1. A Hierarchical Model for Bandwidth Management and Admission Control in Integrated IEEE 802.16&802.11 Wireless Networks Dusit Niyato and Ekram Hossain IEEE Wireless Communications and Networking Conference (WCNC), March 2007 報告者：李宗穎

2. 2 Outline Introduction System Model and Assumptions Bandwidth Allocation Admission Control Performance Evaluation Conclusion

3. 3 Introduction This paper present a hierarchical bandwidth management and admission control framework for integrated IEEE 802.16/802.11 wireless networks Related works considered connections only from standalone subscriber stations

4. 4 Network Model two-level hierarchical model first level a bargaining game between the set of standalone SSs and the WLAN APs second level, connections corresponding to the different service types in the standalone SSs

5. 5 IEEE 802.11/16 AP/wireless router Paper assume that the dual radio interface at a 802.11/802.16 AP/wireless router uses different frequency bands Data packets corresponding to local and Internet traffic are stored in separate queues

6. 6 Uplink Transmission in the IEEE 802.16 Air Interface Paper consider a single BS with multiple connections from SSs using the TDMA/TDD access mode B i : burst size R i : transmission rate for any connection i in a frame C : channel bandwidth I n : the number of transmitted bits per symbol for AMC state n Pr n : the probability of using AMC state n F : frame size

7. 7 Hierarchical Model for Bandwidth Management Paper use sigmoid utility function which represents quantitatively the satisfaction on received transmission rate R

8. 8 Bargaining Game (1/3) The average transmission rate for the groups of standalone SS and WLAN connections can be obtained from γ SS, γ WL, N SS, N WL denote the average SNR and the total number of standalone SSs and WLAN APs/routers

9. 9 Bargaining Game (2/3) The utilities for these groups of connections φ SS (ΣB SS ) = U(R SS (ΣB SS )) φ WL (ΣB WL ) = U(R WL (ΣB WL )) If an agreement between both the players in the game cannot be reached, the utility that the players will receive is given by the threat point is the threat point for this bargaining game

10. 10 Bargaining Game (3/3) The equilibrium strategy of this game refers to the set of strategies for which all the players are satisfied with their received payoff [8] S. Chae and P. Heidhues, “A group bargaining solution, ” Elsevier Mathematical Social Sciences, vol. 48, no. 1, pp. 37-53, 2005.

11. 11 N-Person Game in Coalition Form (1/2) define a finite set A of players (i.e., A = {UGS,PS,BE}) the required burst size for service type (i.e., player) j can be obtained from λ (j) is the bandwidth requirement N (j) is the number of connections in service type j from standalone SSs SS

12. 12 N-Person Game in Coalition Form (2/2) A coalition S is defined as a subset of A, S ⊂ A The coalition form of an N-person game is defined by the pair (A, ν) where ν is a characteristic function of the game

13. 13 Shapley Value the value function φ(ν) as the worth or value of player j in the game with characteristic function ν The Shapley value φ = [φ 1,…,φ i,…,φ n ] can be computed as follows [9] L. S. Shapley, “A value for N-Person game, ” Annals of Mathematics Studies, Princeton University Press, vol. 2, pp. 307-317, 1953

14. 14 Admission Control of Connections in Standalone SSs (1/2) For connections in service type j, the burst size allocated to connection k depends on the channel quality as follows

15. 15 Admission Control of Connections in Standalone SSs (2/2) a new connection in service type j arrives, the 802.16 BS decides whether this connection can be accepted or not by considering the change in total utility a new connection is accepted only when the total utility increases, and rejected otherwise

16. 16 Admission Control of WLAN Nodes This WLAN initial message contains the bandwidth requirement of the new connection If the link between the AP and the 802.16 BS lacks sufficient bandwidth, the BS performs bandwidth reallocation among standalone SSs and WLAN APs

17. 17 Transmission Rate in WLAN in the saturated case, the estimated received bandwidth is obtained as follows λ (j) (k) : the bandwidth requirement of connection k in WLAN j, C WL : the channel rate in the WLAN P s : the measured probability of successful transmission WL

18. 18 Formulation of the Admission Control Game for WLAN (1/2) The burst size allocated to WLAN connection j depends on the channel quality as follows

19. 19 Formulation of the Admission Control Game for WLAN (2/2) The payoff for the case when a new connection is accepted can be obtained as follows A new connection from node k in WLAN j is accepted if for WMAN and WLAN the pure strategy (accept, accept) is a Nash equilibrium

20. 20 Parameter Setting Transmission ModeTDMA Transmission bandwidth25 MHz Frame size1 ms Cell size5 km Average receive SNR7 ~ 26 dB UGS, PS, BE400/500/300 kbps WLAN channel rate10 Mbps WLAN cell radius50 meters WLAN bandwidth400 kbps

21. 21 Variation of Allocated Bandwidth Under Different Channel Qualities

22. 22 Variation of Total Utility of Standalone SSs the number of PS and BE connections is 15 and 20

23. 23 Performance of Admission Control Method for WLANs

24. 24 Conclusions A bargaining game has been used to determine the optimal burst size for WMAN and WLAN connections The Shapley value has been used to obtain the solution of the bandwidth allocation problem for different types of WMAN connections An admission control scheme based on variation in total utility has been presented