1 Auction Based Spectrum Management of Cognitive Radio Networks Advisor Advisor ： Wei-Yeh Chen Student Student ：楊 于 世 Reference H. B. Chang, K. C. Chen, N. R. Prasad and C. W. Su, “Auction Based Spectrum Management of Cognitive Radio Networks,” in Proc. IEEE VTC, Barcelona, Spain, pp. 1-5, April 2009.

2 Outline Introduction Four parties Vickrey auction System Model Management Policy Simulation Result Conclusion

3 Introduction Due to the increasing demand for spectrum dramatically( 引人 注意的 ) and underutilization of spectrum, dynamic spectrum access (DSA) for cognitive radios (CRs) is proposed to resolve the challenge of insufficient( 未充分 ) spectrum usage. To facilitate( 促進 ) dynamic spectrum sharing, spectrum management with appropriate( 適當的 ) economic model would be required for four involved parties in this scenario.

4 Four parties (characters) The spectrum regulator ： general public interests. The service provider (PS-BS) ： operator. PRN users (PS-MSs) ： license users or primary users. CR-MSs ： secondary users.

5 Parties expect The spectrum regulator wishes to fully utilize spectrum bands. The service provider wishes to increase his profit (by increasing revenue) with limited spectrum bands by allowing CRs to access the spectrum bands. The PRN users wishes to share the increasing profit of the service provider. CR-MSs wish to increase opportunity of accessing spectrum bands with surely less pay to utilize spectrum.

6 Vickrey auction The Vickrey auction can also allocate unused spectrum bands to CR-MSs faster, more efficient than traditional English auction in a limited time and meet economic efficiency. Thus we adopt the Vickrey auction for CR-MSs in our spectrum management policy study.

7 System Model Network Topology Traffic Model Pricing Model Compensating Mechanism Model

8 Network Topology The network topology of the CRN

9 Traffic Model(1/2) A super frame

10 Traffic Model(2/2) PR-MSs ： If any spectrum band is free, PS-MSs can access them in any control or data frame. CR-MSs ： We only allow CR-MSs to compete in spectrum bands at the first time slot of one control frame and can utilize the spectrum bands with a superframe time without any spectrum handoff.

11 Pricing Model In our network topology, we have two kinds of users which are PS-MSs and CR-MSs. The service provider charges the price of PS-MSs and CR- MSs at a rate Q P and Q CR per control or data frame time respectively.

12 Compensating Mechanism Model In our system model, the only interference which CR-MSs may make to PS-MS is blocking. We measure the interference by using the number of blocking data frames (denoted as B) due to the occupation of the CR-MSs. P ro = R P (Q P ) ＋ R C (Q CR ) － Q C (B) P ro ： The profit of the service provider Q C (B) ： The PR-MSs as compensation per control or data frame

13 Management Policy(1/3) (1) At the beginning of the control frame, there are N p (D) PS- MSs which come from the period of the D th data frame and attempt to utilize the spectrum bands.  (a) If N p (D) > K, K spectrum bands are first allocated to the K of N p (D) PS-MSs and the number of the remaining unused spectrum bands (denote it as M) is zero (i.e., M = 0).  (b) Otherwise, N p (D) spectrum bands are first allocated to the PS-MSs and M = N p (D) − K.

14 Management Policy(2/3) If M ≠ 0, the PS-BS announces( 宣佈 ) an auction process. Otherwise, the PS-BS would not broadcast any information to the CR-MSs. We reasonably assume that the auction process can be finished in one control frame. The auction process consists of three processes: Announcing, Bidding, and Permitting.

15 Management Policy(3/3) CR-MSs with higher submitted( 屈服 ) bids D data frames to utilize without any spectrum handoff.  The CR-MSs which utilize the M spectrum bands would not interfere with PS-MSs.  Otherwise, the CR-MSs would interfere with PS-MSs. The service provider compensates the operating interference from CR-MSs to the PS-MSs.

16 Simulation Result In our proposed compensation mechanism, if the PS-MSs are interfered with one data frame by CR-MSs. PS-MSs can be free to utilize one data frame and the PS-MSs have higher priority to utilize the spectrum bands in the next data frame. Consequently, we obtain the mean of the profit for service provider per super frame time in our example.

17 Mean profit per super frame time

18 The incremental profit by CR-MSs

19 Spectrum utilization with CR-MSs

20 Conclusion 本篇論文主要提出四個群體，來探討每個群體之間的利益 關係，並提出拍賣的流程及補償機制，對未來要研究拍賣 的議題有實質上的幫助。