Wireless Everywhere! (Part 2)

In the first part of this series, we explored advancements in Wi-Fi technology that makes wireless LANs a viable alternative to wired Ethernet for workstation connectivity.

In part 2 of this series, we'll explore the role of wireless broadband technology in the overall network architecture. Together, Wi-Fi and and wireless broadband will shape the future of both business and consumer wireless networks.

What Is Wireless Broadband?
Essentially, wireless broadband is high-speed wireless network access over a wide area. It's also sometimes referred to as wireless wide area network (WWAN) services.

There are several types of wireless broadband services designed for both fixed and mobile use. This article will examine wireless broadband for mobile network access and as a "last mile" alternative.

Mobile wireless broadband services in the US are provided by cellular phone service providers such as AT&T, Sprint, T-Mobile and Verizon. These service providers use different and, unfortunately, incompatible wireless broadband technologies (as opposed to Wi-Fi which is standard regardless of the provider).

Second generation (2G) mobile broadband technologies include GPRS (general packet radio service) and EDGE (enhanced data rates for GSM evolution). Newer third generation (3G) technologies include EV-DO (evolution data optimized) and HSDPA (high speed downlink packet access).

The 3G Standards
EV-DO (officially known as the TIA-856 standard) and HSDPA (an enhanced version of UMTS), represent the current state of wireless broadband technology in the US. Both Sprint and Verizon offer EV-DO wireless broadband. HSPDA is the current technology used by AT&T and soon by T-Mobile.

The initial EV-DO spec (Rev 0) has a maximum downlink speed of 2.4 Mbps (?) but only a 153.2 Kbps (?) uplink speed. The current Rev A spec provides up to 3.1 Mbps down and 1.8 Mbps up. The emerging Rev B spec will provide peak downlink rates from 4.9 to 14.7 Mbps. Of course, these are theoretical speeds so you'll probably experience around half these speeds or less.

HSDPA is really considered a 3.5G technology with maximum downlink speeds up to 14.4 Mbps, again theoretical, with a 384 Kbps uplink. The next generation of HSDPA (evolved HSPA) promises downlink and uplink speeds of 42 and 22 Mbps, respectively. Right now, AT&T's HSDPA has a 3.6 Mbps peak downlink. T-Mobile will soon offer similar HSDPA service to replace its intolerably slow 2G service.

3G in Action
Wireless broadband services are becoming increasingly prominent in notebook computers as an alternative or complement to Wi-Fi Internet access. Notebook manufacturers are offering internal wireless broadband network adapter options. You can also purchase an external adapter for existing notebooks.

Wireless broadband service costs around $60 per month with coverage available in most major areas. With automatic fall-back to slower/older service, you're bound to have some level of service in most urban/suburban locations and in some rural locations. I've used Sprint's EV-DO service and was amazed to find service available (albeit at its slowest speed) during a visit to Sedona, Arizona.

3G wireless broadband can also be used as a very affordable backup for wired WAN services. With speeds comparable to T1 (1.54 Mbps) service, 3G can be implemented as part of a WAN strategy using a special router. These routers use a standard wireless broadband adapter to provide emergency network service if the wired WAN service fails.

So why not use wireless broadband as your primary WAN service? Well for one, most carriers limit monthly bandwidth usage. Secondly, current uplink speeds are considerably slower than wired connections and could severely impact performance. However, other existing wireless WAN services are specifically designed for primary WAN service (although outside the scope of this article).

Next: 4G and WiMAX
The next step in the evolution of wireless broadband is (you guessed it) 4G. The most promising 4G technology in the US is WiMAX, which is short for Worldwide Interoperability for Microwave Access. WiMAX is a common name for the IEEE 802.16 standard that defines both fixed (802.16d) and mobile (802.16e) variations of this technology.

The promise of WiMAX is to provide affordable high-bandwidth access everywhere it's needed. This includes areas where wired broadband is not economically feasible such as sparsely populated rural areas. WiMAX coverage extends up to 6 miles for non-line-of-sight and up to 30 miles for line-of-sight implementations.

WiMAX also promises sufficient bandwidth to make it practical as a "last mile" alternative for corporate WANs. Bandwidth could be as high as 70 Mbps, but in reality would be closer to 10 Mbps. Since a single WiMAX line-of-sight tower can cover a 30-mile radius, deployment costs would be lower than wired connections providing the same coverage.

WiMAX can also provide direct Internet connectivity for mobile workstations such as notebooks and smart phones. Mobile WiMAX (802.16e) will eventually replace EV-DO and HSDPA, and will solve the interoperability problem inherent in those disparate 3G technologies.

Future of Wireless
The future of network connectivity is wireless, and the future of wireless broadband is WiMAX. Internet connectivity, both mobile and fixed, will soon become ubiquitous.

WiMAX is an exciting advancement in wireless broadband technology and will change the architecture of high-speed wireless networks. With WiMAX for wireless WAN connectivity and 802.11n Wi-Fi for wireless LAN connectivity, wireless will truly be everywhere!

This article only scratches the surface of wireless broadband technologies. For more information on these topics, see the references below.

Also, please submit your comments and questions. I'd very much like to hear about your experiences with wireless broadband, and would be glad to answer any questions.

References:
EDGE
EV-DO
GPRS
HSDPA & HSUPA
HSPA+ (Evolved HSPA)
IEEE 802.11n
IEEE 802.16
UMTS
Wi-Fi Alliance
WiMAX
WiMAX Forum

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By Harry Hiles, HBH Technology LLC — 23 Jun 2008