Novel Rate-Distance Adaptation of Multiple Access Protocols in Cognitive Radio

Cognitive radio has been considered as a key technology toward future wireless communications due to better spectrum efficiency by accommodating secondary user system(s). We observe modern wireless communication systems widely applying adaptive modulation and coding (AMC) based on signal strength/quality, which has been ignored in earlier wireless networking research, and we call it as rate-distance nature. By pioneer introducing the rate-distance properties to slotted ALOHA multiple access (as an example of multiple access protocols) to mitigate interferences from the secondary system(s) to primary systems, we successfully demonstrate optimization of the secondary system´s throughput, while maintain the primary system unchanged. Consequently, we optimize the spectrum throughput of the entire cognitive radio networks via joint physical and medium access control, rather than just spectrum utilization/efficiency at the physical layer.