A hassle-free network for communications assurance

Transcription

1 China Unicom Zhuhai A hassle-free network for communications assurance China Unicom Zhuhai has successfully cut over to the optimized MSC Pool solution, helping it achieve one-time service recovery and centralized management through softswitch networking without wireless network upgrade. Also, this success has prepared China Unicom Group for a large-scale commercial deployment of the MSC Pool. By Yang Xin Editor: Xu Ping x.ping@huawei.com 42

2 Winners Through unified coordination, the operator could reduce management difficulty and complexity and cut the overall management costs while effectively alleviating the constraints of main maintenance resources. Unique communications needs Known as the City of Islands, Zhuhai is one of China s five special economic zones. Though a city with relatively small population, it is one of China s 40 best tourist destinations thanks to its pleasant climate, picturesque scenery, and unique location. Each year, the city receives a large number of tourists, and hosts various major international conventions, exhibitions and fairs, and sports events. Underlying public security systems, communications systems must run reliably to ensure that these important activities and events proceed smoothly. In particular, emergency communications assurance is needed to cope with emergencies. In Zhuhai, tourists largely visit scenic spots during the daytime; in the evening they often gather at restaurants, hotels, and entertainment venues. When it comes to the communications network, this movement of people gives rise to a typical tidal effect, which is characterized by significant changes in network traffic patterns in different areas and periods of time. Coupled with roaming and handover, the effect exacerbates the impact on the network, and in extreme cases, causes switches to break down. In master/ backup mode, the MSC servers on China Unicom Zhuhai s core network could not recover services immediately after a breakdown, and it even took hours to activate the servers, which adversely affected user experience. As one of the leading local telecom operators committed to providing its subscribers with the best services, China Unicom Zhuhai has kept on improving its network capabilities to meet their unique needs. Before 2009, however, the operator had two MSC servers the master server was based in Zhuhai and the backup one in Guangzhou. Two network management systems and two maintenance teams were thus required to take care of these two MSC servers, which ran counter to the philosophy of global planning and maintenance. MSC Pool to solve the issue After extensive research, China Unicom Zhuhai realized that transforming the master/backup MSCs into one MSC Pool would be a solution with notable advantages. The MSC Pool solution, based on 3GPP, is now an industry-leading distributed disaster recovery solution that is generally accepted. Its disaster recovery function is co-delivered by switches in the pool while the network capacity is equivalent to the total capacity of the switches. By fully utilizing the redundant capacity, the solution can improve the network s capability to handle burst traffic. In the case of China Unicom Zhuhai, it could make the best of network capacity resources and avoid the waste of the idle backup server. For real-time service switching in the event of downtime, the MSC Pool solution makes sure that, once a certain MSC in the pool is damaged or overloaded, other switches can immediately take over the affected users and achieve zero service interruptions. If deployed by China 43

3 Unicom Zhuhai, an MSC Pool-based emergency communications system would not only reduce losses from service interruptions, but also effectively improve customer loyalty, its social influence and brand image. The MSC Pool solution could combine two network management systems into one to address the coordination between the two maintenance teams. It could fully adapt to current network statistics and appropriately expand to meet operator requirements for network-level statistics management. With the solution, the two maintenance teams of China Unicom Zhuhai could be reduced to one. Through unified coordination, the operator could reduce management difficulty and complexity and cut the overall management costs while effectively alleviating the constraints of main maintenance resources (human, financial, and material) to its rapid development and delivering high quality O&M at lower cost. Deployment: No easy task At the end of 2009, China Unicom Zhuhai embarked on the project of upgrading to the MSC Pool on its core network, which aimed to transform the master/backup MSC server mode into the MSC Pool. It was China Unicom s first trial MSC Pool project. The MSC Pool deployment did not go without a hitch, though; the operator needed to address the issues of synchronization planning, cost management, and O&M. Synchronization planning would need to address the synchronization of network planning and configuration data. In network planning, the deployment of a traditional MSC Pool solution required upgrading the wireless access network in the first place. Yet access network equipment from different vendors varied in the schedule and capability of support, which affected the whole network s overall planning and implementation progress. In data configuration, the MSC Pool required unified operation and collaboration between the access network and the core network. If pool-level management was conducted in the same way as was the distributed management of traditional network elements, it would entail a lot of collaboration between China Unicom Zhuhai s departments, plus a large amount of data that would easily lead to errors and considerable network security hazards. Investment and operating costs were a top concern to China Unicom Zhuhai. As the deployment of a traditional MSC Pool on a TDM network necessitated wireless base station controllers (BSC) interconnecting with all switches in the pool, enormous TDM transmission resources would be consumed. In general, costs for network building and maintenance would be prohibitive to the operator. Upgrading wireless equipment on the network would also be costly. Compared with traditional networking, the MSC Pool required more complex network management. To implement maintenance management activities such as network configuration, statistics, and monitoring, China Unicom Zhuhai would need to operate massive data through cumbersome procedures. If there were no effective operation management tools, operating costs would soar and 44

4 Winners The optimized MSC Pool solution enabled the MGW to achieve service distribution and circuit management for China Unicom Zhuhai, eliminating the need to upgrade the wireless access network. pose a formidable challenge. O&M issues China Unicom Zhuhai had with the traditional MSC Pool solution mainly included the following: One was that the incoming call recovery scheme was defective so that the first call could not be put through. Another was that the resulting change in the O&M approach had an impact on the operator s O&M and billing mechanism. Optimized MSC Pool eliminates barriers Finally, China Unicom Zhuhai detailed its network transformation requirements. First, the impact on the current network needed to be minimized to ensure normal services. Second, implementation difficulty needed to be reduced to achieve smooth transformation and evolution toward the MSC Pool. Finally, change to the current O&M and billing model needed to be avoided as much as possible to maintain network reliability. Based on the requirements, Huawei helped Zhuhai Unicom develop a network optimization solution involving three phases. Upgrade to VoIP would be completed first for core network softswitches; then a standalone TDM/IP interoperability office would be established; finally a new MSC would be built in Zhuhai. Upon completing the network transformation, China Unicom Zhuhai summed up its experience as one-time service recovery and centralized management through softswitch networking without upgrading the wireless access network. IP softswitch networking reduces transmission investment China Unicom Zhuhai adopted Huawei s IP softswitch with an architecture featuring bearer/ control separation so that the media gateway (MGW) and MSC in the MSC Pool could be fully interconnected on the IP bearer network. When the MGW was in distributed mode on the core network, the BSC only needed to connect to the original softswitch MGW without any alteration. This could avoid the drawback of traditional media gateway distribution technology that required full interconnection between the BSC and all the MGWs in the pool, thus saving on TDM resources and reducing actual deployment costs. The flat IP network structure has allowed China Unicom Zhuhai to share resources with all MSS servers in the MSC Pool. Meanwhile, Huawei s MSC Pool solution supported the Mini- A-flex solution to provide disaster recovery for media gateways and further enhance network security. Expediting deployment without BSC upgrade The optimized MSC Pool solution enabled the MGW to achieve service distribution and circuit management for China Unicom Zhuhai, eliminating the need to upgrade the wireless access network. While saving the investment cost for the BSC upgrade, it facilitated actual planning and deployment of the networking scheme. With open network interfaces, the operator could keep its MSC Pool network open to equipment from multiple vendors so as to benefit from more 45

5 competitive equipment prices. Uninterrupted services improve customer satisfaction When China Unicom Zhuhai had completed its transition to the MSC Pool, it took less than three minutes for a BSC Pool area to access interrupted services while both services and charging were accurate. By utilizing the one-time incoming call recovery function of Huawei s MSC Pool solution, the operator solved the industry issue of incoming call recovery. In other words, a user data backup server was deployed. When an MSS failed, another MSS quickly recovered lost data through the data backup server, and took over users of the failed MSS, thereby performing one-time incoming call recovery. With service uninterrupted, the network failure was not perceptible to users of the failed MSC. User satisfaction improved as a result. Centralized network management system improves O&M efficiency China Unicom Zhuhai adopted the M2000, a centralized MSC Pool network management system, to manage all MSCs and MGWs in the pool and meet the MSC Pool network s requirements for unified configuration, monitoring, assessment, and adjustment. Maintaining configuration parameters across network elements (NEs), the system ensured the correct configuration of Pool parameters on all MSSs and MGWs, which was strengthened by a function of manual/automatic data consistency verification. The system could gather and analyze performance statistics from the MSSs to obtain global reference data. It also conducted performance monitoring based on daily indicators. By viewing the curves of these KPIs, China Unicom Zhuhai s network management people could promptly find out the operational status of its MSC Pool network. Hassle-free network makes Zhuhai more attractive After a period of relentless effort, China Unicom Zhuhai officially launched its MSC Pool for commercial use on April 28, 2010; it rode out the May Day holidays that immediately followed. The new MSC Pool network had no impact on the current 2G/3G services. KPIs such as the call setup success rate and paging success rate were up by 1 to 2 percent; indicators such as the location update success rate, assignment success rate, and handover success rate remained stable; network reliability was %. By eliminating the need to upgrade the wireless network and sharing TDM transmission resources at the A interface, Huawei s MSC Pool allowed China Unicom Zhuhai to dramatically save on network deployment costs and speed up the network deployment cycle. Meanwhile, implementing the sharing of 2G/3G network resources as well as the sharing of network loads between MSCs, it improved resource efficiency for the whole core network of the operator and provided MSC-level disaster recovery. Also, it resulted in a sharp decrease in interoffice switching and better call quality. The new MSC Pool network topology, together with its evolution path, would surely serve as a basis and reference for China Unicom Group in its future upgrade to VoIP and the MSC Pool. Li Haihua, O&M Manager of China Unicom Zhuhai, noted, We re happy to have built a highreliability, high-performance and high-efficiency mobile core network with Huawei s innovative MSC Pool solution that also facilitates operation and maintenance. The effective deployment of this solution at China Unicom Zhuhai will get China Unicom Group ready for the large-scale commercial launch of the MSC Pool in terms of technology and O&M. Selecting a mature, optimal solution always has benefits. With Huawei s optimized MSC Pool, China Unicom Zhuhai has dramatically reduced risks in all phases of its MSC Pool deployment from network planning to O&M. Now, capitalizing on a hassle-free core network, it can easily provide communications assurance for all the tourists and attendees of major international events in the City of Islands. 46