History has proven that Wireless LAN is always used for something it was originally not planned for. On one side, this makes this technology very attractive and also very flexible. On the other side, it is constantly pushing the envelope and has the potential to introduce technical risk.
From the moment WLAN was introduced, users wanted to use it in a nomadic way, requiring mobility between Wireless Access Points. This way of roaming was fully implemented in the original standards of Wi-Fi (although when using a laptop, just scrolling around isn’t that effective and laptop users often relocate themselves before using the WLAN again).
Difficulties really started when users began to use Voice over IP over WLAN (VoWLAN). Users noticed that roaming wasn’t always easy and that phone-calls dropped. This created a general negative experience to WLAN. As VoWLAN was a next step into the future of WLAN, several start-ups jumped into the technical challenge and delivered new (proprietary) technologies to overcome the negative experience.
The Single-Cell (or frequency blanket) was one of these technology solutions. The idea behind Single-Cell is quite simple: The whole network works at one single channel; also called a frequency blanket. Users therefore don’t have to roam across channels, so calls won’t drop.
The idea was perfect, but again not foreseen in the original standards of Wi-Fi: Using just one channel over every access point is against the nature of how channels interact with each other and ran contrary to the originally developed WLAN Collision Avoidance feature. However, in order to use the single channel technology several vendors developed proprietary solutions and provided viable VoWLAN solutions.
Over recent years this Single-Cell technology has been used successfully but solutions have not been able to keep up with the evolution path of WLAN. The solution worked perfectly with small data packages (voice consists of a lot of small packages), but had serious issues when dealing with larger package sizes (data in general). As users besides voice also wanted to send data on the WLAN network, these networks became less scalable.
We therefore do not advise the use of any single-cell driven solution. Firstly, the technology is not future proof; secondly WLAN standards have evolved in such a way that Quality of Service (QoS) for VoIP can now be delivered via industry-standard WLAN technologies.
WLAN Consulting is an initiative of LANCOM Systems. LANCOM Systems is a leading German manufacturer of wireless LAN technology based on industry standards.