Showing papers on "Broadband networks published in 2003"

Optimal routing, link scheduling and power control in multihop wireless networks

Abstract: In this paper, we study the problem of joint routing, link scheduling and power control to support high data rates for broadband wireless multihop networks. We first address the problem of finding an optimal link scheduling and power control policy that minimizes the total average transmission power in the wireless multihop network, subject to given constraints regarding the minimum average data rate per link, as well as peak transmission power constraints per node. Multiaccess signal interference is explicitly modeled. We use a duality approach whereby, as a byproduct of finding the optimal policy, we find the sensitivity of the minimal total average power with respect to the average data rate for each link. Since the minimal total average power is a convex function of the required minimum average data rates, shortest path algorithms with the link weights set to the link sensitivities can be used to guide the search for a globally optimum routing. We present a few simple examples that show our algorithm can find policies that support data rates that are not possible with conventional approaches. Moreover, we find that optimum allocations do not necessarily route traffic over minimum energy paths.

Dynamic bandwidth allocation for quality-of-service over Ethernet PONs

Abstract: Ethernet-based passive optical network (EPON) technology is being considered as a promising solution for next-generation broadband access networks due to the convergence of low-cost Ethernet equipment and low-cost fiber infrastructures. A major feature for this new architecture is the use of a shared transmission media between all users; hence, medium access control arbitration mechanisms are essential for the successful implementation of EPON: i.e., to ensure a contention-free transmission and provide end users with equal access to the shared media. We propose to use the multipoint control protocol defined by the IEEE 802.3ah task force to arbitrate the transmission of different users, and we present different dynamic bandwidth allocation (DBA) algorithms to allocate bandwidths effectively and fairly between end users. These DBA algorithms are also augmented to support differentiated services, a crucial requirement for a converged broadband access network with heterogeneous traffic. We show that queueing delays under strict bandwidth allocation algorithms result in an unexpected behavior for certain traffic classes, and we suggest the use of DBA with appropriate local queue management to alleviate this inappropriate behavior. We conduct detailed simulation experiments to study the performance and validate the effectiveness of the proposed protocols.

Broadband communications access device

Abstract: A integrated phone-based home gateway system is disclosed. The integrated phone-based home gateway system includes a broadband communication device, such as digital subscriber line (“DSL”) device, an analog modem, a wireless interface, integrated into a screen-phone for providing broadband communication service to home users. Multiple home users are able to access the Internet and the content services for conducting e-commerce, receiving content news, entertaining on-demand, making audio or video communications, and telecommuting or working at home. This screen-phone based, modular, plug-n-play home gateway interface allows in-home as well as to-home networking, provides automatic data and broadband initialization, configuration and service provisioning, routing and bridging functionality and allows resource sharing among home devices via the existing phone wire, wireless, coaxial or optical cable connections.

Network Neutrality, Broadband Discrimination

Abstract: This paper examines the the concept of network neutrality in telecommunications policy and its relationship to Darwinian theories of innovation. It also considers the record of broadband discrimination practiced by broadband operators in the early 2000s.

QoS aware adaptive resource allocation techniques for fair scheduling in OFDMA based broadband wireless access systems

Abstract: A system based on orthogonal frequency division multiple access (OFDMA) has been developed to deliver mobile broadband data service at data rates comparable to those of wired services, such as DSL and cable modems. We consider the resource allocation problem of assigning a set of subcarriers and determining the number of bits to be transmitted for each subcarrier in OFDMA systems. We compare simplicity, fairness and efficiency of our algorithm with the optimal and proposed suboptimal algorithms for varying values of delay spread, number of users and total power constraint. The results show that the performance of our approach is appealing and can be close to optimal. We also consider another resource allocation scheme in which there is no fixed QoS requirements per symbol but capacity is maximized.

Flexible optical wireless links and networks

Abstract: The worldwide demand for broadband communications is being met in many places by installed single-mode fiber networks. However, there is still a significant "first-mile" problem, which seriously limits the availability of broadband Internet access. Free-space optical wireless communications has emerged as a viable technology for bridging gaps in existing high-data-rate communications networks, and as a temporary backbone for rapidly deployable mobile wireless communication infrastructure. In this article we describe research designed to improve the performance of such networks along terrestrial paths, including the effects of atmospheric turbulence, obscuration, transmitter and receiver design, and topology control.

Multicarrier DS-CDMA: a multiple access scheme for ubiquitous broadband wireless communications

Abstract: We identify some of the key problems that may be encountered when designing a broadband multiple access system with bandwidth on the order of tens or even hundreds of megahertz. We commence with a comparative discussion in terms of the characteristics of three typical code-division multiple access schemes: single-carrier direct-sequence CDMA (SC DS-CDMA), multicarrier CDMA (MC-CDMA), and multicarrier DS-CDMA (MC DS-CDMA). Specifically, their benefits and deficiencies are analyzed when aiming to support ubiquitous communications over a variety of channels encountered in indoor, open rural, suburban, and urban environments. It is shown that when communicating in such diverse environments, both SC DS-CDMA and MC-CDMA exhibit certain limitations that are hard to circumvent. By contrast, when appropriately selecting the system parameters and using transmit diversity, MC DS-CDMA becomes capable of adapting to such diverse propagation environments at a reasonable detection complexity.

Optical switching technology comparison: optical MEMS vs. other technologies

Abstract: Optical switching technologies are very crucial to future mobile broadband all-optical IP networks. Many different optical switching technologies are currently available or under development. The main purpose of the article is to conduct performance comparisons on optical switching technologies in terms of basic performance, network requirements, and system requirements based on a literature survey. The technologies include switching based on optical microelectromechanical systems (MEMS), thermal optical switching, electro-optic switching, and acousto-optic switching technologies. Each optical switching technology has unique performance characteristics specific to the utilized optical phenomena. It might be crucial to integrate some technologies together to achieve a better solution for optical switching. Optical switching is a very hot topic attracting much research effort. Optical MEMS-based switching technology might be one of the most promising approaches at present. Many new optical switching technologies might be created in the near future. Through the impact of nanotechnology, some innovative approaches to optical switching might emerge.

Introduction to ultra-wideband antennas

Abstract: This paper presents an introduction to ultra-wideband (UWB) antennas, including a summary of key UWB antenna concepts, as well as system and network considerations, and fundamental limits for UWB antennas.

IEEE 802.16 based last mile broadband wireless military networks with quality of service support

Abstract: Future Department of defense warfighting concepts leverage information superiority and will require vast improvements in information transfer in terms of higher bandwidth, Quality of Service (QoS) support and connection to a high speed backbone. The new IEEE 802.16 broadband wireless access system is a viable alternative that can meet such requirements. In addition, this network can be swiftly deployed to interconnect the military theater, emergency response, and disaster relief operations to the backbone. Due to the diverse multimedia traffic with different priorities and QoS requirements, it is a well know fact that it is imperative to provide QoS support in military networks. However, the IEEE 802.16 provides only signaling mechanisms, but does not specify any scheduling or admission control algorithms that ultimately provide QoS support. In this paper we introduce a new scheduling algorithm for IEEE 802.16 broadband wireless access standard. The proposed solution which is practical and compatible to the IEEE 802.16 standard, provides QoS support to different traffic classes. To the best of our knowledge this is the first such algorithm. The simulation studies show that the proposed solution includes QoS support for all types of traffic classes as defined by the standard. We have shown the relationship between traffic characteristics and its QoS requirements and the network performance. This study will help network architects to decide the system parameters as well as the kind of traffic characteristics for which the network can provide QoS support.

Capacity of MIMO systems with closely spaced antennas

Abstract: Wide-band radio channel measurements at 5.2 GHz with four transmit and four receive antennas at variable element spacing are reported, aiming to evaluate the potential of compact antenna arrays at mobile terminals. We show that, for an element spacing d<0.5/spl middot//spl lambda/ (down to 0.2/spl middot//spl lambda/), the link capacity is not smaller than that for much larger d. This is explained by the observation that mutual coupling changes the radiation patterns of closely spaced antenna elements, individually. Compact multi-antenna terminals may thus become practical.

On frequency-domain equalization and diversity combining for broadband wireless communications

Abstract: This paper is concerned with the use of frequency-domain equalization (FDE) and space diversity within block transmission schemes for broadband wireless communications. The expected performance with both multicarrier (MC) and single-carrier (SC) modulations is emphasized, when a cyclic prefix, long enough to cope with the maximum relative channel delay, is appended to each transmitted block. A set of numerical results is presented and discussed, with the help of appropriate, analytical performance bounds which are conditional on a given channel realization. These bounds are used to explain the performance advantage of the SC/FDE option, the benefits of space diversity, and the impact of the criterion for computing the FDE parameters.

Hotspot wireless LANs to enhance the performance of 3G and beyond cellular networks

Abstract: At present, WLANs supporting broadband multimedia communications are being developed and deployed around the world Standards include HIPERLAN/2 defined by ETSI BRAN and the 80211 family defined by the IEEE These systems provide channel adaptive data rates up to 54 Mb/s (in a 20 MHz channel spacing) over short ranges up to 200 m The HIPERLAN/2 standard also specifies a flexible radio access network that can be used with a variety of core networks, including UMTS It is likely that WLANs will become an important complementary technology to 3G cellular systems and will typically be used to provide hotspot coverage In this article the complementary use of WLANs in conjunction with UMTS is presented In order to quantify the capacity enhancement and benefits of cellular/hotspot interworking we have combined novel ray tracing, software-simulated physical layer performance results, and optimal base station deployment analysis The study focuses on an example deployment using key lamppost mounted WLAN access points to increase the performance (in terms of capacity) of a cellular network

Broadband PLC access systems and field deployment in European power line networks

Abstract: Data communications over low voltage power distribution networks provide an alternative and cost-effective last mile access technology. It offers data and voice services to users in residential and business areas. Currently, many field trials with different broadband power line communications systems are running worldwide. This article describes one of these systems for the last mile application in European power line networks. It addresses major field deployment aspects, such as range, coverage, coupling, and intercell interference.

The market structure of broadband telecommunications

Abstract: The recent growth of the Internet is creating markets for broadband telecommunications networks. In the past, virtually all such ‘infrastructure’ networks have been subject to government regulation. Two reasons advanced for this market intervention are (i) such networks constitute a natural monopoly, and (ii) to achieve ‘universal service’, in which all citizens have access to services. In this paper, we develop a model and estimate it using engineering data which tests if these two hypotheses are likely to obtain for broadband networks. We find that oligopolistic competition is likely to emerge for demand levels approaching that of today’s cable television.

Broadband and mobile opportunities: A socio-technical perspective

Abstract: The growth of broadband connectivity expands what can and might be transmitted across the World Wide Web and Internet. Coupled with the increasing levels of mobile Internet connectivity, broadband may allow for a new round of changed patterns in the ways computers are used. Direct effects models of the deployment, use, value and futures of broadband connectivity are unlikely to cope with the social and technological complexity of broadband. A socio-technical theoretical perspective, with its emphasis on the complex relations among social and technical aspects of a phenomenon, can provide useful insight into the potential societal impact, institutional effects and changes to individual work and life behaviours that may arise from the increasing level of bandwidth available. This paper provides a brief overview of broadband and mobile technologies from a socio-technical perspective, organizes and surveys relevant literature and focuses on emerging issues with broadband connectivity where research will help shape policy, strategy and the use of broadband networks.

Systems and methods for broadband network optimization

Abstract: Disclosed are systems and methods for maximizing transmission throughput or capacity in a heterogeneous communications network. The systems and methods may include any one, or combinations, of: a route tracing module for identifying an optimization endpoint or destination; a testing module for sending representative test data to the endpoint/destination and measuring the data throughput/capacity for a given set of transmission variable values; and an optimization module for analyzing the set of transmission variable values and the associated data throughput/capacity, and determining an optimized set of transmission variables/values. Thus, the optimization module changes the transmission variable values of an associated network device operating within the heterogeneous communications network to achieve maximum data throughput/capacity.

Accelerated large data distribution in overlay networks

Abstract: A Method and apparatus for dynamically discovering and utilizing unused resources for practical and efficient creation of optimized network mechanisms for data distribution. Proposed techniques for data distribution, assembly, routing and scheduling in broadband networks can be implemented as content-level server platform architecture enabled by application-level control plane. Such a platform accelerates content transfer, mirroring and replication. It applies coordinated data partitioning and resource discovery and sharing of information replication by multiple network systems. Furthermore, it harvests the unutilized bandwidth in the network by disassembling the large content to be distributed into different components. These components are then routed in spatially and temporally diverse routes through multiple paths and trees and assembled at the destination nodes. The result is accelerated content distribution, added security, scalability and robustness. No modifications of existing network communication protocols is required.

Policy-based QoS-management architecture in an integrated UMTS and WLAN environment

Abstract: Strong demands for public wireless broadband services will require more capacity than even that can be,supplied by advanced mobile cellular systems like the Universal Mobile Telecommunication System. The increasing popularity of WLANs has prompted mobile network operators to consider their deployment in high-density usage areas like indoor/outdoor public hotspots to provide complementary broadband access to their UMTS networks. In order to provide consistent QoS control over an integrated UMTS and WLAN system, a policy-based multidomain QoS management architecture is proposed in this article. Different UMTS-WLAN interworking scenarios are discussed to illustrate the feasibility of the proposed architecture.

Goals of true broad band's wireless next wave (4G-5G)

Abstract: As access technology increases, voice, video, multimedia, and broadband data services are becoming integrated into the same network. Fourth Generation (4G) is the next generation of wireless networks that will replace third Generation (3G) networks sometimes in future. 4G is intended to provide high speed, high capacity, low cost per bit, IP based services.4G is all about an integrated, global network that's based on an open system approach. The goal of 4G is to replace the current proliferation of core cellular networks with a single worldwide cellular core network standard based on IP for control, video, packet data and VoIP. But while 3G haven't quite arrived, researchers want to contribute their ideas to the development of an as-yet undefined "wireless world" that could become operational by around 2010. This paper deals with the fundamentals and issues of networks, technologies, spectrum, standards, terminals, services of 4G and about the visions that the network operators and service providers see for the evolution of 4G mobile systems and where future research is necessary from their perspective.

An UWB relative location system

Abstract: This paper describes an UWB location system that employs relative location principles to provide enhanced location performance in wireless networks. The system takes advantage of peer-to-peer range measurements between the devices and their neighbors. The collective range information is used to jointly estimate the location of the devices in the network providing enhanced performance.

Dynamic resource allocation with finite buffer constraint in broadband OFDMA networks

Abstract: This paper presents a dynamic resource allocation scheme for OFDMA-based wireless broadband networks. The problem of maximizing the total packet throughput subject to individual user's outage probability constraint is formulated. The proposed algorithm assumes a finite buffer for the arrival packets and dynamically allocates the radio resource based on users' channel characteristics, traffic patterns and QoS requirements. By performing the radio resource allocation into two steps, namely bandwidth allocation and channel assignment, efficient admission control is realized with low complexity. Specifically, the number of channels to be assigned to each user is first determined based on its traffic requirement and the average SNR. The second stage of the algorithm finds the best channel allocation for the users. Simulations show that the algorithm yields significant lower outage probability and higher throughput than existing multiple access methods.

Economics of fixed broadband access network strategies

Abstract: This article presents a comprehensive techno-economic evaluation of two upgrade strategy cases for broadband IP services for residential and business customers, and illustrates their respective merits and pitfalls, allowing the definition of a reasonable investment policy. The work should enable establishment of guidelines for broadband infrastructure upgrade strategies from the incumbent operator's view. Following the definition of appropriate service sets, and taking into account demand scenarios established within the project, this work has been focused on developing a techno-economic model, based on the TONIC tool. Tariff structures have been applied to compute the key economic indicators, net present value, internal rate of return, and payback period. This investment analysis was carried using the tool, which was developed by IST-TONIC. The results show that the choice of technology (Ethernet or ATM) has almost no effect on the cost level and profitability of the cases. For the suburban area, a fiber to the cabinet solution is too expensive due to heavy infrastructure investments; for dense urban and urban areas the FTTC solution is worth the investments. The FTTH/office deployment scenario is only profitable in dense urban areas (>5000 potential customers/km/sup 2/) and already highly risky in the urban area.

DS-CDMA: the modulation technology of choice for UWB communications

Abstract: We show that because of drastic differences in the fading statistics between ultra wide bandwidth (UWB) multicarrier and direct sequence code division multiple access (DS-CDMA) approaches, DS easily scales to Gbps rates while multicarrier architectures have severe difficulty. Both DS-CDMA and orthogonal frequency division multiple access (OFDM) are well understood and proven modulation techniques in conventional (narrowband) commercial technologies (e.g. DS-CDMA in cell phones; OFDM in IEEE 802.11a/g). The maturity of these approaches, however, is vastly different when applied to ultrawideband (UWB) systems. Already implemented and operating in silicon, DS-CDMA architectures have proven to be the most mature and scaleable for UWB on both a theoretical as well as implementation basis. Among the proposed approaches before the IEEE 802.15.3a standards committee, the DS-CDMA transmitted waveform (which is the "thing" being standardized) is uniquely capable of serving the broadest diversity of applications. It can, for example, allow very low-cost low-power transmit-only devices (even at Gbps rates) because it requires no FFT or DAC or DSP. At the same time, receivers can incorporate varying degrees of DSP to provide scaleable power/cost versus performance. We present performance comparisons of DS-CDMA [Document IEEE.15-03/153r10, July 2003] vs. the proposed multiband MB-OFDM architecture [Document IEEE 802.15-03/267r0, July 2003] for outage range in a variety of multipath environments. Moreover, we describe how DS-CDMA UWB architectures can support robust and flexible multiuser capabilities, protect against in-band interference, and provide high-resolution ranging capabilities for safety-of-life applications.

High-availability free space optical and RF hybrid wireless networks

Abstract: We introduce hybrid free-space optical and RF wireless links as potential technology for designing next-generation broadband wireless networks. We present various design challenges and potential solutions for real-time link performance characterization and adaptation for enhanced performance during adverse weather conditions. First, we introduce the hybrid wireless architecture and emphasize its significant role in achieving ubiquitous carrier-grade wireless connectivity. Second, we propose a link monitoring scheme that accurately reflects the performance of optical wireless links under various weather conditions. In addition, we examine the role of known link performance restoration schemes - power and data rate control. Third, we propose two novel link restoration schemes that efficiently utilize the hybrid architecture: dynamic load switching and multihop routing. Finally, the article describes an elaborate field testbed based on the hybrid architecture and various link restoration techniques. The dynamic load switching scheme is shown to have a profound impact on the overall hybrid link availability. The results, recorded from the experiments during extreme weather conditions, validate the impact of the hybrid architecture concept and conclusively prove the availability and reliability of the architecture in achieving sustained highspeed wireless connectivity.

The Empirical Case Against Asymmetric Regulation of Broadband Internet Access

Abstract: The United States has asymmetric regulation of the provision of broadband Internet access service. A cable television system operator is not regulated in its sale of cable modem service. In contrast, an incumbent local exchange carrier (ILEC) that offers digital subscriber line (DSL) service faces price regulation as well as the obligation to offer competitors the use of its broadband network on a wholesale (or, unbundled) basis so that they may offer, in the retail market, DSL services that compete with the ILEC's own retail offering to consumers. The social costs of asymmetric regulation are by now familiar. Such regulation leads not to deregulation, but to an enduring managed competition far more complex to administer than traditional regulation of a monopoly service provider ever was. The alternative to asymmetric regulation is either symmetric regulation or symmetric freedom from regulation. Assuming that the latter alternative is preferred, what actual steps would be taken to abolish asymmetric regulation of ILEC provision of broadband Internet access? The Federal Communications Commission (FCC) could remove asymmetric regulation that the agency itself previously imposed. The FCC could declare that broadband Internet access service is not a telecommunications service, subject to numerous regulations applicable to ILECs, but rather an information service, which is free of such regulations. Amid considerable controversy, the FCC invited public comment on such a reclassification in February 2002. Or the FCC could use its power under section 10 of the Communications Act to forbear from regulating ILEC provision of broadband Internet access. A third, and more incremental, approach would be for the FCC to declare ILECs nondominant in the provision of advanced services, such as broadband Internet access. Non-dominant carriers are exempt from price-cap or rate-of-return regulation, as well as the obligation to file tariffs and to establish the reasonableness of those tariffs through the submission of cost data. Much, if not all, of the economic analysis required to determine whether a carrier is nondominant also would be relevant to the FCC's decision whether to forbear from regulating a particular service or whether to reclassify the service in question as unregulated. Although the FCC did not receive its authority under section 10 to forbear from regulation until 1996, the agency has evaluated petitions for nondominance for a longer time and consequently has distilled a body of law on the subject. In this Article, we evaluate the case against asymmetric regulation of broadband Internet access through the lens of the FCC's approach to deciding petitions for non-dominance. We examine the economic evidence relevant to whether ILECs are non-dominant in the provision of mass-market broadband services, the most familiar of which is DSL service. We use a nested-logit discrete-choice model to produce econometric estimates of the own-price elasticity of demand for DSL service and the cross-price elasticity of demand for cable modem service with respect to DSL service. Our findings suggest that demand for DSL service is price-elastic, that DSL and cable modems are in the same product market, and that DSL providers lack market power. The FCC would advance the public interest by ruling that the ILECs are non-dominant in the mass-market broadband services market.

Bandwidth- and power-efficient multi-carrier multiple access

Abstract: Orthogonal frequency division multiple access (OFDMA) gains increasing attention for broadband, high data rate wireless/wireline communications. In this paper, we propose a novel unitary precoded (UP) OFDMA scheme for uplink applications, which increases the system bandwidth efficiency, while preserving constant modulus transmissions. Theoretical analysis for the proposed UP-OFDMA with channel coding quantifies the performance improvement introduced by unitary precoding. It provides guidelines for practical system designs, and reveals performance gap between the proposed system and the single user bound. Simulation results confirm that the proposed system improves performance considerably relative to conventional OFDMA.

Mobile airborne high-speed broadband communications systems and methods

Abstract: Improved high-speed, broadband data communication between a mobile terminal, including aircraft in flight, and secure, private remote networks, can be implemented by using the bandwidth of a single transponder on a satellite. The improved high-speed data communications system uses a single frequency to transmit the broadband data from the mobile terminal to the satellite and the same frequency to transmit the broadband data from the remote network to the satellite. Likewise, the improved high-speed data communications system uses a corresponding frequency on the same satellite transponder to transmit the high-speed, broadband data from the satellite to the mobile terminal and to transmit the high-speed, broadband data from the satellite to the remote network.

Bandwidth- and power-efficient multicarrier multiple access

Abstract: Orthogonal frequency-division multiple access (OFDMA) gains increasing attention for broadband, high data rate wireless communications. We develop a novel unitary precoded (UP) OFDMA scheme that is particularly appealing for the uplink, because it offers high bandwidth efficiency, and constant modulus transmissions for each user. Theoretical analysis of UP-OFDMA with channel coding shows the performance improvement introduced by unitary precoding. It provides useful guidelines for practical system designs, and also quantifies the performance of UP-OFDMA relative to the single-user bound. Simulations confirm that UP-OFDMA improves performance considerably relative to conventional OFDMA.

Comparison of CDMA and OFDM techniques for downstream power-line communications on low voltage grid

Abstract: This paper provides a fair comparison between direct sequence code division multiple access (DS-CDMA) and orthogonal frequency division multiplexing (OFDM) systems for broadband downstream power-line communications (PLCs). The considered schemes seem particularly suitable for high bit rate broadcast flexible communications on low voltage grid in order to guarantee local access. The performance of the considered systems is expressed in terms of bit error rate (BER), derived by simulations under the assumptions of frequency-selective multipath fading channel and additive colored Gaussian noise according to the in-building networks model, under the same overall working conditions of bandwidth occupation, transmitted power, and global data rate.