Wireless Application Protocol - Protocol Design Lessons From WAP

Protocol Design Lessons From WAP

The original WAP model provided a simple platform for access to web-like WML services and e-mail using mobile phones in Europe and the SE Asian regions. As of 2009 it continues with a considerable user base. The later versions of WAP, primarily targeting the United States market, were designed for a different requirement - to enable full web XHTML access using mobile devices with a higher specification and cost, and with a higher degree of software complexity.

Considerable discussion has addressed the question whether the WAP protocol design was appropriate. Some have suggested that the bandwidth-sparing simple interface of Gopher would be a better match for mobile phones and Personal digital assistants (PDAs).

The initial design of WAP specifically aimed at protocol independence across a range of different protocols (SMS, IP over PPP over a circuit switched bearer, IP over GPRS, etc.). This has led to a protocol considerably more complex than an approach directly over IP might have caused.

Most controversial, especially for many from the IP side, was the design of WAP over IP. WAP's transmission layer protocol, WTP, uses its own retransmission mechanisms over UDP to attempt to solve the problem of the inadequacy of TCP over high-packet-loss networks.