802.11n Promises to Let Us Build Bigger, Faster Wireless Networks That Deliver Better Reliability and Capacity. but Tapping This Technology's Enormous Potential Will Require New Products,

The implementation is designed to achieve higher throughput (>100Mbps) at the MAC layer. The end user is expected to see a 4x increase in speeds (approximately 200Mbps) over the current 802.11g transfer rates. These higher transfer rates open the door to many new applications such as streaming video and voice over IP (VOIP). In addition, IEEE 802.11n will be backwards compatible with legacy IEEE 802.11 standards. To achieve this jump in transfer rate and maintain backwards compatibility a number of modifications are being implemented.

MIMO (Multiple Input, Multiple Output) is just one of the modifications being incorporated into the 802.11n standard. This smart antenna technology provides two opportunities for a faster, cleaner and more reliable signal. With the multiple antennas at both the transmitter and receiver end, multipath effects are accounted for resulting in a cleaner, resolved signal at the receiver. In addition the spatial division multiplexing (SDM) used with MIMO technology increases the data throughput.

WLAN uses OFDM (Orthogonal Frequency Division Multiplexing) but there are changes to the packet structure to support legacy 802.11a/b/g standards and increase throughput. The packet structure begins with a 802.11 legacy packet and then a MIMO channel training sequence to identify the individual transmitters and lastly the new higher speed data. There is a possibility that the new standard may reduce the interframe spacing. There is also a small increase in OFDM sub-carriers and provisions for the optional use of wider bandwidth (40MHz), OFDM Spatial Channel Beamforming and Space Time Block Coding (STBC).