1 Current 3G situation and important issues that people focus on
People's focus on 3G has gone through two different stages. 2001-2002, people's energy is mainly focused on mastering 3G basic technology, through indoor testing and field debugging and other means of technical validation; 2003-2004, while continuing to verify the 3G important technology, on the basis of continuous research on 3G experience at home and abroad, 3G requirements and understanding are covered to 3G system-wide requirements, including 3G systems, operations, terminals, operations and support systems.
With the domestic 3G footsteps approaching, people on how to combine China's communications network, especially China's huge 2G network pragmatic construction of 3G more attention. For operators who already have 2G networks, the basic starting point for building 3G is how to "use 2G networks", and all the solutions for building 3G must be discussed around this point.
Several networking strategies involved in the 2 network fusion
For the traditional GSM network operators, with a wide coverage of the GSM/GPRS network, a large user base, for 3G construction is not only an advantage, but also a limiting factor. The traditional GSM operators should keep their network coverage and user advantage, and also need to minimize the adverse effects caused by the introduction of 3G, and the planning and construction mode of the network must be different from the new 3G mobile operators. Because it already has the perfect GSM network, it can be a great advantage to build 3G network. But at the same time, in how to deal with and solve the 3G/2G network integration of how effective networking, and will have to pay a huge "opportunity cost." (Computer science)
In the 3G network planning and construction, in the "economic flexibility to build the network" principle, there are several aspects are particularly prominent and important.
1. Wireless access network: mainly to take into account the 2G/3G network roaming, switching, infrastructure sharing (common site, shared indoor distribution system, the total room, etc.).
2. Core network: Mainly take into account the GSM network signaling network, bearer network, boss system and so on, at the same time, how to carry out 2g/3g between the "number of NMP" and so is an important issue that does not open;
3. Business Network: Intelligent Network, business platform, business management platform, etc.
3 The specific considerations of the networking strategy
3.1 Wireless access Network
1. Roaming issues
3GPP for 2g/3g roaming, cell re-election, for the system equipment, terminal developed a detailed specification. However, the original BSS is required to upgrade the protocol to support the characteristics of broadcasting, switching between systems in 3G neighborhood. In addition, in order to support the switching between systems, the MSC device also needs to carry out corresponding software upgrades.
2G/3G dual coverage, we tend to 3G users priority to access 3G network, and remain in the 3G network. This can provide users with better service, on the other hand can also share the load of 2G network. When the 3G user leaves the 3G coverage area, only then carries on the 3G to the 2G the gravity separation process, enters to the 2G network. Once the user re-enter the 3G coverage area, immediately proceed to the 2G to 3G re-election.
The important point is that at this point, the 2G BSc must be upgraded so that it cannot automatically roam back to 3G, while for roaming, 2GMSC can not be upgraded and 3GMSC does not have to do any adaptation processing.
2. Switching problems
Due to the wide coverage of GSM network, in 3G network construction and operation of the initial stage, for voice business call connection state, the dual-mode terminal from 3G system to GSM system switching function, its importance is greater than from the GSM system to 3G system switching function.
At this stage, there are still many problems in the switch between 2g/2.5g and 3G. 3GPP only developed R99 version of the switch between the 3g/2g, therefore, the original 2G network to upgrade to R99 to support the switch between the system, and upgrade the original network for mobile operators is a huge risk. In order to solve the above problems, can take 3GMSC compatible 2gmsc,2gmsc can not upgrade the practice. According to the current experience of ZTE 3G Network, in addition to the adaptation according to the Protocol 3G MSC, due to the existence of 3G MSC under the suspension RNC, R99/r98 BSc and 2G MSc (V3 and V2 version) under the specific network, it is necessary to 3G MSC to make more specific special requirements.
3. Infrastructure sharing (common site, shared indoor distribution system, common room, common-day feed system, etc.)
A. Common sites and computer rooms:
In the construction of 3G wireless network, and 2G common site is not only feasible but also necessary. According to the survey results, 80% of 2G sites can be used as a 3G station site. In the selection process of 3G site, it is necessary to take special account of such factors as power supply, transmission (especially the high speed data service), room space and the rationality of the original 2G station site.
It is very important to share the computer room. The roof of the room is more complex, the design of civil buildings can not meet 3G room conditions, must be flexible base station construction. When the space, bearing and other conditions to meet the premise of the full use of 2G room.
B. Shared Indoor distribution system:
Since the beginning of the 3G network, it is necessary to consider some indoor hot spots into the special 3G indoor distribution system, so if there are 2G indoor distribution system, should give priority to the sharing of indoor distribution system between 2g/3g. To 3G Indoor
In terms of distribution system, it is a simple, effective and economical and fast construction program to share with GSM. 3G and GSM indoor distribution system, the original system changes are very small, here the most important work is to ensure that the base station device access to meet the isolation between the system duplexer.
C. Common-Day Feed systems:
It is also important to share the feed resource between 3G and 2G systems. It can be achieved through the use of common holding poles, towers and other infrastructure. It is also possible to share a day-feed system with 2G and 3G by using a specific multi-frequency mixer, consistent with the 2G and 3G coverage areas.
3.2 Core Network
1. The question of "number carrying NMP" between 2g/3g
The vast user resources are 2G operators most valuable wealth, the construction of 3G network should be able to the user's impact to a minimum, including: No change, no change card, business handling convenience. The number carrying can make GSM net user turn the net to become 3G user, still keep original telephone number. Mobile phone has a very high personalized characteristics, mobile phone number as a personal identification symbol for users is of great significance. The portability of the 3G network implementation number will help to facilitate the smooth transfer of 2G users to the 3G network. At the same time, from a competitive point of view, the realization of GSM network user number can be carried will reduce the possibility of users to select the operator again, increasing the user's loyalty.
The "number-carrying" between 2g/3g actually involves the question of how to build HLR equipment. 3GHLR how to integrate with 2GHLR regardless of the way, are subject to the number of carrying way, equipment processing capacity, user distribution and many other factors, but the focus of the choice of options is how to solve 2G users to 3G users when the number of the problem.
In order to achieve 2G/3G operation "number carry", can take the following two ways to achieve:
A. Upgrade the whole network 2GHLR to 3GHLR
The whole network 2GHLR all upgraded to 3GHLR, you can achieve 2G users to 3G when the number of the transfer to carry.
Upgrades all HLR devices for the open 3G service to enable interoperability of MAP messages with the GSM network MSC/VLR and R99 network MSC/VLR, and user information for 2G and 3G users is stored in the same set of HLR devices.
The advantages of this scheme are: to protect the current network equipment investment, smooth upgrade, 2G network element does not need to modify signaling routing data, can be easily implemented to carry the number. The disadvantage is: if the need to upgrade the number of HLR more then the initial investment is relatively large, with the increase in the number of users, will give HLR capacity caused pressure.
B. Adopting gateway position Register GLR mode
The original intention of GLR is to reduce the signaling traffic between VPLMN and HPLMN user data management. That is, the addition of a GLR between HPLMN and VPLMN. Adopt GLR idea, is realizes when 2G network upgrades to 3G network, 2G user carries number to turn the net, the basic consideration is 3G HLR realizes part of GLR function.
After adopting this scheme, the user data exists at the same time in the 2G HLR and 3G HLR, the 2G HLR only holds the 2G related business data, the 3G HLR stores the 2G/3G related business data, 3G HLR the user 2G related business data and the 2G HLR to keep in sync.
The advantage of this scheme is that there is no need to adjust the signaling routing data. The disadvantage is: User data exist in 2 HLR, user Data maintenance is very difficult; 2GHLR software also needs to upgrade to meet the requirements of various business processing, increase the complexity of business processing in HLR, the details of business implementation needs to be carefully demonstrated.
Therefore, this scheme should be suitable for the transition scheme of number carrying in the initial stage of 3G network construction.
2. Several other aspects
2G Network Signaling Network, bearer network, boss system, for 3G network construction, are available resources (may need software upgrades), this part of the reasonable use of resources, can greatly reduce the cost of the network. At the same time, considering the increase in the number of users and business development, the old equipment may require expansion.
3.3 Business Network
The construction of 3G service network also exists the integration problem of 2G service network. For the Smart network, there is no quality requirements, but the request to upgrade to support CAMEL3 can be used for 3G Smart network. The vast majority of 2G business networks, such as Sms/mms/lbs/java downloads, can be fully used by the 3G Business Network, requiring additional consideration in the management of the business, especially the management of the data business and new business development (such as POC and 3G integrated video). Even need to add the corresponding business network element.
4 concluding remarks
To maximize the advantages of 2G network, so as to reduce the cost of networking, reduce system and operational risk, to achieve "rapid network building, effective coverage" is a very commercial value of the hot topic. In addition to some of the main strategies we discussed above, we still need a large number of outfield experiments to further discover and solve the specific details of network integration in 2G/3G networks.