Wireless Wide Area Networks: Trends and Issues Wireless Wide Area Networks: Trends and Issues Mobile computing devices are getting smaller and · Specialized equipment and custom applications more powerful, while the amount of information is were needed for deployment over these propri- growing astronomically. As the demand for con- etary wireless systems. necting these devices to content-rich networks · Often the wireless infrastructures themselves rises, WWAN technology seems like the perfect were difficult to deploy. answer. But today's wireless WANs have some lim- itations. This white paper discusses those limita- · Only a small percentage of the working popula- tions and how NetMotion™ overcomes them. tion was mobile, so corporations considered wireless data deployment a significant invest- Historic Trends ment with little return. Wireless wide area data networking is not a new Why the resurgence of interest in wireless data net- phenomenon. The technology has been around for working technologies now? In the late twentieth over 100 years and was used to send information century, a few interesting social and technological well in advance of voice systems. But as radio tech- developments took place. In the late 1990's, busi- nology progressed, the use of radio transmissions nesses began seeing the economic benefit of having for voice became dominant. It was a natural inter- employees who work away from their campuses. face for people to use, and—temporarily—wireless These remote (and sometimes nomadic) workers data transmission became less important. needed access to everyday corporate information to do their jobs. Providing workers with remote In the twentieth century, voice transmission took a connectivity became a growing challenge for the big step with the birth of the cellular concept at information staff. Handheld and pocket-sized Bell Labs in 1947. Not until 1979 were the first computers became powerful enough to be useful. direct dial analog cellular systems deployed in The convergence of Internet networking technolo- Japan. The Nordic countries followed by 1981. Two gies made IP the de facto standard. New standards years later, the U.S. installed the first commercial such as General Packet Radio Services (GPRS) Advanced Mobile Phone Service (AMPS) wireless were being adopted to provide wireless network cellular system in Chicago. Soon it was apparent services. With the development of such technology, that higher capacity, more reliable, and lower cost the promise of faster access speeds from new wide wireless systems were needed to meet growing area wireless interconnects began to approach (or consumer demand. Over the past decade or so, sig- in some cases exceed) standard connections over nificant efforts were made to increase the capacity landlines. These factors created the environment and robustness of these voice systems, thus the for the anytime, anywhere connected worker. development of the digital standards. Wireless WAN Definition It would seem that technology for wireless data communication over radio signals was left behind. A wireless Wide Area Network (WWAN) is a com- But there were many successful efforts over the puter data network that may extend over a large years to provide "wireless" connectivity, including geographical area. Characteristically, a WWAN IBM and Motorola's ARDIS network, Ericsson's receives and transmits data using radio signals Mobitex, and cellular digital packet data (CDPD). over the initial interconnect with the mobile com- These technologies and others continue to provide puter system. At the switching center, WWAN seg- connectivity for many specialized applications ments then connect to either a specialized public or today. private network via telephone or other high-speed There are many reasons why these technologies communication links. These back-haul intercon- did not have broad commercial appeal and why nects then link to an organization's existing LAN/ the time wasn't right: WAN infrastructure. Recent developments now · While computers grew smaller, most were still allow direct connections to generic public net- too bulky to carry around. works, like the Internet, further reducing the cost of deployment. 2 Unlike wireless local area networks (WLANs), the or slower. The average access time may be slower coverage area for WWANs is normally measured than a 28.8 modem connection. Wireless networks in miles rather than feet. Data throughput rates for in general are also more susceptible to environ- WWANs are a great deal slower than they are for mental factors, like weather and terrain, than local area network connections. They are typically wired networks. measured in tens of thousands of bytes per second Figure 1—Components of a wireless WAN Wireless WAN Limitations Wireless WAN Benefits Mobile computing devices are getting smaller, cheaper and more powerful. At the same time the Whether they are in the office or traveling, today's amount of information available today is growing professionals need access to the corporate data and astronomically. The demand for connecting mobile applications that keep them connected to their devices to content- organization's processes. Wireless WAN connectiv- ity means hospitals can track patients and their rich networks is also rising quickly, and it would charts remotely. Sales staff have access to the latest seem that WWAN technology is the perfect product information for customer presentations. answer. But today's wireless WANs have limita- Managers can get the latest data to make decisions tions in several areas, including: when they are away from their offices. Or public · safety officials can access data that they need from Security the field. · Performance It is access to data communications connections · Application persistence wherever and whenever they are needed that is · Roaming driving the market. Dataquest Inc., the San Jose- based research firm, projects that the wireless data · Off-the-shelf solutions market will grow from 3 million subscribers this · Central management year to 36 million in 2003. Cahners In-Stat's num- bers, while lower (2 million users in 1999 growing to 25 million in 2003), echo similar growth. Both agree that in the near term, it is corporate users who will drive this growth. This business demand will eventually lower future wireless access costs and open the doors to the consumer market. 3 To overcome these limitations, organizations usu- area. They may also choose to suspend operations ally have to increase their already steep IT work- to extend battery life. Such normal communication load by developing point solutions. What follows interruptions can wreak havoc with existing trans- is a more detailed look at these problem areas. port protocol implementations and cause user applications to either lock up or terminate. Security: In modern network topologies, physical boundaries between public and private networks To minimize such interruptions, most wireless are blurring. Unless care is taken, when a company solutions require customizing both the applica- decides to add wireless connectivity to this mix, tions and the network. As a result, most current their information security can be compromised. solutions are limited in scope and restricted to a Wireless systems in general broadcast data over specific set of applications. The radio waves into the ether. The security implica- mission-critical applications are still relegated to tions are obvious—what companies broadcast goes stationary or desktop systems. When a company everywhere. One of the first concerns that the IT tries to deploy these applications to their mobile department has is whether the information cross- devices, mobile users spend a lot of time getting ing the wireless network boundary is secure, back on the network after losing their connections. because it is susceptible to eavesdropping. Sec- They must re-login, re-authenticate, possibly navi- ondly, they must feel confident that a user has the gate through multiple screens to find the point necessary network permissions to access informa- where they left off, and then re-enter any lost data. tion, since they cannot rely on the mobile device's In the end, users become frustrated and feel unpro- physical location to tell them. Wirelessly connected ductive, which costs the company precious time devices can easily breech two of the most funda- and money. mental network security policies: authentication and confidentiality. Roaming: Over the past several years, network Performance: Things never encountered in wired installations have been segmented for manage- infrastructures affect wireless connections: envi- ment and security reasons. To aid network seg- ronmental factors, such as user movement, har- mentation deployment, the networking industry monics, terrain, and weather, can easily affect has worked hard to allow dynamic configuration throughput and performance. Today's standard of systems when they attach to a particular seg- network topologies and protocol implementations ment. However, once application sessions are were designed for communications between sta- established over existing protocols, the network tionary systems. In general, when a mobile device assumes that a device remains attached to that seg- communicates with a stationary device, the sta- ment for the duration of the session. But mobile tionary system uses the same algorithms to com- devices can wander to different areas and the com- municate with its mobile peer. It is not aware that munications pipe