Wireless Internet
The wireless Internet is defined by access to the Internet on any wireless or mobile device. The wireless Internet encapsulates a variety of wireless Internet access alternatives including wide-area networks (WANs), wireless local area networks (WLANs), and wireless personal area networks (PANs).
Wide area networks - WANs
Wide-area networks (WANs) are essentially the cellular networks maintained by major carriers, including in the U.S. Verizon Wireless, Sprint PCS, and Cingular Wireless. Wireless internet access over wide-area networks is still slow and is conducted mostly through what are currently known as 2G or 2.5G wireless networks. Data speeds are slow (averages run between 20 and 60 Kbps), but coverage is nearly ubiquitous. 3G, the next generation of wireless wide-area networks, promise greater data speeds (up to 384 Kbps) with the same level of nearly ubiquitous coverage as current wireless networks.
Wireless local area networks - WLANs
Wireless local area networks (WLANs) are smaller-scale wireless networks with a typical radius of several hundred feet. The most prevalent form of Wireless Local Area Network technology is called WiFi, which includes a host of standards including 802.11a, 802.11b, and 802.11g. Wireless Internet via WiFi offers blazing fast data speeds (11Mbps at the low end with 802.11b and 54 Mbps at the high end for 802.11a and 802.11g). While WiFi technology does not offer the degree of ubiquity as wide area networks, the WLAN's data speeds and relatively cheap costs have spurred it ahead in the popular market as a wireless internet solution.

The Cellular Explosion
Probably the most important factor in the birth of wireless Internet has been the proliferation of digital cell phones in the last few years. The expanding network of digital cellular and personal communication services (PCS) has created a solid foundation for wireless Internet services. It is estimated that there are more than 50 million Web-enabled cell phones in use. In 1997, Nokia, Motorola, Ericsson and Phone.com came together to create the WAP because they believed that a universal standard is critical to the successful implementation of wireless Internet. Since then, more than 350 companies have joined them in the WAP Forum.

Making a Web site accessible through a wireless device is quite a challenge. So far, only a small portion of the more than a billion Web sites, about 1.5 million, provide any wireless Internet content. As the use of WAP-enabled devices grows, you can expect that many more Web sites will be interested in creating wireless content.
WAP is designed to work on any of the existing wireless services, using standards such as:
Short Message Service (SMS)
Circuit Switched Data (CSD)
General Packet Radio Service (GPRS)
Unstructured Supplementary Services Data (USSD) For more information on these services, check out this page

Wireless Markup Language
WAP uses Wireless Markup Language (WML), which includes the Handheld Device Markup Language (HDML) developed by Phone.com. WML can also trace its roots to eXtensible Markup Language (XML). A markup language is a way of adding information to your content that tells the device receiving the content what to do with it. The best known markup language is Hyper Text Markup Language (HTML). Unlike HTML, WML is considered a meta language. Basically, this means that in addition to providing predefined tags, WML lets you design your own markup language components. WAP also allows the use of standard Internet protocols such as UDP, IP and XML.
There are three main reasons why wireless Internet needs a different protocol:
Transfer speed
Size and readability
Navigation
Most cell phones and Web-enabled PDAs have data transfer rates of 14.4 Kbps or less. Compare this to a typical 56 Kbps modem, a cable modem or a DSL connection. Most Web pages today are full of graphics that would take an unbearably long time to download at 14.4 Kbps. Wireless Internet content is typically text-based in order to solve this problem.

Wireless Application Protocol
Here's what happens when you access a Web site using a WAP-enabled device:
You turn on the device and open the minibrowser.
The device sends out a radio signal searching for service.
A connection is made with your service provider.
You select a Web site that you wish to view.
A request is sent to a Gateway Server using WAP.
The Gateway Server retrieves the information via HTTP from the Web site.
The Gateway Server encodes the HTTP data as WML.
The WML-encoded data is sent to your device.
You see the wireless Internet version of the Web page you selected.
To create wireless Internet content, a Web site creates special text-only or low-graphics versions of the site. The data is sent in HTTP form by a Web server to a WAP gateway. This system includes the WAP encoder, script compiler and protocol adapters to convert the HTTP information to WML. The gateway then sends the converted data to the WAP client on your wireless device.
What happens between the gateway and the client relies on features of different parts of the WAP protocol stack. Let's take a look at each part of the stack:

WAP protocol stack
WAE - The Wireless Application Environment holds the tools that wireless Internet content developers use. These include WML and WMLScript, which is a scripting language used in conjunction with WML. It functions much like Javascript.
WSP - The Wireless Session Protocol determines whether a session between the device and the network will be connection-oriented or connectionless. What this is basically talking about is whether or not the device needs to talk back and forth with the network during a session. A connection-oriented session means that data will be passed both ways between the device and the network. WSP would then send the packet to the Wireless Transaction Protocol layer. If the session is connectionless, commonly used when information is being broadcast or streamed from the network to the device, then WSP redirects the packet to the Wireless Datagram Protocol layer.
WTP - The Wireless Transaction Protocol acts like a traffic cop, keeping the data flowing in a logical and smooth manner. It also determines how to classify each transaction request:
Reliable two-way
Reliable one-way
Unreliable one-way
The WSP and WTP layers correspond to HyperText Transfer Protocol (HTTP) in the TCP/IP protocol suite.
WTLS - Wireless Transport Layer Security provides many of the same security features found in the Transport Layer Security (TLS) part of TCP/IP. It checks data integrity, provides encryption and performs client and server authentication.
WDP - The Wireless Datagram Protocol works in conjunction with the network carrier layer. WDP makes it easy to adapt WAP to a variety of bearers because all that needs to change is the information maintained at this level.
Network carriers - Also called bearers, these can be any of the existing technologies that wireless providers use, as long as information is provided at the WDP level to interface WAP with the bearer.
Once the information is received by the WAP client, it is passed to the minibrowser. This is a tiny application built into the wireless device that provides the interface between the user and the wireless Internet. Here's a look at the start page of a typical minibrowser:

The minibrowser offers streamlined functionality

The minibrowser does not offer anything more than basic navigation. Wireless Internet is still a long way from being a true alternative to the normal Internet. It is really positioned right now for people who need the ability to connect no matter where they are. The WAP Forum is continually working on the specifications of the WAP standard to ensure that it evolves in a timely and useful manner. For more information on wireless Internet and related topics, check out the links on the next page