Most of the emphasis on cognitive radio is for a secondary user to operate in the same spectrum as a primary user. So there is a lot of focus on dynamic spectrum access and the ability to sense the presence (and modulation code) of a primary user and then vacate the channel.
But with WiMAX MAC is built around a scheduler. Where a base stations schedules packest to users so there is no need for carrier sense and collision detection. The goal was a higher quality of service. But with this dedicated nature of base station to subscriber there is not as much emphasis on searching for a primary user, because teh WiMAX is the primary user.
There is more opportunity to use cogntive abilities to optimize the quality and throughput between endpoints. For example, just like 802.11 based systems, WiMAX will scale up or down the bandwidth depending on how far away the receiving radio is. Closer together--> higher signal--> controller sets a higher bandwidth modulation.
"system would use cognitive radio technology to identify interference and poor links and then change its own signal transmission to improve the weak links." taken from here
So the only factor here is proximity. If more information was used to make the decision such as Bit error rate, snr... a better decision can be made.
A more driving force behind a cogntive WiMAX would be self initialization for easy deployment/startup and long term operations for emergency and 3rd world countries.
There is some effor in 802.16h for interoperation in unlicesened bands but that is different than a complete cognitive function.
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I know Jeff is real big on simplified deployment, but I think as economic drivers go, that'll still be behind the following pair:
a) creating new spectrum (via DSA)
b) improving spectrum efficiency in existing bands
However, one of the great things about cognitive radio (as a design paradigm wherein design decisions are moved from humans to radios) is it enables so many new and different applications and lots of market niches.
Another research idea that I mentioned to Jeff yesterday is Dynamic Spectrum Release - basically I think the mechanisms/algorithms used to determine when to release secondary channels (DSR) will be every bit as important to spectral efficiency as the algorithms used to grab secondary channels (DSA). However, to date the focus has been entirely on DSA algorithms with really simple assumptions on DSR.
-James
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