Application and analysis of 3GPP R4 in 3G test network

The evolution of the next Generation network is mainly based on two routes: the first route is mainly embodied in the transfer of the traditional telecommunication service from the dedicated TDM bearer to the unified shared IP/ATM network, and the network layer service transmission is grouped under the precondition of maintaining the user access mode unchanged. The original circuit switching network equipment is divided into two parts: the physical independent control surface soft exchange and the load-carrying face media gateway, and the end user basically does not feel the business characteristic and the access mode change. The second route realizes the real end-to-end IP service characteristic, and introduces the new real-time multimedia application including voice, the user accesses the network in the way of sip/h.323 Packet terminal, the network architecture and the service mode (such as SIP mode) are completely different from the traditional circuit exchange network.

The 3GPP R4 and R5 phases correspond to the two routes of network exchange and development. In this paper, the correlation analysis of SoftSwitch in R4 stage is limited.

1, Soft exchange

Compared with traditional networks, the benefits of SoftSwitch are well known:

Open

Open system, so that operators are free to choose to design their own network, easy to improve competitiveness, so that the cost of integrated construction network down.

Low cost

The idea of constructing network in combination of three nets makes the construction cost and network operation cost of operators greatly reduced.

Easy planning, distributed network building

Non-level network, scalability, network can be on demand side of the planning side of the construction, distributed network to enable operators of the business "low-cost, wide coverage." When the initial capacity is small, the cost advantage is obvious and the cost of the network increases linearly.

Richer business

can support the wired/wireless/Multimedia integration of the business, any user can be anywhere, using any access means, any time to obtain the basic same business, "a bit to provide, full network sharing" to support the third party business, support user business customization, business personalization. (Computer science)

Because the 3G test network is required by the R99 format, therefore softswitch in this 3G test network does not have a significant application, the external interface of each manufacturer's equipment is the standard R99 version, but from the manufacturer equipment's internal connection and the network can have the profound feeling to R4 already in each manufacturer's equipment obtains the widespread application. Its MSC has been divided into MGW parts, its HLR and MSC have adopted IP (SIGTRAN), already has the ability to carry out R4 interconnection.

UT Tatsu Kang's MSC has been divided into TG, SG, WMG and other parts, split very thoroughly, in addition to IU interface, the various network elements are entirely IP exchange, you can say UT think of the R4 standard support is very perfect.

To sum up, although in this 3G test network, the manufacturer's equipment is provided by the R99 standard, but there are a lot of manufacturers of equipment has been fully equipped with R4 network capacity, but also has a smooth transition to the R4 capacity (R4 Ready), the various manufacturers based on R4 equipment has been basically mature.

2, the analysis of the multi-service Network Load

For the successful application of R4, the maturity of the equipment is only on the one hand, based on R4 network, load, operation, business and other aspects are very important. Especially in the bearing aspect, the problem is more. The following is an analysis of ATM, IP, and TDM hosting.

ATM-based Bearer

The current problem is that CS domain is hosted by ATM, existing TDM TMSC devices will not be able to continue to use, need to build ATM-enabled MSC Server, TMSC, MGW and other devices and need to increase the ATM switch, increase the cost of equipment investment. The increase of ATM switch increases the fault source in the network, and the downtime of ATM switch will reduce the reliability of the network.

Using IP network for carrying

IP is currently the most widely used network technology, 3GPP also IP as a long-term goal of the development of the network. IP hosting is more bandwidth-saving than TDM hosting, and can save 25% to 50% of the bandwidth depending on the length of the packet in different protocols. However, the reliability of router device cannot be compared with TDM switch device, the router device needs redundant configuration, and a fast fault detection and switching strategy is needed. Although the QoS of IP network can be improved through MPLS, Dfferv and other technologies, the real-time performance of the network can not be compared with TDM. In order to ensure the security of transmission will need to create a new dedicated IP network, a large number of equipment investment. In order to ensure the security of the network, the network structure and routing strategy become complex, and the network maintenance becomes more complicated.

All hosted by TDM network

TDM bearer will need to occupy more bandwidth resources, but can reuse the current network of TMSC, STP equipment, network structure is relatively clear, equipment maintenance has continuity, CS domain Service QoS and security can be guaranteed.

From the comprehensive comparison and analysis, the current use of IP/ATM is not as good as using TDM carrier, but TDM-hosted R4 will lose some advantages, such as TRFO. Fundamentally, the problems encountered by the application R4 are similar to those encountered in the current IP network telecommunications.

3, still need to explore the issues

In addition to the load problem, the comprehensive R4 equipment can be used to build a commercially available network, there are still many problems to be explored and groping.

IP QoS and security issues

Based on IP packet hosting components R4 Network, the most prominent how to ensure that the best IP network to provide the circuit domain real-time business needs of the QoS, as well as the security on the open IP networks, this is also in the fixed network VoIP and NGN field for a long time and has been in the research and discussion of the problem , although there are some theoretical solutions, but basically did not get the scale of practice (according to the current situation of network infrastructure, R4 stage can also choose to use ATM core network, However, if the relay ATM switch does not support SVC or Q.AAL2 exchange capability, the configuration of the network will be too complicated or even exceed the limit of operational dimension management.

Tiered structure issues

The most important difference of the R4 network in the system composition is the layered type of the control separation of the R99, the large capacity MSC server of the control plane can correspond to multiple distributed MGW, so how to choose the appropriate capacity and matching relation for the control and bearing surface equipment to achieve the core network design optimization is worth exploring The increased business capacity of MSC server, which provides end-office business, requires further network-level reliability (e.g., dual attribution technology) for equipment reliability Technology

Changes in the operational model

The MSC server in R4 Network has a higher network status than R99 MSc, so it is necessary to consider how to use this feature to facilitate unified service delivery and upgrade, and the maintenance and management of R4 broadband hosting network will be a new challenge for traditional telecom operators.

To sum up, although currently based on R4 equipment is mature, but based on R4 business operations still have a lot of problems, before these problems are properly resolved, operators in the construction of 3G network, R4 and R99 choice and specific deployment remains an important issue.