2G-3G Interworking

8/4/2019 2G-3G Interworking

1/50

2G-3G Interworking

Suitable for Staff with P&O Skill Certificate III or Lower

Issued by GSM Network P&O Dept

GSM P&O Training Materials for Special Subjects


2/50

Internal Use OnlyVersion introduction

Version Date Writer Assessor Translator Amendment Records

V1.0 2009-03-01 Guo Hongchang Zheng Hao Lu Yan No


3/50

Internal Use Only

Purpose of the course

To know 2G-3G interworking principles

To know similarities and differences of

2G-3G interworking solutionsTo know the issue of the interference

between 2G-3G


4/50

2G-3G interworking targets

2G-3G interworking principles

2G-3G interworking solutions

2G-3G interworking implementation solutions suggested

2G-3G subscribers demand and technology support

2G-3G co-location and interference issues


5/50

5

2G-3G interworking targetsTo guarantee the continuity of 3G service by making full use of

the present network investment

To solve the capacity problems in areas where 2G radio resources

are already very limited

To achieve the communications of 2G and 3G network with

minimum costs of network upgrade

Targets come from classification and organization of subscriber requirements. E.g.,

2G/3G complementary coverage to guarantee the continuity of 2G/3G

Solve 2G capacity problems in areas where 2G radio resources are limited

Try ones best not to change the using habits of subscribers: no change of phonenumber, no change of card, and so on

Operate together with 2G network including 2G network upgrade and evolutionUse same/different 3G PLMN number

Prevent unauthorized subscribers from being connected to 3G network

Minimize 2G/3G networking impact on 2G network

Issues about equipment compatibility of 2/3G networking and about charging


6/50

6

2G-3G interworking targets at different stages

With the improvement of network construction, 2G-3G interworking targets also change:

evolution at different stages

Keep the continuity of 2G-3G service

Avoid impact on 2G network stability

Initial stage of construction

2G-3G network load balance

2G-3G network will manage the operation

together

Mature stage of network

2G

3G


7/507

Initial planning of networkby 2/3G resources, develop 3G subscribersrapidly

Areas of high value

Important areas

3G/HSDPAVoice/visual/medium or high rate data service

Suburbs and countryside

GSM/GPRS

Voice/low rate data services

Capacity:

Coverage: Full coverageContinuous coverage forimportant areas

Certain Capacitypressures

Idle, subscribers to bedeveloped

Initial strategy of

coexistence of two

networks: 3G forms complete

coverage on basis of GSM;

GSM reduces expansion

pressures through 3G;

With advantages of 3G,

develop 3G subscribers

rapidly

2G/3G develop together One Radio Network


8/508

Middle planning of networkimprove 3G coverage, make full use ofresources released by 2G

Important areas

3G/HSDPAVoice/visual/medium or high rate data service

Suburbs and countryside

GSM/GPRS

Voice/low rate data service

Capacity:

Coverage: Full coverage

Basically continuous coverage,and development towards thecountryside

Become idlegradually Rapid development, andpressures of urban areas

3G coverage is gradually improved, and countryside subscribers should be developed quickly.

The number of 2G subscribers is reduced, and the network becomes idle gradually, so value areas can consider to use

released DCS 1800M resources to develop LTE.

64QAM will be introduced to urban HSDPA network, and software upgrade HSPA+ will be realized, and the competitive

power of data service will be enhanced.

Planning of trial service in LTE value areas will be speeded up to experience super high rate data service.

Areas of high value

LTE trial service

Trial service in valueareas

Trial service of superhigh rate data serviceNetworkstrategy

64QAM is introduced to some 3G areas to realize HSPA+


9/50








10/5010


Principles: Manage to use 2G network to expand 3G coverage, and keep the

continuity of service for 3G subscribers;

Manage to reduce handover times between systems;

Manage to provide 3G subscribers with 3G network service;

Manage to avoid upgrade of present 2G/2.5G network;

Observe the principle of giving priority to subscribers experience.Node B

BTS

BTS

3/2G

2G

Dual mode

Dual mode


11/5011

Suggestions for the realization of 2G-3G interworking

Manage to form continuous signal coverage within 3G coverage areas Reduce the zones which have no signals or weak signals, and especially avoid these zones in areas where there

is a high pedestrian flow. In these areas, 3G signals usually fade suddenly, and have no time to do

measurement or handover between systems, so the failure probability of handover between systems might be

quite high.

Manage to choose areas where there is a low pedestrian flow as 3G

network edge Avoid the choice of edge in areas where there is a high pedestrian flow, like stations, docks and so on, so as to

reduce the possibility of intersystem handover. In addition, this can also avoid signaling interaction

delay/failure, and the following handover call drop, which result from inefficient processing ability.

Choose well covered GSM areas as 3G edge

This is good for successful handover from 3G to GSM. In other words, there should be no overlapping areas

between GSM edge and 3G edge. This can reduce the possibility of intersystem measurement failure,

signaling interaction failure and the following call drop, which are caused by the problem of GSM network

signal strength.


12/50




2G-3G interworking implementation solutions

suggested




13/5013


Overview

2G network protocol doesnt consider 2G-3G interworking until R99 edition, while

3G protocol starts to consider the issue of 2G-3G interworking from its initial

formulation.

Main network element related to the realization of 2G/3G

interworking

3G MSC/VLR, 3G SGSN, 3G HLR network element

Dual mode mobile phone

Main implementation solutions of 2G-3G interworking Solution of no upgrade of 2G network equipment;

Solution of a small number of upgrades of 2G network equipment;

Solution of a large number of upgrades of 2G network equipment; (not

recommended)


14/5014


Basic functions realized by 2G-3G interworking Choice of PLMN;

Cell reselection;

Handover

Main network element related to the realization of 2G/3G interworking

3G MSC/VLR, 3G SGSN, 3G HLR network element;

Dual mode mobile phone

Solutions to realize 2G-3G interworking All the interworking solutions consist of 3 interworking functions (choice of

PLMN, cell reselection, and handover). Each solution corresponds to a different

2G network upgrade scale.


15/5015

2G-3G interworking solution: No upgrade of 2G network equipment

The solution is realized through The Selection of PLMN

2G and 3G network are

assigned a different PLMN

number. The connection to

3G is realized by the

reselection function of dual

mode terminal HPLMN

(home PLMN), and not by 2G

equipment upgrade;

The premise is thatHPLMN in SIM card or

USIM card is 3G PLMN. So

3G2G one-way handover

and cell reselection can be

realized.


16/5016

UERNC 3G CNBSC 2G CN

6 minutes

Some dual mode terminals firstly choose GSM network toregister.

Every six minutes, dual mode terminals, which use a new card, will try 3G network whichperforms as a home network.

Problem: within the same coverage area,

some dual mode terminals will firstly stay

in GSM network, and can not use 3G

service.

Theory of PLMN solution: 3G subscribers all use a newly

made USIM card, 3G network uses a new network number,

and the length of time for making a USIM card belongs to

network choice information. So all 3G subscribers who use a

new USIM card will firstly stay in 3G network.



17/5017

3G GSM

3G>GSM It is realized by cell

reselection, and voice

handover and PS handover

will be configured.

GSM>3G In idle state, reconnection to 3G is

realized by HPLMN reselection. Voice handover is not configured, and

PS handover is not supported.

3G network must be constructed with a network numberdifferent from GSM network.

For 3G subscribers, 3G network will be configured as

HPLMN.

Advantages

There is no need of the functions of GSM present

network to upgrade software.

There are fewer cooperating tests of GSM and 3G.

Disadvantages

If GSM subscribers become 3G subscribers, SIM card must be

changed.

HPLMN reselection needs 6 minutes, so subscribers may be less

dissatisfied.

Requirements of the solution

Choice of PLMN solution is suitable for those mobile telecommunications

carriers who cant realize GSM to 3G cell reselection.



18/5018

2G-3G interworking solution: Small scale upgrade of 2G networkequipment

The result of this solution is that priority is given to connection to 3Gnetwork, and one-way voice handover between 2G/3G network is

realized.

Service handover between

2G/3G systems is rapidlyrealized by cell reselection

and handover. Voice

handover,data service

handover, and cell reselection

function from 3G to 2G are

all realized.

2G to 3G data service

handover and cell reselection

function are both realized.


19/50

19

UERNC 3G CNBSC 2G CN

Some terminals firstly choose GSM network toregister.

Configuration of broadcast message parameter makes it easy for dual mode terminals to realize2G-3G reselection.

Someseconds

System broadcast message

Parameters configuration delivered by RNC makes terminals to stay in 3G network if possible.

Problem: within the same coverage area,

some dual mode terminals will firstly stay

in GSM network, and can not use 3Gservice.

Theory of cell reselection solution: 2G BSC

delivers broadcast message to require dual

mode terminals to be reconnected to 3G by

intersystem cell reselection.



20/50

20

3G

GSM

3G>GSM It is realized by cell

reselection, and voice

handover and PS handover

will be configured.

GSM>3G In idle state, reconnection to 3G is

realized by cell reselection.

Voice handover is not configured and

PS handover is configured.

Both same network numbers or different network numbers are

accepted. Construction of the same network numbers is

recommended.

GSM network is required to support 2G ->3G cell reselection

function.

Requirements of the solution

Advantages

Subscribers dont need to change SIM card and

phone number.

Rapid return from 2G to 3G makes subscribers

feel satisfied.

Disadvantages

Upgrading GSM network is required to support 2G->3G cell reselection.

Debugging of present network involves a lot of work.

The cell reselection solution is a 2G-3G interworking solution which is preferred by world

mainstream mobile telecommunications carriers at present in this industry.



21/50

21

2G-3G interworking solution: Large scale of upgrade of 2G network equipment(not recommended)

The result of this solution is that priority is given to connection to 3Gnetwork, and 2G/3G networking realizes one-way speech handover.

Service handover between

2G/3G systems is rapidlyrealized by cell reselection

and handover. Voice

handover,data service

handover, and cell reselection

function from 3G to 2G are

all realized.

2G to 3G data service

handover and cell reselection

function are both realized.


22/50

22

2G-3G interworking solutions: Comparison of these three solutions Comparison of functions and upgrade requirements

First solution:

Choice of PLMN

Second solution:

One-way speech handover

Third solution:

Two-way handover

Functions 3G2G voice handover: 3G2G PS handover: 3G2G cell reselection: 2G3G voice handover:

2G3G cell reselection:

2G3G PS handover:

3G2G voice handover: 3G2G PS handover: 3G2G cell reselection: 2G3G voice handover:

2G3G cell reselection: 2G3G PS handover:

3G2G voice handover: 3G2G PS handover: 3G2G cell reselection: 2G3G voice handover: 2G3G cell reselection: 2G3G PS handover

Similarities Upgrade 2G HLR or construct a new 3G HLR based on the number portability feature supported by the network

2G MSS/BSS

equipment

modifying

requirements

No modification BSS modifies system message SI2ter to add WCDMA

adjacent cell information; add system message

SI2quater (optional); modify system message SI3

If PLMN in system broadcast message is different, 2G

MSC location upgrade response message and

the like need to be upgrade to R99 protocol edition.

Modifications of the second solution +

upgrade to support measurement

control for handover between systems

handover judgment, and

handover signaling

procedure. BSS and MSC of 2G system

both need to be modified.

Requirementfor the

original

subscribers

The card must be changed. None None

Handover

Speed

Between

systems

3G2G is realized by cell

reselection, and is quick;

2G3G is realized by the

choice of HPLMN, and is

slow.

3G2G two-way handover is realized by cell

reselection, and is quick.

The same as the second solution


23/50

23

2G-3G interworking solution: Analyses of risk costs

Comparative analyses of risk costs

First solution: Choiceof PLMN

Second solution: One-wayspeech handover

Third solution: Two-wayhandover

Networking

risks

No risks BSC needs to do a small number

of software upgrades, and there

is some risk.

A large number of upgrades of

both BSS and MSC, and there

is a high upgrade risk.

Networking

costs

3G network

construction costs

First solution + 2G network

software upgrade costs 1(system message)

The second solution + 2G

network software upgradecosts 2 (judgment process of

intersystem handover)

Operation

and

maintenance

costs

3G network operation and

maintenance costs


maintenance costs + 2G

network operation and

maintenance costs


maintenance costs + 2G

network operation and

maintenance costs

Subscriber

costs

The card must be

changed/or the mobile

phone has preferred access

function.

No requirements No requirements


24/50

24

2G-3G interworking solution: Construction solutions at different stages

In consideration of the interworking features described above,

construction solutions at different stages are recommended.Network status Interworking

solutions

recommended

Remarks

First

stage

At the initial

construction stage,present network

equipment upgrade

requirements cant besatisfied. So in a short

term, requirements for

2G3G cell reselection

cant be satisfied.

First solution Subscribers use a new

SIM card to realizepreferred access to 3G by

HPLMN reselection.

Second

stage

2G equipment upgrade

conditions are mature

Second solution From 2G/3G interworking

to the same PLMN

network number


25/50








26/50

26

HLR construction solution:

Cell configuration strategy

Local area network networking strategy

Signaling network sharing, long distance tandem switch

Network element sharing

Influence over performance and functions caused by thecombination of PLMN and LAI

2G-3G interworking implementation solutions suggested: Main points


27/50

27

2G/3G use the same network number:

2G and 3G HLR entity are integrated. 2G HLR has the function to support 3G subscribers to create an

account. 2G HLR needs to be upgraded to support contracting service for 3G subscribers.

(recommended)

2G and 3G each has an independent HLR entity. They use different IMSI, MSISDNsection numberto

distinguish 2G HLR and 3G HLR. HLR doesnt need to be upgraded. However, its obvious disadvantage

is that original 2G subscribers must use a new MSISDN number, if they want to use 3G service.

2G/3G network use different network numbers:

2G and 3G HLR entity are integrated. 2G HLR has the function to support 3G subscribers to establish

a new account. 2G HLR needs to be upgraded to support contracting service for 3G subscribers, and

telephone number function of different network numbers.

2G and 3G HLR entity are independent.Number portability service is used to keep MSISND of

subscribers so as to provide the subscribers with the greatest convenience. 2G HLR doesnt need to be

upgraded. By number portability, the original 2G subscribers can change SIM card. In this way, the

subscribers can not only firstly use 3G service but also make full use of the advantage of number

portability, that is, MSISDN number is reserved for subscribers. (recommended)

2G-3G interworking implementation solutions suggested:HLR construction solution


28/50

28

Strategy recommended:

Within 3G coverage areas, 3G2G interworking is not supported, but the edge of 3coverage areas support handover towards 2G, and cell reselection.

Disadvantages of 3G->2G handover supported by the whole network:

High probability of call drop will exist, because success rate of intersystem handover is

much lower than that of intra-system handover.

It is hard to control the target coverage area which is selected during cell reselection and

handover, because of the ping-pong effect.

If the compact model is used, it can increase downlink emission power of the base station

and the mobile phone, increase interference, and reduce capacity.

Network configuration and maintenance is complicated. The initial optimization and

manual configuration involves much work, and signaling costs a lot.

2G-3G interworking implementation solutionsrecommended: Cell configuration strategy


29/50

29

Hybrid networking

Create dual mode MSC/SGSN or upgrade the original 2G MSC/SGSN to

2G/3G dual mode MSC/SGSN.

Independent networking

Create 3G MSC/SGSN, and keep the original 2G MSC/SGSN; local traffic

between 3G network and 2G network is connected by GMSC of 2G.

Independent networking can support independent service of the two networks.They wont influence each other, but they can integrate with each during their

development.

2G-3G interworking implementation solutions suggested:Local area network


30/50

30

Signaling networksharing, and long

distance tandem

exchangeLocal switch

terminates BICC

signaling (by SIGTRAN)and IP bear traffic,

traditional TDM

interface is provided

outside.

Network element

sharingEquipment sharing

GMSC/SCP/GGSN/SC

2G-3G interworking implementation solutions suggested:Make use of network sharing function


31/50

3131

2G-3G interworking implementation solutions suggested: Networkelement and requirements for equipment version

Functions Network

element

Version

requirements

Special needs

2G3Gcell reselection

BSC R993GPP TS 05.08

3GPP TS 04.18

ARD control access CN R6 3GPP TS 29.002

Compatible withoriginal 2G

equipment

3G MSCMAPCompatible with MAP-Prep-Handover req

of MAP Phase 2

3G MSCCompatible with original BSC equipment, and

capable of circumventing influence from SAI

3G MSC Forced to add Cipher information

Video phone fall back 3G CN R6 MAPAlternative Channel Type

UE R6 Support CS64 decline to AMR processing

RNC R6 Alternative RAB Parameters


32/50

3232

2G-3G interworking implementation solutions suggested:Influences over PLMN and LAI

3GGSM

Cell reselection solution

Different PLMN solution

2G/3G interworking

Same PLMN, different LAI Different PLMN

IMSI (SIM card) No change Change the card

Choice of

network

Connected to the network by

cell reselection

Choose the network by cell

reselection and HPLMN

Access control HLR controls whether 2G

subscribers will be allowed to be

connected to 3G network.

MSC/VLR/SGSN can control

whether subscribers will be

connected to 3G network.

The mainstream mobile telecommunications carriers

will prefer the reselection solution

e.g., adopt the solution of using different network numbers of

Hutch

Suggestion: Upgrade the present GSM equipment

according to the requirements of the target network

so as to guarantee the satisfactory experience of

future 3G subscribers!


33/50





suggested




34/50

3434

Requirements analysis of user policy and technology support

Reduced costs of

switch to other

networks

Subscribers can use

3G service without the

change of card or

number.

Controllable

subscribersswitch to

other networks

Some areas have the

demand for

controlling

subscribersswitch to

other networks

Convenient and rapidswitch to other

networks

Both telephones and

business halls will be

ready for 3G service.

Business marketing

2/3G use the same

network number.

Adopt cell reselection

solution.

ARD

Control subscribers

access connection to

3G

Initial demandfrom carriers

Analysesof demand

Technologysupport

IMSIsection number

segment number

controls subscribers

connection to 3G.

Make use of

advantages of 3G and

adopt positive

marketing strategies

Obvious costs

advantages of 3G voice

and data service


35/50

3535

User policyARD-based access control of 2/3Gsubscribers Upgrade 2G and 3G HLR, add an information ID field:

Subscriber data extension in HLR is used to add control information ID field (ARD: Access Restriction Data)

to show subscriber access attribute. 2G and 3G subscriber access control is realized by ARD.

During location upgrade, the ADR information is transmitted to MSC Server/VLR by extendedInsertSubscriber Data signaling.

Core network equipment MSC Server/VLR distinguishes the radio networks which

subscribers are connected to:

VLR distinguishes the radio network property used by a subscriber, that is, whether the subscriber logs in

from BSS or UTRAN.

According to the radio network attribute used by a subscriber, and ARD value delivered in ISD operation,VLR defines the relationship between the subscriber property and access network property, and corresponding

application scenarios. This is shown in the following table:

Access result Meaning of ARD field ARD value Application scenarios

UTRAN system access denied UTRAN Not Allowed 01 Control whether to be connected

to 3G network

GREAN system access denied GREAN Not Allowed 10

Constraints:

Both HLR and VLR need to support ARD function.ARDUser Data

01: UTEAN not allowed

10: GREAN not allowed


36/50

3636

Business policy of analyzing demand and technology support

Attach importance to

subscriber experience

Make use of 3G

service advantages,

and make full use of

3G service

Fewer parameter

configurations

No ping-pong

handover

Improve service QoS

2/3G service continuity

Convenient

deployment/maintenance

3G selective

preference strategy

Reliable 2/3G

handover

Cell reselection

2G BSC is only

configured with 3G

frequency points

One-way handover

Cell parameter

control

Initial demand

from carriers

Analyses of

demand

Technology

support


37/50

3737

Service strategy3G selective preference in cellreselection, improvement of service QoS

Criterion for UE starts measurement of UTRAN :

Qsearch_I


38/50





suggested




39/50

39

Analysis of the need for 2/3G co-location construction

330

920

470

390

GSM1800 GSM900 WCDMA

CS12.2K

WCDMA

CS64K

m Reduce space of equipment room,

and need of antenna feeder

Reduce project construction

difficulty, and speed up project

construction progress

Save costs

Transmission sharing

Layout of 2G site may not guarantee

the best quality of 3G network.

Some solutions may lead to

deteriorated loss.

Interference isolation needs to be

considered.

The original 2G network performance

may be influenced.

Advantages Disadvantages

GSM and 3G co-location is

based on GSM1800 and this

guarantees continuous coverage

of video phone service.

According to overseas network construction

experience of ZTE, 2/3G co-location can help carriers

to build a network with low costs but in a high speed.

Statistics of 2/3G co-location

proportion of overseas carriers

Comparison of GSM and 3G coverage

performance (dense urban areas)


40/50

40

Antenna and feeder design solution 1 2/3Gindependent antenna and feeder

Site of Shang Bu Industry and

Trade Mansion in

Huaqiangbei in Shenzhen

Site of Heng Xun

Communications building

in Shenzhen

GSM900

3G

GSM900

GSM1800

3G

Advantages1. It doesnt influence the original system.

2. Optimization adjustment of each system is totally independent.

DisadvantagesThe costs is high, because each system needs an additional

antenna and feeder.

Application

scenarios

1. There is enough installation space and isolation space

between the base station and the antenna.

2. The additional costs of installation pole and antenna is

controllable.

When a new antenna and feeder is added, the configuration of antenna azimuth and antenna downtilt parameters can refer

to that of 2G system so as to guarantee the two systems cover the same range. In other words, 2/3G networks are integrated

into one network.


41/50

41

Antenna and feeder design solution 2 2/3G use a samefeed line but a different antenna

WCDMA

GSM 900/PCS 1800

A site in Hong Kong

Advantages

1. The optimization adjustment of each system is totally independent.

2. It saves investment of feed line.

Disadvantages The combiner causes extra loss, and this influences the original system coverage.

Application

scenarios

The feed lines installation space and length is a major impact on rent costs. For

dense area were coverage is narrow, 3dB loss is allowed.


42/50

42

A multiport wide beam antenna, whose downtilt can be

adjusted, is recommended so as to guarantee relatively

independent optimization adjustment of each system.

Antenna and feeder design solution 3 2/3G use a samefeed line and a same antenna

A site in Hong Kong (six ports and tri-band

antenna)

Advantages It saves investment of feed lines.

Disadvantages

1. The combiner causes extra loss, and this influences the

original system coverage.

2. Since the antenna is shared, it makes RF optimization

adjustment for each system more difficult. So intersystem

coordination is needed.

3. If we change 2G parameter, considering impact for 3G

performance.

Application

scenarios

There isnt enough installation space and isolation space

between the base station and the antenna.


43/50

43

Antenna and feeder design solution 4 2/3G use a sameantenna and a different feed line

Advantages 1. It saves the investment for antenna and feeder.

2. It avoids the use of combiner, and the loss caused by it.

Disadvantages Since the antenna is shared, it is more difficult to do RF optimization

adjustment for each system. So intersystem coordination is needed.

Application

scenarios

There isnt enough installation space and isolation space between BBU and

the antenna.

RRU is directly installed under the

multiport wide beam antenna, this method

saves the investment for a combiner and

avoids the loss caused by it.

Improvement

of path loss

Coverage area

improvement %

1dB 7%

2dB 14%

3dB 22%

4dB 30%

5dB 40%

A site of Gang Ao Shopping Mall in Huaqiangbei in

Shenzhen

(GSM1800+WCDMA)

If7/8 feed line is at 2100MHz frequency band, 100 meters loss is 6.3 dB. As to China

Unicoms equipment room environment for present network, the proportion of feed

lines which are longer than 50 meters is not small, especially in dense urban areas, the

proportion is larger. However, RRU solution can avoid this kind of loss.


44/50

44

Summary of the adoption of a wide beam antenna

Possible influences over the original network

caused by the use of a wide beam antenna

Directional antenna Isotropic antenna

Interference degradation

In areas where there are dense sites, the slight change of antenna

indicator will not have much influence over network coverage

performance.

Directional broadband antenna can be adopted to replace narrowband

antenna without any negtive impact.

After the replacement of antenna, the primary service area of the

cell may change.

The traffic attribution of the edges of the original cell may change,

and then influence the load distribution of the cell.

For those areas where there is the coverage performance

degradation, the traffic may be lost.

An accidental problem:

After the adoption of a wideband antenna, there is aslight 5dB effect interference degradation.


45/50

45

Interference control principle for wireless communications

Mutual interference between different

communication systems (interference dead zone)

-3000 -2000 -1000 0 1000 2000 3000-2500

-2000

-1500

-1000

-500

0

500

1000

1500

2000

2500

ZTE emulation research

UMTS

BS

Interference

GSM

BS

Dead

Zone

GSM

mobile

The purpose of interference protection and control is not to totally

eliminate the interference, but to control the interference at an

acceptable level with reasonable costs so as to guarantee the normal

operation of different communication systems.

The basic solution for solving the problem of interferences from

different wireless communication systems is frequency government

and standardization of equipment standard specifications. Since the

spectrum resources decrease gradually, it is more difficult to do

interference protection control.

When 3GPP establishes the technical specifications for 3G

equipment, the interference with the present equipment has been

fully considered, which normally satisfies30dB base station space

isolation.

However, during the time when the other existing networks (GSM

and PHS and so on) are constructed, it is not possible to take into

consideration the future networks like 3G. So the interference with

3G is inevitable, and this must be solved in construction.


46/50

46

2/3G mutual interference main consideration (1) GSM900/1800

According to the theoretical analysis, based on 3PP protocol, the blocking requirement of

WCDMA to GSM, or WCDMA to GSM1800, is 43dB. The intermodulation isolation of

GSM1800 to WDCMA is 94dB.

Since WCDMA duplexer has 80dB out-band rejection, 94dB intermodulation isolation only

needs 12dB spatial separation, so it can be completely neglected.

Similarly, GSM1800 has 80dB out-band rejection, so the blocking interference can be neglected.

30dB isolation is enough to satisfy the mutual interference of WCDMA2100,

GSM900/1800the isolation design for multi-band antenna port is 30dB.

Interference

mechanism

3GPP theoretical isolationdB

WCDMA to

GSM1800

GSM1800 to

WCDMA

WCDMA to

GSM900

GSM900 to

WCDMA

Spurious isolation 25 28.87 25 28.87

Blocking isolation 43 30 35 30

Intermodulation

isolation

-- 94 -- 94

Duplexer 80dB No

influence after filtering

30dB


47/50

47

Practical engineering solution for GSM-3G interferencecoexistence

No interference coexistence can be realized by drawing on the rich overseas

3G engineering experience, and making use of the excellent anti-

interference performance indicator of ZTE 3G equipment.

For 65 degree horizontal beamwidth sector antenna, the vertical isolation

should be less than 0.2 meter, and the horizontal isolation should be less

than 0.4 meter.

3G independent antenna and feeder, spatial isolation solution

2/3G independent feed line, replacement of wide beam antenna solution

The isolation of multiport wide beam antenna is relatively low, 30dB isolation between different

dipoles can guaranteed, which satisfies the isolation indicator described above.900M, 1800M, and

2100M can share an antenna.

A G/D/U tri-band

antenna of Tian Di

Hotel site in Shenzhen

Spatial isolation of a

site in Huaqiangbei in

Shenzhen

Note: For a wide beam antenna, its interference with PHS, and 1.9G

CDMA decreases by 5dB!


48/50

48

Summary of interference

Interference of GSM900, and GSM1800 is not the main problem. Interference of PHS, and CDMA1.9G of some areas must be solved during the

construction of WCDMA network.

Each area needs to consider its actual situation, and offers instructive suggestions

about interference and makes preparations as soon as possible.

National policy of radio frequency spectrum;improvement of old equipment indicator


49/50

49

Summary of 2G 3G network sharing operation

Result of 2G3G integration One Radio Network Network interworking

Service, load, and subscriber interworking

System equipment, terminals

Terminals

System equipment: CNNode BRNC/BSC and network

management

Project construction and network maintenance

Site locationcoordination/sharing

Feeders and antennascoordination/sharing

Power transmissionsharing


50/50

Documents

2G-3G Interworking