Impact of Legacy Devices on 802.11n Networks
The 802.11n specification defines several mechanisms by which HT (High Throughput) STAs may coexist with non-HT (802.11a/b/g) STAs. This concept (and many of the procedures for doing so) is not new, or unique to 802.11n. In fact, many of the issues of coexistence and backwards compatibility are present in 802.11g whereby protection mechanisms are employed allowing ERP (802.11g) STAs to coexist with HR/DSSS (802.11b) STAs. To be sure, the designers of 802.11n certainly understood that in order for the technology to be successfully adopted, it must contend and coexist with legacy WLAN deployments - especially in the enterprise, where significant investment has already been made in (legacy 802.11 a/b/g) WLAN infrastructure.