1. Joint Base Station and Relay Station Placement for IEEE 802.16j Networks Hsiao-Chen Lu and Wanjiun Liao Department of Electrical Engineering, National Taiwan University,Taiwan IEEE GLOBECOM 2009

2. Outline Introduction System Model Problem Definition and Formulation The Two Stage BS and RS Deployment Algorithm Computational Experiments Conclusion

3. Introduction IEEE 802.16j Network components Base station (BS) Subscriber Station (SS) Mobile station (MS) Relay station (RS) BS SS MS RS

4. Transparent Model RS Non-Transparent Model RS Introduction IEEE 802.16j – Relay Station placement issue Low cost Throughput enhancement Coverage extension BS MS

5. Introduction-Motive and Goal Network planning problem Deploying a number of BSs and RSs to serve mobile stations distributed arbitrarily in a given geographic area. … … Deployment Let the cost is within the budget and the system capacity is maximized.

6. System Model Demand Node (d i ) W i = The number of the MS. W i = 10 Other Assumption Only consider at most two-hop relaying. Transparent and non-Transparent model. Candidate site for BS : b i Candidate site for RS : r i

7. = 6 Problem Definition and Formulation The Joint BS and RS Deployment Problem (JBRDP) Given the geographic area in which DNs are distributed, we want to determine the locations for a number of BSs and RSs, with the total cost within the pre-determined budget, such that each DN is covered by at least one BS or RS and the system capacity can be maximized. d i = 10 Mbps 60 Mbps

8. Problem Definition and Formulation Subject to constraints: b1= 1b1= 1 b2= 0b2= 0 b3= 0b3= 0 b4= 0b4= 0 b5= 0b5= 0 b6= 1b6= 1 b7= 0b7= 0 b8= 1b8= 1 b9= 0b9= 0 r1= 0r1= 0r2= 1r2= 1r3= 0r3= 0 r5= 0r5= 0r6= 0r6= 0r 7 =0 r9= 0r9= 0r 10 = 1r 11 = 0 r4= 0r4= 0 r8= 1r8= 1 r 12 = 1 r 13 = 1b 14 = 0r 15 =0r 16 = 0 (1) (2)

9. = 1 Problem Definition and Formulation Subject to constraints: (3) (4) djdj b i = 1 = 1 r i = 1

10. Problem Definition and Formulation Subject to constraints: r i = 1r j = 1 (5)

11. The Two Stage BS and RS Deployment Algorithm To find the placement of BSs and RSs for a specific deployment profile ( n B, n R ). The number of BSs deployed in the network. The number of RSs deployed in the network. (3) The Two Stage BS and RS Deployment Algorithm First Stage : BS Deployment Second Stage : RS Deployment input ( n B, n R ) output Deployment vector: B = [b 1 b 2... b N ] and R = [r 1 r 2... r M ].

12. The Two Stage BS and RS Deployment Algorithm First Stage : BS Deployment Second Stage : BS Deployment

13. First Stage : BS Deployment Determine a set of BS locations such that the longest distance between a DN and its nearest BS is minimized. The number of BSs deployed is equal to n B. The Two Stage BS and RS Deployment Algorithm NP-complete problem: the k-supplier problem [9] [9] “A unified approach to approximation algorithms for bottleneck problems,” Journal of the ACM, July 1986. V sup … V cust … Weight i = Distance i bibi didi B = n B

14. The Two Stage BS and RS Deployment Algorithm Second Stage : RS Deployment Achieve rate gain

15. Computational Experiments Simulator: The C++ program Simulation parameters The coverage radius of a BS7km The coverage radius of a RS4km L I ( The interference threshold for RSs )3km The deployment budget80 units The cost of a BS10 units The cost of a RS3 units 25 km 1 km

16. Computational Experiments

17. The network aggregate data rate versus the number of BSs and RSs deployed for the MS hotspot scenario

18. Computational Experiments The fairness index versus the number of BSs and RSs deployed for the MS hotspot scenario.

19. Conclusion This paper Formulate the joint BS and RS deployment problem under budget and coverage constraints as a capacity maximization problem. Design a two-stage network deployment algorithm which considers both issues of capacity enhancement. The numerical results indicate that deploying relay stations can enhance system capacity and fairness under the condition that the number of base stations deployed is not too small.

20. Thank you very much ~