Agent-Based Forwarding Strategies for Reducing Location Management Cost in Mobile Networks

Ing-Ray Chen, Tsong-Min Chen, and Chiang Lee

CS5214Spring 2001

Elango Sundaram

Jeffery W. Wilson

18 April 2001 CS5214 2

Problem statement

• For a Personal Communication Service (PCS) network, we desire to minimize the cost of– Mobile user (MU) location updates– Searches in response to a call

18 April 2001 CS5214 3

Background

• Desire is to reduce communication cost associated with keeping track of MUs

• Balance between frequency of incoming calls and MU mobility rate

• Two extremes:– High call reception rate, low mobility– Low call reception rate, high mobility

18 April 2001 CS5214 4

Location update/search strategies

• IS-41

• High Call-to-Mobility Ratio (CMR)– Location cache

• Low CMR– Forwarding and resetting algorithm– Alternative location strategy– Two location algorithm (TLA)

18 April 2001 CS5214 5

PSTNSTP STP

HLR

V1

V5

V2V3

V6

V4

Mobile Communication Network

PSTN: Public Switched Telephone Network

STP: Service Transfer Point

HLR: Home Location Register

VLR: Visitor Location Register

18 April 2001 CS5214 6

PSTNSTP STP

HLR

V1

V5

V2V3

V6

V4

Mobile Communication Network

PSTN: Public Switched Telephone Network

STP: Service Transfer Point

HLR: Home Location Register

VLR: Visitor Location Register

For the basic IS-41 scheme, the MU is

permanently registered in the HLR. When a MU moves to a new VLR,

the HLR is notified and updated.

18 April 2001 CS5214 7

Markov models

• Three Markov models are built; these are described in later slides

• Each state in these Markov models is described by a three-component state description vector (a, b, c)

18 April 2001 CS5214 8

State description vector

(a, b, c)

Call state; 0 if idle, 1 if busy

MU movement to new VLR; 0 if no,

1 if yes

MU location table inconsistent with HLR; 0 if no, 1 if

yes

18 April 2001 CS5214 9

TLA

• MU and its HLR keep a location table to store two most recently visited VLRs

• When MU moves to a VLR which is not one of two most recently visited VLRs, location table in MU unit and HLR are updated

18 April 2001 CS5214 10

TLA Algorithm

Movement HLR LocationTable

MU LocationTable

Update Cost

(a)V2-V1 (V1,V2) (V1,V2) VLR-HLR

(b)V1-V2 (V1,V2) (V2,V1) No

(c) V2-V3 (V3,V2) (V3,V2) VLR-HLR

(d) V3-V4 (V4,V3) (V4,V3) VLR-HLR

18 April 2001 CS5214 11

Parameters

λ Arrival rate of calls to the MU

σ Mobility rate of the MU

θ Probability of MU moving to previous VLR

CMR Call-to-mobility ratio

σ1 Mobility rate to new VLR

σ2 Mobility rate to previous VLR

δ HLR location table update rate

μg Rate in locating MU when in consistent state

μb Rate in locating MU when in inconsistent state

18 April 2001 CS5214 12

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

18 April 2001 CS5214 13

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

18 April 2001 CS5214 14

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

Call arrives

18 April 2001 CS5214 15

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

18 April 2001 CS5214 16

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

18 April 2001 CS5214 17

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

18 April 2001 CS5214 18

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

Call serviced; HLR, MU consistent

18 April 2001 CS5214 19

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

18 April 2001 CS5214 20

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

18 April 2001 CS5214 21

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

18 April 2001 CS5214 22

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

Call serviced; HLR, MU tables

inconsistent

18 April 2001 CS5214 23

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

18 April 2001 CS5214 24

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

18 April 2001 CS5214 25

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

18 April 2001 CS5214 26

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

MU moves to new VLR

18 April 2001 CS5214 27

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

18 April 2001 CS5214 28

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

HLR updated

18 April 2001 CS5214 29

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

18 April 2001 CS5214 30

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

MU moves topreviously-visited VLR;no HLR update required

18 April 2001 CS5214 31

Two location algorithm (TLA)

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δ

σ1

σ1

σ1

σ2

σ2

σ2σ1

δσ2

μb

Inconsistent state

18 April 2001 CS5214 32

ATLA

• Agent based forwarding using locality and access history of MU

• HLR points only to one VLR (unlike TLA)• Local agent replaced as MU moves from one

VLR to another• When MU moves from local agent to nearby

VLR, a Forwarding Pointer is set up

18 April 2001 CS5214 33

ATLA AlgorithmMovement HLR Pointer Local Agent

PointerMU Table Update

Cost

(a)V2-V1 V2 V1 (V1,V2) VLR-VLR

(b)V1-V2 V2 V1 (V2,V1) No

(c) V2-V3 V2 V3 (V3,V2) VLR-VLR

(d) V3-V4 V4 V3 (V4,V3) VLR-HLR

18 April 2001 CS5214 34

Parameters

λ Arrival rate of calls to the MU

σ Mobility rate of the MU

θ Probability of MU moving to previous VLR

CMR Call-to-mobility ratio

σ1 Mobility rate to new VLR

σ2 Mobility rate to previous VLR

δ HLR location table update rate

μg Rate in locating MU when in consistent state

μb Rate in locating MU when in inconsistent state

18 April 2001 CS5214 35

Additional parameters

δa HLR location table update rate

μa Rate in locating MU when local agent is not current

18 April 2001 CS5214 36

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

18 April 2001 CS5214 37

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

18 April 2001 CS5214 38

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

MU moves fromlocal agent to new

second VLR

18 April 2001 CS5214 39

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

18 April 2001 CS5214 40

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

Update agent’slocal table

18 April 2001 CS5214 41

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

18 April 2001 CS5214 42

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

18 April 2001 CS5214 43

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

18 April 2001 CS5214 44

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

MU moves to new VLR (not

the agent)

18 April 2001 CS5214 45

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

18 April 2001 CS5214 46

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

Update HLR location table

18 April 2001 CS5214 47

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

18 April 2001 CS5214 48

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

MU moves to previously-visited VLR

18 April 2001 CS5214 49

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

18 April 2001 CS5214 50

Agent-based TLA

0, 0, 0 0, 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λ λ λ λ

δ

δ

μg

δaσ1

σ1

σ1

σ2

σ2

σ2σ1

σ2

μa

δa

18 April 2001 CS5214 51

CATLA

• Similar to ATLA

• Update operation occurs when MU moves across switch boundary

• Logic is that VLR-VLR communication crossing a STP is expensive

• CATLA may perform better than ATLA as CMR increases

18 April 2001 CS5214 52

CATLA Algorithm

Movement HLR Pointer Local AgentPointer

MU Table UpdateCost

(a)V2-V1 V2 V1 (V1,V2) VLR-VLR

(b)V1-V2 V2 V1 (V2,V1) No

(c) V2-V3 V2 V3 nil VLR-HLR

(d) V3-V4 V3 V4 (V4,V3) VLR-VLR

18 April 2001 CS5214 53

Parameters

λ Arrival rate of calls to the MU

σ Mobility rate of the MU

θ Probability of MU moving to previous VLR

CMR Call-to-mobility ratio

σ1 Mobility rate to new VLR

σ2 Mobility rate to previous VLR

δ HLR location table update rate

μg Rate in locating MU when in consistent state

μb Rate in locating MU when in inconsistent state

18 April 2001 CS5214 54

Additional parameters

δa HLR location table update rate

μa Rate in locating MU when local agent is not current

δc Rate in updating location table in local agent

μc Rate in locating MU when local agent is not the current VLR

γ Probability of MU moving within same network

switch

18 April 2001 CS5214 55

Additional parameters (cont.)

σn Mobility rate of MU moving to VLR not covered by same network switch

σc Mobility rate of MU moving to new VLR covered by same network switch

18 April 2001 CS5214 56

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2

18 April 2001 CS5214 57

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2

18 April 2001 CS5214 58

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2

MU moves to VLR not in

same network

18 April 2001 CS5214 59

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2

18 April 2001 CS5214 60

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2Update HLR location table

18 April 2001 CS5214 61

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2

18 April 2001 CS5214 62

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2

MU crosses network switch

boundary

18 April 2001 CS5214 63

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2

18 April 2001 CS5214 64

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2Update HLR location table

18 April 2001 CS5214 65

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2

18 April 2001 CS5214 66

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2MU moves to new VLR covered by same network

switch

18 April 2001 CS5214 67

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2

18 April 2001 CS5214 68

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2

MU moves to new VLR

covered by same network switch

18 April 2001 CS5214 69

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2

18 April 2001 CS5214 70

Cross-update ATLA

0, 0, 0 0. 0, 10, 1, 0 0, 1, 1

1, 0, 0 1, 0, 11, 1, 0 1, 1, 1

λλ λ λ

δ

δ

μg

δcσc

σc

σc

σ2

σc

σ2σc

σ2 μa

δc

0, 1, 0* 1, 1, 0*0, 0, 0* 1, 0, 0*

σc

σn

λ

σn+σ2 μg

λσn+σ2

δ

σn δ

σn

σnσ2

18 April 2001 CS5214 71

Analysis

• Markov models for TLA, ATLA, and CATLA were used to compare performance among themselves and with basic IS-41 scheme under identical conditions

• Cost parameters were developed to describe network operation costs

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Analysis (cont.)

• All three models were parameterized– MU-dependent parameters σ, λ, and, θ

were varied to determine sensitivity– Remaining parameters are network

structure dependent

• SHARPE was used to conduct the analysis

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Analysis (cont.)

• Results are provided graphically in the paper

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Summary

• Markov models (and SHARPE) were effective in conducting the analysis necessary to demonstrate performance of proposed schemes

• Parametric analysis allows affordable examination of a large number of test cases

• Sensitivity to individual parameter values can be easily explored

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Conclusion

• ATLA and CATLA consistently out-perform IS-41 and TLA for the same conditions, especially for low MU CMR

• Advantage is increased for hierarchically-structured networks where VLR-VLR communication costs are lower than those for VLR-HLR

18 April 2001 CS5214 76

Future work

• The paper described future research work

• Additional areas of investigation include examination of tuning algorithm selection to geographic area or to service use by individual customers