Call admission control (JABA-SD = MBA-SD)

1. Call admission control(JABA-SD = MBA-SD) May 14, 2002 김 영 덕

2. Outline • Introduction • CAC Review • JABA-SD, MBA-SD • Formulation of the burst admission control • Measurement Sub-Layer • Scheduling Sub-layer • Optimal Solution • Implementation issue • Result • Considerations • Reference

3. Review • Call admission control • Preventive congestion control. • Typical Condition of decision to accept • New connection dose not affect the QoS of current connection • Can provide the QoS requested by the new connection? • CAC schemes • Non – Statistical allocation (peak bandwidth allocation) • Statistical allocation • Basic components of Admission control

4. Introduction • Contribution • Formulate the burst admission as an integer programming problem. • Optimal burst scheduling algorithm for multiple burst requests • Illustration of the importance of interaction between adaptive physical layer and the burst algorithm. • CDMA • Spreading limit : Increase BW -> Wideband • Law of large number -> Burst admission contorl

5. Channel model(P layer) • Fading Channel model • Fast fading (Rayleigh fading) • Slow fading (log-normal fading)

6. Adaptive coding & Modulation • Adaptive coding • Using CSI(Channel State Information) • Variable coding Scheme depending on channel condition • Ex) • Spreading stage • Spreading by PN sequence Tb : bit duration Ts : Symbol duration Tc : Chip duration W : system BW : Instantaneous bit rate g : spreading gain Overall Processing gain : Instantaneous Symbol Energy to interference ratio :

7. Adaptive coding & Modulation(Cont’d) • Relative average bit rate of SCH • Required Tx power ratio

8. Measurement Sub-Layer Forward Link Measurement Admissible region Factor of measurement Current cell loading Pk Current forward link loading Reverse Link Measurement Soft- Handoff Cells Neighbor cells not in soft -handoff Admissible region(reverse link) Factor of measurement Reverse link inteference Reverse pilot strength measurement from soft hand off cells Forward link pilot strength measurement reported from mobile user Formulation

9. Formulation(Cont’d) • Scheduling Sub – layer • Objective function • System resource utilization • Overall system delay • Delay penalty function

10. Optimal solution • Optimization problem • Contnstraint • Recursive form • Problem solve step • Step1 : Resource space partitioning • Step2 : Quantization • Step3 : Partial Resource allocation • Step4 : Termination

11. Step I • Resource Space Partitioning • Resource space • Define Set • Non overlaping sub space • Completet pattition                  :

12. Step2/3 • Quantization • Quantize non-empty partitions to evaluation of . • Define Quantization partition • Partial Resource Allocation

13. Step 4 • Termination • Resulting optimal allocation

14. Sub-optimal Solution • Resource Index • Priority Function • Higher priority : Occupy Small system resource & long wait time • Iteration start : p=1 where • Try to allocate m resource to one of the competing requests accoding ti their priorities. • Highest priroity : • Iteration Stop :

15. Simulation result • Base line I : First come First serve • Base line II : JABA (Physical layer & Burst admission layer are isolate) • Number of channels available on the forward link with Varying distances from the base-station Forward link coverage area as a function of number of channels.

16. Simulation result(Cont’d) Average admission probabilities on the reverse link. Outage probabilities for voice users.

17. Consideration • Challenging Problem • Additional dimension • first investigate the effects of the inter-dependence among new and backlog requests • the variations in channel conditions (which may render pre-determined scheduling decisions obsolete or irrelevant) • Avenue Research • to incorporate fairness considerations in making admission control and scheduling decisions • considering incorporating fairness factor