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Effects of Call Arrival Rate and Mobility on Network Throughput in Multi-Cell CDMA

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. Outline. CDMA Capacity and Inter-cell Effects Feasible Region Mobility Model and Blocking Net Revenue Implied Costs

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Effects of Call Arrival Rate and Mobility on Network Throughput in Multi-Cell CDMA

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  1. 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

  2. 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

  3. Probability of Outage • Single Cell • Multiple Cells

  4. Probability of Outage

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

  6. Probability of Outage for Multiple Cells Iji : Inter-cell interference from cell j to cell i.

  7. Nine Cell Network

  8. Probability of Outage For Each Cell

  9. Inter-Cell Interference

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

  11. Soft Handoff

  12. Inter-Cell Interference Factor • Kji : per user inter-cell interference factor from cell j to cell i • nj users in cell j produce an amount of interference in cell i equal to njKji

  13. Feasible Region

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

  15. Handoff Rate

  16. Probability of State n

  17. Fixed Point

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

  19. 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

  20. Three Cell Network

  21. Blocking in Cell 3

  22. Normalized Arrival Rate

  23. Net Revenue W=1 C=2

  24. Net Revenue W=1 C=10

  25. Optimization of Subscribers • Best Scenario:

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

  27. Maximized Subscribers

  28. Optimization of Net Revenue

  29. Maximized Net Revenue

  30. 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

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

  32. Equal Number of Users

  33. Implied Cost

  34. Shaping with PCF

  35. Two Cell Network Mobility

  36. Feasible Region

  37. Shaped Feasible Region

  38. Maximized Subscribers

  39. Maximized Net Revenue

  40. 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

  41. 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

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