Many companies have planned to use Voice over WLAN. What is VoWLAN? What should you consider? The following article describes basic selection criteria.
Voice over Wireless Local Area Networks (VoWLAN) is the name of a voice transmission technology via a mobile radio network, specifically designed for the local area (Wireless Local Area Network, WLAN). Other names are VoWi-Fi (Voice over Wi-Fi).
In the past, you used mainly cordless telephone sets and the necessary base stations to provide your mobile users with telephone services from your central telephone system.
Wireless Local Area Networks
With the advent of Wireless Local Area Networks (WLANs), you provided your users with mobile access to company data. Your infrastructure allows your employees to query a wide variety of data without cable connection from almost any location in the company premises (internal, but also outdoors). The transmission speeds for communication over the radio links have increased considerably in recent years and will continue to increase in the future in order to satisfy the very large demand for more bandwidth. The specified data rates are now already in the Gbps range. In a few years, this speed will increase again by more efficient technologies. Descriptions of the current activities of the IEEE 802.11 workgroups dealing with the further development of WLAN technology can be found here: http://grouper.ieee.org/groups/802/11/
Voice over Internet Protocol (VoIP)
Voice over Internet Protocol (VoIP) shifts the voice communication from conventional telephone systems into the data networks. Companies replace existing system telephone sets with IP telephones that are directly attached to the in-house data network (Local Area Network, LAN). This saves costs and offers many other advantages.
Voice over WLAN (VoWLAN)
With Voice over WLAN, the transmission of the digitized voice information is embedded in IP packets as with other VoIP solutions. The special feature is that the IP packets are transmitted over radio links using the wireless local area network (WLAN) technology.
Voice over Long Term Evolution (VoLTE)
With VoLTE, packets are transferred across public mobile radio networks using the LTE data transmission technology. This technique is not covered in this article.
Digital Enhanced Cordless Telecommunications (DECT)
Many customers are dissatisfied with the cost of DECT (Digital Enhanced Cordless Telecommunications) solutions. For WLAN solutions, infrastructure and operating costs are lower than for DECT solutions. The flexibility of the WLAN solution for a wide variety of applications also clearly stands out for this network technology.
What you should consider with Voice over WLAN
Voice over WLAN Readiness Tests
Measurements with VoWLAN Readiness tests showed that existing WLANs often do not provide sufficient quality for voice transmission (low packet loss rates, low packet delay, low delay variations or jitter, variable bandwidth).
The interference susceptibility in the 2.4 GHz range is very high. However, this is often not easily measurable because disturbances often occur very sporadically (for example, every week at different hours). The causes are often unknown or caused by sources of interference to which you have no influence.
What to do? The easiest solution is to switch to the frequency range of 5 GHz. Is this the best solution? No, but why? Because, in standard WLAN solutions, the devices must share the available channel bandwidth, and thus the available transmission capacity, e.g. during a telephone call via WLAN, varies. Thus, the audible speech quality also varies.
Voice Readiness of VoWLAN Solutions
Two solutions are available to improve your WLAN quality for Voice over IP. Firstly, you can increase the transmit power of the access points to improve the coverage area and close dead holes. I recommend implementing prioritization technology in your WLAN cells (access points). This increases the transfer speed of IP packets with voice information, but can not prevent aborted calls in case of faults.
The second measure is the change of technology in the in-house area. The frequency range of DECT in Europe is exclusively reserved. You will find the description of the DECT technology in more detail in my blog “DECT – Is there still a Future?”
Ask your supplier for available solutions that support Voice over IP over DECT. The devices transmit digitized voice in IP packets via DECT wireless technology. The advantage is the almost interference-free frequency range of the DECT system paired with very high transmission quality.
Special solutions for the integration of special devices such as potential-free contacts in the industry can be integrated very well with DECT technology. I expect techniques for the Internet of Things (IoT) (like BlueTooth ™) to replace DECT solutions in the future.
If telephony is the main application in a susceptible environment, DECT is a good solution. If you need other communications services, select Wireless Local Area Networks technology as the better choice.
Also, consider that a DECT solution requires a separate DECT infrastructure.
About the author
Ronald Schlager is an independent trainer, consultant, book author and blogger with an emphasis on communications technologies and their application.
Image source: pixabay.com, artist: tejasp