This presentation gave a high-level technical overview to several approaches under consideration as the best blend of performance and cost in the final 802.11n spec, due in 2007.
Specifically, the IEEE Task Group N (TGn) is considering which carrier frequencies to use: The two currently under consideration are 20MHz and 40MHz.
The latter can deliver better performance at a lower cost since it requires fewer antennas and less-expensive radios.
Using the 40MHz carrier, researchers have been able to achieve top throughputs of around 240Mbits/sec, although taking into account regulatory constraints, this figure drops to about 140Mbits/sec.
One of the key components to enabling the targeted 5X performance increase over current-generation 802.11 technology is MIMO (multiple-in, multiple-out) achieved via SDM (spatial division multiplexing).
This differs from the approach espoused by the WWiSE (World-Wide Spectrum Efficiency), which includes chip-set makers Motorola, TI, Broadcom and Airgo.