一种基于包络跟踪的宽带Doherty放大器设计

效率可重构宽带Doherty在实际应用中需要手动调节主功放的漏压和辅助功放的栅压,包络跟踪是解决此问题的有效方法。然而,包络跟踪设计比较复杂。为此,提出了线性映射的设计方法,设计实现了1.0~1.4 GHz包络跟踪宽带Doherty放大器,在10 dB大回退范围较固定偏压Doherty放大器效率提升了8%。同时,包络跟踪显著降低了手动调节偏压的人力和时间成本,仿真结果验证了设计的有效性。     

SC-FDE宽带航空数传接收机的设计与实现

为满足航空信道条件下的远距离宽带数据传输需求,基于单载波频域均衡传输（SC-FDE）体制,采用8PSK调制体制进行了宽带数字接收机的设计,包括传输帧同步、载波同步、定时同步、信道估计和频域均衡。同时,为保证灵活应用的需求,采用数字内插的方式进行了可变传输速率设计。基于Xilinx现场可编程门阵列（FPGA）平台对硬件实现进行优化,最终实现了传输速率能够从112.5 Mbit/s覆盖到900 Mbit/s的数传接收机。仿真分析和硬件测试结果表明,该接收解调设备能够实现很好的性能指标,同时SC-FDE架构具备有效补偿多径传播影响的能力,适合应用于高动态无线宽带航空数据传输系统中。     

宽带数字接收机IQ不平衡估计与自适应补偿算法

针对宽带调制解调技术中广泛存在的IQ不平衡问题,在IQ不平衡模型及补偿原理的分析基础上提出了一种宽带数字接收机IQ不平衡估计与自适应补偿算法。首先利用解调数据对IQ不平衡参数进行实时估计,然后利用估计参数对接收信号进行自适应补偿。实验结果表明,所提算法可以有效解决宽带调制解调系统中普遍存在的IQ不平衡问题,提升系统误码性能。     

基于Linux的宽带计费与运营管理系统的设计与实现

研究并实现了对宽带上网进行计费及提供运营管理的软件系统,充分利用了Linux内核的NetFilter技术、Socket数据通信技术、电力线上网技术.重点讨论了解决即插即用、网段隔离、数据传输、远程控制等技术难题.最后,在高效性、稳定性、可靠性、易扩充性等重要方面给出了分析.     

采用预测算法的卫星CFDAMA MAC协议时延性能分析

提出了地面站采用预测预约算法的混合式按需／自由分配-预测预约（CFDAMA-PR）卫星媒体接入控制协议。CFDAMA-PR协议可采用预定预约时隙或轮询预约时隙发送预约请求。在文中，通过计算机仿真对预定时隙预约CFDAMA-PR、CFDAMA-PA与基本DAMA协议进行性能比较，同时还对轮询预约CFDAMA-PR和CFDAMA-RR协议进行了仿真性能比较，仿真中采用IFP突发信源，仿真结果说明CFDAMA-PR协议采用预测预约算法，实现了更好的时延／吞吐量性能。     

我国宽带接入市场的有效竞争状况研究——基于SCP框架的分析

文章通过对2008—2011年的数据进行统计分析发现,我国的宽带接入市场一直是一种行政垄断下的双寡头垄断型市场结构;市场行为上尽管竞争在不断加剧,但基础电信运营商强大的市场势力一定程度上恶化了市场竞争条件。市场结构和市场行为方面的问题是导致宽带市场绩效总体欠佳的主要原因。为了形成一个有效竞争格局,进而改善宽带业务绩效,依靠市场机制和政府规制双管齐下的策略才会取得成效。     

我国宽带产业战略联盟分析

当前在宽带产业内存在着普遍的战略联盟行为,本文从研究宽带产业内部战略联盟的形成机理入手,从价值链、知识学习、资金结构、管理权等角度对产业内战略联盟进行分析,指出了产业内战略联盟所存在的深层次问题,并基于战略联盟的视角对产业的健康发展提出了相应的对策建议。     

Effects of economic conditions and policy interventions on OECD broadband adoption

The positive effects of broadband networks and services on productivity and economic growth are well established. Looking at broadband as an engine of economic prosperity, the OECD and its member states are seeking to foster its widespread adoption. However, which public policies best promote the adoption of broadband remains controversial. This article contributes in two ways to this discussion. It offers a comprehensive discussion of the factors that influence broadband adoption and uses an econometric approach that is well-suited to overcome the challenges of modelling broadband adoption. This framework allows drawing more robust and nuanced policy recommendations.     

Broadband penetration and economic growth nexus: evidence from cross-country panel data

This article investigates whether there are Granger causal relationships between broadband penetration, degree of urbanization, foreign direct investment and economic growth using a panel data set covering the G-20 countries for the period 1998–2011. Using our multivariate framework, we first find that all of the variables are cointegrated. Our findings further reveal a network of causal connections between the variables including short-run bidirectional causality between broadband penetration and economic growth among the more developed countries within the G-20. On the other hand, for the developing countries within the G-20, there is evidence of unidirectional causality from economic growth to broadband penetration.     

Exploring additional determinants of fixed broadband adoption: policy implications for narrowing the broadband demand gap

Using data from the survey ‘Aspects of daily life’ conducted on Italian individuals in 2014 by the Italian Institute of Statistics, we propose new evidence on the factors that encourage the adoption of fixed broadband, a topic relevant for the reduction of the so-called broadband demand gap. We estimate a probit model through the two-step Heckman procedure for the selection bias, and find that, besides the already studied socio-demographic determinants, Internet-capable devices other than personal computers, as well as recreational (essentially video contents) and cloud-related uses of the Internet, have a relevant positive role. Policies aimed at fostering the diffusion of smart homes and more generally of the Internet of things at the residential level might be very effective in favouring fixed broadband adoption, provided that the network be neutral, not discriminating between data based on their contents and/or the destination device, and that possible foreclosing behaviours in the access to (premium) contents be properly and promptly addressed.