Cable Modem Access Research Articles

RF Transport Over Optical Fiber in Urban Wireless Infrastructures [Invited

The technology for transport of RF signals over optical fibers at long (metropolitan-scale) distances which enables today's hybrid fiber/coax networks for community antenna TV and cable modem access is being leveraged for coverage and capacity enhancements in wireless networks providing affordable anywhere/anytime services. This is particularly important in high-traffic urban and in-building arenas where RF propagation is challenging. A hybrid Fiber/Cable (HFCa) approach utilizing legacy urban cabling infrastructures is shown to be highly cost effective, since the installation cost (which often dominates over equipment cost) is greatly reduced or eliminated. Optimum HFCa system architectures are discussed in this paper with Ca = C (coax) and C5 (Cat-5 unshielded twisted pair cables) for outdoor urban/metropolitan and indoor/in-building arenas, respectively. The general results in this paper apply to both. A quantitative evaluation of capacity gain by traffic trunking in a distributed antenna system is given. All-fiber RF transport for remote radio head systems serving outdoor metropolitan areas is briefly discussed.

'Net Neutrality', Non-Discrimination and Digital Distribution of Content Through the Internet

The vast majority of US residential consumers face a monopoly or duopoly in broadband Internet access. Up to now, the Internet was characterized by a regime of “net neutrality” where there was no discrimination in the price of a transmitted information packet based on the identities of either the transmitter or the receiver or based on the application or type of content that it contained. The providers of DSL or cable modem access in the United States, taking advantage of a recent regulatory change that effectively abolished net neutrality and non-discrimination protections, and possessing significant market power, have recently discussed implementing a variety of discriminatory pricing schemes. This paper discusses and evaluates the implication of a number of these schemes on prices, profits of the network access providers and those of the complementary applications and content providers, as well as the impact on consumers. We also discuss an assortment of anti-competitive effects of such price discrimination, and evaluate the possibility of imposition of net neutrality by law.

Resolving Policy Chaos in High Speed Internet Access

Public policy for high-speed internet access is in chaos. The nation's primary regulator of the communications sector, the Federal Communications Commission, has pursued asymmetric regulation (that is, different rules) for the technologies that can provide some form of high-speed internet access (telephony, cable television, wireless data networks, and satellite distribution systems). Three federal courts (two circuit courts of appeals and one district court) have issued contradictory decisions regarding whether cable modem access can be regulated and, if so, by whom. Two federal regulatory agencies, the Federal Communications Commission and the Federal Trade Commission, have adopted mutually inconsistent policies regarding cable modem access, each in the context of approving a merger. Numerous local franchising authorities have reached mutually vastly different conclusions about whether they can and should impose equal access requirements on cable modem access. Much has been written about whether high-speed internet access should be regulated, and if so, what those regulations should be and which bodies - whether franchising entities, utility regulators, or antitrust authorities, and whether local, state or federal government - should have front-line responsibility for making the rules. With few exceptions, these analyses are adversarial documents written by individuals who work as consultants for parties that have a major financial stake in this issue. And even the few exceptions usually are defenses of a particular policy position. Although many, if not most, of these arguments are logically correct, they tend to be partial and incomplete. The purpose of this essay is to step back from this adversarial debate for the purpose of describing the issues on which access policy should turn, and to provide a guide to policy makers about how to sort out the adversarial arguments. The foundation for this essay is the idea that decision theory provides useful framework for thinking about regulatory policy in this domain. Specifically, each regulator is one player in a sequential game with incomplete information that involves other regulators, the courts, state and federal legislatures, the firms in the industry, customers of internet services, and nature. Nature's role is periodically to deliver random technology shocks that disrupt the relative costs and performance characteristics of communications technologies and the competitive positions of the firms that supply access, navigating and operating services, and end-use services. The structure of the essay is as follows. Section I reviews the current state of policy chaos, the policy choices to be made, and the arguments for and against these choices. Section II reviews the debate about high-speed access policy using the analytical framework of antitrust policy. Section III explores the relationship between the timing of decisions and the net benefits of a decision to impose an equal access requirement. Section IV provides a brief conclusion.

The PacketCable architecture

PacketCable/sup TM/ defines a multimedia system architecture that overlays a high-speed cable modem access network, with the goal of enabling a wide variety of Internet protocol-based multimedia services, such as voice over IP, unified messaging, PBX extension, videoconferencing, and online gaming. Currently, the architecture provides a complete solution for delivering VoIP services. We present the core capabilities necessary to implement such services in a scalable fashion. Next, we describe the major functional components that comprise the PacketCable architecture and illustrate how they work together to form an integrated IP multimedia-enabled system architecture, which is presently focused on voice over IP. Finally, we present some possible next steps in the evolution of PacketCable.

Cable modem access to picture archiving and communication system images using a web browser over the Internet.

This presentation describes our experiences using a web-based viewing software and a browser to view our picture archiving and communication system (PACS) images at a remote site with cable modem-internet communications. Our testing shows that using a cable modem to access our radiology webserver produces acceptable transmission speeds to remote sites. The average time-to-display (TTD) for 16 computed tomography (CT) images on the web-based intranet system in our hospital was 7 to 8 seconds. Using a cable modem and comparable equipment at a remote site, the average TTD is 16 seconds over the internet. The TTD does not significantly change during various hours of the day. Security for our hospital-based PACS is provided by a firewall. Access through the firewall is accomplished using virtual private network (VPN) software, a secure ID, and encryption. We have found that this is a viable method for after-hours subspecialty radiology consultation.

TCP behavior over HFC cable modem access networks

Hybrid Fiber-Coax based CATV networks have the potential for two-way data services. Such network providers are presently re-inventing the CATV network to provide Internet access. This paper presents a simulation study of the dynamic behavior of TCP over HFC cable modem networks. We believe that this is the first such study as per our knowledge that considers asymmetry and its impact on TCP behavior. The performance of TCP connections with respect to flow control, adaptive retransmission mechanism and slow-start congestion control are studied and analyzed. In particular, we explain the dramatically different behavior and dynamics that are observed for TCP connections using interactive data (remote-login), bulk data (FTP) and Web traffic (HTTP). We further study and discuss the impact of several important TCP and system parameters to optimize performance in CATV networks.