Showing papers on "Broadband networks published in 2008"

An overview of limited feedback in wireless communication systems

Abstract: It is now well known that employing channel adaptive signaling in wireless communication systems can yield large improvements in almost any performance metric. Unfortunately, many kinds of channel adaptive techniques have been deemed impractical in the past because of the problem of obtaining channel knowledge at the transmitter. The transmitter in many systems (such as those using frequency division duplexing) can not leverage techniques such as training to obtain channel state information. Over the last few years, research has repeatedly shown that allowing the receiver to send a small number of information bits about the channel conditions to the transmitter can allow near optimal channel adaptation. These practical systems, which are commonly referred to as limited or finite-rate feedback systems, supply benefits nearly identical to unrealizable perfect transmitter channel knowledge systems when they are judiciously designed. In this tutorial, we provide a broad look at the field of limited feedback wireless communications. We review work in systems using various combinations of single antenna, multiple antenna, narrowband, broadband, single-user, and multiuser technology. We also provide a synopsis of the role of limited feedback in the standardization of next generation wireless systems.

Always Best Connected

Abstract: This chapter contains sections titled: Product Definition for Broadband Wireless Systems Technology Drivers Evolving Wireless Broadband Market Segments Open Systems and Intelligence at the Edge Radio Network System Engineering References

Wireless relays for broadband access [radio communications series]

Abstract: This article presents the outlook of the overall broadband market and operators' challenges in offering profitable mass market mobile data services. The concept of wireless relaying and its state of the art are then introduced, followed by a comprehensive description of a multihop relay system for WiMAX and related use cases. The article explains the impact of relays on network planning and presents an example of deployment cost analysis in different traffic scenarios and propagation conditions. Performance results show that multihop relaying is one of the most promising technologies that enables cost-effective enhancement of coverage, user throughput, and system capacity, and is especially suitable for the emerging markets and rural areas.

Recent Developments in the Standardization of Power Line Communications within the IEEE

Abstract: Broadband connectivity to and within the home has been available to consumers for some time through various technologies. Among those technologies, power line communications is an excellent candidate for providing broadband connectivity as it exploits an already existing infrastructure. This infrastructure is much more pervasive than any other wired alternative (both to and within the home), and it allows virtually every line-powered device to become the target of value- added services. Therefore, PLC may be considered as the technological enabler of a multitude of future applications that probably would not be available otherwise. The most fundamental barrier to the widespread adoption of broadband PLC is the current lack of an international technical standard issued by a credible and globally recognized standards-setting body. Hopefully, this barrier will be eliminated soon through the work of the IEEE P1901 Corporate Standards Working Group. This group, which was created in June 2005, is entering a crucial phase. This article stresses the importance of standardization in the PLC context, gives an overview of the current activities of the IEEE P1901 working group, and also describes some of the technical challenges that the future 1901 standard must address to ensure the success of PLC in the marketplace.

The effects of broadband deployment on output and employment: a cross-sectional analysis of U.S. data

Abstract: While most communications sector analysts concur that the ability to deliver broadband communications is a critical feature of the modern global communications infrastructure, there is limited recent empirical research on the economic effects of broadband. In particular, much of the available research is now several years old or refers to the benefits of the Internet generally or more broadly of the "digital economy" rather than to the broadband telecommunications infrastructure per se.

Wireless Mesh Networks for Public Safety and Crisis Management Applications

Abstract: Wireless mesh networks (WMNs) are multihop wireless networks with self-healing and self-configuring capabilities. These features, plus the ability to provide wireless broadband connectivity at a comparatively low cost, make WMNs a promising technology for a wide range of applications. While discussing the suitability of WMN technology for public safety and crisis management communication, this article highlights its strengths and limitations and points to current and future research in this context.

Real-Time Video Multicast in WiMAX Networks

Abstract: IEEE 802.16e WiMAX is a promising new technology for broadband access networks. Amongst the class of applications that can be supported is real time video services (such as IPTV, broadcast of live events etc.). These applications are bandwidth hungry and have stringent delay constraints. Thus, scalable support for such applications is a challenging problem. To address this challenge, we consider a combination of approaches using multicast, layer encoded video and adaptive modulation of transmissions. Using these, we develop algorithms to ensure efficient, fair and timely delivery of video in WiMAX networks. The corresponding resource allocation problem is challenging because scheduling decisions (within a WiMAX base station) are performed in real-time across two dimensions, time and frequency. Moreover, combining layered video with appropriate modulation calls for novel MAC algorithms. We model the multicast resource allocation problem in WiMAX and demonstrate this problem to be NP-hard. We present a fast greedy algorithm that is (i) provably within a constant approximation of the optimal solution (based on a metric that reflects video quality as perceived by the user), and (ii) performs within 87-95% of the optimal as demonstrated by realistic simulations. We also demonstrate that our algorithm offers a 25% improvement over a naive algorithm. Moreover, in terms of the average rate received by each user, our algorithm out-performs the naive algorithm by more than 50%.

Out-of-band management for broadband over powerline network

Abstract: A management system for broadband over power lines is disclosed, using wireless communications interfaced with broadband over power lines management components to establish a wireless out-of-band system management network.

WiMAX fractional frequency reuse for rural environments

Abstract: WiMAX paves the way for wireless DSL to play a significant role in the broadband wireless access market, especially for rural areas with low population density. Conventional cellular planning methods can be used for point-to-multipoint network design. As an alternative, the Fractional Frequency Reuse (FFR) planning strategy has been recently proposed for cellular systems based on the OFDMA/OFDM radio interface (e.g., WiMAX). In this article we analyze the FFR scheme in rural areas evaluating the increase of the overall system capacity. FFR performances are reported in terms of the average number of bits that can be transmitted per symbol in the area. Finally, comparisons with classical frequency reuse planning are analyzed taking into consideration rural environment characteristics. We show that the FFR scheme can provide extra capacity, slightly penalizing the users at the cell edge.

Access methods to WiMAX femtocells: A downlink system-level case study

Abstract: Over the last two years, GSM and UMTS femtocell access points have been proposed as a solution to the poor indoor coverage problem experienced in certain areas. Research on these devices has shown that femtocells will not only increase indoor system coverage, but also system capacity. Femtocells will allow new services and business models to be offered to indoor users. Almost parallely, the WiMAX standard has emerged as a potential candidate technology for the future wireless networks. WiMAX femtocells are currently under development and will therefore play an important role in the world of indoor broadband wireless access. However, several aspects of this new technology, such as the access method and interference avoidance techniques play a crucial role in the amount of interference caused to co-channel deployed macrocells. This paper provides a framework for the study of WiMAX macro-femtocell hybrid scenarios. An in-depth description of the necessary radio coverage prediction and system-level simulation for this kind of scenarios is introduced. Simulations and numerical results for two different types of access methods (public and private) in the downlink are also presented.

OFCDM: a promising broadband wireless access technique

Abstract: Future mobile communication systems aim to provide extremely high-speed data transmission, especially in the downlink. The broadband orthogonal frequency- and code-division multiplexing system with two-dimensional spreading (time and frequency domain spreading) is becoming a very promising technique for highspeed wireless communications due to its advantages over OFDM. This article presents the basic structure and main functions of the OFCDM system. A nonsequential code assignment scheme is introduced. The novel detection method for the OFCDM, called hybrid multi-code interference cancellation and minimum mean square error detection, is described. The application of advanced techniques to the OFCDM, such as turbo coding and MIMO, is also discussed. It is shown in this article that OFCDM is superior to OFDM.

Downlink Control Channel Design for 3GPP LTE

Abstract: With the emergence of packet-based wireless broadband systems, work has begun on long term evolution (LTE) of the UMTS Terrestrial Radio Access and Radio Access Network aimed for commercial deployment in 2010. Goals for the evolved system include support for improved system capacity and coverage, high peak data rates, low latency, reduced operating costs, multi-antenna support, flexible bandwidth operations and seamless integration with existing systems. To reach these goals, a new design for the air interface including control channel is envisioned. This paper provides a preliminary look at an efficient downlink control channel design to reduce the overhead required to support data transmission. Initial performance results show that close to optimal system performance can be achieved with downlink control overhead of less than 14%.

Handover management in integrated WLAN and mobile WiMAX networks

Abstract: Recently there has been much effort, in both academia and industry, to integrate a plethora of wireless technologies in order to provide ubiquitous broadband access to mobile users. Handover management is still one of the most challenging issues to be solved for seamless integration of wireless networks. This article addresses the integration of IEEE 802.11 WLANs and IEEE 802.16 WMANs, focusing mainly on the handover management aspects. First, we describe architectures, futuristic application scenarios such as the envisioned heterogeneous multihop wireless networks (HMWNs) and moving networks, as well as the related research issues. Second, we present IEEE 802.21, a new emerging standard aimed at providing a framework for media-independent handover(MIH) among heterogeneous networks. Finally, we discuss how the MIH framework can help handover management for the integrated network.

Seamless integration of mobile WiMAX in 3GPP networks

Abstract: As the wireless industry makes its way to the next generation of mobile systems, it is important to engineer solutions that enable seamless integration of emerging 4G access technologies within the currently deployed and/or evolved 2G/3G infrastructures. In this article we address a specific case of such a seamless integration, that of mobile WiMAX in evolved 3GPP networks. In this context we investigate the architecture and the key procedures that enable this integration, and we also introduce a novel handover mechanism that enables seamless mobility between mobile WiMAX and legacy 3GPP access, such as UTRAN or GERAN. The core characteristic of this novel handover mechanism is that mobile terminals do not need to support simultaneous transmission on both WiMAX and 3GPP accesses; therefore, it mitigates the RF coexistence issues that exist otherwise and improves handover performance. In addition, we provide a brief overview of mobile WiMAX and the evolved 3GPP network technologies, and we set the appropriate background material before presenting our proposed handover mechanism. Our main conclusion is that integrating mobile WiMAX in evolved 3GPP networks is a compelling approach for providing wireless broadband services, and mobility across WiMAX and 3GPP access can become seamless and efficient with no need for mobile terminals to support simultaneous transmission on both types of access.

Analytical Modeling of Contention-Based Bandwidth Request Mechanism in IEEE 802.16 Wireless Networks

Abstract: The IEEE 802.16 wireless metropolitan area network (WMAN) standard is a promising and cost-effective, last-mile wireless technology for the provision of broadband Internet access to end users. In this paper, we present an accurate analytical model that describes the contention-based bandwidth (BW) request scheme of the 802.16 standard, which is also known as WiMAX, for the persistent and nonpersistent request generation cases. We first model the contention procedure with a Markov chain, taking into account the exponential back-off procedure as well as the waiting time for a BW assignment and the possible timeout for lost messages. The accuracy of the model is then evaluated by comparing it with simulation results for a wide range of values of the parameters involved. We use this model to accurately calculate the capacity of the contention slots in delivering BW requests, from which the average access delay is also found. These measures are used to determine a proper configuration for the efficient operation of the contention-based BW request scheme. The proposed model provides a useful analytical tool for devising adaptive configuration mechanisms for the contention access mode of the 802.16 medium access control (MAC) layer.

A novel delay-aware routing algorithm (DARA) for a hybrid wireless-optical broadband access network (WOBAN)

Abstract: A hybrid wireless-optical broadband access network (WOBAN) is a promising architecture for future access networks. Recently, the WOBAN has been gaining increasing attention, and early versions are being deployed as municipal access solutions. This architecture saves on network deployment cost because fiber need not penetrate to each end user. However, a major research opportunity exists in developing an efficient routing algorithm for the wireless front-end of the WOBAN. We propose and investigate the characteristics of the delay-aware routing algorithm (DARA) that minimizes the average packet delay in the wireless front-end of a WOBAN. In DARA we model wireless routers as queues and predict wireless link states periodically. Our performance studies show that DARA achieves less delay and congestion, and improved load balancing compared to traditional approaches such as the minimum-hop routing algorithm, shortest-path routing algorithm, and predictive throughput routing algorithm.

Hybrid wireless-optical broadband access network (WOBAN): network planning and setup

Abstract: In a WOBAN, the back end is a wired optical network, the front end is managed by wireless connectivity, and, in between, the tail ends of the optical part [known as optical network unit (ONU)] communicate directly with wireless access points (AP). We study a WOBAN deployment scenario and investigate an algorithm to optimize the placement of multiple ONUs. To obtain some representative data on locations of typical wireless users, we have conducted a survey on the distribution and types of wireless routers in the Wildhorse residential neighborhood of North Davis, CA. We also formulate the multiple-ONU deployment problem using a combinatorial optimizer, viz., simulated annealing. Having found the suitable locations for ONUs, we compare the expenditures of a WOBAN vs. a wired access solution, namely Passive Optical Network (PON). To capture the challenges behind a complete WOBAN setup, we propose and investigate a joint optimization algorithm, which considers design aspects of both the wireless front end, such as avoiding interference among neighboring APs, and the optical back end, such as minimizing expensive fiber layout.

Broadband multi-drop local network, interface and method for multimedia access

Abstract: A broadband multi-drop local network, interface and method for multimedia access. A local network architecture include a wired bus coupleable directly to an external data network terminal and configured for carrying broadband packetized data traffic over a frequency spectrum uninterrupted by other defined data channels or services; and one or a plurality of network transceivers operable individually for coupling an addressable network device processing a defined class of information to the bus wherein each network appliance is configured for and further operable for providing communication interfacing of the class of information of each addressable network appliance with the packetized IP data traffic on the wired bus.

Packet Loss in Real-Time Services: Markovian Models Generating QoE Impairments

Abstract: Real-time Internet services are gaining in popularity due to rapid provisioning of broadband access technologies. Delivery of high quality of experience (QoE) is important for consumer acceptance of multimedia applications. IP packet level errors affect QoE and the resulting quality degradations have to be taken into account in network operation. We derive the second order statistics of the number of packet losses in finite Markov models over several relevant time scales and adapt them to loss processes visible in wired and wireless transmission channels. Higher order Markov chains offer a large set of parameters to be exploited by complex fitting procedures. We experience that the 2-state Gilbert-Elliott model already captures a wide range of observed loss pattern appropriately and discuss how such models can be used to examine the quality degradations caused by packet losses.

Distributed Space-Frequency Coding for Cooperative Diversity in Broadband Wireless Ad Hoc Networks

Abstract: A distributed space-frequency (SF) coded cooperative technique is proposed for broadband wireless ad-hoc networks, where both the channels from the source node to relay nodes and from the relay nodes to the destination node are characterized by frequency-selective fading. Using an SF coding at the source node and a circular shift at each relay node, we propose a scheme that can achieve both cooperative and multi-path diversity. The pairwise error probability is analyzed and the result demonstrates that a diversity gain of min(ML1, ML2) can be achieved, where M is the number of the relay nodes, and L1 and L2 are the number of taps of the multipath fading channels from the source node to the relay nodes and from the relay nodes to the destination node, respectively. Furthermore, the proposed distributed SF coding can achieve full-rate transmission for any number of relay nodes. In particular, it does not need IFFT/FFT processing or decoding at each relay node, thus providing a low-complexity design of the relay nodes in broadband wireless ad-hoc networks.

Programming Content Reconstruction in a Content Delivery System

Abstract: Methods and apparatuses for programming content reconstruction in a content delivery system are described. In one embodiment, a method to repair programming content at a receiver controller includes receiving a programming content on the receiver controller from a broadcast transmission; identifying, if present, a portion of the programming content received on the receiver controller that is corrupted; determining in a broadband network, other servers and receiver controllers connected to the broadband network that have an uncorrupted version of the corrupted portion of the programming content; sending a request to one of the other servers and receiver controllers for the uncorrupted version of the corrupted portion of the programming content; and receiving the uncorrupted version of the corrupted portion of the programming content from the one of the other servers and receiver controllers.. Other embodiments are also described.

A broadband wireless communications system for emergency management

Abstract: Wireless communications have received much attention during the last decades due to easy implementation, the possibility of delivering multimedia services to rural communities, and the suitability for public safety and for communicating in emergency situations. In particular, a wireless network designed for an emergency scenario must be capable of monitoring sensitive areas and must enable people to connect immediately after a disaster. This article discusses the main features of a wireless network that aims to interconnect several heterogeneous systems and provide multimedia access to groups of people to better monitor a specific area, to have a fast response in case of a disaster, and to efficiently coordinate all of the forces during the disaster management phase.

Personalized and mobile digital TV applications

Abstract: The introduction of mobile and broadband networks in complement to the existing satellite, cable, and terrestrial platforms, opens new opportunities for interactive TV (ITV) applications In addition, the widespread adoption of multimedia computing has enabled the processing of TV content on personal devices such as mobile phones and PCs The above developments raise novel issues and require the adoption of new multimedia standards and application frameworks In particular, the explosion in the amount of available TV channels over digital television platforms (broadcast or internet protocol) makes searching and locating interesting content a cumbersome task In this context, personalization research is concerned with the adaptation of content (eg movies, news, advertisements) Personalization is achieved with the employment of algorithms and data collection schemes that predict and recommend to television viewers content that match their interests In addition, the distribution of TV content to mobile devices over broadband wireless raises the issue of video quality Video quality depends on many aspects of the video encoding systems, such as bit rate and algorithms that model human perception of video on small screens In this article, we examine contemporary research in personalized and mobile digital TV applications Moreover, we present a critical survey of the most prominent research and provide directions for further research in personalized and mobile digital TV (DTV) applications

The VC-1 and H.264 Video Compression Standards for Broadband Video Services

Abstract: The MPEG committee standardized the MPEG AVC (H.264) video coding standard in May 2003. The standard has since seen strong interest and adoption from the industry. A competing standard developed by Microsoft, referred to as VC-1, was standardized in SMPTE in April 2006. VC-1 is essentially a standardized version of Microsoft's Windows Media Video (WMV-9). Both H.264 and VC-1 are highly efficient compression standards that enable high-quality video services such as IPTV and Blu-ray Disc. H.264 and VC-1 are both mandated for high definition video services on Blu-ray Disc. These two standards are expected to form the basis for a new generation of high-quality broadband video services. The VC-1 and H.264 Video Compression Standards for Broadband Video Services covers these video coding standards, as well as issues in broadband video delivery. No other book about H.264 or VC-1 covers the standards in such detail. This book interprets the complex standards specifications and makes these new technologies accessible. Both authors have more than 12 years experience working on video compression and communications. The VC-1 and H.264 Video Compression Standards for Broadband Video Services is designed for researchers and a professional audience, including video engineers, and practitioners in consumer electronics, telecommunications and media compression industries. This book is also suitable as a secondary text or reference for advanced-level students in computer science and electrical engineering.

Adaptive Random Network Coding in WiMAX

Abstract: The IEEE 802.16 standard, or WiMAX, has emerged as one of the strongest contenders for broadband wireless access technology. In our previous work, we proposed a protocol using random network coding in WiMAX MAC layer, which has indeed offered important advantages. In this paper, we propose adaptive random network coding in WiMAX by introducing two algorithms in order to further improve the performance. First, we utilize the channel state information feedback to dynamically construct the packets that could be better matched to the fluctuating channel conditions, so as to obtain a higher throughput. Second, we design the algorithm by adapting the number of upstream nodes, which helps to minimize the overhead of sender push of redundant coded blocks to the receiver even after the receiver has completely received the data segment. Coupled with random network coding, both algorithms offer salient performance improvement as evidenced in our simulation evaluation.

Optical wireless communications for broadband access in home area networks

Abstract: As a part of the EU-FP7 R&D programme, the OMEGA project (hOME Gigabit Access) aims at bridging the gap between mobile broadband terminals and the wired backbone network in homes. To provide Gb/s connectivity a combination of various technologies is considered. Beside radio frequencies, the wireless links will use infrared and visible light. Combined with power-line communications this enables a home area network (HAN) that meets the vision of broadband home networking dasiawithout new wirespsila. A technology-independent MAC layer is foreseen to control such network and to provide services as well as connectivity to any device the user wishes to connect. Moreover, this MAC layer should allow the service to follow the user from device to device in any room of a building /apartment. The contribution presents ideas and approaches for broadband optical wireless (OW) communications using infrared Gb/s hotspots and 100 Mb/s information broadcasting by means of interior lighting based on white-light LEDs. Important issues concerning the physical layer are discussed.

A Coarse-Grained Array Accelerator for Software-Defined Radio Baseband Processing

Abstract: A shrinking energy budget for mobile devices and increasingly complex communication standards make architecture development for software-defined radio very challenging Coarse-grained array accelerators are strong candidates for achieving both high performance and low power The C-programmable hybrid CGA-SIMD accelerator presented here targets emerging broadband cellular and wireless LAN standards, achieving up to 100-Mbps throughput with an average power consumption of 220 mW

An optimization framework for balancing throughput and fairness in wireless networks with QoS support

Abstract: Quality-of-service (QoS) provisioning, high system throughput, and fairness assurance are indispensable for heterogeneous traffic in future wireless broadband networks. With limited radio resources, increasing system throughput and maintaining fairness are conflicting performance metrics, leading to a natural tradeoff between these two measures. Balancing system throughput and fairness is desired. In this paper, we consider an interference-limited wireless network, and derive a generic optimization framework to obtain an optimal relationship of system throughput and fairness with QoS support and efficient resource utilization, by introducing the bargaining floor. From the relationship curve, different degrees of performance tradeoff between throughput and fairness can be obtained by choosing different bargaining floors. In addition, our framework facilitates call admission control to effectively guarantee QoS of. multimedia traffic. The solutions of resource allocation obtained from the optimization framework achieve the pareto optimality, demonstrating efficient use of network resources.

Super-Broadband Optical Wireless Access Technologies

Abstract: Network enabling technologies and architectures design for delivering super-broadband wireless services at >1 Gb/s over optical access networks are reviewed. Cost-efficient optical mm-wave generation and transmission technology, optical OFDM, and hierarchical architecture for high-mobility access are discussed.