宽带卫星通信中的ACM技术

采用自适应编码调制技术(ACM)的卫星数字视频广播新标准(DVB-S2)应用到宽带卫 星通信网中,将极大提升系统吞吐量,提供更丰富的交互式业务。从实际应用的角度,分析 了ACM的控制机制并提出其编码调制方案的简化方法。仿真结果表明,在几乎不影响系统性 能的前提下,该方案可以大幅降低ACM机制的复杂度。     

Examining the prospects for Gigabit Broadband: Lessons learned from Google Fiber

This study examines possible lessons learned from the deployment of residential Gigabit networks based upon the novel approach taken by the Google Fiber project started in 2010. Even though Google Fiber paused any project expansion in 2016, calling into question the viability of their business model, the approach taken by Google Fiber elicits further research interest given four major innovations that this analysis identifies in its fiber-to-the-home business model. Based on a “top-down” financial model to estimate the costs of fiber deployment, this analysis shows that these four innovations pursued by Google Fiber, and now adopted on a widespread basis by other broadband providers, lower the costs of building residential Gigabit networks, and therefore can improve the prospects for new entry of service providers of residential broadband services. With technology advances pointing to further cost reductions in the cost of Gigabit networks, this analysis elevates the need for more detailed study of ongoing changes in the cost structure of local access networks to better anticipate future prospects for broadband competition.     

The reluctant regulator: The Rural Utilities Service and American broadband policy

Drawing on the increasing body of literature on policy stakeholders and the ever-growing acknowledgement that communication policy is crafted by more than just parliamentarians and formal communication regulators this paper examines the role that another set of regulators plays in communication policy: agriculture regulators. Based on a study of the United States Department of Agriculture's Rural Utilities Service (RUS), this paper explores alternative agents of communication policy. More specifically, through document analysis we examine the way in which the Rural Utilities Service has shaped rural broadband policy in the United States over the last three decades. The implications for this research are wide, as it brings another policy actor into the policy making melee, and pushes communication policy scholars to consider the role that non-traditional communication regulators play in the communication policy making process.     

Was household internet adoption driven by the reform? Evaluation of the 2013 telecommunication reform in Mexico

In 2013 the Mexican Telecommunications and Broadcasting Reform was launched with the goal of promoting competition and access in the telecommunications sector. The aim of this paper is to evaluate whether the 2013 reform had an impact on household fixed internet adoption and to what extent Mexican households, classified into ten wealth groups, had adopted internet. For the assessment, after a revision of supply and demand Reform's measures to reduce the digital divide, data from the 2010 Census and 2015 Intercensal Survey were used to create adoption indexes using Poisson estimations. The results were analyzed by ten wealth groups, constructed on principal components based on household characteristics (type of dwelling, electricity availability, availability of drinking water, sewer system, internet and ICT devices: computer, telephone, cell phone and internet). Additionally, the impact of both indexes was validated by a difference in differences method. The results suggest a 66% overall increase in internet adoption between 2010 and 2015. The decile analysis showed considerable internet adoption in the low and middle wealth groups (deciles 2–8), while in the highest wealth groups (deciles 9–10) the impact of internet adoption has been relatively moderate. It is worth noting that internet adoption is unequally distributed, as less than 1% of households in deciles 1 to 6 had adopted internet in 2015, while nearly all of the wealthiest ten percent of households have internet access. Nevertheless the increment in internet adoption was not only the result of the reform but the combination of the broadband penetration trend and the reform together.     

Explaining cost escalation on Ireland's national broadband plan: A path dependency perspective

Ireland's national broadband plan (NBP), announced in 2012, aimed to provide access to a minimum of 30 Mbps download speed to all households in the country ahead of the EU's Digital Agenda for Europe 2020 target for such speeds. The projected cost of the government subsidy was originally €175 million. However, when the contract for the procurement of the NBP was eventually signed in 2019 the estimated subsidy had risen to between €2.2 and €2.9 billion. Using a path dependency framework, this paper finds that the escalation in the cost of subsidy was driven by two main factors. First, the decision to roll out fibre-to-the-premises (FTTP) technology was inconsistent with the geographic/legacy path dependencies related to Ireland's low-density rural population. Second, the gap-funding/PPP procurement model adopted for the intervention failed to attract competitive bids and was at odds with the competitive path dependency and the dominant role of the incumbent operator.     

Municipal fiber in the United States: A financial assessment

Despite growing interest in broadband provided by municipally owned and operated fiber-to-the-home networks, the academic literature has yet to undertake a systematic assessment of these projects' financial performance. To fill this gap, we utilize municipalities' official reports to offer an empirical evaluation of the financial performance of every municipal fiber project in the U.S. operating in 2010 through 2019. An analysis of the actual performance of the resulting fifteen-project panel dataset reveals that none of the projects generated sufficient nominal cash flow in the short run to maintain solvency without infusions of additional cash from outside sources or debt relief. Similarly, 87% have not actually generated sufficient nominal cash flow to put them on track to achieve long-run solvency. In addition, 73% generated negative nominal cash flow over the past three fiscal years, leaving them poorly positioned to make up their deficits and causing them to fall farther into debt. An assessment based on the net present value of these projects' operating cash flow indicates that 53% of projects would not be on track to breakeven even assuming the theoretical best-case performance in terms of capital expenditures and debt service. Close analysis of these projects’ performance reveals that revenue generation likely plays a more important role in generating cash flow than efficiency in construction costs or operating efficiency.     

Impacts of the Broadband Initiatives Program on broadband adoption and home telework

This study investigates the impacts of the Broadband Initiatives Program (BIP), established by the American Recovery and Reinvestment Act in 2009, on growth in broadband adoption and use of home telework. We find robust positive impacts across multiple econometric models and methods using census tract-level data in first differences. Across models and methods, the estimated average impact of BIP is in the range of 1.1–3.0 percentage point increase in the share of households adopting broadband and 0.2 to 0.4 percentage point increase in the share of workers using home telework. The estimated impacts of BIP represent roughly one-fourth to two-thirds of the average increase in broadband adoption and one-third to two-thirds of the average increase in home telework in the study tracts during the study period. The impacts of BIP vary across geographic contexts. Broadband and home telework adoption are also affected by prior levels of broadband availability, adoption, and telework, and by demographic and socioeconomic characteristics of the population and the industrial structure of the economy.     

飞机雷达散射特征提取技术研究

雷达采用宽带信号后,分辨率远小于目标尺寸,就可以对目标进行二维逆合成孔径成像(ISAR),而二维ISAR图像反映了目标在成像平面上的几何投影及散射点的强弱分布,本文从ISAR图像中确定目标轮廓沿距离向和方位向的分布范围,对目标区域尺寸信息进行分析,根据图像中散射点的强弱分布,提取了目标强散射点的分布情况,达到了对目标电磁散射分布特征研究的目的,对于飞机隐身设计具有一定的指导意义。     

Forecasting with limited data: Combining ARIMA and diffusion models

Forecasting diffusion of new technologies is usually performed by the means of aggregate diffusion models, which tend to monopolize this area of research and practice, making the alternative approaches, like the Box-Jenkins, less favourable choices due to their lack of providing accurate long-term predictions. This paper presents a new methodology focusing on the improvement of the short-term prediction that combines the advantages of both approaches and that can be applied in the early stages of a diffusion process. An application of the methodology is also illustrated, providing short-term forecasts for the world broadband and mobile telecommunications' penetration. The results reveal that the methodology is capable of producing improved one-year-ahead predictions, after a certain level of penetration, as compared to the results of both methods individually. This methodology can find applications to all cases of the high-technology market, where a diffusion model is usually used for obtaining future forecasts. The paper concludes with the limitations of the methodology, the discussion on the application's results and the proposals for further research.     

The impact of regulation on the retail prices in fixed-line telephony across the European Union

This paper estimates reduced-form models for incumbent prices in the fixed telecommunications industry using data for European Union (EU) countries from 1998 to 2002. The regulation of fixed-line telephony has a significant impact on prices for residential consumers. Liberalization of the telecommunications industry decreased retail prices by about 8.2%. The introduction of carrier pre-selection and number portability had a negative impact on price levels. The estimation results also suggest that a 1% decrease in termination charges on the incumbent network led on average to a 0.17% decrease in the cost of usage basket for residential consumers. Furthermore, in the pricing regressions for incumbent local and national calls at peak and off-peak times interconnection charges are significant only in the estimation of national peak prices. A 1% decrease in single transit interconnection charges on the incumbent network led to a 0.31% decrease in incumbent national prices at peak times, as calculated for the average prices in the EU in 2002.