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MAIN TOPIC MAIN TOPIC It s Booming mobile broadband services and rapidly evolving mobile network technologies have pushed mobile networks into an ALL IP era. Traditional transport networks that TDM services are struggling to keep pace with the new trend of moving to ALL IP. By Li Hongsong 19 MAR 2008. ISSUE 39
ALL IP trend for mobile transport IP-based mobile transport networks first appeared in backbone bearer networks. IP/ MPLS (multi-protocol label switching) routers over the wave division multiplexing (WDM) system efficiently bear mobile softswitch services. China Mobile, BT, Vodafone, and Etisalat, have all seen greater profits and consumer satisfaction after building IP backbone bearer networks. Mobile base stations are gradually adopting ALL IP technology and the air interface rate has been increasing rapidly, for example, from 144Kbps in GPRS to 14.4Mbps in HSPA, and to 100Mbps in Long-Term Evolution (LTE). As a result, transport bandwidth required by mobile backhaul networks has been booming. The forecast for 2010 is that the growth of data services will quadruple the demands on mobile backhaul bandwidth. In this scenario, an IP-based mobile backhaul is inevitable for future mobile transport networks. Desired features To improve transport efficiency and reduce transport costs, an IP mobile transport network has to satisfy the following requirements. ALL IP architecture: Packet requirements of transport networks can be mostly attributed to the rapid growth of data services that have uncertain and unexpected traffic. The transport network should be designed and deployed on the basis of a pure IP-based kernel to guarantee the highest level of efficiency. Multi-service transport capability: Recent developments have shown that a unified transport network must adapt to various mobile network t e c h n o l o g i e s, i n c l u d i n g G S M, WC D M A, CDMA2000, WiMAX, HSPA+ and LTE. The transport network should be able to transport services of multi-mode radio access networks (RANs) in a unified way. Traditional 2G networks are based on time division multiplexing (TDM); 3G R99/R4 network adopts the asynchronous transfer mode (ATM) protocol; 3G/WiMAX/LTE networks evolve into ALL IP. During the evolution of mobile networks, services based on TDM, ATM and packet will coexist in the same network for a long time. The transport network should be able to support unified transport of multiple services, including TDM, ATM and Ethernet services. This can be realized with the pseudo-wire emulation edge-toedge (PWE3) technology. Multi-scenario access and networking capability: As different access resources are allocated to different base stations, no single access technology can cater to all requirements. Base stations in Asia-Pacific like China have relatively rich optical fiber access resources. In Europe, the microwave access mode is mostly adopted, plus there are some leased lines and small quantity of twisted pair cables. When a mobile network is extended from wide coverage to indoor microcells and hotspot access points (APs), the transport network must provide customized multi-scenario access and networking capabilities. The network has to support multiple combined access technologies involving optical fibers, microwave and copper cables. Precise IP clock transfer capability: Clock synchronization is a key demand for mobile networks. Traditional transport networks transfer clocks through SDH and the global positioning system (GPS). ALL IP transport networks need precise clock synchronization capabilities to handle mobile service roaming and handover. High reliability: 3G services include data and voice services, which place different requirements on network reliability. Transport networks must offer carrier-class protection on services. By using the QoS strategy and the network protection mechanism, transport networks can offer differentiated services to reliably handle voice, video and data services. Excellent scalability: As data services develop quickly, mobile data services and mobile traffic will boom. Transport networks should have fine flexibility and scalability regarding interface types, transport bandwidth, and network scale. End-to-end management capability: The provision of mobile 3G services and wide network coverage will drive transport network evolution into multi-service bearer networks. End-to-end management capability can efficiently decrease network operations and maintenance costs. Huawei sets IPTime At the Mobile World Congress (3GSM) Barcelona 2008, Huawei formally released the IP Transport Infrastructure for Mobile Evolution (IPTime), an ALL IP-based carrier-class IP transport network solution. A media report commented that Huawei s new solution embodied the development of transport networks into the ALL IP era, as mobile networks have been evolving to ALL IP. The IPTime solution has the following features: Multi-service transport and multi-scenario MAR 2008. ISSUE 39 20
MAIN TOPIC It s IPTime! access. The IPTime solution is based on the ALL IP architecture and helps operators in constructing ALL IP networks, which are future-oriented strategic investments. Based on the PWE3 technology, IPTime is able to transport various types of services and provide interface diversity such as TDM, Ethernet, xdsl (digital subscriber line), xpon (passive optical network) and microwave. IPTime helps operators to smoothly evolve from 2G networks to 3G networks, then to 4G networks. It supports access-layer transmission media like optical fiber, microwave and copper cable, as well as access requirements in various complicated scenarios. It also supports flexible transport in case of deep coverage by mobile networks. Unique IP clock transport with GPS-like precision. IPTime offers IP clock transport schemes for ALL IP mobile networks. It adopts packet over SDH (POS) interface timing, synchronous Ethernet and IEEE 1588v2 to meet the synchronization requirements of GSM, WCDMA, WiMAX, CDMA, and future 4G networks. High reliability and strong manageability. IPTime enables transport networks to offer end-toend, differentiated QoS, operations, administration and maintenance (OAM) capabilities to meet different needs from base station access to the core convergence point. It supports complicated networking like star, link, ring and mesh, and enables carrier-class protection switching in the whole network within 50ms. It also supports unified network management to simplify network operation and maintenance for a significant improvement in the operator s core competitiveness. Smooth evolution of existing transport networks. IPTime adopts SDH-like management and maintenance mechanism, offers ports that are compatible with existing transport network, and supports smooth evolution of existing networks to ALL IP transport networks. Adding real benefits Huawei s IPTime ALL IP transport network solution embraces the idea of proper management now will guarantee a bright future, which enables operators win big in the transformation towards ALL IP. Simplified architecture In a backbone bearer network, IPTime adopts the IP over OTN/WDM scheme, and decreases network costs by 30 percent. It introduces the reconfigurable optical add-drop multiplexer (ROADM) technology to the traditional WDM system and changes the point-to-point WDM system into a network that can enable cross-connect dispatching of wavelength. In addition, the IPTime enables intelligent dispatching of various service granules by introducing OTN. The backbone bearer network can provide complete OAM functions and fault location. Routers and the OTN/ WDM layer adopt unified general multi-protocol label switching (GMPLS) control plane to enable interactions between the IP layer and the optical layer. In mobile backhaul, the IPTime solution makes use of the PWE3 technology to allow IP transport of TDM, ATM and Ethernet traffic. The unified transport network leads to simpler network architecture, more convenient maintenance, and lower costs. The IPTime solution implements end-to-end unified network management from the mobile 21 MAR 2008. ISSUE 39
Huawei s IPTime ALL IP transport network solution embraces the idea of proper management now will guarantee a bright future, which enables operators win big in the transformation towards ALL IP. backhaul to the backbone bearer network. The ALL IP transport network can offer higher transport efficiency, more convenient operations and maintenance, and faster deployment of new services. Enhanced reliability The backbone bearer network provides end-to-end protection on the IP layer through various protection technologies, including MPLS traffic engineering (MPLS TE), MPLS OAM, virtual private network fast reroute (VPN FRR), and virtual router redundancy protocol (VRRP). In the optical layer, the OTN/ROADM technology enables protection on WDM subnets and cross-connect dispatching of services throughout the entire network. The advanced technologies guarantee carrier-class protection switching within 50ms in all network layers and meet the requirements of mobile IP networks. They also improve the reliability of the IP-based transport network to 99.999%. China Mobile s carrier-class backbone bearer network was built by Huawei and is one of the largest mobile backbone bearer networks in the world. The network has successfully handled hundreds of exponential rises in traffic volume over the past three years. Other mobile backbone bearer networks constructed by Huawei such as Vodafone and Etisalat, have also been running smoothly for over two years, proving that the IPTime transport network solution can fully meet the requirements of mobile backbone bearer networks. In mobile backhaul, Huawei provides a complete series of carrier-class packet transport network (PTN) platforms based on ALL IP kernels. Offering carrier-class transport performance and diversified interfaces, these platforms support unified transport of traditional 2G services, 3G services, and future 4G mobile broadband services. They also support provider backbone transport (PBT), transport MPLS (TMPLS), and layer-2 (L2) MPLS technologies. The platforms support the clock synchronization in various modes of mobile networks by using high-precision packet clock transport technologies like adaptive clock recovery, clock synchronization over Ethernet, and clock over IP based on IEEE 1588v2. The twolayer, multi-mode carrier-class transport platform can transport comprehensive services in a highly efficient and reliable way and support mobile networks in ALL IP evolution. Smooth network evolution Access resources can be obtained by different types of base stations in mobile backhaul. Huawei s IPTime solution offers various access modes. The solution adopts SDH-like management and maintenance as well as NG-SDH-compatible ports. These measures ensure minimal impact on the existing transport network during the network s evolution to PTN. The existing management and maintenance mode can be inherited, and existing service interface boards can be reused. Optical fiber-based mobile backhaul: The IPTime solution provides various optical fiber access modes, including MAN Ethernet and PON. The MAN Ethernet based on optical fibers is a multi-mode PTN transport platform with an IP kernel and provides the transport network with fine OAM and protection functions. The transport network can significantly lower network evolution costs by inheriting the OAM features of a traditional SDH system and by reusing the interface boards of traditional SDH networks. The PON effectively improves the utilization of optical fiber resources. The WDM-PON, which integrates WDM and PON technologies, can provide bigger transport capacity and better networking capabilities. Microwave-based mobile backhaul: IPTime provides pure packet microwave and integrates with the PTN for smooth mobile network evolution. Microwave transport is also moving toward ALL IP as base stations develop towards ALL IP, due to the increase of bandwidth demands. There are three scenarios: First, if base stations are partially IPbased, microwave equipment supporting both IP access and E1 access should be adopted for combined transport. Second, if interfaces of base stations are mainly inverse multiplexing over ATM (IMA) E1, the microwave equipment supporting large-capacity E1 interfaces can be adopted. PTN equipment can be used at convergence points to enable service convergence and packet transport. Third, if base stations are ALL IPbased, the packet microwave equipment supporting self-adaptive modulation and coding of air interfaces can be adopted for packet transport. Packet microwave equipment can be integrated with the PTN to decrease operation and maintenance costs of the transport network, and Huawei is fully able to realize microwave transport networking. Copper cable-based mobile backhaul: Huawei s IPTime solution provides rich xdsl access modes. At present, base stations mainly adopt the single-pair highspeed DSL (SHDSL) leased lines for service access. As the demands for mobile bandwidth increase, the offload mode can be used to separate voice and data services in base stations. Voice and signaling services requiring high QoS can be transported through high-quality E1 lines, and Abis/lub compression technology can be used to save leased lines. Data services can then be transported through leased xdsls. Editor: Liu Zhonglin liuzhonglin@huawei.com MAR FEB 2008. ISSUE 38 39 22