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Introducing DynamicSteering – Band/Client Steering, Load Balancing and Sticky Client Prevention Technology

The diversity of today’s client device types has grown far and wide from Bring Your Own Devices (BYOD) to Internet of Things (IOT) to Augmented/Virtual Reality with each its own unique connectivity and roaming decision making behaviors. Ensuring an exceptional Wi-Fi end user experience is challenging – especially when client devices, with their limited view of the network, are ultimately in charge of the decision of what access point (AP) to connect to, when to roam and at what speed.

DynamicSteering is ADTRAN’s standards-based band/client steering, load balancing and sticky client prevention technology that opens up a brand new dialogue between the Wi-Fi infrastructure and client devices, allowing the Wi-Fi infrastructure to take charge making informed, coordinated, connectivity and roaming decisions from the vantage point of both the Wi-Fi infrastructure and the clients. Unfortunately every client and or operating system has its own algorithm to determine connectivity and roaming decisions and many clients are known for making poor decisions. For example dual band 2.4GHz/5GHz capable devices often connect to slower, more congested 2.4 GHz spectrum when cleaner, faster 5 GHz spectrum is available or sticking on to further away APs when more nearby APs are available (sticky clients). Clients tend to attach based on strongest signal. In high density areas where people congregate, such as lobbies, auditoriums, cafeterias, gymnasiums, lecture halls, classrooms, and conference centers, APs become overloaded. Once attached to an AP, clients tend to stay attached - even when the signal weakens, transmit rate reduces and user experience deteriorates.

These poor decisions not only reduce that particular client’s performance but also the overall network. Given Wi-Fi is a shared medium, only one client can transmit at a particular time and everyone else must wait. As such one slow client can significantly degrade performance while everyone else waits for access to the channel. Even the latest clients capable of the fastest rates drop back to slower rates as they move further away from the AP, dragging down the overall network. This results in unpredictable network performance, dissatisfied users and customers, helpdesk and support calls and increased operating expenditures (OPEX).

To date, traditional legacy band-steering and beam-forming approaches have attempted to put the Wi-Fi infrastructure in charge of client connectivity and roaming decisions by leveraging a systems-level view of the network. This approach does not however take the perspective of the clients into consideration and does not coordinate steering events with clients. This approach is often unidirectional (2.4GHz towards 5 GHz) resulting in oversaturated 5 GHz spectrum. This approach often only steers clients upon first association (pre-association steering). This works by the access point suppressing probe responses and denying associations on the 2.4 GHz band.

Given the client’s perspective is not taken into consideration, the steering event is not coordinated with the client. The fact that the client is ultimately in charge of what access point to connect to and when to roam, the client will often continue to try and associate to the 2.4 GHz band, resulting in a very slow initial association time or sometimes no association at all. Furthermore, proprietary smart antenna beamforming approaches increase signal strength out at the client causing sticky clients and only providing downlink enhancements. With more and more applications moving to the cloud, a better approach is required.

ADTRAN’s DynamicSteering technology is bidirectional, resulting in balanced spectrum usage. For example if the signal of the client on the 5 GHz was beginning to diminish as 5 GHz doesn’t travel quite as far, the client would be steered towards the 2.4 GHz. DynamicSteering only performs pre-association steering when it is appropriate, when the load or channel utilization is high. For example if channel utilization is high on the 2.4 GHz spectrum, which would result in a poor user experience, the client would be steered towards the 5 GHz spectrum or vice versa. Otherwise it performs post-association steering, allowing the client to associate, taking the perspective of the client into consideration leveraging 802.11k and then coordinating a steering event with the client leveraging 802.11v. Because the steering event is coordinated with the client it can be steered while active without impacting applications. For those clients that don’t support standards based 802.11k/v they will be steered by suppressing probe responses and denying associations when idle for 10 seconds as to not impact applications. Instead of increasing the signal strength to a further way access point which results in sticky clients and only downlink enhancements, DynamicSteering monitors clients and automatically matches them to the appropriate radio on the appropriate AP, delivering consistent, predictable downlink and uplink performance and finally eliminating sticky clients once and for all. While it is true that this capability enables better network performance and end user experience, the true value lies in the IT department’s ability to take back control of their network and save critical network management and help desk resources.

DynamicSteering works with all clients, across all operating systems without the need for client software and is available as part of the Bluesocket vWLAN and ProCloud for Wi-Fi software release 2.9 and higher on Bluesocket Access Point 19XX, 2XXX and 304X series.

Kenneth Fernandes has 17 years experience in networking and security. Since 2007, he has been focused totally on wireless networking and security. Kenneth currently serves as a Product Manager at ADTRAN where he oversees the wireless product lines such as the Bluesocket virtual Wireless LAN (vWLAN). Kenneth is considered an “engineer’s engineer” by his peers and an authority on Wi-Fi technology. Based out of the Boston, Massachusetts area, Kenneth considers himself a Wi-Fi Enthusiast and is passionate about Wi-Fi. Follow him on Twitter at @wifiblogdotcom and at http://wifiblog.com