後卓越計畫成果報告

楊舜仁老師實驗室

2005.12.5

2

Outline Our Previous Work

Modeling UMTS Discontinuous Reception (DRX) Mechanism

A Novel Analytic Model for UMTS DRX with Bursty Packet Data Traffic

Analytic Model Numerical Results

3

UMTS MS Receiver Activities

DRXcycle 1

DRXcycle 2

DRXcycle 3

inactivitytimer

expired

wakeup

wakeup

sleep period tS

time

power active mode power saving mode

wakeup

tD

tI

busyperiod

(a)

inactivitytimer

activated

packetarrival

(d)

packetarrival

(inactivitytimer stopped)

packetarrival

inactivityperiod

(b)inactivity

period

(c)

inactivitytimer

activated

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An M/G/1 Vacation Model (1)

Input parameters Poisson packet arrivals with rate λa

Packet service time tx with mean 1/λx and variance Vx

The inactivity timer threshold tI

The DRX cycle tD

The cost of wakeup ζ

MSATMWCDMA

Buffer

Node B

Processor

RNC

UMTSCore

Network

ExternalNetwork

UTRAN

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The UMTS DRX is modeled as a variant of the M/G/1 queue with multiple vacations.

Output measures Mean packet waiting time E[tw] Power saving factor Ps

An M/G/1 Vacation Model (2)

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Bursty Packet Data Traffic

First packet arrival to base station buffer

Last packet arrival to base station buffer

A packet service session

A packet call

The instances of packet arrivals to base station buffer

t

• Geometric number of packet calls in a session• Geometric number of packets in a packet call• Geometric (Exponential) reading time

• Geometric (Exponential) inter-packer arrival time

• Cut-off Pareto packet size

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An Embeded Markov Chain Model

t. . . . .State 1 State 1 State 2 State 4 State 1

Inactivity timer

expired

Inactivity timer

expired

State 3

(Sleep) (Sleep)

Session 1 Session 2

…

State 1 State 3

State 2 State 4

• State 1: Busy period + Inter-packet

call idle period• State 2: Busy period + Inter-session

idle period• State 3: Sleep period entered from State 1• State 4: Sleep period entered from State 2

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Analytic Model (1)

The derivation of power saving factor Ps

Total time

Sleep time

Ps = Sleep time / Total time

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9

Analytic Model (2)

The derivation of mean packet waiting time E[tw] Number of packets

Total waiting time

E[tw] = Total waiting time / Number of packets

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Effect of tipc on Ps and E[tw]

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Effect of tis on Ps and E[tw]

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Effect of tI on Ps and E[tw]

13

Effect of tD on Ps and E[tw]