1. Call Admission Control in Mobile Cellular CDMA Systems using Fuzzy Associative Memory Rupenaguntla Naga Satish Dilip Sarkar Computer Science University of Miami
January 1, 2019
Uinversity of Miami

2. Outline of the talk What is QoS? Review of CAC Algorithms
Proposed CAC System
Assumptions
Design of FAM for Mobile Cellular Systems
Operation of the FAM-based CAC System
Evaluation of the FAM-based CAC System
Conclusion
January 1, 2019
Uinversity of Miami

3. What is QoS? QoS parameters Blocking probability
Handoff failure probability
Forced termination or dropping probability
All of these parameters cannot be improved simultaneously
Our objectives
Keep forced termination rate below a desired level
Maximize channel utilization
January 1, 2019
Uinversity of Miami

4. Review of CAC Algorithms:
Handoff prioritization Schemes
Guard channels
Early channel reservation
January 1, 2019
Uinversity of Miami

5. Review: Call Pre-blocking Scheme
New alls may be pre-blocking even when resource is available:
January 1, 2019
Uinversity of Miami

6. Review: Call Pre-blocking scheme
Forced termination prob. at or below desired level
Very high channel utilization
January 1, 2019
Uinversity of Miami

7. Review: Call pre-blocking scheme variable call holding time
January 1, 2019
Uinversity of Miami

8. Review: Call pre-blocking scheme Variable cell dwell time
January 1, 2019
Uinversity of Miami

9. Call Preblocking Criteria for CDMA systems
Pft = (λ, η, μ, C)
C is the capacity of a cell using CDMA and is given by
C = (W/Rα)/(Eb/N0) – (NTW)/S + 1, where
W is the available bandwidth
R is the data rate
S is the signal strength
NT is thermal noise spectral density
Eb/N0 is the ratio of bit energy to noise power
spectral density
January 1, 2019
Uinversity of Miami

10. Call Preblocking Criteria for CDMA systems
TIM : total interference margin
TIM = (C + 1) NTW
CIM: current interference margin
CIM = IC((C + 1) – N)/(C - N)
CIM < TIM for avoiding outage of ongoing calls
January 1, 2019
Uinversity of Miami

11. Proposed CAC: Variable Parameters
Call arrival rate
Call holding time
Cell dwell time
Number of channels/codes remains constant
January 1, 2019
Uinversity of Miami

12. Proposed CAC System using FAM
January 1, 2019
Uinversity of Miami

13. Design assumption:Parameter values change gradually, not abruptly
Pft
Load
January 1, 2019
Uinversity of Miami

14. Fuzzification of call holding time
Membership functions
January 1, 2019
Uinversity of Miami

15. FAM: Fuzzy Associative Memory
January 1, 2019
Uinversity of Miami

16. Inference rules from the FAM
IF <fuzzy proposition> THEN <fuzzy proposition>
Example:
IF cell dwell time is VerySmall and call holding time is High THEN slope shall be VeryVeryHigh
January 1, 2019
Uinversity of Miami

17. Operation of the System
Estimation of the parameters
Fuzzification of call holding time and cell dwell time
Firing of fuzzy rules using FAM inference mechanism
Estimation of pre-blocking load’s slope
Computation of pre-blocking load from the estimated slope
January 1, 2019
Uinversity of Miami

18. Firing of Rules, and Inference
Cell dwell time = 18 sec, call holding time = 120 sec
IF cell dwell time is Small and call holding time is Medium THEN slope shall be High
1.0
0.7
0.7
January 1, 2019
Uinversity of Miami

19. Defuzzification
January 1, 2019
Uinversity of Miami

20. Evaluation of the FAM-based CAC System: variable call holding time
January 1, 2019
Uinversity of Miami

21. Evaluation of the FAM-based CAC scheme: Variable cell dwell time
January 1, 2019
Uinversity of Miami

22. Conclusion and Future directions
FAM-based CAC System can
Keep forced termination at or below desired level FOR
variable call arrival rate
variable call holding time
variable cell dwell time
Future directions
Extend for multiple service classes
voice, data, video, and multimedia
Extend for CDMA systems
January 1, 2019
Uinversity of Miami

23. THANK YOU
January 1, 2019
Uinversity of Miami

24. ?
Comments!!!
January 1, 2019
Uinversity of Miami