7/27/2019 Fang_041103

1/40

1

Soft Handover Performance study in the Direct

Sequence WCDMA Radio network Simulator

Author: Yang Fang / Communication Laboratory

Supervisor: Professor Sven-Gustav Hggman

Instructor: PH.D Michael Hall

7/27/2019 Fang_041103

2/40

2

Table of Content

Handover Introduction

NETSIM Introduction

NETSIM Structure and modules Introduction

Channel Simulator

Network Simulator

Soft Handover algorithms Introduction

Window-average algorithm

Real-time algorithm

Simulation result and Performance study Drop call trace tool

Future work

7/27/2019 Fang_041103

3/40

3

Handover Introduction

7/27/2019 Fang_041103

4/40

4

Handover Introduction

7/27/2019 Fang_041103

5/40

5

Handover Introduction --- Interfrequency Handover

7/27/2019 Fang_041103

6/40

6

Handover Introduction --- Intrafrequency Handover

7/27/2019 Fang_041103

7/40

7

Handover Introduction ---Intersystem Handover

7/27/2019 Fang_041103

8/40

8

Handover Introduction ---Soft Handover

7/27/2019 Fang_041103

9/40

9

Handover Introduction ---Softer Handover

7/27/2019 Fang_041103

10/40

10

NETSIM Introduction

7/27/2019 Fang_041103

11/40

11

NETSIM Introduction

NETSIM - simulation tool for study of planning methods and control

algorithm for WCDMA cellular Radio Network

Platform: Unix

Language: C

NETSIM can simulate: Voice and data service, packet switched traffic,

circuit switched traffic, different user behavior,

Radio network control functions (HO, Admission,

Power Control)

Simulation result: System capacity as a function of traffic,

performance of network control algorithm, etc.

7/27/2019 Fang_041103

12/40

12

NETSIM Structure and Modules ---Structure

Traffic Model

Network Performance Analysis

Network Model

WCDMA Simulation

1. Uplink algorithm;

2. Downlink algorithm;

3. Access Control4. Admission control;

5. Soft handover

6. Power control

Channel Simulator

Ne

two

rkS

imulat o

r

NETSIM

7/27/2019 Fang_041103

13/40

13

Channel Simulator of NETSIM

=

=1

0

)exp()()(K

k

kkk jttath

Advantage: Model considered as accurate

Disadvantages: Computing intensive (large

Memory and long simulation time required)

Current version using Raytracing

model Impulse response is

Map of simulation environment

7/27/2019 Fang_041103

14/40

14

Network Simulator of NETSIM

Traffic Model Network Model

WCDMA Simulation

1. Uplink algorithm;

2. Downlink algorithm;

3. Access Control4. Admission control;

5. Soft handover

6. Power controlNe

two

rkS

imulat o

r

Network Performance Analysis

7/27/2019 Fang_041103

15/40

15

NETSIM Structure and Modules --- Modules

Initialization Module

Generation Module

Traffic Module

Mobility Module

Propagation Module

Interference Module

Average Module

Access Module

Admission Module

Active set Module

Quality Module

Power Module

Mobile Station

Radio Channel

Base

Station

7/27/2019 Fang_041103

16/40

16

Soft Handover algorithms Introduction

7/27/2019 Fang_041103

17/40

17

Handover Introduction --- Soft Handover

7/27/2019 Fang_041103

18/40

18

Soft Handover algorithm Introduction

--- Window-average algorithm

AS_Th AS_Th_HystAs_Rep_Hyst

As_Th + As_Th_Hyst

Cell 1 Connected

Event 1A

Add Cell 2

Event 1C

Replace Cell 1 with Cell 3

Event 1B

Remove Cell 3

CPICH 1

CPICH 2

CPICH 3

Time

Measurement

Quantity

T T T

Figure of window-average algorithm from 3GPP 25.922_3/02

7/27/2019 Fang_041103

19/40

19

M e a s _ S i g n > B e s t _ S s

A s_ T h

a s _ T h _ H y s t

for a per iod o f TY e s

N o

( E v e n t 1 B )R e m o v e W o r st _ B s in

the Act ive Set

M e a s _ S i g n > B e s t _ S s A s _ T h

+ a s _ T h _ H y s t

for a per iod o f

TN o

Y e s

( E v e n t 1 A )

A d d B e s t_ B s i n t h e A c t iv e

S e t

B e s t _C a n d _ S s > W o r st _ O l d _S s +

A s _ R e p _ H y s t

for a per iod o f TY e s

( E v e n t 1 C )

N o

Ac t ive Set Fu l l

N oY e s

A d d B e s t B S i n A c t i veS e t a n d R e m o v e W o r st

B s f r o m t h A c t iv e S e t

B e g i n

Soft Handover algorithm Introduction

--- Window-average algorithm flow chart

Flow chart of window-average algorithm from 3GPP 25.922_3/02

7/27/2019 Fang_041103

20/40

20

Parameters for Window-average algorithm

Parameters:

AS_Th Threshold of Marco-diversity gain in Window-average algorithm

AS_Th_hyst Hysteresis of AS_Th

AS_Rep_hyst Replacing Hysteresis in Window-average algorithm

HO_Add_time Evaluating window size to add candidate to active set list

HO_Drop_time Evaluating window size to drop one from active set list

7/27/2019 Fang_041103

21/40

21

Soft Handover algorithm Introduction

--- Real-time algorithm

Always connect to the cells with better or best signal quality

Swap the cells in the active set frequently

Response quickly to the change of the communication channel

No window to evaluate the receiving signal

Soft handover gain is fixed (equal to the Marco-diversity gain)

7/27/2019 Fang_041103

22/40

22

Parameters for Real-time algorithm

Parameters:

AS_3_ratio Marco-diversity gain when using 3 active set in the

Soft handover procedure in Real-time algorithm

AS_2_ratio Marco-diversity gain when using 2 active set in the

Soft handover procedure in Real-time algorithm

7/27/2019 Fang_041103

23/40

23

Simulation result and Performance study

7/27/2019 Fang_041103

24/40

24

Performance study for different algorithms

--- Window-average algorithm (1-1)

AS active Threshold 3.98(equal to 6 dB)

AS active Threshold Hysteresis 1.58(equal to 2 dB)

AS active Replacement Threshold Hysteresis 3.98(equal to 6 dB)

AS active Handover add window size 0.5(second)

AS active Handover drop window size 0.5(second)

Group 1 Parameters set

7/27/2019 Fang_041103

25/40

25

Performance study for different algorithms

--- Window-average algorithm (1-2)

Successful call vs. drop call

(Window size = 0.5 s, AS_Th = 6 dB, AS_Rep_Th = 6dB)

79.50% 79.19%

20.50% 20.81%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

AS=3 AS=2

Maximum active set size

Percentage

(%)

Calls ended normally

Nr. of quality fail calls

Percentage of acting different radio links in the SHO procedure

(Window size = 0.5 s, AS_TH = 6 dB, As_Rep_Th = 6 dB)

0.03%1.75% 0.83%

98.23% 99.17%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

AS=3 AS=2

Maximum active set size

Percentage

(%) Acting 3 radio link case in this

simulation loop

Acting 2 radio link case in this

simulation loop

Acting 1 radio link case in this

simulation loop

Simulation result of parameter set group1

7/27/2019 Fang_041103

26/40

26

Performance study for different algorithms

--- Window-average algorithm (2-1)

AS active Threshold 2.512(equal to 4 dB)

AS active Threshold Hysteresis 1.58(equal to 2 dB)

AS active Replacement Threshold Hysteresis 2.512(equal to 4 dB)

AS active Handover add window size 0.5(second)

AS active Handover drop window size 0.5(second)

Group 2 Parameters set

7/27/2019 Fang_041103

27/40

27

Performance study for different algorithms

--- Window-average algorithm (2-2)

Successful call vs. Drop call

(Window size = 0.5 s, AS_Th = 4 dB, AS_Rep_Th = 4 dB )

79.22% 81.65%

20.78% 18.35%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

AS=3 AS=2

Maximum Active set size

Percentage

(%)

Calls ended normally

Nr. quality failures ul

Percentage of acting different radio links case in SHO procedure

(Window size = 0.5 s, AS_Th = 4 dB,AS_Rep_Th = 4 dB)

0.01%0.69% 1.03%

99.31% 98.97%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

AS=3 AS=2

Maximum Active Set size

Percentage

(%) Acting 3 radio link case in this

simulation loop

Acting 2 radio link case in this

simulation loop

Acting 1 radio link case in this

simulation loop

Simulation result of parameter set group2

7/27/2019 Fang_041103

28/40

28

Performance study for different algorithms

--- Window-average algorithm (3-1)

AS active Threshold 2.512(equal to 4 dB)

AS active Threshold Hysteresis 1.58(equal to 2 dB)

AS active Replacement Threshold Hysteresis 2.512(equal to 4 dB)

AS active Handover add window size 0.1(second)

AS active Handover drop window size 0.1(second)

Group 3 Parameters set

7/27/2019 Fang_041103

29/40

29

Performance study for different algorithms

--- Window-average algorithm (3-2)

Successful calls vs. Drop calls

(Windowsize = 0.1 s AS_Th = 4dB, AS_Rep_Th= 4 dB)

72.83%

80.95%

27.17%

19.05%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

AS=3 AS=2

Maximum active set size

Percentag

e(%)

Calls ended normallyNr. quality failures ul

Percentage of acting different radio links case

(Window size = 0.1 s AS_Th = 4dB, AS_Rep_Th= 4 dB)

0.07%1.96% 3.18%

97.97% 96.82%

0.00%

20.00%

40.00%

60.00%

80.00%

100.00%

120.00%

AS=3 AS=2

Maximum active set size

Percentage

(%) Acting 3 radio link case in this

simulation loop

Acting 2 radio link case in this

simulation loop

Acting 1 radio link case in this

simulation loop

Simulation result of parameter set group3

7/27/2019 Fang_041103

30/40

30

Performance study for different algorithms

--- Window-average algorithm summary(1)

Comparison table of successful calls and drop calls

(MaximumActive set size is 3)

79.50% 79.22%

72.83%

20.50% 20.78%

27.17%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

WS = 0.5;

As_Th= 6db

WS = 0.5;

As_Th= 4db

WS = 0.1;

As_Th= 4db

Different Parameterssets

Perce

ntage

Calls ended normally

Nr. of quality failures

Percentage of acting different radio links case with different

parameters sets (Maximumactive set size is 3)

0.03% 0.01% 0.07%1.75% 0.69% 1.96%

98.23% 99.31% 97.97%

0.00%

20.00%

40.00%

60.00%

80.00%

100.00%

120.00%

WS = 0.5;

As_Th= 6db

WS = 0.5;

As_Th= 4db

WS = 0.1;

As_Th= 4db

Different parameterssets

Perce

ntage

Acting 3 radio link case in this

simulation loop

Acting 2 radio link case in this

simulation loopActing 1 radio link case in this

simulation loop

Simulation result of different parameter sets of Window-average algorithm (AS=3)

7/27/2019 Fang_041103

31/40

31

Performance study for different algorithms

--- Window-average algorithm summary(2)

Percentage of acting different radio links case with different

parameters sets (Maximumactive set size is 2)

0.83% 1.03% 3.18%

99.17% 98.97% 96.82%

0.00%

20.00%

40.00%

60.00%

80.00%

100.00%

120.00%

WS = 0.5;As_Th= 6db

WS = 0.5;As_Th= 4db

WS = 0.1;As_Th= 4db

Differnt parameterssets

Percentage(%)

Acting 2 radio link case in this

simulation loop

Acting 1 radio link case in this

simulation loop

Comparison Table of successful call and drop call

(Maximumactive set size is 2)

79.19% 81.65% 80.95%

20.81% 18.35% 19.05%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

WS = 0.5;As_Th= 6db

WS = 0.5;As_Th= 4db

WS = 0.1;As_Th= 4db

Different parameters sets

Percenntage(%)

Calls ended normally

Nr. of quality failures

Simulation result of different parameter sets of Window-average algorithm (AS=2)

7/27/2019 Fang_041103

32/40

32

Performance study for different algorithms

--- Window-average algorithm summary(3)

Conclusion:

The performance is a little better when the active set size is 2

In most time of the call procedure, the communication between the MS and

BS only using one radio link

Its difficult for find the optimal parameters set for the Window-average

algorithm, we have to try a lot of parameters sets to get one better solution for

the Window-average algorithm

7/27/2019 Fang_041103

33/40

33

Performance study for different algorithms

--- Real-time algorithm simulation result

Successful call rate vs. drop call rate

(Real-time algorithm)

99.11% 100.00%

0.89% 0.00%0.00%

10.00%

20.00%

30.00%

40.00%50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

AS=3 AS=2Maximum Active set size

percentage(%)

Calls ended normally

Nr. of quality fail calls

Percentage of acting radio links in the simulation loop

(Real-time algorithm)

4.09%8.62%

11.76%

87.29% 88.24%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

AS=3 AS=2

Maximum active set size

Percen

tage(%) Acting 3 radio link case in this

simulation loop

Acting 2 radio link case in this

simulation loopActing 1 radio link case in this

simulation loop

Simulation result of Real-time algorithm

7/27/2019 Fang_041103

34/40

34

Performance study for different algorithms

--- comparison between two algorithms

Conclusion: The Real-time algorithm is better than Window-average algorithm

The Real-time algorithm always adopt the better channel for the

conversation. But the window-average algorithm need some average

window to adopt the optimal link

7/27/2019 Fang_041103

35/40

35

Drop call trace tool

7/27/2019 Fang_041103

36/40

36

Drop call Trace tool

--- Network drop call situation in Time 510

Relatioinship between Base Station SIR and Drop call

0 0 0 0 0 0 00 0 0 0 0 0 00

12

0

1

0 0

-10.0525

-8.06245

-11.0327

-3.01484

-8.51664

-7.44165

-10.1732-12

-10

-8

-6

-4

-2

0

2

4

The 0

Base

station

The 1

Base

station

The 2

Base

station

The 3

Base

station

The 4

Base

station

The 5

Base

station

The 6

Base

station

Base station

Rxvalue(dB)

Value

DropcallNr.

The drop call in SHO with 3AS

The drop call in SHO with 2AS

The drop call in SHO with 1AS

The Base station's average SIR

Time:510

7/27/2019 Fang_041103

37/40

37

Relationship between Base Station and Drop call

0 0 0 0 0 0 00 0 0 0 0 0 001 2

0

2

0 0

-6.78302 -6.90614

-11.7081

-5.74579

-14.02674

-9.8939

-29.3006

-35

-30

-25

-20

-15

-10

-5

0

5

The 0

Basestation

The 1

Basestation

The 2

Basestation

The 3

Basestation

The 4

Basestation

The 5

Basestation

The 6

Basestation

Base station

Rxvalue(dB)

Value

DropcallNr.

The drop call in SHO with 3AS

The drop call in SHO with 2AS

The drop call in SHO with 1AS

The Base station's average SIR

Time:520

Drop call Trace tool

--- Network drop call situation in Time 520

7/27/2019 Fang_041103

38/40

38

Future Work

7/27/2019 Fang_041103

39/40

39

Future work

More simulations with different parameters set are needed

The Packet data service performance with different SHO algorithms is

need to be investigated

More drop call trace analysis tool need to be integrated in NETSIM

7/27/2019 Fang_041103

40/40

40

Thank you!

Questions?