2G-3G Interworking
Suitable for Staff with P&O Skill Certificate III or Lower
Issued by GSM Network P&O Dept
GSM P&O GSM P&O Training Materials for Special SubjectsTraining Materials for Special Subjects
Internal Use Only▲
Version introduction
Version Date Writer Assessor Translator Amendment Records
V1.0 2009-03-01
Guo Hongchang
Zheng Hao Lu Yan No
Internal Use Only▲
Purpose of the course
To know 2G-3G interworking principles
To know similarities and differences of
2G-3G interworking solutions
To know the issue of the interference
between 2G-3G
一级目录标题楷体 GB2312(加粗 )
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24 ~ 28号
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
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
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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/3GSolve 2G capacity problems in areas where 2G radio resources are limitedTry one’s best not to change the using habits of subscribers: no change of phone number, no change of card, and so onOperate together with 2G network including 2G network upgrade and evolutionUse same/different 3G PLMN numberPrevent unauthorized subscribers from being connected to 3G networkMinimize 2G/3G networking impact on 2G networkIssues about equipment compatibility of 2/3G networking and about charging……
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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
2G2G2G2G
3G3G3G3G
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Initial planning of network—by 2/3G resources, develop 3G subscribers rapidly
Areas of high valueAreas of high valueImportant areasImportant areas
3G/HSDPA : Voice/visual/medium or high rate data service3G/HSDPA : Voice/visual/medium or high rate data service
Suburbs and countrysideSuburbs and countryside
GSM/GPRS : Voice/low rate data services
Capacity:Capacity:
Coverage:Coverage: Full coverageContinuous coverage for important areas
Certain Capacity pressures
Idle, subscribers to be developed
Initial strategy of Initial strategy of
coexistence of two coexistence of two
networks:networks: 3G forms complete
coverage on basis of
GSM; GSM reduces expansion
pressures through 3G; With advantages of 3G,
develop 3G subscribers
rapidly2G/3G develop together One Radio Network2G/3G develop together One Radio Network
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Middle planning of network—improve 3G coverage, make full use of resources released by 2G
Important areasImportant areas
3G/HSDPA : Voice/visual/medium or high rate data service3G/HSDPA : Voice/visual/medium or high rate data service
Suburbs and countrysideSuburbs and countryside
GSM/GPRS : Voice/low rate data service
Capacity:Capacity:
Coverage:Coverage: Full coverage
Basically continuous coverage, and development towards the countryside
Become idle gradually
Rapid development, and pressures 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 valueAreas of high value
LTE trial serviceLTE trial service
Trial service in value areas
Trial service of super high rate data service
Netw
ork strateg
yN
etwo
rk strategy
64QAM is introduced to some 3G areas to realize HSPA+ 64QAM is introduced to some 3G areas to realize HSPA+
一级目录标题楷体 GB2312(加粗 )
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24 ~ 28号
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
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
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2G-3G interworking principles
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
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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.
一级目录标题楷体 GB2312(加粗 )
Arial(加粗 )白色
24 ~ 28号
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
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
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2G-3G interworking solutions
Overview 2G network protocol doesn’t 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)
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2G-3G interworking solutions
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.
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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 that HPLMN in SIM card or USIM card is 3G PLMN. So 3G 2G one-way handover and cell reselection can be realized.
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UERNC 3G CNBSC 2G CN
66 minutesminutes
Some dual mode terminals firstly choose GSM network to Some dual mode terminals firstly choose GSM network to register.register.
Every six minutes, dual mode terminals, which use a new card, will try 3G network which Every six minutes, dual mode terminals, which use a new card, will try 3G network which performs as a home network.performs 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.
2G-3G interworking solution: No upgrade of 2G network equipment
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3G3GGSMGSM
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 number different 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 solutionRequirements of the solution
Choice of PLMN solution is suitable for those mobile telecommunications carriers who can’t realize GSM to 3G cell reselection.Choice of PLMN solution is suitable for those mobile telecommunications carriers who can’t realize GSM to 3G cell reselection.
2G-3G interworking solution: No upgrade of 2G network equipment
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2G-3G interworking solution: Small scale upgrade of 2G network equipment
The result of this solution is that “priority is given to connection to 3G network, and one-way
voice handover between 2G/3G network is realized”.
Service handover between 2G/3G systems is rapidly realized 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.
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UERNC 3G CNBSC 2G CN
Some terminals firstly choose GSM network to Some terminals firstly choose GSM network to register.register.
Configuration of broadcast message parameter makes it easy for dual mode terminals to realize Configuration of broadcast message parameter makes it easy for dual mode terminals to realize 2G-3G reselection.2G-3G reselection.
SomeSomesecondsseconds
System broadcast messageSystem broadcast message
Parameters configuration delivered by RNC makes terminals to stay in 3G network if possible.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 3G service.
Theory of cell reselection solution: 2G BSC delivers broadcast message to require dual mode terminals to be reconnected to 3G by intersystem cell reselection.
2G-3G interworking solution: Small scale upgrade of 2G network equipment
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3G3GGSMGSM
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 solutionRequirements of the solution
Advantages
Subscribers don’t 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.The cell reselection solution is a 2G-3G interworking solution which is preferred by world mainstream mobile telecommunications carriers at present in this industry.
2G-3G interworking solution: Small scale upgrade of 2G network equipment
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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 3G network, and 2G/3G
networking realizes one-way speech handover”.
Service handover between 2G/3G systems is rapidly realized 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.
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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/BSSequipmentmodifyingrequirements
No modification BSS modifies system message SI2ter to add WCDMAadjacent cell information; add system messageSI2quater (optional); modify system message SI3If PLMN in system broadcast message is different, 2GMSC location upgrade response message andthe like need to be upgrade to R99 protocol edition.
Modifications of the second solution +upgrade to support measurementcontrol for handover between systemshandover judgment, andhandover signalingprocedure. BSS and MSC of 2G systemboth need to be modified.
Requirementfor theoriginalsubscribers
The card must be changed. None None
HandoverSpeedBetweensystems
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
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2G-3G interworking solution: Analyses of risk costs
Comparative analyses of risk costsFirst solution: Choice of PLMN
Second solution: One-way speech handover
Third solution: Two-way handover
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 networkconstruction costs
First solution + 2G network software upgrade costs 1 (system message)
The second solution + 2G network software upgrade costs 2 (judgment process of intersystem handover)
Operation and maintenance costs
3G network operation and maintenance costs
3G network operation and maintenance costs + 2G network operation and maintenance costs
3G network operation and 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
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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 can’t be satisfied. So in a short term, requirements for 2G3G cell reselection can’t be satisfied.
First solution Subscribers use a new SIM card to realize preferred 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
一级目录标题楷体 GB2312(加粗 )
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24 ~ 28号
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
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
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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 the combination of PLMN and LAI
2G-3G interworking implementation solutions suggested: Main points
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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, MSISDN section number to distinguish 2G HLR and 3G HLR. HLR doesn’t 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 doesn’t 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
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Strategy recommended:
Within 3G coverage areas, 3G2G interworking is not supported, but the edge of 3 coverage 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 solutions recommended: Cell configuration strategy
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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 won’t influence each other, but they can integrate with each during their development.
2G-3G interworking implementation solutions suggested: Local area network
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Signaling network sharing, 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
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2G-3G interworking implementation solutions suggested: Network element and requirements for equipment version
Functions Network
element
Version
requirements
Special needs
2G3G
cell reselectionBSC R99
3GPP TS 05.08
3GPP TS 04.18
ARD control access CN R6 3GPP TS 29.002
Compatible with original 2G equipment
3G MSCMAP : Compatible 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 MAP : Alternative Channel Type
UE R6 Support CS64 decline to AMR processing
RNC R6 Alternative RAB Parameters
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2G-3G interworking implementation solutions suggested: Influences over PLMN and LAI
3G3GGSMGSM
Cell reselection solution
Different PLMN solution
2G/3G2G/3G interworkinginterworking
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 The mainstream mobile telecommunications carriers
will prefer the reselection solutionwill prefer the reselection solution- - e.g., adopt the solution of using different network numbers e.g., adopt the solution of using different network numbers
of Hutchof Hutch
Suggestion: Upgrade the present GSM equipment Suggestion: Upgrade the present GSM equipment
according to the requirements of the according to the requirements of the target network target network
so as to guarantee the satisfactory experience of so as to guarantee the satisfactory experience of
future 3G subscribers!future 3G subscribers!
The mainstream mobile telecommunications carriers The mainstream mobile telecommunications carriers
will prefer the reselection solutionwill prefer the reselection solution- - e.g., adopt the solution of using different network numbers e.g., adopt the solution of using different network numbers
of Hutchof Hutch
Suggestion: Upgrade the present GSM equipment Suggestion: Upgrade the present GSM equipment
according to the requirements of the according to the requirements of the target network target network
so as to guarantee the satisfactory experience of so as to guarantee the satisfactory experience of
future 3G subscribers!future 3G subscribers!
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24 ~ 28号
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
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
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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 subscribers’ switch to
other networks
Some areas have the demand for controlling
subscribers’ switch to other networks
Convenient and rapid switch 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.
ARDControl subscribers’ access connection to
3G
Initial demand from carriers
Analyses of demand
Technology support
IMSI section 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
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User policy—ARD-based access control of 2/3G subscribers
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 extended “Insert
Subscriber 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 resultAccess result Meaning of ARD field Meaning of ARD field ARDARD valuevalue Application scenariosApplication 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
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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
二级目录标题楷体 GB2312(加粗 )
Arial(加粗 )红色 /黑色24 ~ 28号
3737
Service strategy–3G selective preference in cell reselection, improvement of service QoS
Criterion for UE starts measurement of UTRAN :
Qsearch_I <=7 && RLA_C< R(Qsearch_I)
If Qsearch_I =7 , R(Qsearch_I) = +
3G 3G prioritypriority
Unconditional measurement of 3G signal
Voice service If average GSM MOS value is 3.45, and average
3G MOS value reaches 4.2, user experience is
high .
Data service 3G provides special service like video phone, and
video streaming media and so on, which can’t be
provided by 2G.
Download rate of HSDPA is 13 times higher than
that of GPRS and 7 times higher than that of
EDGE. So internet surfing is more smooth.* Hong Kong 3G network values measured in practice
Test scenario
MOS value
(Sampling of more than
one hundred times of
calling)
Intra-NodeB calling* 4.245
Inter-NodeB calling (not pass
Iur)*4.284
Inter-NodeB calling (pass
Iur)*4.125
Average GSM MOS value 3.54
一级目录标题楷体 GB2312(加粗 )
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24 ~ 28号
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
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
二级目录标题楷体 GB2312(加粗 )
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Analysis of the need for 2/3G co-location construction
330
920
470390
GSM1800 GSM900 WCDMACS12.2K
WCDMACS64K
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.
AdvantagesAdvantagesAdvantagesAdvantages DisadvantagesDisadvantagesDisadvantagesDisadvantages
GSM and 3G co-location is GSM and 3G co-location is based on GSM1800 and this based on GSM1800 and this
guarantees continuous coverage guarantees continuous coverage of video phone service.of video phone service.
According to overseas network construction According to overseas network construction
experience of ZTE, 2/3G co-location can help carriers experience of ZTE, 2/3G co-location can help carriers
to build a network with low costs but in a high speed.to build a network with low costs but in a high speed.
Statistics of 2/3G co-location Statistics of 2/3G co-location
proportion of overseas carriersproportion of overseas carriers
Comparison of GSM and 3G coverage performance (dense urban areas)
二级目录标题楷体 GB2312(加粗 )
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Antenna and feeder design solution 1 — 2/3G independent antenna and feeder
Site of SSite of Shang Bu Industry and hang Bu Industry and Trade Mansion in Trade Mansion in
Huaqiangbei in ShenzhenHuaqiangbei in Shenzhen
Site of Heng Xun Site of Heng Xun Communications building Communications building
in Shenzhenin Shenzhen
GSM 900
3G
GSM 900
GSM 1800
3G
Advantages
1. It doesn’t 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 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 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”.into one network”.
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Antenna and feeder design solution 2 — 2/3G use a same feed line but a different antenna
WCDMA
GSM 900/PCS 1800
A site in Hong KongA site in Hong Kong
Advantages1. 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
scenariosThe feed lines’ installation space and length is a major impact on rent costs.
二级目录标题楷体 GB2312(加粗 )
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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 same feed line and a same antenna
A site in Hong Kong (six ports and tri-band A site in Hong Kong (six ports and tri-band antenna)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.
Application
scenarios
There isn’t enough installation space and isolation space
between the base station and the antenna.
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Antenna and feeder design solution 4 – 2/3G use a same antenna 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 isn’t 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)
If 7/8’ feed line is at 2100MHz frequency band, 100 meters’ loss is 6.3 dB. As to China
Unicom’s 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.
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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 antennaDirectional antenna Isotropic antennaIsotropic antenna
Interference degradationInterference 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 a
slight 5dB effect interference degradation.
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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
U M T SB S
I n t e r f e r e n c e
G S MB S
D e a dZ o n e
G S Mm o b i l e
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.
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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 isolation ( dB)
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
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Practical engineering solution for GSM-3G interference coexistence
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 solution3G independent antenna and feeder, spatial isolation solution
2/3G independent feed line, replacement of wide beam antenna 2/3G independent feed line, replacement of wide beam antenna
solutionsolution
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 Note: For a wide beam antenna, its interference with PHS, and 1.9G
CDMA decreases by 5dB!CDMA decreases by 5dB!
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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
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Summary of 2G – 3G network sharing operation
Result of 2G – 3G integration - One Radio Network
Network interworking
Service, load, and subscriber interworking
System equipment, terminals
Terminals
System equipment: CN 、 Node B ; RNC/BSC and network
management
Project construction and network maintenance
Site locationcoordination/sharing
Feeders and antennascoordination/sharing
Power transmissionsharing