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Call admission control (JABA-SD = MBA-SD). May 14, 2002 김 영 덕. 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. Review.
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Call admission control(JABA-SD = MBA-SD) May 14, 2002 김 영 덕
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
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
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
Channel model(P layer) • Fading Channel model • Fast fading (Rayleigh fading) • Slow fading (log-normal fading)
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 :
Adaptive coding & Modulation(Cont’d) • Relative average bit rate of SCH • Required Tx power ratio
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
Formulation(Cont’d) • Scheduling Sub – layer • Objective function • System resource utilization • Overall system delay • Delay penalty function
Optimal solution • Optimization problem • Contnstraint • Recursive form • Problem solve step • Step1 : Resource space partitioning • Step2 : Quantization • Step3 : Partial Resource allocation • Step4 : Termination
Step I • Resource Space Partitioning • Resource space • Define Set • Non overlaping sub space • Completet pattition :
Step2/3 • Quantization • Quantize non-empty partitions to evaluation of . • Define Quantization partition • Partial Resource Allocation
Step 4 • Termination • Resulting optimal allocation
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 :
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.
Simulation result(Cont’d) Average admission probabilities on the reverse link. Outage probabilities for voice users.
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