Multiple Radio Frequency WLAN Technologies

By Edward Tetz from Cisco Networking All-in-One For Dummies

The latest technologies for WLAN allow you to operate in both of the major RF frequencies. Being able to choose either frequency when operating the WLAN provides you with the best of both worlds and will likely be the trend moving forward.

Early in WLAN development, many people were trying different technologies to achieve the goal of wireless LAN communication. As some clear winners started to emerge, a need existed for interoperation among these technologies. This desire for interoperation led to the development of standards around WLAN communications.

Right now the only relevant specification is IEEE 802.11n. In early versions of the draft specifications, this standard was only to use the 2.4-GHz RF spectrum. However, the final specification, ratified in September 2009, allowed operating in the 5-GHz RF spectrum as well.

By allowing both of the previous RF spectrums to be used, it allows IEEE 802.11n devices to be backward compatible with both IEEE 802.11b/g and IEEE 802.11a devices and maximizes its possible acceptance in a network setting.

IEEE 802.11n uses both OFDM and MIMO RF modulation techniques. Although ranges are comparable with the IEEE 802.11 network specifications, it allows a maximum throughput of 600 Mbps when using four MIMO streams, or 150 Mbps for a single stream.

IEEE 802.11n offers many advantages over the previous IEEE 802.11 network specifications because it operates in both major RF bands, is backward compatible with other standards, and operates at higher data speeds.

Because it has only recently been ratified, many of the existing devices on the market conform to draft specifications, but you can expect that if you have any of these, a firmware-based upgrade to the final standard should be released soon.