VoWLAN (Voice over WLAN) is a method of sending voice information in digital form over a wireless broadband network. Essentially, VoWLAN is VoIP delivered through wireless technology. The technology is sometimes called "VoWi-Fi" or "Wi-Fi VoIP" because it uses the IEEE 802.11 set of specifications (informally known collectively as Wi-Fi) for transporting data over wireless local area networks and the Internet.
VoWLAN requires a voice-enabled wireless device, most commonly a PDA or a "Wi-Fi handset," which looks and operates like a cell phone, but sends voice as discrete data packets rather than an analog voice stream. Callers can also use a software-based phone, known as a softphone, that resides on devices including laptop and desktop computers. The VoWLAN system routes calls from the phone to a WLAN access point and then to a VoIP gateway or IP PBX. The call is sent to its appropriate destination within the private network or out onto the Internet or PSTN.
The VoWLAN system allows all regular functions and messaging applications available on wired phones to be available on the VoWLAN devices. Like VoIP, VoWLAN also contributes to cost efficiency. Because calls can be routed over the data network internally or over the Internet externally, mobile telephony costs can be eliminated or decreased significantly.
Major barriers to VoWLAN include inconsistent voice performance and the need for quality of service (QoS); slow and unreliable encryption and authentication; and the proprietary nature of current products. The IEEE and the Wi-Fi Alliance have been developing standards improvements to mitigate VoWLAN limitations. The recent 802.11i standard implemented intelligent security to speed up authentication while roaming. Other upcoming standards enhancements include:
- The 802.11e standard will define QoS measures that will prioritize voice traffic using two methods, Wireless MultiMedia (WMM) and WMM Scheduled Access
- 802.11r will specify a fast-roaming protocol to minimize packet loss when users move from one access point to another within a WLAN
- 802.11k will include the Radio Resource Management protocol to enable a handset to pre-discover the conditions of the WLAN network and choose the best available paths.
VoWLAN is most frequently found in the retail, manufacturing and health care industries, where WLAN was adopted early and use has progressed quickly. In the long term, VoWLAN deployment is a significant step toward interoperability and seamless mobile connectivity between private WLANs and public wireless and cellular networks.
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