Wireless Wide Area Network(WWAN)

Once you begin using wireless data, you'll wonder how you ever lived without it. Wireless data gives you the freedom to work from almost anywhere and gives you access to personal information when you are on the go. Whether the wireless sytem is accessing e-mail from an airport or receiving dispatch instructions as a taxi driver, you'll find it extremely effective to be able to maintain a data connection with a remote network from almost anywhere.

Radio communications has been with us for a long time, with analog voice as the principal application. Today, tens of millions of people in the United States are using two-way radio for point-to-point or point-to-multipoint voice communications. Although engineers have known for some time how to modulate a radio signal to send binary data, only recently have they been able to develop and deploy wireless data services on a large comme rcial scale.

Wire or fiber-based data communications spans a huge range of throughputs and distances--28.8 Kbps over a modem connection; 10/100 Mbps over an Ethernet segment; and gigabit speeds over fiber. Similarly, wireless connections span a huge range. The world of wireless data includes fixed microwave links, wireless LANs, data over cellular networks, wireless WANs, satellite links, digital dispatch networks, one-way and two-way paging networks, diffuse infrared, laser-based communications, keyless car entry, the Global Positioning System and more.

The benefits of wireless include connections when no others are possible, connections at lower cost in many scenarios, faster connections, backups to landlines, networks that are much faster to install and data connections for mobile users. That last benefit is the focus of this chapter.

In this chapter, we'll concentrate on wide-area wireless data; a future chapter will discuss wireless LANs. The types of WANs we will examine include cellular-based systems, paging networks and dedicated wireless WANs, such as CDPD, Metricom's Ricochet, ARDIS and RAM Mobile Data.

First, let's walk through a planning process that highlights the key issues in working with wireless data. From there we drill into the technology, including protocols and interfaces, hardware, middleware. Next we survey the various wireless networks. We conclude with some pointers for integrating your wireless solution.

One important distinction in the uses wireless data is between vertical market applications and horizontal market applications. In vertical markets, applications addresses a very specific business need for a particular company or industry. The applications provides a clear benefit through higher productivity or other competitive advantage. Today most wireless applications are in the vertical arena. But wireless vendors strongly desire to address much larger horizontal markets where a broad spectrum of business users and consumers wil l use wireless communications. This transition will occur once wireless communications is inexpensive enough, broadly deployed and easy to use and once a large number of off-the-shelf applications are available.