Your customer has been pleased with his 802.11g WLAN for years, so why upgrade to 802.11n now? Clearly it's the latest Wi-Fi technology, but does it really deliver useful benefits that outweigh the cost of upgrading?
The most widely touted benefit is speed. That's because IEEE 802.11n uses multiple antennas on sending and receiving stations to increase data rate and coverage area, in contrast with the previous standard, 802.11g. The new standard promises a theoretical maximum data rate of 300 Mbit/s, though most rates are reported at something over 100 Mbit/s. In comparison, 802.11g has a theoretical maximum of 54 Mbit/s, with actual rates typically being between 25 and 30 Mbit/s.
The press has also raved about 802.11n's dependable coverage. Signals from the sender's multiple antennas travel different paths to the receiver. If one path is blocked by an obstacle such as a file cabinet, another signal may get through. In most environments, therefore, coverage area is increased.
But there are many benefits that go above and beyond data rate and coverage. In fact, data rate and coverage alone do not justify the cost and effort of an upgrade unless they provide an overall cost saving or improvement in efficiency. Here are five reasons why an upgrade can benefit your customer:
New applications: Voice and video
Moving voice to the WLAN to support dual-mode phones can reduce your customers' cellular bills. In many companies, when staff members spend part of their time on the road and use cell phones to communicate, they tend to continue to use those phones once back in the office. Now, you can replace their phones with dual-mode phones, so when they're on the road, they continue to use cellular, but in the office, their calls go through the WLAN.
WLANs also address the space coverage issues in warehouse settings where customers often have to use cellular because cordless phones won't cover the distance of the facility. Using 802.11n extends the WLAN to the warehouse, reducing cell phone expenses by moving staff calls to the WLAN.
802.11n also addresses the integrity of wireless voice calls. While voice traffic does not require the data rate that 802.11n can deliver, achieving the sound quality that we have come to expect requires that voice packets not be delayed by a busy network. The additional bandwidth offered by 802.11n greatly reduces the possibility of delay.
Beyond voice, 802.11n also makes wireless video possible. The higher data rate enables wireless classrooms so, for example, students can view video training material individually with the ability to start and pause when necessary.
Solid wireless video and good coverage also enable surveillance applications. The larger coverage area provided by 802.11n makes it possible to mount video cameras in distant areas of the facility without the need to string network cable.
802.11n also enables prioritization of voice and video packets for urgency. Many 802.11n APs include the IEEE 802.11e Quality of Service (QoS) standard. 802.11e provides a way to separate traffic based on the QoS characteristics required. For example, voice packets are short but require immediate access to the network. Video packets, on the other hand, are longer and can be delayed, as long as the delay time remains roughly constant. The AP sorts and prioritizes packets by application and supplies the type of service needed.
Eliminating bandwidth contention
As more and more WLANs are deployed, customers in shared office buildings have difficulty finding an available channel. After all, the 2.4 GHz band used by 802.11g has just three non-overlapping channels, but 802.11n can use either the 2.4 GHz or the 5.0 GHz band. In most cases it will be configured to use the 5.0 GHz band with its 12 non-overlapping channels.
Also, the 5.0 GHz channel is relatively free of noise, while many cordless phones operate in the 2.4 GHz band, causing further contention for 802.11g. In addition, an operating microwave oven generates a 2.4 GHz signal that can completely disrupt WLAN operation.
More users and more floor space
Even without added applications, as your customer adds more employees and occupies a larger office area, a single 802.11g AP may no longer be sufficient. A second AP can be added, but why buy a new 802.11g AP and deal with the complexity added by a second AP?
Go with a new AP that supports both 802.11g and 802.11n operating simultaneously so laptops don't all have to be upgraded immediately. Upgrade remaining units gradually as they reach end of life.
Improved network security
WEP, the original WLAN encryption protocol, has proven to be no barrier for those who would intercept and read your customers' wireless data. It has been replaced by WPA and more recently by WPA2. If a customer's network cannot support WPA2, an immediate upgrade is a security necessity.
Improved support in the future
Finally, your customers' equipment may require replacement because it is reaching the end of support. IEEE 802.11n products have been available from all the major vendors since 2007 and have proven to be stable. Purchasing new 802.11g equipment does not make sense.
A few things to consider
Work on the 802.11n standard began in 2004 but will not be completed until sometime in 2009. In general, it is best to wait for a standard to be finalized, but for more than a year major vendors have been shipping products based on the latest draft standard. Any changes in the final document will be dealt with through firmware updates.
Currently deployed switches will need to be upgraded to 1 Gbit/s or replaced. Also, some vendor architectures centralize functions in a controller. In these cases, the controller must also be replaced.
Despite these issues, IEEE 802.11n has proven its value to early adopters. Its greater data rate and wider coverage can deliver new efficiencies and cost savings to your customers.
David B. Jacobs of The Jacobs Group has more than 20 years of networking industry experience. He has managed leading-edge software development projects and consulted to Fortune 500 companies, as well as software startups.
