From the Editor
Considering wireless LANs: proceed with caution O ne of the problems associated with the use of any technology is the fact that the unexpected can be expected to occur. In the wonderful world of wireless LANs the unexpected has occurred as a result of the US Federal Communications Commission (FCC) which provides the potential to affect the performance of your network. Let me explain.
The IEEE 802.11b wireless LAN standard provides a data transmission operating rate of 11 Mbps, which is a significant improvement over the original 802.11 operating rate of 2 Mbps. Unfortunately, both standards, as well as Bluetooth, microwave ovens, and the emerging HomeRF standard all use the 2.4 GHz unlicensed frequency band. To compound this problem, the FCC recently allowed HomeRF to use 5 MHz from its previously allocated 1 MHz to permit a data transmission rate of 10 Mbps at distances up to approximately 150 feet.
While HomeRF was originally oriented towards the home market it is now being considered as a lowcost wireless LAN. While any mechanism to provide networking personnel with an additional option at a potential lower cost is normally laudable, in this case it could be a disaster waiting to happen. This is because HomeRF uses frequency hopping, in which traffic can move from one frequency to another within the 2.4 GHz band. While this should not be a problem if Home RF is used in a one-story tenement building, what happens if it is used in a multi-story building with numerous tenants operating IEEE standard LANs? In this situation HomeRF hopping around in 5 MHz frequency segments represents interference all over the unlicensed band within a 150 feet radius. Although the IEEE 802.11 standard supports either frequency hopping or direct-sequence operations, when HomeRF is operating within 150 feet of an IEEE wireless LAN you can expect interference.
While the FCC response to the potential problem noted in this column is to point out that an unlicensed band carries certain risks, I would personally expect more than this. It seems to me that while an unlicensed band is unlicensed, the FCC as a minimum could provide guidance that could eliminate potential problems before they occur. After all, isn't part of their job to minimize interference instead of providing a situation where competing technologies can represent an unanticipated problem to each other? In closing this column, this is unfortunately one more example of a network manager having to consider the fact that the unexpected can be expected to occur. Thus, prior to thinking about installing an 802.11 LAN you may now need to consider the plans of any organizations within a 150-feet radius of the locations where you expect to install your wireless LAN components. As my Macon TV announcer would say, 'That's my opinion, what's yours?' -Gilbert Held