite shouty as they advertise to non-existant 802.11b clients, but the trend is generally towards lower power and higher data rates (which mean less time with the transmitter turned on). Strategies for sharing available spectrum are also improving, from basic frequency hopping to things like directional signal shaping in 802.11ac.
We are also starting to use spectrum more efficiently. For example switching to digital TV gave us more channels in less spectrum.
Noise floor isn't necessarily all that important for modern devices either. Consider that GPS signals are actually below the thermal noise floor when received on the ground. DSPs are cheap.
Re:Don't judge too much from early implementations (Score:4, Interesting)
Realistically few devices will ever implement 16 antennas. Aside from the impracticality of fitting 16 antennas into a portable device the power consumption of all those LNAs and PAs is going to be considerable, as is the DSP power needed to decode and correlate it all.