Gigabit Wireless Surveillance Review (802.11ac)
This month, an upcoming wireless standard called 802.11ac, more colloquially known as 'Gigaibit Wifi' is starting to gain significant attention. At the CES show, a number of large mainstream electronic vendors including Broadcom [link no longer available], Buffalo, DLink [link no longer available] and Trendnet are already starting to announce products. There's definitely big momemtum behind this but what does this mean for video surveillance? In this note, we examine the potential impact and applications.
802.11ac is the fifth generation of the 802.11 wireless Ethernet standard. Three key improvements to 802.11a/b/g/n are claimed:
- Increased throughput: First and foremost, 802.11ac specifies maximum speeds of over 1 Gbps. Current 802.11n APs are capable of 150 Mbps, making this a 6-7x increase in throughput. This is accomplished through an increase in channel width from 40 MHz in 802.11n to 80 MHz, or optionally 160 MHz in 802.11ac. The number of spatial streams is also increased from four to eight, allowing better MIMO performance.
- Frequency and modulation change: 802.11ac will operate in the 5 GHz band only, unlike 802.11, which operated in both the 2.4 and 5 GHz spectrum. 802.11ac also uses 256-QAM modulation versus 11n's 64-QAM method, allowing more data to be encoded on a carrier.
- Beam steering: Simply put, beam steering allows the wireless AP to better "aim" signal towards clients. This allows speed or range to be increased, but not both. Maintaining the same distance from the AP, better and more consistent speeds can be maintained, as the stronger signal handles interference better.
For a lower level examination of 802.11ac , we recommend AnandTech's solid primer on 802.11ac technology.
Potential for Surveillance
While all of the above improvements will likely make 802.11ac more useful for the consumer and business markests as a whole, they may be of limited use for surveillance purposes and may even cause problems:
- Line of Sight Restrictions: 802.11ac's use of the 5 GHz spectrum results in poorer penetration of obstructions than existing technologies, limiting it strictly to applications where line of sight is clear.
- Distance Limitations: Typically the higher the bandwidth supported, the more limited the distance achievable as higher signal to noise ratios are needed.
- Additional Bandwidth Unnecessary: The increased throughput of this standard is overkill for a single camera or a handful of cameras, even multi-megapixel models. We expect that low-cost non-802.11 solutions such as Ubiquiti and Mikrotik will still be most popular in these applications.
- Pollute the 5Ghz range: Currently, the 5Ghz range is much less congested than the 2.4Ghz range. As more people use 802.11ac, this will increase probability of interference with surveillance systems that choose the 5Ghz range to avoid the congested 2.4Ghz.
The main application which comes to mind when thinking of high-throughput line of sight wireless is backhaul. 802.11ac's throughput is likely high enough to carry dozens of cameras and beyond. However, 802.11 wireless is not typically used for backhaul, due to concerns of security and reliability. Proprietary radios are usually chosen for this application for their generally better handling of interference, which results in better distance and availability.
802.11ac will have the most impact on in-building wireless. However, in-building wireless has seen the least movement from surveillance. Wireless cameras based on 802.11b/g, generally, have been available for years, but very few commercial systems use wireless connectivity. Even if wireless connectivity is available and reliable, cameras must still be powered, requiring 120VAC power to be located near wherever a wireless camera is to be installed. Typically, power over Ethernet and/or low-voltage 12VDC/24VAC power are much more cost effective, limiting even 802.11ac's use in this application.
This standard may be of use for users implementing devices such as tablets and smartphones, on which video may be viewed by a mobile guard force, for instance. 802.11ac will provide better coverage and speed for these devices, potentially allowing for increased resolution and framerate to be delivered to the client device.
While a number of consumer-focused network hardware providers are announcing product, to date, no surveillance-focused wireless manufacturers have announced any 802.11ac gear. We have found none that are willing to even discuss plans for its implementation, as the standard is not yet adopted. This will likely occur in the next 12-18 months. While typically, the draft of the standard does not vary grealy from the final product, some changes may occur. Early adopter manufacturers claim that any changes may be handled via software updates, as the chips will not change, but users should be aware of this potential risk.