Fixed wireless fills a niche

If you can't wait for DSL or cable modem to be installed at your corporate headquarters or if it seems like broadband will never be available at your remote sites, fixed wireless is becoming a viable alternative for last-mile Internet access.

Fixed wireless has some advantages over wired broadband: It can be installed in a matter of days. Once line of sight is established, the connection isn't susceptible to the types of weather-related or accidental outages that can occur with wired networks.

But there are important issues that network executives will need to resolve before signing up for fixed wireless, including security and possible performance degradation from interference with other service providers.

On the island of Anguilla, a British territory six miles north of St. Martin in the Caribbean, Weblinks Limited has installed a wireless Internet system that covers the entire 16-mile-long island, offering services to a growing number of e-commerce companies.

On a hurricane-prone and remote island like Anguilla, fixed wireless offers several benefits over DSL and cable modem. "We have much higher performance with Weblinks' wireless Internet as compared to other options. Reliable and cost-effective wireless access to the Internet is necessary for us to conduct our business," says Bob Green, president of Robelle, a Canadian software company that he runs from the island.

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Standard procedure
Fixed wireless research

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A fixed wireless Internet system, such as Weblinks' in Anguilla, consists of centralized transceiver towers and directional antennas mounted at each end-user location to maximize range and minimize the number of towers needed to cover a large area.

Michael Mussington, who represents National Commercial Data Services, a company providing data services for Anguilla's National Bank of Anguilla and Caribbean Commercial Bank, adds, 'The Weblinks system provides high-speed performance to effectively support our bank transactions and enables us to rapidly reconfigure our networks as needs change. There really is no other comparable choice for us here in Anguilla.'

"It's difficult to maintain a cable system because of the harsh weather we often have in Anguilla," says Lee Bertman, president of Caribbean Cable Television, referring to hurricanes. As a result, wireless Internet is proliferating in places such as Anguilla.It's also making inroads in small towns throughout the U.S., Europe, and Asia.

According to Jeff Lobb, vice president of sales at Wave2Wave Communication, "Since fixed wireless bypasses the local loop and the phone company, we can deliver a high-speed T-1 connection in five to seven days at one-third the cost of a typical, hardwired T-1."

Mike Evans, IS operations manager at RSA Insurance Group in Clifton, N.J., says his fixed wireless service was installed in five days and costs significantly less than a wired T-1.

In fact, Sprint is now offering fixed wireless with 1.5M bit/sec downstream and up to 250K bit/sec upstream for $200 per month.

Interference penalties

With fixed wireless, radio frequency interference from competing systems causes problems for service providers and end users. An interfering signal of one wireless system will corrupt and sometimes block the transmission of another wireless system, causing significant performance degradation.

For example, Weblinks' 802.11-based direct sequence spread spectrum (DSSS) system experienced radio frequency interference problems, even on the tiny island of Anguilla. After Weblinks' system was operational and supported a large number of end users, the system experienced performance degradation that seemed to coincide with Cable & Wireless testing a competing 802.11-based frequency hopping spread spectrum (FHSS) system.

Because FHSS spreads its signal power over the entire 2.4-GHz band, FHSS hops all over the narrower DSSS signal, letting FHSS interfere with DSSS systems (but not vice versa). "When the Cable & Wireless system was operating, the Weblinks' system's signal-to-noise ratio would drop significantly. This would cause the data rates to automatically switch from 11M to 5.5M bit/sec and lower," says Griffin Webster, Weblinks managing director.

Weblinks and Cable & Wireless ended up in court. The Anguillian High Court ordered Cable & Wireless to cease operation of their system because the Anguillian government had previously licensed Weblinks to be the sole operator in the 2.4-GHz band.

But in most areas, the use of the 2.4-GHz band is public, which means service providers have little control over the systems that competitors might install. Many companies install DSSS-based systems and later experience performance degradations from FHSS that competitors install in the same area. The 2.4-GHz band gets pretty crowded when you have competing wireless systems operating next to each other.

But the newer IEEE 802.11a products should significantly reduce interference issues. 802.11a provides up to 54M bit/sec data rates using orthogonal frequency division multiplexing in the 5-GHz frequency band. Most wireless Internet service providers will likely migrate to this standard as 802.11a products become available by year-end.

In addition to higher performance, 802.11a systems will avoid the crowding issues of the congested 2.4-GHz band. For network executives, this means higher performance and greater reliability.

Security concerns

Another key issue with wireless Internet is security. A poorly secured system lets eavesdroppers access sensitive information.

If you plan to transmit credit card numbers, Social Security numbers and passwords over a wireless network, then you'd better be sure the system supports adequate security mechanisms. IEEE 802.11 wired equivalent privacy (WEP) might not be good enough.

Researchers at the University of California at Berkeley have found flaws in the 802.11 WEP algorithm and claim it is not capable of providing adequate security. A problem with the 802.11 WEP is that it requires the use of a common key throughout the network for encrypting and decrypting data, and changing the keys is difficult to manage. This makes the system vulnerable to breaches in security, and network executives should be cautious when implementing 802.11 networks.

Network executives should ensure that wireless service providers implement enhanced security beyond 802.11 WEP (such as IEEE 802.1x). Some vendors, such as Cisco, implement security mechanisms that utilize a different key for each end user and automatically change the key often for each session. This greatly enhances information security.

Conclusion

Fixed wireless is a good option for networks in locations where DSL and cable modem access is not available. Small and midsize companies might also benefit from wireless Internet in larger cities because of cost savings.

With the availability of the solid IEEE 802.11b products and the upcoming IEEE 802.11a and IEEE 802.16 products, network executives can count on having performance that exceeds DSL and cable modem access. However, network executives should strongly consider provisions in contracts for specific performance and availability. Because of potential interference in the 2.4-GHz band, the contract should be checked for provisions to recover investments if the system doesn't deliver what it's stated to do.

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Geier provides consulting services to companies implementing wireless Internet systems and in-building wireless LANs. He is the author of Wireless LANs (2nd edition). His Online Guide to Wireless Networking is located at www.wireless-nets.com/guide.htm. He can be reached at jimgeier@wireless-nets.com.

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