1. 1 A Novel Capacity Analysis for Wireless Backhaul Mesh Networks Tein-Yaw David Chung, Kung-Chun Lee, and Hsiao-Chih George Lee Department of Computer Science and Engineering Yuan Ze University, Taiwan, R.O.C. April 1, 2008

2. Abstract Primary design goal –To find an analytic method to determine the capacity upper bound for network planning of wireless backhaul mesh networks 2

3. 3 Outline 1.INTRODUCTION 2.RELATED WORK 3.SYSTEM MODEL 4.ANALYTIC ANALYSIS AND SIMULATION RESULTS 5.CONCLUSION AND FUTURE WORK

4. Inter-flow Intra-flow Internet Wireless Mesh Backhaul WiFi Networks Cellular Networks Wireless Mesh Link Other type of link SS Mesh Client Mesh Client Mesh Client SS BS 4 INTRODUCTION Architecture of Wireless Mesh Networks (WMNs) –Subscriber Station (SS) –Base Station (BS) –Mesh Client Traffic on the backhaul –Multi-hop forwarding –Intra-flow & inter-flow Inter-flow Intra-flow

5. Inter-flow Intra-flow Internet Wireless Mesh Backhaul WiFi Networks Cellular Networks Wireless Mesh Link Other type of link SS Mesh Client Mesh Client Mesh Client SS BS 5 Wireless Mesh Network (WMN) Scheduling –Centralized vs. distributed Transmission –Time Division Duplex (TDD ) vs. Frequency Division Duplex (FDD) Question: Capacity upper bound for inter-flow in centralized-control TDD-based WMNs Inter-flow

6. RELATED WORK Bottleneck Collision Domain (BCD) [7]   –Distributed –Pessimistic –Need simulation  Bottleneck Collision Area (BCA) –Centralized –Optimistic  Tighter upper bound –A closed-from expression  Analytic  Readily used 6 [7] J. Jun and M.L. Sichitiu, “The Nominal Capacity of Wireless Networks”

7. No overflow No contention No error 7 SYSTEM MODEL Assumptions –Transmission Single channel, single-radio (SC-SR) Omni-directional antenna Fixed transmission power *   Single-rate transmission * Interference model: Protocol model [2]   –Traffic Pattern Equal downlink and uplink inter-flows per node Shortest path routing –MAC scheme Symmetric MACA   [2] P. Gupta and P.R. Kumar, ``The Capacity of Wireless Networks."

8. Network Model Network nodes –Infinity number of nodes * –Uniformly distributed Centralized scheduling TDD (Time Division Duplex) 8 Inter-flow Intra-flow Internet Wireless Mesh Backhaul WiFi Networks Cellular Networks Wireless Mesh Link Other type of link SS Mesh Client Mesh Client Mesh Client SS BS

9. Scheduling-Based Method Period of schedule ε: (1) Throughput over link l with schedule ε is (2) where |ε l | = number of timeslots assigned to ε l W = channel capacity Per-node capacity with schedule ε (3) 9 

10. Ring-based Network Model Fig. 1Diagram of a ring-based network and various collision areas 10

11. Distance between two links –The maximum distance between their terminal nodes  11 [Case 1] Two p-links on a line[Case 2] Two p-links not on a line

12. Minimum reuse distance, d reuse –[Case 1] Two p-links on a line 12

13. –[Case 2] Two p-links not on a line 13

14. Collision area (CA) –An area in which no any two links can transmit simultaneously  14

15. Maximal collision area –Two p-links on a line –The circle with diameter d reuse 15 [Case 2] two p-links not on a line [Case 1] two p-links on a line

16. Bottleneck collision area (BCA) –CA with the maximum traffic load.  16

17. ANALYTICAL ANALYSIS Per-node capacity upper bound: (12) where n = number of SSs  = density of SSs p = transmission range d = radius of the network W = channel capacity   17

18. For MC-MR WMNs, given n = number of nodes  = per-node capacity c = number of non-overlapping channels m = number of radios per node through a proper channel assignment: –maximum per-node capacity = –maximum network capacity = 18

19. 19 Fig. 3Per-node capacity with various p, where and n = 100. 21% 3%

20. 20 Fig. 4 Total capacity with various n, where and d = 1km.

21. SIMULATION RESULTS Compare –BCA –BCD [7] –Linear programming algorithm [4] [4] M. Kodialam and T. Nandagopal, “On the Capacity Region of Multi- Radio Multi-Channel Wireless Networks” [7] J. Jun and M.L. Sichitiu, “The Nominal Capacity of Wireless Networks” 21

22. 22 Fig. 5 Per-node capacity with various p, where, n = 100, d=1 km

23. 23 Fig. 6 Total capacity with various n, where, p = 1, and d = 0.5 km.

24. 24 CONCLUSION Bottleneck Collision Area (BCA) –Analytic analysis –Closed-form expression –Tighter capacity upper bound Much larger than that of the BCD [7] Close to linear programming algorithm [4]

25. p 25 FUTUR WORK Finite node density Non-uniform transmission power Multi-rate transmission 25

26. 26 Thank you ! Q & A

27. Analytical (BCD) –Per-node capacity: (p) Asymmetric vs. Symmetric   –Per-node capacity: (d) Asymmetric vs. Symmetric   Simulation (BCD, Algorithm [4], and BCD [7] –Per-node capacity: vs.   –Per-node capacity: (p) Asymmetric vs. Symmetric   –Per-node capacity: (n) Asymmetric vs. Symmetric   27

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