小型基地台叫好不叫卖，标准统一是最大障碍

小型基地台(small cell)在纾解日益沉重的行动网络资料流量负担方面扮演关键角色，不过在达到大量布建的目标之前，工程师们还有很多工作得做。 在近日于美国旧金山举行的次世代移动网络联盟(NGMN Alliance)大会上，Powerwave 展示了市场上首批出货的小型基地台产品；不过该产品虽然已经应用在美国政府部门的小型基地台网络中，却无法与传统的大型基地台互通。 到目前为止，传统基地台供货商还未公布可让Powerwave 等公司产品与大型基地台连结的X2互连技术细节；第十版(Release 10)的 LTE 规格内包含了基于 X2 的基地台间干扰消除(inter-cell interference mitigation standard)标准，不过网络业者预期到2013年之前恐怕不会开始布署地十版LTE。 高通(Qualcomm)也在大会上展示了一款基地台间干扰消除技术，该方案所采用的芯片组原型已经装置在该公司总部所装设的基地台中，不过正式上市时间未定。 韩国移动通讯服务业者KT的网络策略部门副总裁Andrew Jun表示，蜂巢式网络覆盖区域会发生基地台间干扰的比例，在仅包含单纯大型基地台的情况下是25%，但若加入小型基地台，该区域比例将增加至40%。 KT 已经建立了基地台数量在144个到1,000个不等的中央化集中区(centralized pools)；“这也是我们推广基地台虚拟化(virtualization)的原因。”Jun表示：“能在单一位置管理多个基地台，让我们得以协调传输来控制干扰，特别是在基地台边缘。” Powerwave首席技术官在NGMN Alliance大会的一场座谈中表示，小型基地台与大型机大台之间的互通：“只是时间的问题；”他指出，该公司的小型基地台能同时支持 LTE 与 Wi-Fi ，可为服务业者将网络负载量提升十五倍，同时基地台电池寿命则延长了五倍。 通讯设备大厂爱立信 (Ericsson)的技术策略主管Erik Ekudden则表示，若采用小型与大型基地台组成的异质网络(heterogeneous network)，通讯服务业者能将网络负载量提高至二十倍，但前提是必须将所有的频宽集中到一个结合3G与LTE的网络中；他补充指出，目前大多数厂商 的小型基地台仍在设计阶段，现场测试则是明年展开。 中国通讯设备业者华为(Huawei)则在大会上介绍一种以第八版标准 (Release 8)为基础的、融合LTE与802.11n Wi-Fi 的热点设备；该公司工程师表示，该产品支持256 QAM、1.2Gbps传输速率，采用FPGA与DSP组件，目前仍在实验室原型阶段。 “每个人的演示文稿里都有好东西，但当我 试着去找一款不错的商业化小型基地台，却无法找到一家能提供的厂商；”俄罗斯4G通讯服务业者Yota的技术长Konstantin Yurganov在会中表示，该公司在部分城市中有近15%的基地台流量负担沉重，光是单一个基地台的用户数量就有70~160人。 小型基地台最终将会布署在如路灯柱等公共场所，以及咖啡厅、办公室等商业区域，这些应用为企业网络方案供货商带来了新商机。 思科(Cisco Systems)行动部门首席技术官Paul Mankiewich于一场专题演说中，呼吁产业界订定一个网络应用程序接口(API)，以实现横跨服务业者网络与商业网络的广泛虚拟化。该API可望建 立在目前Wi-Fi Alliance正在开发的技术之上；他表示，该技术是为了协助定义公共与私人Wi-Fi网络热点之间的流量。 “今日的企业网络与服务业者网络之间并没有连贯性；”Mankiewich表示：“目前一切都是依据两套彼此不对话的标准。” 本文授权编译自EE Times，版权所有，谢绝转载 编译：Judith Cheng 本文下一页：参考英文原文：Small cells still not ready for mobile prime time，by Rick Merritt

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{pagination} Small cells still not ready for mobile prime time Rick Merritt SAN FRANCISCO – Engineers still have significant work ahead to deliver small cell base stations, a key piece of the puzzle for easing congestion on heavily loaded mobile data networks. Powerwave Technologies (Santa Ana, Calif.) showed what it claimed was one of the first shipping small cell base stations at the NGMN Alliance conference here recently (below, left). Although it is being used in a small-cell network for a U.S. government department, the small cells do not yet interoperate with traditional macro base stations. So far the traditional base station suppliers have not disclosed details of their X2 interconnects that companies such as Powerwave need to link to the macro cells. Release 10 of Long Term Evolution specifies an inter-cell interference mitigation standard over X2, but operators are not expected to start deploying Release 10 until sometime in 2013. Qualcomm showed a demo at the event of the inter-cell interference technology working on prototype chip sets installed in base stations at its San Diego headquarters. It did not say when those chip sets will ship. The amount of cellular coverage area subject to inter-cell interference grows from 25 percent with macro cells to 40 percent with macro and small cells, said Andrew Jun, vice president of network strategy at cellular operator KT in Korea that has created centralized pools of 144 to 1,000 cell sites. “This is why we introduced [base station] virtualization” said Jun. “With one location managing multiple cells we could have coordinated transmissions to control interference, especially at the cell edge,” he said. “It’s only a matter of when” until small and macro cell interoperability is ready, said Khurram Sheikh, chief technologist of Powerwave in a panel session at the event. He claimed his company’s small cells support both LTE and Wi-Fi and can increase an operator’s network capacity fifteen-fold while increasing battery life five-fold. A carrier can increase its capacity as much as twenty-fold adopting heterogeneous networks of small and macro cells, but only if it pools all its spectrum into one combined 3G and LTE net, said Erik Ekudden, head of technology strategy at Ericsson. Most OEMs are still in the design phase for small cells with field trials starting next year, he added. For its part, Huawei described at the event a merged LTE and 802.11n Wi-Fi hotspot based on Release 8. It can support downloads at about 1.2 Gbits/second using 256 QAM and is now in a lab prototype based on FPGAs and DSPs, said a Huawei engineer. “Everybody has nice stuff on their slides, but go try to find a good commercial small cell--I can’t find a single vendor to supply one, said Konstantin Yurganov, chief technology officer at Yota, a 4G supplier in Russia, in a talk at the event. The carrier has as many as 15 percent of its base stations heavily loaded in some cities with as many as 70 to 160 subscribers on a single base station, he said. Ultimately, small cells will be deployed both in public areas such as lamp posts and in businesses such as cafes and offices. That’s opening up an opportunity for enterprise networking companies to participate. In a keynote talk, Paul Mankiewich (right), chief technologist for mobility at Cisco Systems, called for a network API enabling broad virtualization across carrier and business nets. The API could build upon technology already in the works at the Wi-Fi Alliance to help identify traffic on public versus private Wi-Fi hotspots, he said. “We don’t have coherence between enterprise and service provider networks today,” said Mankiewich. “All that depends on two sets of standards that don’t speak to each other today,” he said.