1、Vulnerability and Protection of Channel State Information in Multiuser MIMO Networks Yu-Chih Tung, Sihui Han, Dongyao Chen, and Kang G. Shin The University of Michigan Email: yctung,sihuihan,chendy,kgshinumich.edu ABSTRACT Multiple-In-Multiple-Out (MIMO) offers great potential for in- creasing netwo
2、rk capacity by exploiting spatial diversity with mul- tiple antennas. Multiuser MIMO (MU-MIMO) further enables Ac- cess Points (APs) with multiple antennas to transmit multiple data streams concurrently to several clients. In MU-MIMO, clients need to estimate Channel State Information (CSI) and repo
3、rt it to APs in order to eliminate interference between them. We explore the vulnerability in clients plaintext feedback of estimated CSI to the APs and propose two advanced attacks that malicious clients can mount by reporting forged CSI: (1) sniffi ng attack that enables con- currently transmittin
4、g malicious clients to eavesdrop other ongoing transmissions; (2) power attack that enables malicious clients to en- hance their own capacity at the expense of others. We have imple- mented and evaluated these two attacks in a WARP testbed. Based on our experimental results, we suggest a revision of
5、 the current CSI feedback scheme and propose a novel CSI feedback system, called the CSIsec, to prevent CSI forging without requiring any modifi cation at the client side, thus facilitating its deployment. Categories and Subject Descriptors C.2.0 Computer-Communication Networks: SecurityandPro- tect
6、ion Keywords Multiuser MIMO Networks; Physical Security; Channel State In- formation 1.INTRODUCTION Multiple-Input Multiple-Output (MIMO) has the potential for solving the problem of insuffi cient bandwidth in WLANs, and has already been included in several wireless standards, such as IEEE 802.11n/a
7、c 6, 45. By exploiting spatial diversity, a transmitter with multiple antennas can either use its antennas to transmit the same stream to achieve power gain for the enhancement of the re- ceivers SNR or enable concurrent transmission of multiple (differ- ent) streams to achieve multiplexing gain. Mo
8、reover, to realize the potential benefi t of multiple antennas, 802.11ac supports the mul- tiuser MIMO (MU-MIMO) mode, in which multiple clients can be served concurrently without interfering with each other, achieving multiplexing gain even for those clients with a single antenna. A key component i
9、n all MIMO technologies is Channel State In- formation (CSI). Due to the multipaths a wireless signal takes, the received signal is actually a combination of different, delayed and Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without
10、fee provided that copies are not made or distributed for profi t or commercial advantage and that copies bear this notice and the full cita- tion on the fi rst page. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwi
11、se, or re- publish, to post on servers or to redistribute to lists, requires prior specifi c permission and/or a fee. Request permissions from permissionsacm.org. CCS14, November 37, 2014, Scottsdale, Arizona, USA. Copyright 2014 ACM 978-1-4503-2957-6/14/11 .$15.00. http:/dx.doi.org/10.1145/2660267.
12、2660270. CSI (h11,h12) CSI (h21,h22) Known sequence CSI (h11,h12) Forged CSI (f21,f22) Known sequence (a) Genuine CSI feedback fl ow CSI (h11,h12) CSI (h21,h22) Known sequence CSI (h11,h12) Forged CSI (f21,f22) Known sequence (b) Forged CSI feedback fl ow Figure 1Attack models based on forged CSI. a
13、ttenuated copies of each sent signal, and CSI can be regarded as the coeffi cient of this combination. This information is critical to MIMO networks since it is used by transmitters to precode signals either for boosting received signal strength at a client or removing interference to the other clie
14、nts. Researchers have also shown that the network capacity can be improved via transmission with known CSI 38. Note that only receivers know the CSI from transmitters to themselves, which is estimated by using a pre-defi ned known se- quence. For example, in downlink transmission, only clients know
15、their own CSI from the Access Point (AP) to themselves, which is estimated by dividing the received signal by the known sequence, and the clients are responsible for feeding back this information to the AP for precodingmessages as shown in Fig. 1(a). Moreover, the freshness of CSI is critical to the
16、 performance of wireless networks, as stale CSI does not represent the current state of multi-path fad- ing and may result in precoding errors. In MU-MIMO networks, when the CSI feedback delay is greater than 200ms, the achievable network capacity decreases by more than 50% 4. Thus, receivers are re
17、quired to report CSI in plaintext as quickly as possible. We uncover the vulnerability caused by this plaintext CSI feed- back, and propose two advanced attacks in MU-MIMO networks withforgedCSI.AsshowninFig.1(b), weassumemaliciousclients can fi rst sniff other clients CSI, modify/fabricate and then
18、 report it. In general, clients have no incentive to report a wrong estimation of CSI, as it does nothing but decreases its own received signal-to- interference-plus-noise ratio (SINR). However, in MU-MIMO net- works, data can be transmitted to multiple clients concurrently who share the same wirele
19、ss medium, and hence, clients can intention- ally mislead the precoding process at the transmitter by reporting forged CSI for malicious purposes. Based on this observation, we fi rst introduce a potential threat, called the sniffi ng attack, which enables a client to eavesdrop packets sent to other
20、s even under the protection of physical security which is theoretically proven to be immune to eavesdropping 12, 24. The other potential threat we identifi ed is the power attack, which manipulates the APs power allocation to antennas based on the reported (forged) CSI. By re- porting forged CSI, a
21、client can receive a favorable power alloca- tion for its own transmission. To the best of our knowledge, we are the fi rst to discover, implement, and prove the possibility of ma- licious attacks on the MU-MIMO precoding process by reporting forged CSI. These attacks are very different from the oth
22、ers pro- posed before 14, 23, 32 which also provide wrong metrics to fool systems in that ours actively exploits the precoding proce- dure by forging CSI which is unique in MU-MIMO networks. The vulnerabilities caused by forging CSI are expected to become a crit- ical issue as MU-MIMO is becoming po
23、pular and deployed widely; it is thus important to prevent such attacks before they become ram- pant. We propose CSIsec to protect existing MU-MIMO networks from the attacks with forged CSI. CSIsec is a novel CSI feedback system in which transmitters send a “cheated” known sequence in- stead of the
24、genuine known sequence to mislead the CSI estima- tion process at clients before they forge CSI. Using this approach, no clients can estimate their own CSI correctly, and it is also im- possible to know CSI of another client because even that client doesnt know its own CSI. Under CSIsec the transmit
25、ter is the only one who knows the CSI estimated at clients, and this infor- mation is acquired through a process similar to Diffi e-Hellman key exchange 10. It is important to note that CSIsec requires no modifi cation at clients, and hence it provides backward compatibil- ity and can be easily appl
26、ied to existing systems. We also suggest adding randomization in existing MU-MIMO mechanisms to disin- centivize clients from reporting forged feedback under CSIsec. WeimplementtheattackmodelsandCSIsecinaWARPtestbed 20, and validate that by reporting forged CSI, a client can success- fullydecodepack
27、etsdestinedforotherclientswithlessthan2%bit- error-rate (BER) on average even with physical security enabled. On the other hand, a client can also acquire an unfairly higher ca- pacity (by 20%) only by repo是由中小企业完成的。当前，中小企业创新活动更加活跃、创新领域更加广泛，不仅在原有的传统产业中保持旺盛活力，而且在信息、生物、新材料等高新技术产业和信息咨询、工业设计、现代物流、电子商务等服
28、务业中成为新兴力量。2014年我国电子商务交易额达到13万亿元，同比增长25%，其中网络零售额增长49.7%，绝大部分都是中小企业贡献的。目前，中小企业已占全国经济总量的半壁江山以上，要完成转变发展方式、提高发展质量的任务，就必须大力支持中小企业发展，充分调动和发挥中小企业在促进经济发展方式转变和实施创新发展战略中的重要作用。近年来，产业集群已经成为我国中小企业发展的重要组织形式和载体，对于提高专业化分工与协作配套、促进生产要素有效集聚和优化配置、降低创业创新成本以及节约社会资源等方面具有重要作用，是工业化和信息化发展到一定阶段的必然趋势。目前，产业集群已覆盖了纺织、服装、皮革、五金制品、工艺
29、美术等大部分传统行业，在信息技术、生物工程、新能源、新材料以及文化创意产业等新技术领域发展加速，涌现出一批龙头骨干企业和区域品牌，在县域经济发展中作用显著。2、中共中央、国务院发布关于深化投融资体制改革的意见，提出建立完善企业自主决策、融资渠道畅通，职能转变到位、政府行为规范，宏观调控有效、法治保障健全的新型投融资体制。改善企业投资管理，充分激发社会投资动力和活力，完善政府投资体制，发挥好政府投资的引导和带动作用，创新融资机制，畅通投资项目融资渠道。从促进产业发展看，民营企业机制灵活、贴近市场，在优化产业结构、推进技术创新、促进转型升级等方面力度很大，成效很好。据统计，我国65%的专利、75%
30、以上的技术创新、80%以上的新产品开发是由民营企业完成的。从吸纳就业看，民营经济作为国民经济的生力军是就业的主要承载主体。全国工商联统计，城镇就业中，民营经济的占比超过了80%，而新增就业贡献率超过了90%。（二）法人治理结构xxx科技公司按照现代企业制度的要求进行组织和运行，建立有股东大会、董事会、监事会、总经理及高层管理人员分级权限决策的治理结构；股东大会拥有对公司资产的最终所有权并根据股权比例行使相应股东权；由股东大会选举的董事组成公司董事会作为决策机构对股东大会负责并行使相应权限的经营决策权；由股东大会选举产生的监事和职工代表监事组成的监事会行使监督权，维护股东利益，对股东大会负责；由
31、董事会聘请的公司总经理及高级管理人员根据董事会决策进行企业的日常经营管理指挥活动，保持企业的市场竞争力和经营效率。xxx科技公司组织经营机构的设置按照“精简、高效”的原则，而且业务开展、专业技术培训、经营管理活动必须服从公司统一管理；为保证各部门及全体员工之间的协调配合，以完成企业生产经营目标，按照中华人民共和国公司法的规定并结合企业实际情况对企业的组织机构进行设置。（三）公司管理体制xxx科技公司的机构设置按现代化企业制度设置管理体制，根据生产经营管理工作的实际需要，本着“力求精简、实行全员聘用制，管理机构精简，适用和提高效益”的原则确定。本期工程项目按车间及现代企业体制运作，实行生产管理现
32、代化。实行生产管理现代化基础是技术装备水平先进、工人技术水平优良，在此基础上精简机构，建立一套科学管理机构和管理体制，减少管理人员，人员编制根据生产设备的需要进行配置。生产设备、辅助生产设施、公用工程设施由生产车间统一管理。生产车间对主要生产设备的正常运行、安全、产品质量负责。xxx科技公司实行董事会领导下的总经理负责制，各部门按其规定的职能范围，履行各自的管理服务职能，而且直接对总经理负责；公司建立完善的营销、供应、生产和品质管理体系，确立各部门相应的经济责任目标，加强产品质量和定额目标管理，确保公司生产经营正常、有效、稳定、安全、持续运行，有力促进企业的高效、健康、快速发展。第四章 风险因
33、素分析及规避措施一、社会影响评价范围及内容的界定该项目社会影响评价范围是以xx产业园区项目建设地为重点，分析“氨基酸表面活性剂项目”对节约能源、减少排放、当地社会就业、居民收入、生活水平、不同群体、文教卫生、弱势群体、社会服务容量等方面的影响。二、社会影响因素分析（一）项目实施对当地居民收入的影响项目建设区域为xx产业园区项目建设地，无特殊环境功能区，也不属于农业生产种植区，在该区域实施项目建设，不仅不会影响当地农民正常种植生产，还能够充分利用当地剩余的丰富劳动力资源，项目实施后能够提供就业机会，吸收当地居民参与第二产业，带动和发展第三产业，在一定程度上缓解当地居民的就业问题，因此，可以改变当
34、地农民仅靠种植获得收入的状况，因此，可以明显地提高当地居民的收入。（二）对所在地区文化、教育、卫生的影响文教卫生是提高人口素质的摇篮，是保护人类健康的基石；本期工程项目的技术含量、管理水平要求较高，需要引进培养一部分文化、技术素质高的人才和有熟练技能、身体健康的一大批从业人员，也就是说要强化文化教育、卫生事业是工业经济发展基础的意识，促进当地政府在发展公共社会事业方面做出部署，如进一步加强幼儿教育、义务教育、职业技术教育等；同时项目获益后又以缴纳税金来回报社会，从而为进一步发展当地的文化、教育、卫生事业打下坚实的经济基础。（三）对当地基础设施、社会服务容量和城市化进程等的影响本期工程项目的建成
35、，将完善区域间路网结构和功能，提升xx产业园区项目建设地的整体形象，明显改善当地的交通条件和出行环境，直接服务于xx产业园区项目建设地的规划开发，促进项目区域的城镇化进程。三、社会影响效果分析（一）主要社会影响效果分析本期工程项目建设有利于繁荣地方经济，取得较好的社会经济效益；项目建成后，可以极大地改善xx产业园区项目建设地的环境状况，进一步改善眉山市的投资环境，加快附近区域的建设与开发，引导该区域氨基酸表面活性剂产业结构和产业布局的调整，促进城乡贸易的流通，带动商业、建筑业、运输业、加工业及文化教育产业等迅速发展，从而促进项目影响区域的经济繁荣。（二）对土地利用效果分析1、本期工程项目拟总用
36、地面积29094.54平方米（折合约43.62亩），项目的实施将会进一步减少土地可用量；此外，近年来，城市化、工业化的加速发展对建设用地的需求不断扩张，而建设用地需求的扩张又导致占用耕地面积的不断扩大。（三）对环境污染影响分析1、项目施工活动对自然环境会造成污染性破坏，必然对生态环境产生一定的影响，项目建设因大量的开挖取土破坏土体的原有自然结构，土壤水循环被破坏，相应的生物链随之改变，改变了动植物的生存环境，影响其生长活动规律，对生态系统的漫延造成障碍。2、中小企业清洁生产推行计划。提升中小企业清洁生产技术研发应用水平，开展政府购买清洁生产服务试点，实施中小企业清洁生产培训计划。继续实施粤港清
37、洁生产伙伴计划，在其他地区推广示范。工业节水专项行动。围绕钢铁、纺织印染、造纸、石化化工、食品发酵等重点行业实施节水治污改造工程，实施用水企业水效领跑者引领行动，推进节水技术改造，在缺水地区实施工业节水专项行动，加强非常规水资源利用。研究表明，70%的资源消耗和环境影响取决于产品设计阶段。要把提升绿色设计能力作为“十三五”工业清洁生产的重中之重，推动关键绿色设计技术和支撑绿色设计的管理技术和工具的研发、应用和推广，逐步建立面向产品全生命周期的关键资源环境基础数据库。采用数字化研发设计工具，发展基于“互联网+”的个性化定制、众包设计模式，推动工业云、工业大数据与产品绿色设计资源共享，优化研发设计
38、流程，提升产品设计开发效率，打造网络化、协同化的绿色设计体系。以绿色设计为核心，推进产品设计、制造、包装、运输、使用维护和回收利用各环节的并行工程，推进绿色制造体系不断完善。3、生态文明建设提升到前所未有的高度，生态环境保护、资源高效利用、温室气体排放控制等工作持续推进。循环经济作为提高资源利用效率、减少资源消耗、降低环境污染的有效措施之一，已于2008年以循环经济促进法的形式奠定了其在全国社会经济发展中的地位；2013年国务院印发循环经济发展战略及近期行动计划（国发20135号），明确提出资源产出率大幅提高的中长期目标；2016年开始实施的循环经济促进条例进一步以法律条文的形式体现了循环经济
39、在经济社会发展中的重要性。“十三五”时期，我国工业将以系统节能改造为突破口，促进工业节能从局部、单体节能向全流程、系统性优化转变，实现工业能源利用效率大幅提升。在继续推进单体节能的同时，更加注重设备、企业、园区的多层级系统节能，在抓好重点行业节能的同时，面向工业全行业全面推进工业节能，在继续重视大企业能效提升的同时，着力推动中小企业节能。（四）项目区绿色节能发展当前和今后一个时期，我国仍然处在大力推进节能减排的关键时期。要全面完成“十三五”规划提出的节能减排目标，企业还需要在未来几年中继续努力，做好节能减排的大文章。值得注意的是，节能减排是一个循序渐进的过程。企业节能减排应当在原有的工作与成绩的基础上继续深入推进，把企业的短期利益与长远发展相结合，在加强技术创新和改造、提升管理能力与完善长效机制等方面下功夫，积极履行社会责任，有效开展节能减排，从而实现企业经济效益与节能减排之间的良性循环。第五章 综合评价1、使开发区成为引领全省转型升级创新发展的先导区；先进制造业、高新技术产业（包含战略性新兴产业）和现代服务业等产业优化升级基地和新兴产业的集聚区；环境友好型城市、循环经济发展区域的示范区。强化开发区产业发展规划的刚性约束。立足当前实际，与所在地的城市“十三五”
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