2. 4 Introduction 1 2 3 5 Semi-Structure Routing Framework System Model Performance Analytical Framework Simulation 6 Conclusion

3. 3

4. 4  Cognitive Radio Networks (CRNs)  The utilization of spectrum assigned to licensed users varies from 15% to 85% temporally and geographically (FCC report)  Unlicensed users (Secondary Users, SUs) can sense and learn the communication environment, and opportunistically access the spectrum without causing any unacceptable interference to licensed users (Primary Users, PUs)

5.  Routing in CRNs  Metric/rule based routing protocols  Resource aided routing protocols  Optimization based routing protocols  Motivation  Shortcomings of existing works  Lacking of analytical models for routing protocol behaviors  Our contributions  A spectrum-aware Semi-Structure Routing (SSR) framework  A latency and scalability analytical framework  Extensive simulations 5

6. 6

7.  Primary Network  m Primary Users (PUs):  Network time is slotted:  licensed spectrum bands  Primary transmitters are Poisson distributed with density  Secondary Network  n randomly distributed Secondary Users (SUs)  Dense scaling 7

8.  Power Model  l levels of power  Transmission radius:  Topology graph  Communication Model  Distance (power) constraint  Available spectrum constraint  Interference-free constraint 8

9. 9

10.  Inner area and outer area 10

11. 11  Routing zone and Forwarding zone

12. 12  Routing in inner area

13. 13  Routing in CRN  Case 1: both source and destination in the inner area  Case 2: source in the outer area, destination in the inner area  Case 3: source in the inner area, destination in the outer area  Case 4: both source and destination in the outer area

14. 14

15.  Expected routing latency  k : the number of routing zones on the route  : the lower bound on the single node to single node spectrum opportunity  : the lower bound on the single node to a set spectrum opportunity 15

16.  Routing Scalability  : the physical distance from source to destination  Which is consistent with the scaling law on the connectivity-scalability of CRNs 16

17. 17

18.  Latency performance 18

19.  Energy consumption performance 19

20.  A Semi-Structure Routing Framework  A Performance Analytical Framework  Simulation results are conducted to validate the design routing algorithm 20