Laptops, PDAs, smartphones and VoIP handsets can be connected to the Internet in many ways. Start by eliminating methods that are clearly impractical. Bluetooth is found in most smartphones and new laptops, but limited speed and range make Bluetooth better at peripheral connection than network access. WiMAX is generating plenty of buzz, but mobile WiMAX services won't be available until 2009-2010. Satellite services such as Inmarsat BGAN are perfect for venues without infrastructure (e.g., disaster areas) but too expensive for general use. After narrowing the field, most road warriors have just two truly viable wireless Internet access alternatives:
Next, specify your coverage needs. List the locations (local, regional, national, international) where wireless Internet access will be required. Do you work inside or outside? Must you use the Internet while in motion? Such questions should be considered in choosing wireless service(s) that will help -- not hinder -- productivity.
According to JiWire, nearly 142,000 free and paid Wi-Fi hot spots exist in 132 countries, primarily in North America and Europe. The vast majority deliver indoor Internet access over 802.11b/g to confined areas such as lobbies, restaurants or meeting halls. Some hot spots are becoming "hot zones," using mesh networks or 802.11n to blanket entire airports and hotels. To serve commuters, a few trains, ferries and even planes offer Wi-Fi service on board. Dozens of U.S. cities are also deploying metropolitan-area Wi-Fi networks. Nonetheless, Wi-Fi is still best for those users who don't need to leave the building or a designated coverage area while accessing the Internet.
On the other hand, 3G is better for those who must stay online while traversing the great outdoors. In the U.S., AT&T now offers HSDPA in dozens of cities, backed by national EDGE coverage in 162 metro areas. Verizon Wireless offers EV-DO Revision A in 27 metro markets, downshifting to EV-DO Rev. 0 and 1xRTT (available in 242 metro areas). Sprint/Nextel delivers EV-DO Rev. A to 35 metro markets, with Rev. 0 and 1xRTT coverage that reaches 220 metro areas. All three footprints are expanding rapidly, so check carrier-coverage maps for locations of importance to you. Individual experiences vary, but urban users can expect to enjoy HSDPA or EV-DO outdoors, with automatic fallback to EDGE or 1xRTT when working indoors, at home, or in less populous areas. Despite national network expansion, there are still many rural areas without any cellular data service. While domestic 2G/3G data service roaming is often available, international roaming is not.
Sure, working from anywhere is convenient, but convenience is also a matter of style. Some users cannot be bothered to switch from EV-DO outside to Wi-Fi indoors and prefer to stick with 3G everywhere -- even if that means perching by a window to get good signal. Others are comfortable carting a laptop to increasingly ubiquitous Wi-Fi hot spots but would find it tedious to read email on a 3G-enabled PDA or smartphone. Connection type plays a big role, but so does computing device and network adapter.
From a hardware perspective, Wi-Fi is very convenient. Your laptop probably already has an 802.11b/g Wi-Fi adapter. A growing number of PDAs now include Wi-Fi, and smartphones are expected to follow suit over the next two years, adding 802.11n to support VoIP. Numerous aftermarket Wi-Fi options exist, from mini SDIO cards to USB sticks to travel routers that enable Internet connection sharing with co-workers. In short, Wi-Fi enablement is easy -- but getting online is less so (see Cost).
3G hardware is less ubiquitous or flexible. Every smartphone -- and some PDAs and laptops -- offer embedded 3G, but those devices bind you to a carrier. Changing carriers or upgrading from EDGE to HSDPA means new hardware (e.g., adding an ExpressCard to your laptop, replacing your smartphone). Product selection is limited in part because 3G has not yet been commoditized to the same degree as Wi-Fi. As a result, going 3G requires planning and commitment; but once you make that leap, use will be simple.
For those few devices without embedded Wi-Fi, adapters are readily available for under $50. By comparison, 3G PC cards are pricey: $50-200 when purchased with a service contract, plus an activation fee. Rebates and volume discounts are often available with both technologies.
Purchasing Wi-Fi service is more complicated. Over time, most users connect to dozens of independently operated hot spots, ranging from free to $7.95/day (Boingo) to $29.99/month (T-Mobile). Alternatively, enterprises can buy Internet access from a single roaming provider (e.g., iPass, Fiberlink). Occasional users can log into any hot spot but must adjust to each by adding network names, logging into portals, and paying by credit card. Frequent users find unlimited-access accounts less expensive but must then hunt for included hot spots. Client software can help to locate hot spots and provide a consistent experience.
Performance is where the rubber hits the road. 2G services were sufficient for low-bandwidth applications but frequently disappointed workers who exchange larger messages. Part of Wi-Fi's appeal has been support for common Internet applications -- email and Web -- at speeds similar to office Ethernet and residential broadband. At today's 802.11b/g hot spots, data rates range from 1 to 54 Mbps, shared with nearby users. This is fine for best-effort applications but supports only a few latency-sensitive or high-throughput sessions. Over the next two years, 802.11e and 802.11n upgrades will help hot spots support more demanding applications such as VoIP and video.
EDGE and 1xRTT were far better than 2G for such applications as email, but users who were accustomed to broadband found surfing and downloads painfully slow. This is no longer true for 3G. For EV-DO Rev. 0, Sprint claims 50-70 Kbps upstream and 400-700 Kbps downstream. Rev. A boosts this to 350-500 Kbps up, 600-1400 Kbps down. For HSDPA, AT&T claims 384 Kbps upload and 400-700 Kbps download throughput. This is slower than Wi-Fi, but many users find 3G comfortable for Web and business applications.
Many workers use Wi-Fi hot spots and 3G smartphones without corporate oversight, but spiraling costs and security concerns are driving some employers to change that.
For example, employees who use hot spots often leak cleartext, including business fileshares. Even those who use VPNs can end up traversing a phony hot spot, exposing tunneled data to man-in-the-middle attackers. Many personal 3G smartphones used to check business email will be lost, along with stored messages and credentials. End users often lack the information to choose the most secure or economical access method.
One way to encourage workers to avoid risky Wi-Fi hot spots is to supply 3G on IT-managed devices. Why 3G rather than Wi-Fi? As a carrier service, coverage areas are larger, spoofing is unlikely, and everything over the air is sure to be encrypted. Some companies will go further, contracting their carrier to relay sessions to a corporate gateway or mobile application server. In fact, such IT-controlled arrangements are readily available for other Internet access methods -- including Wi-Fi hot spots.
Mix and match
Ultimately, no single wireless internet access method can optimize availability, price and performance for all applications. According to Gartner, cellular (3G/4G) services will be dominant for truly mobile workers by 2010, but most remote workers will require multiple access technologies. Instead of choosing 3G or Wi-Fi, we may buy both and decide which to use at any given moment, based on availability, speed, cost and other policy attributes.
This can be done to some degree today. For example, you can purchase 3G and Wi-Fi services from AT&T, using the Cingular Connection Manager to manage both. The Connection Manager first tries to connect to an available Wi-Fi network, then to AT&T's cellular network. Multi-service wireless connection managers like this are currently available from carriers and roaming providers. Enterprises that purchase Internet access for their workforces should give serious consideration to services that support both 3G and Wi-Fi (and other methods for backup or international use). Doing so lets you change wireless network preferences for some or all users without changing providers.
Deciding which network to use is one thing; handing a session over without disruption is quite another. Unlicensed Mobile Access (UMA, a.k.a. GAN) lets a dual-mode handset maintain a voice call when roaming between a GSM cellular network and an unlicensed wireless network like a Wi-Fi hot spot. UMA trials have been conducted worldwide, including T-Mobile here in the U.S. Broader initiatives like FMC and IMS are expected to go further, letting data and voice applications run over a broader set of wired and wireless networks. In the near term, companies should expect application disruption when roaming between 3G and Wi-Fi. If that poses problems for your workforce, consider using a mobile VPN to bridge the gap.
About the author:
Lisa A. Phifer is vice president of Core Competence Inc. She has been involved in the design, implementation and evaluation of data communications, internetworking, security and network management products for more than 20 years and has advised companies large and small regarding security needs, product assessment, and the use of emerging technologies and best practices.
This was first published in April 2007