Com & Net

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

May 14, 2002김 영 덕

2 ydkim

Call admission control ISDL

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 ydkim

Call admission control ISDL

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 ydkim

Call admission control ISDL

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 alg

orithm.

CDMA Spreading limit : Increase BW -> Wideband Law of large number -> Burst admission contorl

5 ydkim

Call admission control ISDL

Channel model(P layer) Fading Channel model

Fast fading (Rayleigh fading) Slow fading (log-normal fading)

6 ydkim

Call admission control ISDL

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 ydkim

Call admission control ISDL

Adaptive coding & Modulation(Cont’d) Relative average bit rate of SCH

Required Tx power ratio

8 ydkim

Call admission control ISDL

Formulation 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 measureme

nt from soft hand off cells Forward link pilot strength measur

ement reported from mobile user

9 ydkim

Call admission control ISDL

Formulation(Cont’d) Scheduling Sub – layer

Objective function System resource utilization Overall system delay

Delay penalty function

10 ydkim

Call admission control ISDL

Optimal solution Optimization problem

Contnstraint

Recursive form

Problem solve step Step1 : Resource space partitioning Step2 : Quantization Step3 : Partial Resource allocation Step4 : Termination

11 ydkim

Call admission control ISDL

Step I Resource Space Partitioning

Resource space

Define Set

Non overlaping sub space

Completet pattition

                  :                             

12 ydkim

Call admission control ISDL

Step2/3 Quantization

Quantize non-empty partitions to evaluation of . Define Quantization partition

Partial Resource Allocation

13 ydkim

Call admission control ISDL

Step 4 Termination

Resulting optimal allocation

14 ydkim

Call admission control ISDL

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 ydkim

Call admission control ISDL

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 withVarying distances from the base-station

Forward link coverage area as a function of number of channels.

16 ydkim

Call admission control ISDL

Simulation result(Cont’d)

Average admission probabilities on the reverse link.

Outage probabilities for voice users.

17 ydkim

Call admission control ISDL

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