In most organizations today, Internet access via the LAN is the norm. Workers share applications, data, and services through their hub- or switch-based LAN connection. When they require Internet access to do research on the Web or send e-mail to someone on another network, for example, the traffic goes through a router connected to the hub or switch and then out to the ISP via a dedicated, “always on” connection such as a Digital Subscriber Line (DSL) or T1 link or even cable.
Telecommuters may have to rely on dialup services that offer no more than 56 kbps. However, there are two trends that make the case for wireless Internet access. One trend has to do with the workforce itself; more and more workers are becoming mobile and require a flexible method of Internet access from wherever they happen to be. This greatly improves flexibility in that the user does not have to find an available phone line in order to dial into the Internet.
Wireless access to the Internet also increases productivity in that the user can accomplish work-related tasks at the most opportune time, even while traveling or taking a “vacation.” Second, more companies require high-speed Internet access and cannot always get ISDN, DSL, or cable in their areas or afford the price of one or more T1 lines.
Larger companies that require broadband Internet access in the multimegabit range via T3 or OC-3 may not be able to wait for fiber installation to their locations. These companies are looking to fixed wireless providers for fast installation as well as cheap bandwidth. Whereas a new fiber build may take months to complete under a best-case scenario, wireless broadband connectivity from the customer premises to the service provider’s hub antenna can be accomplished in a matter of days.
Business users have a growing number of wireless Internet access services to choose from, and vendors and service providers are emphasizing technologies designed to let users take the Internet with them wherever they go. Already, wireless offerings run the gamut from Wireless Application Protocol (WAP)–enabled mobile phones to broadband architectures that offer fixed wireless access to IP-based networks at megabit-per-second speeds.
In addition, Internet connectivity is now available with all major mobile phone protocols, including Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), and Global System for Mobile (GSM) telecommunications.
Wireless Access Methods
There are several methods to wirelessly access the Internet, including analog cellular and cellular digital packet data networks, packet radio services, and satellite.
Cellular Networks Analog cellular phone subscribers can send files and e-mail wirelessly via the Internet by hooking up a modem to their phones. Of course, this method of access requires that the user have a cell phone in the first place, as well as an adapter cable to connect the phone to the modem. Cellular modems work anywhere a cell phone does. The problem is that they work only as well as the cell phone does at any given moment.
Checking e-mail on the Internet can be slow, and connection quality varies from network to network. To access Web content on the Internet, however, really requires a digital cellular service [also called Personal Communication Service (PCS)] and a special phone equipped with a liquid-crystal display (LCD) screen. AT&T’s PocketNet phone, for example, lets users access the Internet in areas served by its Cellular Digital Packet Data (CDPD) network.
With this type of cellular service, standard analog cell phones will not work; a digital CDPD phone is required. An alternative is to use a dual-mode phone that operates in standard analog cellular mode for voice conversations and CDPD mode for access to the Internet at 19.2 kbps. AT&T’s PocketNet service includes a personal information manager (PIM) that contains an address book, calendar, and to-do list that are maintained on AT&T’s Web site and accessed through the phone.
The personal address book is tied to the PocketNet phone’s “easy dialing” feature for fast, convenient calling. Another feature offered by CDPD is mobility management, which routes messages to users regardless of the location or the technology. Gateways provide the cellular network with the capability to recognize when subscribers move out of the CDPD coverage area and transfer messages to them via circuit-switched cellular.
Packet Radio Networks An example of a radio network is provided by the Ricochet service developed by Metricom, now a subsidiary of Aerie Networks, that provides network solutions and wireless data communications for industrial and PC applications. The Ricochet service comprises radios, wired access points (AP), and network interconnection facilities (NIF) that enable data to be sent across a network of intelligent radio nodes at speeds of over 176 kbps, with bursts of up to 400 kbps.
The network uses frequency-hopping spread-spectrum packet radios. Alarge number of these low-power radios are installed throughout a geographic region in a mesh topology, usually placed on top of streetlights or utility poles. These radio receivers, about the size of a shoebox, are also referred to as “microcell radios.”
Only a small amount of power is required for the radio, which is received by connecting a special adapter to the streetlight. No special wiring is required. These radios are placed about every quarter to a half mile and take only about 5 minutes each to install. Using 162 frequency- hopping channels in a random pattern accommodates many users at the same time, along with providing a high degree of security.
Distributed among the radios are APs, which are used to route the wireless packets on to the wired backbone. Gathering and converting the packets so that they can be transmitted to the wired backbone is accomplished via a T1- based Frame Relay connection. The packets can then be sent to another AP, the Internet, or the appropriate service provider. If the packet is sent to another WAP, it is being used as an alternate route through the mesh.
The number of paths a packet can take through the network enhances speed throughput, since network blockage is not as frequent and many possible repeaters exist for the packet. The Ricochet modem weighs only 8 ounces and thus is very portable. It can be plugged into the serial port of a computer and can be connected to online services and networks just like a standard phone modem.
The modem works with most communications software, as well as with Intel-based and Macintosh hardware platforms and operating systems. Ricochet’s wired backbone is based on standard Internet Protocol (IP) technology, routing data via a metropolitan service area. If a data packet has to move across the country, Ricochet’s NIF system is used. The NIF functions as a router, collecting packets from the WAPs and using leased lines to connect with NIFs situated in the different metropolitan areas.
A name server is part of the Ricochet network backbone, providing security by validating all connection requests. Metricom had been testing a new wireless data technology that would have provided data rates equal to that provided by wired ISDN 128-kbps service. This technology, called Ricochet II, uses two bands of unlicensed spectrum: the 900- MHz band and the 2.4-GHz band.
The new network is compatible with the company’s existing Ricochet network and modems. After investing $1.3 billion in infrastructure, Metricom declared bankruptcy and discontinued operations in August 2001. Under new management, the company is in the process of reactivating the existing network and expanding Ricochet to areas where high-speed broadband access is currently unavailable.
The outlook for Ricochet is unclear. Newer, cheaper Wi-Fi networks are being set up that greatly surpasses the speed of Ricochet. In fact, a new type of wireless Internet service provider (WISP) has emerged, such as Boingo Wireless, which uses the 2.4-GHz frequency band to offer data rates of up to 11 Mbps in public places.
Fixed Wireless Access As an alternative to traditional wirebased local telephone service, fixed wireless access technology provides a wireless link to the Public Switched Telephone Network (PSTN). Unlike cellular technologies, however, which provide services to mobile users, fixed wireless services require a rooftop antenna to an office building or home that has a line of sight with a service provider’s hub antenna.
Fixed wireless access systems come in two varieties: narrowband and broadband. Anarrowband fixed wireless access service can provide bandwidth up to 128 kbps, which can support one voice conversation and a data session such as Internet access or fax transmission. Abroadband fixed wireless access service can provide bandwidth in the multimegabit-per-second range, which is enough to support telephone calls, television programming, and broadband Internet access.
A narrowband fixed wireless service requires a wireless access unit that is installed on the exterior of a home or business to allow customers to originate and receive calls with no change to their existing analog telephones. Voice and data calls are transmitted from the transceiver at the customer’s location to the base station equipment, which relays the call through carrier’s existing network facilities to the appropriate destination. No investment in special phones or facsimile machines is required; customers use all their existing equipment.
Narrowband fixed wireless systems use the licensed 3.5- GHz radio band with 100-MHz spacing between uplink and downlink frequencies. Subscribers receive network access over a radio link within a range of 200 meters (600 feet) to 40 kilometers (25 miles) of the carrier’s hub antenna. About 2000 subscribers can be supported per cell site. Broadband fixed wireless access systems are based on microwave technology.
Multichannel Multipoint Distribution Service (MMDS) operates in the licensed 2- to 3-GHz frequency range, while Local Multipoint Distribution Service (LMDS) operates in the licensed 28- to 31-GHz frequency range. Both services are used by Competitive Local exchange Carriers (CLECs) primarily to offer broadband Internet access. These technologies are used to bring data traffic to the fiberoptic networks of Interexchange Carriers (IXCs) and nationwide CLECs, bypassing the local loops of the Incumbent Local Exchange Carriers (ILECs).
Fixed wireless access technology originated out of the need to contain carriers’ operating costs in rural areas, where pole and cable installation and maintenance are more expensive than in urban and suburban areas. However, wireless access technology also can be used in urban areas to bypass the local exchange carrier for long-distance calls. Since the IXC or CLEC avoids having to pay the ILEC’s local loop interconnection charges, the savings can be passed back to the customer. This arrangement is also referred to as a “wireless local loop.”
Satellite Services Satellites are another solution for the rapidly growing demand to transmit Internet and other networking traffic because they offer reliable connections to virtually anywhere in the world.
CyberStar, for example, offers a portfolio of business services, including a global broadband IP multicasting service that allows business users to send high-bandwidth voice, video, and data files to branch offices. By integrating IP, applications, video and audio streaming, IP multicast, Webcasting, and high-speed delivery onto an independent, satellite-based platform, CyberStar gives the IT manager a scalable broadband network.
The satellite service enhances, not replaces, existing enterprise communications infrastructures. The CyberStar system is intended as an overlay that fits with whatever companies are currently running. They can keep missioncritical applications on the current network and run dataintensive and media-rich applications over a reliable and cost-efficient satellite network.
Customers pay for the bandwidth they use rather than signing up for a flat-rate service. Pricing is based on the amount of traffic that is sent each month and the number of sites that are receiving that traffic. Customers are charged initial installation costs per site, which includes antennas, satellite receiver cards, and service activation fees. Other satellite service providers also support Internet traffic.
For homes and businesses, Hughes Network Systems (HNS) has given has been offering its one-way DirecPC Internet access service for several years as well as a newer one- and two-way broadband service, called DirecWAY, which offers 400 kbps. In the near future, low-earth-orbit (LEO) satellites such as Teledesic will provide Internet access and support other broadband applications with bandwidth on demand ranging from 64 kbps to multimegabit-per-second speeds.
Service Caveats
The biggest and most obvious concern to those interested in wireless technology is that it is more expensive than its wired counterpart and requires an investment in special equipment. As portability becomes more of a factor with regard to Internet access, corporations will become more willing to pay the higher cost of wireless technology. As history has shown, once prices drop due to corporate participation, consumers also will be able to reap the benefits of wireless technology.
Another concern is how network managers are going to integrate the wireless and wired worlds. This involves not only two skill sets, but also two network management systems and two separate application development paths. Nevertheless, wireless technology is becoming more accepted because it can now be economically integrated with wired networks. This can be done with wireless LAN access points that are connected to the hub or switch with Category 5 cable.
Performance is another issue that needs to be improved in wireless Internet access, particularly for real-time applications. The perception is that a wireless connection should have the same throughput and latency as a wired connection, but this is usually not possible. This tends to give the notion that there is not a reasonable response time for interactive applications with wireless connections.
While good response time can be had with fixed wireless systems that use MMDS and LMDS, these technologies have other issues that bear consideration, such as limited distance and a lineof- sight requirement. These technologies also falter during heavy rain, dense fog, and dust storms. While the service is out periodically, wired links for backup may be required.
As noted, there are some wireless Internet access providers that are starting to use the 2.4-GHz ISM (industrial, scientific, medical) frequency band to offer commercial Wi-Fi services. But this is unlicensed spectrum, which means that there is no guarantee against interference. MMDS and LMDS, on the other hand, are services provided over licensed spectrum. Since the FCC controls the use of this spectrum, business users can expect interference-free wireless connections for Internet access.
There are a variety of technologies available for wireless Internet access. Although wide-scale deployment of wireless Internet access services is still somewhere in the future, the long-term prospects for those services may be brighter than ever, due in large part to the number of carriers getting involved with the various technologies and the increasing investments being made toward further development.
In many parts of the United States, there is the growing realization that obtaining broadband Internet access through cable and DSL will not be available anytime soon, if ever. Wireless technologies have an important role to play on filling this niche.
