Ohrtman F. Voice over 802.11

Издательство Artech House, 2004. - 278 p.The emergence of voice over 802.11 (Vo802.11) was made possible by simply moving VoIP over 802.11 as an access mechanism, thereby replacing the copper wires of the PSTN. Once the VoIP stream reaches the wired part of such a network (the access point), it is transported on an IP network (LAN, IP backbone).
By being based on the IP, VoIP can be managed (switched) by a VoIP-specific switch, the softswitch discussed in the preceding section. Although the conversation may originate and be switched on an IP network, it is still possible to originate and terminate calls on the PSTN. This is made possible with the interface of a VoIP gateway between the IP network and the PSTN. This gateway, depending on the direction of the flow of the traffic, packetizes or depacketizes the voice traffic traveling between the two dissimilar networks.
In summary, it is now possible to completely bypass the PSTN. By supplanting the elements of the PSTN with IP-based technologies, it is now possible to completely replicate the PSTN function for function. Not only does this represent a replacement of the PSTN, it is also makes possible a myriad of new elements for such a function. Application servers that operate with softswitches allow for the rapid creation of new features that were either not possible with the circuit-switched PSTN or would have cost the service provider too much to justify deployment.
This thesis is not without opposition. A number of objections to the deployment of Vo802.11 remain. Those objections are focused on concerns that the two chief elements of Vo802.11, that is, VoIP and 802.11, have perceived weaknesses that prevent them from delivering the same levels of service as the PSTN. After explaining the workings of the PSTN, 802.11, and VoIP, this book will overcome those objections.
In his book The Innovator’s Dilemma [1], author Clayton Christensen describes what he terms disruptive technology. Initially, disruptive technology is cheaper, simpler, smaller and more convenient to use. Eventually it matches the incumbent technology point for point and then ultimately triumphs, displacing the incumbent technology because the disruptive technology had a number of attributes of its own that the incumbent technology could not compete against. The following chapters will demonstrate how Vo802.11 is cheaper, simpler, smaller and more convenient to use, while ultimately offering qualities that are superior to the incumbent technology.
Overview of Vo802.11.
802.11: Alternative Access.
Voice over Internet Protocol.
Switching TDM and VoIP Networks.
Objections to Vo802.11.
Vo802.11: Range Is a Matter of Engineering.
Security and Vo802.11.
Objections Due to Interference and QoS on Vo802.11 Wireless Networks.
Engineering Vo802.11 Networks for Maximum QoS.
Scalability in Wireless VoIP Networks.
Vo802.11 Reliability.
Vo802.11 Features and Applications.
Regulatory Considerations for Vo802.11 Networks.
Economics of Vo802.11 Networks.
Conclusion: Vo802.11 Is the Future of Voice Communications.