The Wi-Fi “congestion crisis”: Regulatory criteria for assessing spectrum congestion claims

“Wi-Fi congestion is a very real and growing problem.” So said then-Chairman of the FCC Genachowski in a recent proceeding, and this sentiment is widely heard. However, we are aware of very few engineering studies that have a bearing on this matter, and their conclusions are equivocal. Beyond this, evidence for “congestion problems” in the 2.4 GHz ISM band is anecdotal at best.While some users no doubt sometimes have service difficulties they ascribe to congestion, that is not sufficient to prove that there is a policy problem. In order to provide a basis for policy decisions, we offer an analysis of congestion metrics and results in the engineering literature. We conclude that there is little consensus on how to measure congestion, and that network metrics are difficult to correlate with user experience.We therefore propose a list of user experience-oriented service impairment criteria that, if met, would demonstrate that congestion exists to a degree that justifies regulatory intervention: For more than one of the key scenarios that are supported by an operator or technology there is a significant increase in the percentage of users who cannot complete a valuable task on a persistent, ubiquitous basis in spite of the use of state-of-the-art engineering/deployment best practices, and users׳ willingness to pay the market rate for the best available service level.Based on our assessment of public reports and experimental data, we conclude that there is currently no evidence for pervasive Wi-Fi congestion. We do not claim that the absence of evidence of congestion amounts to evidence for the absence of congestion. However, we do question the argument that congestion occurring somewhere, sometimes is a justification for regulatory intervention.     

计算机广域网在物流系统中的信息交换应用

在物流交换系统中,目前应用最为普及的是计算机广域网与局域网。在信息交换方式方面,局域网主要由以下几种模型组成,一是索取信息交换模型,二是网站平台信息交换模型,三是直接信息交换模型。上述三种模型都各有各的优势与缺点,同时它们所使用的领域与规模也有所不同。商业流动、第三方以及制造业物流企业对于信息交换方式的选择,笔者认为应当充分结合企业的实际情况,如经济实力、企业规模等,最优化地选择出恰当信息交换方式来满足企业物流发展需求。     

考虑伪码跟踪误差影响的码片内多径分离研究

<正> 刘光溪同志是我国第一位国际贸易专业WTO研究方面的博士并作为中国代表团主要成员参与了13年中国复关/入世的实质性谈判工作,写过多本有关世贸组织和区域经济合作方面的专著,《碰撞、融合、发展——亲历13年复关/入世谈判的思索》是他在这方面的一本新著。已由上海人民出版社于2002年2月正式出版发行。     

一种降低开销及时延的自组网AODV改进算法

对无线自组网中研究热点之一的AODV路由协议算法进行了描述,然后对协议中的hello机制、链路修复及断开处理等算法进行了改进与优化,并通过NS2仿真验证了改进后的协议能够降低网络的开销及减少时延。     

The future of accessibility in disaster conditions: How wireless technologies will transform the life cycle of emergency management

By describing a transformed life cycle of emergency management, this paper re-envisions how emergency managers may prepare for, respond to, recover from, and mitigate against disaster impacts in the future. Additionally, this paper also reveals how the broader social, political, economic, and cultural levels must change to foment a culture of safety with and for people with disabilities. The authors use the framework to identify how future wireless technologies can empower people with disabilities with regards to individual (or household) emergency preparedness and in coping with the drastic life changes following a disaster.     

校园照明分布式控制系统设计方法

介绍了校园照明监控网的结构和网络通信协议,重点叙述了以单片机为核心的照明开关柜测控器数据通信接口的设计原理.     

BP机的妙用

论述了一种利用无线寻呼网广播数字信息的银行ＩＣ卡收费系统的设计，并对截取ＢＰ机信息的几种方法进行了深入的分析。     

Reexamining the effect of packet pricing in the wireless internet

In this paper, we compare the market performances of circuit pricing whereby users are charged based on their length of usage time with packet pricing whereby users are charged based on the amount of information received. We show that, if packet pricing is introduced, the market price rises contrary to a widely held belief, but that the overall social welfare is unambiguously increased. Also, we show that a move to packet pricing lowers the price of multimedia transmission which requires a much higher speed, thereby increasing the usage of multimedia data in the absence of congestion, although this may not be the case in the presence of congestion.     

论ERP架构下的企业信息化

本文论述了在ERP技术日趋成熟的情况下,实现企业信息化的要求、特点及系统建设目标。     

Strategic incentives under vertical integration: the case of wireline-affiliated wireless carriers and intermodal competition in the US

In its review of the Cingular/AT&T Wireless merger, the FCC noted the potentially conflicting incentives of wireline-affiliated (vertically integrated) versus independent (non-integrated) wireless carriers to act as intermodal competitors in the wireline exchange access market. Specifically, because Cingular and Verizon Wireless are owned by wireline carriers, they may have an incentive to compete “less aggressively” within their parents’ wireline territories while AT&T Wireless, an independent wireless carrier, would not. This paper examines these and other hypotheses by examining pre-merger data on the wireless plans offered by the three carriers. The empirical analysis suggests that AT&T Wireless did not design its plans based upon a regional strategy, whereas Cingular offered substantially smaller-minute wireless plans within its parents’ wireline territories. However, the results also suggest that Verizon Wireless did not design its plans in a markedly different fashion within and outside of its parent’s wireline region. It is posited that these findings might reflect the differing ownership and control structures of Cingular and Verizon Wireless.