Channel Blanket
To enable today’s Wi-Fi networks meet the requirements of high performance and always-on access, some key challenges must be overcome: co-channel interference, and the ability of user devices to roam between APs.
Overcoming Challenges
For new Wi-Fi networks, enough access points (AP) must be installed to ensure adequate wireless signal strength across the entire premises. This complete coverage allows user devices to wirelessly connect to online resources and applications from anywhere.
In real-world environments, an AP radio signal pattern is a hard-to-predict polygon influenced by reflections, the material of building walls, the furniture, and many other factors. Moreover, the radio signal pattern changes with changes in the environment, and as people open and close doors and move between rooms.
To simplify our understanding of the hard-to-predict radio signal patterns, we can consider them as a circle with the AP at the center. With this idea in mind, we can see that covering the entire premises requires that the radio signal from each AP must overlap.
Co-Channel Interference
To avoid radio signal interference in overlapping areas (which reduces performance), neighboring APs must work on different channels. This approach is called multi-channel architecture (MCA), and requires an accurate site survey and precise channel planning as part of a new Wi-Fi network deployment.
The Wi-Fi 5 and Wi-Fi 6 wireless network standards include the capability to aggregate up to eight channels to improve performance and throughput. Channel planning must include working out which channels to use on each AP to avoid co-channel or adjacent channel interference, as well as the optimal channel aggregation ratio to maximize performance. Quite a challenge!
The Roaming Problem
Roaming is the capability of client devices to swap Wi-Fi connectivity between APs as users move around the premises, so online access is maintained. The handover of client devices between APs is managed by the wireless network, but as a device moves from one AP to another, it must disconnect and reconnect to the network. This disconnection and re-connection can be quite fast and not cause too many problems for casual users – but for dynamic environments like logistics and manufacturing where wireless devices are very mobile, or for mission critical applications like medical care, loss of connectivity cannot be tolerated and can even be dangerous.
The Answer: Channel Blanket
The majority of traditional Wi-Fi networks today use a multi-channel approach, where APs operate on a range of fixed channels, with manual channel planning to avoid co-channel and adjacent channel interference between APs whose radio signals overlap.
Allied Telesis has developed Channel Blanket technology to solve both the channel interference and roaming limitations of multi-channel wireless architectures, while reducing implementation cost and complexity. Channel Blanket is a single-channel wireless architecture, and is enabled by our Autonomous Wave Control (AWC) Wi-Fi controller.
The main difference between architectures is the use of the Wi-Fi channels. Multi-channel uses all available channels which are carefully managed to avoid interference, whereas single-channel uses one wireless channel to create a single ‘blanket’ of wireless coverage, thereby eliminating interference.
When using an Allied Telesis Channel Blanket network, wireless client devices see only a single virtual AP covering the entire premises, and the devices connect to this virtual AP.
Once the Channel Blanket is enabled, wireless devices connect to this single virtual AP, but may be in radio signal range of more than one physical AP – with all reachable APs operating on the same channel. When the client device transmits data to the network, more than one physical AP may receive the data, and the AWC controller will decide the optimal AP to forward that data, while any other APs will simply drop the packets. For return traffic, once the network sends data to a client device, the AWC controller decides the optimal AP to forward that data. Our Channel Blanket wireless technology maximizes network performance by optimizing AP use.
Installing a Channel Blanket wireless network removes the need for accurate site surveys and channel planning. The only requirement is to have enough APs to cover the premises, as the AWC controller will fully manage the Channel Blanket, with the single-channel architecture eliminating any possible interference issues. Channel Blanket can handle a large number of mobile users who all see the network as one big virtual AP, and is compatible with a full range of wireless clients.
Channel Blanket also solves the problem of mixed performance in different areas. When planning has not been precise enough, or changes to the environment occur, areas of weak signal can result. With a multi-channel approach, adding a new AP to cover a weak signal area is a challenge, and avoiding overlapping channels requires redoing channel planning with the associated time and cost. With a single-channel approach, channel planning is not required as it is simply a matter of installing a new AP, adding it to the Channel Blanket, and the weak signal area is resolved.
As discussed earlier, the disconnection and re-connection associated with client devices roaming between APs in multi-channel networks is not acceptable in dynamic and mission-critical environments. A Channel Blanket Wi-Fi network removes this problem, as the entire network operates as a single virtual AP, with seamless roaming for client devices between physical APs. This ensures seamless access to business and production systems in dynamic environments, as well as always-on connectivity for critical applications.
The Best of Both Worlds
A Channel Blanket network solves some of the main challenges of Wi-Fi networks: co-channel and adjacent channel interference, and roaming. But the advantages gained are not for free, as a single-channel network provides overall lower throughput than a multi-channel network with the same number of APs.
Normally, before deciding whether to implement a single-channel or a multi-channel wireless network, it would be necessary to clearly understand the final user and business requirements to choose the best architecture. However, Allied Telesis has a powerful solution that enables the best of both architectures.
Our world-first hybrid APs can operate a Channel Blanket network and a multi-channel network simultaneously. The 3-radio AP design supports having two Channel Blankets and one radio operating on multi-channel, or one Channel Blanket and two radios operating on multi-channel – with the ability to change anytime to meet evolving demands using the AWC wireless controller.
Allied Telesis's innovative hybrid Wi-Fi solutions are the most flexible available today, supporting maximum throughput and seamless roaming, so all user requirements are met with the best possible performance for both stationary and highly mobile wireless network users.