全球用戶最多的電信業(yè)者中國移動(China Mobile)在 2012年行動通訊世界大會(MWC)上表示，該公司打算把服務(wù)器變身為蜂窩式基地臺──他們正在利用資料中心技術(shù)，從根本上降低蜂窩式網(wǎng)絡(luò)的成本與耗電量。 在去年3月，一個成員包括電信服務(wù)業(yè)者與設(shè)備供貨商的產(chǎn)業(yè)組織NGNM，發(fā)起一項名為“云端無線接取網(wǎng)絡(luò)(Cloud Radio Access Network，C-RAN)”的計劃，初始參與成員包括英特爾(Intel)、IBM、華為 (Huawei)與中興(ZTE)等大廠；該計劃的主要目標(biāo)是降低蜂窩式基地臺的功耗與相關(guān)成本。盡管該計劃仍面臨許多技術(shù)與商業(yè)障礙，支持者已經(jīng)建立了一套示范系統(tǒng)并進行現(xiàn)場實測，期望最快能在2013年中推出商用產(chǎn)品。 C-RAN的概念是要把至少1,000個基地臺的功能集合到資料中心，再將之以光纖與多個無線頭端連結(jié)；與今日的分布式3G網(wǎng)絡(luò)架構(gòu)相較，這種中央化系統(tǒng)據(jù)說可節(jié)省15%的設(shè)備成本、讓營運成本減50%，功耗更可大幅降低70%。 “基本上，我們將顛覆目前的標(biāo)準(zhǔn)分層原理，并讓電信網(wǎng)絡(luò)看來更像是一種混搭式(mash up)的?！敝袊苿友芯吭?China Mobile Research Institute)院長黃曉慶(Bill Huang)表示：“在現(xiàn)有的網(wǎng)絡(luò)架構(gòu)下，戶外基地臺的功耗就占據(jù)整體網(wǎng)絡(luò)的67%，而且其比例還在增加中；如果我們持續(xù)采用這種省電效率不佳的方案，后果真是很難想象?！?

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為此，IBM與英特爾出手協(xié)助，將3GPP標(biāo)準(zhǔn)程序移植到x86服務(wù)器所執(zhí)行的軟件 上、而非傳統(tǒng)基地臺內(nèi)的ASIC與DSP；華為與中興則以通用繪圖處理器以及軟件無線電組件，開發(fā)了兩套示范系統(tǒng)。據(jù)了解，上述示范系統(tǒng)已經(jīng)在數(shù)個中國城 市進行實驗性布署；而雖然有部分蜂窩式網(wǎng)絡(luò)已經(jīng)朝更中央化邁進，但并沒有采納C-RAN概念。 “目前該技術(shù)尚未達到商用階段，但我們已經(jīng)證明，它具備可利用現(xiàn)有處理器與常見連結(jié)方案實現(xiàn)的潛力?！秉S曉慶指出：“我們期望在接下來的3~4年讓該技術(shù)量產(chǎn)?！? 英特爾最近為其Xeon處理器推出一款搭配芯片，可協(xié)助一部分封包處理以及網(wǎng)絡(luò)安全任務(wù)；此外該公司還表示，正在開發(fā)能扮演基地臺任務(wù)中DSP角色的下一代 芯片?？傊壳癈-RAN還有許多障礙有待克服，其中主要的是缺乏寬頻骨干網(wǎng)絡(luò)連結(jié)方案，來滿足這種蜂窩式資料中心的需求。 中國移動所倡導(dǎo)的方案，是以光纖來連結(jié)C-RAN與無線頭端，因為該公司已經(jīng)大量布建光纖網(wǎng)絡(luò)；但全球其它區(qū)域的電信業(yè)者，因為缺乏光纖網(wǎng)絡(luò)，大多數(shù)是采用微波(microwave)或是銅線連結(jié)。事實上，有些供貨商就認(rèn)為C-RAN會成為亞洲電信業(yè)者專屬方案，因為此區(qū)域業(yè)者大多都有布建所需的光纖網(wǎng)絡(luò)。 黃曉慶也認(rèn)為，做為C-RAN計劃的一部分，可能需要整套全新的骨干網(wǎng)絡(luò)接口。例如在服務(wù)器方面，會需要新一代的軟件定義網(wǎng)絡(luò)布置方案，降低對硬件的依賴程 度；這種新方案需要進一步將目前數(shù)秒的反應(yīng)時間縮短，達到僅數(shù)毫秒(millisecond)的實時反應(yīng)。“可以選擇布建一種包含實時與非實時反應(yīng)部分的二階層(two-tier)無線云端網(wǎng)絡(luò)。”黃曉慶指出。 而就算以上的障礙都可以克服，究竟目前大型資料中心的省電技術(shù)，是否也能適用于無線網(wǎng)絡(luò)架構(gòu)，其實還不是很確定。在技術(shù)障礙之外，要實現(xiàn)C-RAN概念，服務(wù)器制造商需要延攬具備電信專長的人員；此外包括阿爾卡特-朗訊 (Alcatel-Lucent)、愛立信(Ericsson)、諾基亞西門子(Nokia Siemens Networks)等電信設(shè)備業(yè)者，都需要采納這種服務(wù)器架構(gòu)。 所以問題在于“如何建立一種我們需要的產(chǎn)業(yè)競合模式?！秉S曉慶指出：“在過去4~5年，傳統(tǒng)基地臺設(shè)備業(yè)者從一開始的不信任轉(zhuǎn)變?yōu)樵敢馓峁┵Y源，現(xiàn)在則是將C-RAN視為策略性關(guān)注議題?！? C- RAN概念也需要去了解目前讓產(chǎn)業(yè)界興趣正濃的小型基地臺，廠商將之視為能以具成本效率方式擴張蜂窩式網(wǎng)絡(luò)覆蓋率的方案，特別是都會區(qū)的新一代LTE網(wǎng)絡(luò)。“我的看法是，未來將會出現(xiàn)單一基地臺可處理1萬個收發(fā)器的解決方案，也會出現(xiàn)只要單一芯片就能做為基地臺的SoC?！? 業(yè)界廣泛認(rèn)為，混合蜂窩式通訊與Wi-Fi的小型基地臺將會興起；黃曉慶表示，他們在這方面也與芯片業(yè)者共同合作，投入研發(fā)同時提供手機與小型基地臺應(yīng)用的 蜂窩式/Wi-Fi芯片組：“今日的基地臺使用的嚴(yán)苛規(guī)格是可能放寬的，因此我們將可運用手機芯片?！倍@也意味著未來不只能用x86服務(wù)器打造C- RAN中心設(shè)施，也可以使用ARM核心處理器。 編譯：Judith Cheng 本文授權(quán)編譯自EE Times，版權(quán)所有，謝絕轉(zhuǎn)載 參考英文原文： 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.