The mobile communication service has always been the focus of the operator's business development. The mobile backhaul (MobileBackhualing) transmission bearer network plays an important role in supporting and guaranteeing the mobile service.
At present, in the 2G/2.xG mobile communication network (GSM/GPRS/EDGE), China Mobile provides bearer for the voice and data services returned by the base station, mainly based on the SDH-based multi-service transmission platform, MSTP technology. The BTS base station generally uses a 2M TDM interface, the base station controller BSC is a 2M or STM-1 TDM interface, the MSC/GMSC provides an STM-N or 2M TDM interface, and the SGSN/GGSN provides an STM-N POS interface. For the inter-office relay service, the traffic of each node is large, and the service granularity is generally 2M, 155M, 622M or FE/GE. For the BTS-to-BSC service, the network traffic flows are concentrated, and the traffic of each node is small, and the service particles are mainly 2M.
The metropolitan transport network that China Mobile carries 2G/2.xG base station backhaul services can be logically divided into three levels: the core layer, the aggregation layer and the access layer, as shown in Figure 1. The backbone node is composed of an exchange, a gateway, a long-distance bureau, and a data center node to form a core layer. Generally, a metro WDM or a 10G/2.5G SDH device is used to form a ring network (a mesh network is used in some areas). The aggregation node is composed of important stations and data aggregation points to form an aggregation layer. It is mainly composed of 2.5G SDH/MSTP devices, supplemented by a small number of 622M/155M SDH/MSTP devices, and a ring network is established. ), the number of nodes on the ring is generally 3 to 6. The access node is composed of a base station, a community broadband network service, and other service access points to form an access layer. The 622M/155M SDH/MSTP device is mainly used, supplemented by PDH, microwave, 3.5G or other wireless access technologies. The ring network (usually adopts the channel protection mode) can also adopt the star, tree or chain structure according to the access cable routing. Currently, the number of MSTP ring nodes is generally 6 to 15, and the number of individual MSTP rings can reach 50 or more.
In the past, SDH played a strong role in the process of China Mobile's “boutique network†with its reliable transmission carrying capacity, flexible add/drop multiplexing technology, powerful protection and recovery functions, and carrier-level maintenance management capabilities. . However, MSTP's packet processing or IPization is not "complete", its IP is mainly embodied in the user interface (ie, surface layering), but the core is still circuit-switched (ie, kernel circuitized). This makes MSTP less efficient in carrying IP packet services and cannot adapt to the needs of 3G and full-service eras, which are dominated by a large number of data services. With the relative shrinkage of TDM services and the gradual maturity of the "all-IP environment", the transmission equipment needs to evolve from the existing "TDM circuit-switched core" to "IP packet-switched core".
New challenges for mobile 3G base station backhaulIP transmission requirements for 3G base station backhaul
Mobile 3G network construction is also designed to meet the increasing bandwidth requirements of business applications. Whether it is TD-SCDMA or WCDMA, 3G systems are designed for mobile multimedia communications. All kinds of services are developing in the direction of IP, and new services are also based on IP. 3G networks are no exception.
In the field of mobile communications, the two major third-generation mobile communication standardization organizations, 3GPP and 3GPP2, have set the development strategy of the third-generation mobile communication as an all-IP architecture. The ITU believes that IMT-2000 can be redefined as IMT-Internet Mobile/MulTI media TelecommunicaTIons, ie "Internet Mobile/Multimedia Communications".
In the 3G world, mobile phones are personal mobile information tools, and are information assistants that meet the individual needs of users. Users can choose information, applications and service content according to their own needs. The 3G network greatly expands the user communication method and provides users with more abundant business choices. As shown in Table 1, the service performance indicators in the 3G network defined by the 3GPP show that the voice, video, and multimedia services have strict requirements on delay, jitter, and packet loss rate. Because 3G networks can provide a wide variety of services and focus on multimedia services, this will definitely break the mobile operators' revenue mainly from voice services. Video telephony, broadband data and information assistants will become mobile operations. Business new revenue growth point.
IP-based multi-service applications are the mainstream of future development. For fixed, mobile, and commercial applications, bandwidth, security isolation, and transmission QoS requirements are also different. The construction of the 3G network makes the service type of the bearer and transport layer change from TDM to IP/ETH. The service interface changes from E1 to FE, and the service granularity is from 2M to 10M/100M. Some telecom experts expect that the downlink access bandwidth of fixed user bandwidth requirements can reach 20~30Mbit/s and the uplink access bandwidth can reach 4~8Mbit/s in the next 5 to 10 years, and the bandwidth requirement of each base station of mobile communication system will also reach 30M to 100Mbit/s.
At present, the development of 3G/B3G, mobile+internet and all-IP trend puts forward higher requirements on the bearer and transmission network of the base station backhaul. The IP-based service presents a sudden burst of bandwidth and a high peak-to-average ratio. The traditional circuit-switched MSTP transport network is characterized by rigid pipelines, which can not meet the transmission requirements of these packet services. How to build a metropolitan area that can carry a variety of new and old services, is easy to expand, reliable, and has low OPEX and CAPEX. The network is a problem that telecom operators should seriously consider.
Breaker Rcbo,Rcbo Protection,Leakage Protection Rcbo,Leakage Protection Switch
ZHEJIANG QIANNA ELECTRIC CO.,LTD , https://www.traner-elec.com