中国移动欲将服务器打造成基地台

全球用户最多的电信业者中国移动(China Mobile)在 2012年行动通讯世界大会(MWC)上表示，该公司打算把服务器变身为蜂窝式基地台──他们正在利用资料中心技术，从根本上降低蜂窝式网络的成本与耗电量。 在去年3月，一个成员包括电信服务业者与设备供货商的产业组织NGNM，发起一项名为“云端无线接取网络(Cloud Radio Access Network，C-RAN)”的计划，初始参与成员包括英特尔(Intel)、IBM、华为 (Huawei)与中兴(ZTE)等大厂；该计划的主要目标是降低蜂窝式基地台的功耗与相关成本。尽管该计划仍面临许多技术与商业障碍，支持者已经建立了一套示范系统并进行现场实测，期望最快能在2013年中推出商用产品。 C-RAN的概念是要把至少1,000个基地台的功能集合到资料中心，再将之以光纤与多个无线头端连结；与今日的分布式3G网络架构相较，这种中央化系统据说可节省15%的设备成本、让营运成本减50%，功耗更可大幅降低70%。 “基本上，我们将颠覆目前的标准分层原理，并让电信网络看来更像是一种混搭式(mash up)的。”中国移动研究院(China Mobile Research Institute)院长黄晓庆(Bill Huang)表示：“在现有的网络架构下，户外基地台的功耗就占据整体网络的67%，而且其比例还在增加中；如果我们持续采用这种省电效率不佳的方案，后果真是很难想象。”

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为此，IBM与英特尔出手协助，将3GPP标准程序移植到x86服务器所执行的软件 上、而非传统基地台内的ASIC与DSP；华为与中兴则以通用绘图处理器以及软件无线电组件，开发了两套示范系统。据了解，上述示范系统已经在数个中国城 市进行实验性布署；而虽然有部分蜂窝式网络已经朝更中央化迈进，但并没有采纳C-RAN概念。 “目前该技术尚未达到商用阶段，但我们已经证明，它具备可利用现有处理器与常见连结方案实现的潜力。”黄晓庆指出：“我们期望在接下来的3~4年让该技术量产。” 英特尔最近为其Xeon处理器推出一款搭配芯片，可协助一部分封包处理以及网络安全任务；此外该公司还表示，正在开发能扮演基地台任务中DSP角色的下一代 芯片。总之目前C-RAN还有许多障碍有待克服，其中主要的是缺乏宽频骨干网络连结方案，来满足这种蜂窝式资料中心的需求。 中国移动所倡导的方案，是以光纤来连结C-RAN与无线头端，因为该公司已经大量布建光纤网络；但全球其它区域的电信业者，因为缺乏光纤网络，大多数是采用微波(microwave)或是铜线连结。事实上，有些供货商就认为C-RAN会成为亚洲电信业者专属方案，因为此区域业者大多都有布建所需的光纤网络。 黄晓庆也认为，做为C-RAN计划的一部分，可能需要整套全新的骨干网络接口。例如在服务器方面，会需要新一代的软件定义网络布置方案，降低对硬件的依赖程 度；这种新方案需要进一步将目前数秒的反应时间缩短，达到仅数毫秒(millisecond)的实时反应。“可以选择布建一种包含实时与非实时反应部分的二阶层(two-tier)无线云端网络。”黄晓庆指出。 而就算以上的障碍都可以克服，究竟目前大型资料中心的省电技术，是否也能适用于无线网络架构，其实还不是很确定。在技术障碍之外，要实现C-RAN概念，服务器制造商需要延揽具备电信专长的人员；此外包括阿尔卡特-朗讯 (Alcatel-Lucent)、爱立信(Ericsson)、诺基亚西门子(Nokia Siemens Networks)等电信设备业者，都需要采纳这种服务器架构。 所以问题在于“如何建立一种我们需要的产业竞合模式。”黄晓庆指出：“在过去4~5年，传统基地台设备业者从一开始的不信任转变为愿意提供资源，现在则是将C-RAN视为策略性关注议题。” C- RAN概念也需要去了解目前让产业界兴趣正浓的小型基地台，厂商将之视为能以具成本效率方式扩张蜂窝式网络覆盖率的方案，特别是都会区的新一代LTE网络。“我的看法是，未来将会出现单一基地台可处理1万个收发器的解决方案，也会出现只要单一芯片就能做为基地台的SoC。” 业界广泛认为，混合蜂窝式通讯与Wi-Fi的小型基地台将会兴起；黄晓庆表示，他们在这方面也与芯片业者共同合作，投入研发同时提供手机与小型基地台应用的 蜂窝式/Wi-Fi芯片组：“今日的基地台使用的严苛规格是可能放宽的，因此我们将可运用手机芯片。”而这也意味着未来不只能用x86服务器打造C- RAN中心设施，也可以使用ARM核心处理器。 编译：Judith Cheng 本文授权编译自EE Times，版权所有，谢绝转载 参考英文原文： China drives servers to base station role，by Rick Merritt

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{pagination} China drives servers to base station role Rick Merritt China Mobile wants to turn computer servers into cellular base stations, using data center technologies to radically lower the cost and power consumption of cellular networks. BARCELONA – China Mobile wants to turn computer servers into cellular base stations. The world’s largest carrier discussed at the Mobile World Congress here its effort to use data center technologies to radically lower the cost and power consumption of cellular networks. The so-called Cloud Radio Access Network (C-RAN) initiative aims to lower the power consumption of cellular base stations by a factor of five and cut their costs by an order of magnitude. Intel, IBM, Huawei and ZTE were among the initial partners in the program kicked off last March by NGNM, a trade group of telecom operators and vendors. The plan faces several technical and business hurdles. But proponents have already created demonstration systems, conducted field trials and hope to start development of commercial products as early as mid-2013. “Fundamentally, we could shake up the standard layered philosophy and make the telecom network look more like a Web mash up,” said Bill Huang, general manager of the China Mobile Research Institute, the R&D arm of China Mobile that serves 650 million subscribers. The C-RAN concept is to pack the functions of as many as a thousand base stations on data centers connected by fibre to multiple radio head ends. Such centralized systems could provide 15 percent reductions in capital costs, 50 percent decreases in operating costs and 70 percent reductions in power consumption compared to today’s distributed 3G nets. “With the current architecture, outdoor base stations already consume 67 percent of the network’s energy,” a slice set to increase, said Huang. “It’s mind boggling to imagine what will happen if we continue on this road of low power efficiency,” he said. IBM and Intel helped move 3GPP standard processes to software running on x86 servers rather than the ASICs and DSPs in traditional base stations. Along with Huawei and ZTE they created two demo systems that also tapped general-purpose graphics processors and software-defined radio components. “It’s clearly not product-ready technology, but we’ve demoed the potential that with modern processors and comms links it becomes viable,” said Huang. Several China cities conducted experimental deployments of the systems. Some are already moving toward more centralized cellular nets, but not yet including the C-RAN concept. “We hope over the next three to four years to bring this technology to volume shipments,” said Huang. Separately, Intel recently introduced a companion chip for its Xeon processors that helps handle a range of packet-processing and network security processes. As part of the roll out it said it is working on a next0-generation chip to handle DSP jobs for base station tasks. Plenty of hurdles are ahead, chief among them the lack of broadband backhaul links to serve such cellular data centers. China Mobile advocates linking the radio heads and C-RAN via optical fibre because it has plenty of installed fibre. But most global operators use microwave or copper links because they lack installed fibre. Indeed, some vendors say Cloud RAN could be limited to Asian operators who have the installed fibre the concept needs. Huang suggested a whole new backhaul interface may be needed as part of the C-RAN strategy. As for the servers, they need a new generation of software-define network implementations that require less support hardware. They also must close the gap between current response times of a few seconds to required real-time responses in a few milliseconds. “You can build a two-tier radio cloud that could consist of a real-time portion and a non- real time portion,” said Huang. Even if those hurdles are overcome, it’s not clear how the power savings achieved in today’s big Web data centers could be leveraged in installations running radio networking jobs. Beyond the tech hurdles, the C-RAN concept requires server makers acquire telecom expertise and telecom giants such as Alcatel-Lucent, Ericsson and Nokia Siemens Networks embrace server architectures. The question is how to foster “the kind of working co-opetition we need,” Huang said. “In the last four or five years [traditional base station vendors] went from disbelief to devoting resources and now to being strategically focused” on Cloud RAN, said Huang. The C-RAN concept also must come to grips with rising interest in small cell base stations seen as a way to cost effectively extend cellular coverage, particularly with new LTE networks in urban areas. “My opinion is the big will get bigger and the small will get smaller,” said Huang. “It will become a world where one base station handles 10,000 transceivers and another is a single chip base station SoC,” he said. Indeed, blended cellular and Wi-Fi small cells are widely expected to emerge. Huang said he has been working with silicon vendors to encourage design of cellular/Wi-Fi chip sets that could serve both handsets and small cell base stations. “Today’s stringent requirements for cell sites could be relaxed so we can use handset chips to build them,” he said Such a move could also pave the path for C-RAN hubs to use either x86 or emerging ARM-based servers.