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Seamless Roaming
 
Is the slow roaming speed between your mobile network's access points hindering your industrial application's performance? If so, then high-speed roaming is the perfect solution. High-speed roaming allows for fast seamless roaming between APs as well as ensures a secure connection between the client and network. We recommend two methods to give your roaming speed an extra boost by unlocking the power of high-speed roaming for mobile applications.
  Roaming by Signal
 

Roaming by Channel

What is Roaming?
In mobile applications with multiple access points (APs), roaming refers to when a client moves between two or more access points, and the speed of the roaming mechanism can be crucial to an application's success.
As the client physically moves from one AP to another, the signal strength of the first AP will drop while the signal strength of the second AP will increase. When the signal strength of the first AP drops below the signal strength of the second AP, we say that the client has roamed to the second AP.
Factors that affect the smoothness of roaming include the topology of the access points, the gain and coverage of the antennas, and the roaming threshold settings of the client. To ensure smooth roaming, we need to take into consideration the route of the moving object, and then carefully plan the wireless AP's deployment and configuration.
 
Basic Roaming
The diagram below illustrates a client moving from left to right through regions governed by three different APs. As the client moves, the signal strength of the first AP drops and the signal strength of the second AP increase. Most commercial wireless clients only consider communication quality when making roaming decisions. That is to say, when the signal strength of the first AP drops and frames cannot be transmitted, the client in an IEEE 802.11b application will first reduce the communication speed from 11 Mbps to 5.5 Mbps, and then to 2 Mbps, and finally to 1 Mbps. If the communication quality is still poor and frame transmission continues to fail, the client will decide that it's time to roam from the first AP to the second AP.

A roaming mechanism of this sort might be able to satisfy common non-critical applications. However, this type of mechanism severely impairs the smoothness of data transmission for video and audio applications, which require better data transmission performance.

 
Roaming by Signal

The first method for increasing the roaming speed is to use what is referred to as “roaming by signal,” which only allows roaming when the current AP's signal drops below a certain threshold and roaming to another AP will improve transmission quality and provide a stronger signal.In this case, the client constantly scans for the best AP signal and roams only when a particular threshold has been reached. This can prevent the ping-pong effect, in which unnecessary handovers take place when the client moves back and forth between two APs.

 
Roaming by Channel
The second method to increase the roaming speed is to unify AP channels to avoid wasting channel hopping time during roaming. However, a unified channel selection can also cause interference. Users are advised to properly separate channels between roaming APs to reduce interference.