How to build a 3G optical transmission network

1.3G Requirements for the transfer network

WCDMA, CDMA2000 and TD-SCDMA as the three major standards of 3G, the main difference is the air interface part, the network's logical structure is basically the same. From the perspective of the transport layer, the three standard network structures are similar, so the requirements for the transport network are similar to each standard. For example, cdma2000ev-do is equivalent to the WCDMAR99 version of the specification. Considering that the WCDMA standard has been adopted by many 3G networks worldwide, we analyze 3G's functional requirements for the transmission network based on the standard.

For the construction of Utran transmission network, our most concern is actually IUB, Iur, IU three kinds of physical interface, these three kinds of physical interface type and rate level directly affect the network form of transmission networks. In the WCDMAR99 or R4 specification, the IUB is the physical interface between the NodeB and the RNC, and NodeB or E1 interfaces are mainly used in the IMAE1 side, and the ATM 155M interface is used in small quantities, with ATM 155M interface or IMA E1 interface on the RNC side. Iur is the interface between RNC and RNC, the interface type is ATM STM-1/4 and IMA E1 interface, IU is the interface between RNC and CN (Core network), ATM STM-1/4 interface is mainly used, and Ima E1 interface is used in special cases.

3G as a service network of transmission network, on the configuration of WCDMA network equipment on transmission network, 3G service network mainly relies on optical transmission network to provide transmission support. From the network structure, optical transport network consists of three-layer structure, namely access layer, convergence layer, core layer. Since the number of RNC and Mscserver and MGW is close and often located in the same room, the RNC and MSC can be centrally planned to the core of the metropolitan transport network in the transmission network. The core layer undertakes the transmission between RNC, Mscserver, MGW, Gmsc, SGSN and GGSN. The access Layer transmission network mainly completes the service access and transfer function between the base station NodeB and the base station controller RNC. Because node B is usually very decentralized, the transmission from Node B to RNC often requires access and aggregation of two tiers of network, while the implementation of Node B traffic statistics multiplexing and convergence to improve transmission bandwidth utilization and reduce the ability to support the RNC port too high requirements, In Utran transmission network, 3G service is often required to converge on ATM/IP. (Computer science)

3G-oriented transport network architecture

2.3G Backbone transmission Network construction Strategy

3G backbone transmission to solve the provincial cities, provinces and SGSN connections between the Mscserver, MSG, the connection between the main consideration of SDH or DWDM as a means of transmission. The WCDMAR4 specification can be used in the cluster domain and the circuit domain of the core network with the same IP packet-based bearer network, which can access the Sdh/ason network through the GE interface of the MSTP, or the WDM network through the GE interface of the Tmux/otu.

The core hosting network of the WCDMAR4 specification will be based primarily on IP. The scalability and cost and availability of IP core routers are issues to consider. Compared with the traditional hosting solution of IP network, it can save about 30% of the integrated investment and greatly improve the business performance by using OXC to build the data service's bearer network. The traditional IP network construction scheme is to classify the data network, using IPOVERWDM or IP over fiber to provide a fiber or a wavelength directly between routers. In this scheme, the source and host of IP packet packets need multiple routers to connect, which leads to a large number of direct business, that is, the business that is not directly up and down the local. The direct service can account for 60% of the total processing capacity of a core router, resulting in a large amount of additional costs, even the core routers of the largest capacity will soon be faced with the problem of expansion. At present, the expansion of IP routers uses the heap cluster (cluster) method, the equipment interconnection at the same location is expensive, and often leads to network internal blocking. In the future, in order to better support VoIP, IPTV and other real-time IP services, also requires data network to improve business quality.

Considering that the same I/O port core routers have a market price of 5 times times the SDH device, it is recommended to use a light crossover machine to transfer IP direct service to improve efficiency, while IP routers focus on 3-tier processing capabilities. The built-in data interface and processing function of the optical crossover machine can efficiently handle the direct service, which greatly reduces the pressure of the IP router to deal with capacity and enlarge, thus reducing the total investment cost. The mesh network constructed by OXC has strong network survivability and can greatly improve the quality of the core data network.

In addition, the development of 3G Mobile services will change the network facilities of operators. The number of E1 and STM1/16 will be turned over, especially in converged, resource-sharing, and gateway/core nodes that interact with other operators ' networks. Now the manual operation of digital wiring racks is an inflexible and expensive way to operate the transfer of resources. If the introduction of flexible automatic switching devices in the core node oxc the formation of Intelligent Optical Network Ason, it will significantly improve network survivability, reduce the cost of flexible service delivery, equipment maintenance and leased lines, and provide new services such as optical virtual private network.

3.3G Utran Transmission Network construction Strategy

3GUTRAN transmission network needs to solve the connection from NodeB to RNC, mainly consider using MSTP based on SDH as transmission means, this not only can meet the trend of 3G transmission interface evolving to IP interface, but also improve bandwidth utilization and reduce the interface burden of RNC and other nodes under current situation. 3G to the transmission network requirements, not only for more than 2G business needs more than a few 2M, more importantly, the content of the transfer has been completely different from the previous fixed-slot TDM format into a grouped ATM format (R99 or R4 specification). In general, the wireless control plane and the Transmission control plane of the various control signaling load in the AAL5 format, and the transmission of the user plane data and signaling in the AAL2 format, so the final transmission on the physical layer of the data format have become ATM.

Since the transmission interface provided by the 3G Utran node is ATM, it is a hot and controversial issue for the 3G optical transmission network to have ATM processing function on the optical transmission network in the process of NodeB to the RNC. We suggest that in the early days of network construction, in view of the small proportion of the total business volume of the 3G, the NodeB IMA E1 service does not do any processing in the access layer, directly transmits into the aggregation node of the RNC side of the aggregation layer, and realizes the IMA of Node B by the ATM card built into the aggregation transport node. E1 traffic is used for statistical multiplexing and aggregation to improve transmission bandwidth utilization and reduce excessive requirements for RNC port capabilities. After the network development to the medium term, as the number of Node B in the access layer increases, it is considered to set up ATM switch board at the relevant convergence node and even the access node to converge the IMA E1 business, through network bandwidth utilization. For example, a transport convergence node gathers processing from multiple node B ima E1 circuits with a board with the IMA ATM exchange capability, and the business enters the ATM processing board via VC-12, and the statistical multiplexing is pooled into ATM VC-4 via a converged network to the RNC side, Then, the operation is further statistically multiplexed via the ATM switch board card at the RNC side and then transmitted to the RNC node to reduce the number of STM-1 interfaces of the RNC in the VC-4 level. In this way, the bandwidth utilization is improved by using the statistical multiplexing of ATM services at different network levels in Utran transmission network.

For the capacity of the network, in the initial stage of 3G network construction, the capacity of the access ring is mainly STM-1, some business-intensive areas can consider the STM-4 loop capacity, with the development of 3G service and data service capacity in the network, the access ring needs to expand to STM-4 capacity, At this point, you can consider a new part of the access ring or expansion of the original access ring. With regard to the convergence layer of the network, the capacity of the convergence ring is considered stm-16/stm-64, in addition, due to the need to converge the access loop and other convergence points to send a large number of low-level VC12 services, while the need to deal with local business network elements such as BSC/MSC/RNC transmission to the backbone of the trans-ring business So it is very important to have a large low order crossover ability. It can improve the efficiency of VC filling of Network group, reduce the capacity of network group, improve the efficiency of operation in backbone network, improve the environment of business protection and reduce the whole net investment by improving the low order VC12 crossover ability of convergence node and dredging and gathering the business. For example, if the Community business capacity of a converging node is 128 equivalent VC4, with a maximum of 70% filling efficiency, the discrete levels of service from the access ring and other converging nodes of the converging node are more than 183 equivalent VC4, located at 80% VC12 levels in the 3G business, Considering that 50% of the VC12 are multiplexed in VC4, the results are as follows: The number of VC12 operations entering the node is 75 equivalent VC4. Under the ring network structure, the service protection is equal to the traffic volume itself, that is, using the Ring network mode, the convergence capacity of the low order VC12 of the core node should be no less than 150 equivalent VC4.

4. Conclusion

As for the 3G transmission network, we think Ason and WDM technology will be useful in the core network. In Utran network, MSTP is the preferred technology for network construction. This is because, MSTP can achieve a variety of services in the unified transport platform transmission, through the flexible configuration of related modules to meet the transmission requirements of 3G multiple signals, and with the 3G Business synchronization evolution, the superiority is self-evident. The R5 and future versions of 3G tend to be IP based systems. At the core network level, the introduction of Ason and WDM can help to improve the core network meta Service direct routing, and greatly improve the security of the network. Alcatel Shanghai Bell has a full range of optical network products and perfect 3G-oriented bearer network solutions, is committed to contributing to the construction of 3G in China.