Unlocking High Speed Roaming For Mobile Applications
Is slow roaming speed between your mobile network's access points hindering your industrial application's performance? Then high speed roaming may be the solution you're looking for. In this article, we'll discuss two simple ways to give your roaming speed an extra boost by unlocking the power of high speed roaming for mobile applications.
Linear Roaming Basics
Roaming conditions vary depending on the application. Here, we will use linear roaming as an example to illustrate how roaming is conducted and what factors we need to pay special attention to.
In the following diagram, a client is moving from left to right across three different APs. As the client moves, the signal from the first AP drops and the signal strength from the second AP increases. Most commercial wireless clients only monitor the communication quality as the basis for roaming decisions. That is to say, when the signal from first AP drops and frames cannot be transmitted, the client, in an IEEE 802.11b application, will first drop the communication speed from 11 Mbps to 5.5 Mbps, and then to 2 Mbps and 1 Mbps. If the communication quality is still poor and frame transmission continues to fail, the client will decide to roam from the first AP to the second AP.
A roaming mechanism of this sort might be able to satisfy many non-critical applications. However, this type of mechanism severely impairs the smoothness of data transmission for video and audio applications, which require higher quality data transmission.
One: Use the Threshold
One of the most common methods for increasing the roaming speed is to use the Threshold-based Handover Algorithm.
The Threshold-based Handover Algorithm allows roaming only when the current AP's signal drops below a certain threshold so that roaming to another AP improves the transmission quality and provides a stronger signal at the same time.
In short, the Threshold-based Handover Algorithm means the client will constantly scan for the best AP signal quality and roam only when the threshold is reached. This can prevent the ping-pong effect—unnecessary handovers that might take place when the client moves back and forth between two APs. Also, this can increase the roaming speed for smoother data transmission.
Two: Unify AP Channels
The second way to increase the roaming speed is to unify AP channels to avoid wasting channel hopping time during roaming. However, a unified channel selection will also cause interference. Users are advised to properly separate channels between roaming APs to reduce interference.
Words to the Wise
As with all new technologies, there are a few limitations users should be aware of but can easily avoid. First, the Threshold-based Handover Algorithm results in wireless resource consumption because the client is constantly scanning for APs that also need to respond in due time. To solve this problem, the network topology and system configuration needs to be carried out in greater detail.
The second limitation is that there is currently no unified high speed roaming standard so roaming between APs from different manufacturers might not be possible. Fortunately, this issue can be easily resolved by using access points from the same device manufacturer for your entire cellular network.
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