2. Effects of Call Arrival Rate and Mobility on Network Throughput in Multi-Cell CDMA Manju Hegde, Robert Akl, Paul Min Washington University St. Louis, Missouri USA

3. Outline CDMA Capacity and Inter-cell Effects Feasible Region Mobility Model and Blocking Net Revenue Implied Costs Effects of Mobility Maximization of Subscribers Maximization of Revenue Shaping Feasible Region

4. Probability of Outage Single Cell Multiple Cells

5. Probability of Outage

6. Gaussian Approximation We approximate the Poisson by a Gaussian variable with the same mean and variance:

7. I ji : Inter-cell interference from cell j to cell i. Probability of Outage for Multiple Cells

8. Nine Cell Network

9. Probability of Outage For Each Cell

10. Inter-Cell Interference

11. Soft Handoff User is permitted to be in soft handoff to its two nearest cells.

12. Soft Handoff

13. Inter-Cell Interference Factor K ji : per user inter-cell interference factor from cell j to cell i n j users in cell j produce an amount of interference in cell i equal to n j K ji

14. Feasible Region

15. Total Offered Traffic New call arrival process to cell i is Poisson. Total offered traffic to cell i is:

16. Handoff Rate

17. Probability of State n

18. Fixed Point

19. Net Revenue W Revenue generated by accepting a new call Cost of a forced termination

20. Implied Costs Find derivative of W wrt new call arrival rate Capture knockon effect of increases in an arrival rate Maximize net revenue for a given blocking probability vector

21. Three Cell Network Low Mobility q ii 0.26 q ij 0.02 High Mobility q ii 0.00 q ij 0.15

22. Blocking in Cell 3

23. Normalized Arrival Rate

24. Net Revenue W=1 C=2

25. Net Revenue W=1 C=10

26. Optimization of Subscribers Best Scenario:

27. Optimization of Subscribers Worst Scenario: For all values of the arrival rates summing to S, the blocking probabilities do not exceed the threshold.

28. Maximized Subscribers

29. Optimization of Net Revenue

30. Maximized Net Revenue

31. Shaping Feasible Region Increases capacity Fine tune the nominal power of the users through PCF PCF defined for each cell PCF is a design tool to maximize the capacity of the entire network

32. Power Compensation Factor Interference is linear in PCF Allows us to reshape the Feasible Region.

33. Equal Number of Users

34. Implied Cost

35. Shaping with PCF

36. Two Cell Network q ii 0.04 q ij 0.26 Mobility

37. Feasible Region

38. Shaped Feasible Region

39. Maximized Subscribers

40. Maximized Net Revenue

41. Conclusions For a given network topology we calculate: –Inter-cell and intra-cell interference and Feasible Region –Maximized net revenue –Maximized subscriber capacity –Effects of Mobility Shape feasible region to increase maximized net revenue and subscriber capacity

42. Future Work Design Problem: given a user demand distribution, what are the optimal location and coverage of Base Stations to: –Maximize Net Revenue –Maximize Subscriber Capacity