Showing papers on "Broadband networks published in 2005"

Broadband wireless access with WiMax/802.16: current performance benchmarks and future potential

Abstract: The IEEE 802.16 family of standards and its associated industry consortium, WiMax, promise to deliver high data rates over large areas to a large number of users in the near future. This exciting addition to current broadband options such as DSL, cable, and WiFi promises to rapidly provide broadband access to locations in the world's rural and developing areas where broadband is currently unavailable, as well as competing for urban market share. WiMax's competitiveness in the marketplace largely depends on the actual data rates and ranges that are achieved, but this has been difficult to judge due to the large number of possible options and competing marketing claims. This article first provides a tutorial overview of 802.16. Then, based on extensive recent studies, this article presents the realistic attainable throughput and performance of expected WiMax compatible systems based on the 802.16d standard approved in June 2004 (now named 802.16-2004). We also suggest future enhancements to the standard that could at least quadruple the achievable data rate, while also increasing the robustness and coverage, with only moderate complexity increases

Link performance models for system level simulations of broadband radio access systems

Abstract: This paper gives an overview of some so-called link performance models used in system level simulations to determine the link packet error rate (PER) at reduced complexity. A subset of link performance models is evaluated in terms of PER prediction accuracy focusing on a single receive and transmit antenna OFDM link with different coding options and channel characteristics. The results demonstrate that a mutual-information based metric which accounts for the modulation alphabet is preferable in the considered cases and, furthermore, applicable to the large class of MIMO-OFDM transmission techniques with linear pre- and post-processing

Broadband CDMA techniques

Abstract: A very high-speed wireless access of 100 Mb/s to 1 Gb/s is required for fourth-generation mobile communications systems. However, for such high-speed data transmissions, the channel is severely frequency-selective due to the presence of many interfering paths with different time delays. A promising wireless access technique that can overcome the channel frequency-selectivity and even take advantage of this selectivity to improve the transmission performance is CDMA. There may be two approaches in CDMA technique: direct sequence CDMA and multicarrier CDMA. A lot of attention is paid to MC-CDMA. However, recently it has been revealed that DS-CDMA can achieve good performance comparable to MC-CDMA if proper frequency domain equalization is adopted. This article discusses their similarities and performances. A major transmission mode in 4G systems is packet-based. Automatic repeat request combined with channel coding is a very important technique. Recent research activity on this technique is also introduced.

Utility-based resource allocation and scheduling in OFDM-based wireless broadband networks

Abstract: This article discusses downlink resource allocation and scheduling for OFDM-based broadband wireless networks. We present a cross-layer resource management framework leveraged by utility optimization. It includes utility-based resource management and QoS architecture, resource allocation algorithms, rate-based and delay-based multichannel scheduling that exploits wireless channel and queue information, and theoretical exploration of the fundamental mechanisms in wireless resource management, such as capacity, fairness, and stability. We also provide a solution that can efficiently allocate resources for heterogeneous traffic with diverse QoS requirements.

Energy saving mechanism in the IEEE 802.16e wireless MAN

Abstract: In this paper, we study energy consumption for the IEEE 802.16e broadband wireless access (BWA) network, A mobile subscriber station goes to sleep-mode after negations with the base station and temporarily wake-up periodically for a short interval to check whether there is downlink traffic to it to decide whether it goes to wake-mode or continues to be in the sleep-mode. The sleep interval is increased exponentially upon no arrival traffic. We analytically model the sleep-mode scheme and validate the model with simulations.

A service flow management strategy for IEEE 802.16 broadband wireless access systems in TDD mode

Abstract: A fair and efficient service flow management architecture for IEEE802.16 broadband wireless access (BWA) systems is proposed for TDD mode. Compared with the traditional fixed bandwidth allocation, the proposed architecture adjusts uplink and downlink bandwidth dynamically to achieve higher throughput for unbalanced traffic. A deficit fair priority queue scheduling algorithm is deployed to serve different types of service flows in both uplink and downlink, which provides more fairness to the system. Simulation results show the proposed architecture can meet the QoS requirement in terms of bandwidth and fairness for all types of traffic.

Bandwidth allocation for multiservice access on EPONs

Abstract: Ethernet passive optical networks are a low-cost high-speed solution to the bottleneck problem of the broadband access network. A major characteristic of EPONs is the shared upstream channel among end users, mandating efficient medium access control to facilitate statistical multiplexing and provision multiple services for different types of traffic. This article addresses and provides an overview of the upstream bandwidth allocation issue for multiservice access provisioning over EPONs, and proposes an algorithm for dynamic bandwidth allocation with service differentiation. Based on the multipoint control protocol (MPCP) and bursty traffic prediction, our algorithm enhances QoS metrics such as average frame delay, average queue length, and frame loss probability over other existing protocols

Wavelength-Division-Multiplexed Passive Optical Network (WDM-PON) Technologies for Broadband Access : A Review

Abstract: Feature Issue on Optical Access Networks (OAN) The passive optical network (PON) is an optical fiber based network architecture, which can provide much higher bandwidth in the access network compared to traditional copper-based networks. Incorporating wavelength-division multiplexing (WDM) in a PON allows one to support much higher bandwidth compared to the standard PON, which operates in the

Fast handover scheme for real-time downlink services in IEEE 802.16e BWA system

Abstract: IEEE 802.16 WirelessMAN aiming to broadband wireless access (BWA) is evolving to 4G mobile communication systems through the standardization of IEEE 802.16e supporting mobility on existing fixed WirelessMAN systems. Because IEEE 802.16e system is based on OFDM(A) technology, a mobile subscriber station (MSS) basically conducts hard handover operation when it moves to another base station (BS). Therefore, the MSS is not able to send or receive the data during handover process and these data should be delayed. As a result, real-time packet could be dropped by handover delay. In this paper, we propose an enhanced link-layer handover algorithm that an MSS can receive downlink data before synchronization with uplink during handover process. Our proposed scheme reduces data transmission delay and packet loss probability for real-time downlink service.

Remote configuration and control of local devices via a broadband access gateway

Abstract: A system and method for the remote configuration and control of a access devices via a broadband access gateway is disclosed. The broadband access gateway may comprise a wireless interface and a broadband network connection for exchanging information via, for example, a digital subscriber loop, a cable connection, a T1 connection, and T3 network connection. A user using any of a plurality of access devices may communicate with the broadband access gateway via the wireless interface or the broadband network connection to make remote requests of another of the access devices. Such requests may comprise, for example, accessing, recording, playing, exchanging, transmitting, receiving, converting, translating of multimedia information. The remote requests may include enabling, disabling, configuring, monitoring, administering, and scheduling of smart appliances and premise systems such as, for example, security, heating, and cooling systems.

Towards maximum achievable diversity in space, time, and frequency: performance analysis and code design

Abstract: Multiple input multiple output (MIMO) communication systems with orthogonal frequency division multiplexing (OFDM) modulation have a great potential to play an important role in the design of the next-generation broadband wireless communication systems. In this paper, we address the problem of performance analysis and code design for MIMO-OFDM systems when coding is applied over both spatial, temporal, and frequency domains. First, we provide an analytical framework for the performance analysis of MIMO-OFDM systems assuming arbitrary power delay profiles. Our general framework incorporates the space-time and space-frequency (SF) coding approaches as special cases. We also determine the maximum achievable diversity order, which is found to be the product of the number of transmit and receive antennas, the number of delay paths, and the rank of the temporal correlation matrix. Then, we propose two code design methods that are guaranteed to achieve the maximum diversity order. The first method is a repetition coding approach using full-diversity SF codes, and the second method is a block coding approach that can guarantee both full symbol rate and full diversity. Simulation results are also presented to support the theoretical analysis.

Method and system for providing registration, authentication and access via broadband access gateway

Abstract: A system and method supporting user registration, authentication and access to multimedia services via a broadband access gateway is disclosed. A representative embodiment of the present invention may comprise a wireless interface and may be capable of exchanging multimedia communication between the wireless interface and a broadband network. The gateway may determine access to available media-related services based upon information that is provisioned in a broadband access gateway prior to the first access by a user of an access device. The gateway may automatically allow access to access devices that are pre-registered, and may support opportunistic registration for those users of access devices that have not been pre-registered. Restricted access to services and networks available through the gateway may be provided even when registration is not successful, or when the access device is not pre-registered. Interactive registration for gateway access may be supported, and one-button access using either soft or hard buttons may be provided.

An integrated QoS control architecture for IEEE 802.16 broadband wireless access systems

Abstract: This paper proposes a new integrated QoS architecture for IEEE 802.16 broadband wireless MAN in TDD mode. After analyzing the current strategies to provide IntServ for the Internet connection via IEEE802.16-2004 WirelessMAN, a mapping rule and a fast signaling mechanism for providing both InterServ and DiffServ are given under point to multi-point (PMP) and mesh mode. Comparison and performance analysis of traditional and proposed signaling mechanism are given. The simulation is conducted for VoIP, FTP and HTTP traffic with different QoS requirements. The results show that the proposed integrated QoS control mechanism is more fast and efficient for service setup and maintenance. What is more, bandwidth requirements of different applications can be satisfied by the proposed architecture

Improving the system capacity of broadband services using multiple high-altitude platforms

Abstract: A method of significantly improving the capacity of high-altitude platform (HAP) communications networks operating in the millimeter-wave bands is presented. It is shown how constellations of HAPs can share a common frequency allocation by exploiting the directionality of the user antenna. The system capacity of such constellations is critically affected by the minimum angular separation of the HAPs and the sidelobe level of the user antenna. For typical antenna beamwidths of approximately 5/spl deg/ an inter-HAP spacing of 4 km is sufficient to deliver optimum performance. The aggregate bandwidth efficiency is evaluated, both theoretically using the Shannon equation, and using practical modulation and coding schemes, for multiple HAP configurations delivering either single or multiple cells. For the user antenna beamwidths used, it is shown that capacity increases are commensurate with the increase in the number of platforms, up to 10 HAPs. For increases beyond this the choice of constellation strategy becomes increasingly important.

System and method for content transmission network selection

Abstract: A content transmission selection system is disclosed. The content transmission selection system receives requests from viewers for specific video content items. Using characteristics of the designated content item, the content transmission selection system determines whether to transmit the content item over a broadcast network or a broadband network.

Performance Analysis of the Random Access in IEEE 802.16

Abstract: Recently, the IEEE has standardized the 802.16 protocol for metropolitan broadband wireless access systems. According to the standard, the random access scheme based on the slotted binary exponential backoff algorithm is used in this system for initial ranging and bandwidth requests transmission. This paper provides both the simulation and analytical models for the investigation of the random access in IEEE 802.16. Based on the assumption of finite number of subscriber stations and ideal channel conditions the delay is evaluated for varying number of transmission opportunities and different backoff window sizes

Enhanced wide area network support via a broadband access gateway

Abstract: A wireless broadband access gateway having a wireless interface compatible with any of a number of commercial wireless wide area network standards provides enhanced wire area network coverage via a broadband network. The gateway may function as a wireless wide area network base station having a small coverage area, and may be communicatively coupled via a broadband access provider to a broadband wireless controller that cooperatively coordinates call management for access devices comprising cellular or mobile multimedia handsets. The broadband network may comprise cable, digital subscriber line, satellite, T1, or T3 type networks, and may carry traffic unrelated to the signaling, control, voice, and multimedia information of associated with wide area network calls. The wireless broadband access gateway may comprise a set-to-box, and may operate to convert from air interface protocols used to communicate with mobile handsets of the wireless wide area network, to/from the packet-based protocols that may be used in the broadband network.

Integrating users into the wider broadband network via high altitude platforms

Abstract: An overview of CAPANINA, a project funded by the European Commission's 6th Framework Programme, is presented. The project is developing communications technologies for use with aerial platforms with the aim of integrating users in hard to reach areas and those disadvantaged by geography into the wider broadband network. The article discusses the three broad areas of the project. Specific aspects covered include broadband applications and services selection, along with appropriate integrated delivery configurations to deliver the required capacity and upgradeability; and the associated trials, along with the required wireless and free space optical equipment. Longer-term research underway into delivering broadband backhaul to high-speed trains from aerial platforms, enabling integration with onboard WLAN access points, is also discussed.

Optical wireless communication networks for first- and last-mile broadband access[Invited]

Abstract: "http://www.osa-jon.org/features/OAN_2005.html". Feature Issue on Optical Access Networks (OAN). We review the progress in optical wireless communication networks for first- and last-mile broadband access. The link budget is discussed. Modulation and coding are studied to deal with the atmospheric turbulence channel. Topics related to efficient topology design, survivable routing, and dynamic reconfiguration algorithms are discussed. It is shown that optical wireless communication networks have great potential to provide enough bandwidth for first-mile broadband applications. However, major challenges need to be overcome in pointing and acquisition, coding, and network design to make optical wireless networks more popular with customers.

WCDMA enhanced uplink - principles and basic operation

Abstract: The WCDMA uplink has recently been enhanced with hybrid ARQ, scheduling, and shorter TTI to provide improved performance for packet data services in terms of reduced delays, improved availability of high data rates, and increased capacity. This paper gives an overview of the design targets, the basic principles, and how they are integrated into WCDMA.

0.18 μm 3-6 GHz CMOS broadband LNA for UWB radio

Abstract: A 3–6 GHz CMOS broadband low noise amplifier (LNA) for ultra-wideband (UWB) radio is presented The LNA is fabricated with the 018 µm 1P6M standard CMOS process Measurement of the CMOS LNA is performed using an FR-4 PCB test fixture From 3 to 6 GHz, the broadband LNA exhibits a noise figure of 47–67 dB, a gain of 13–16 dB, and an input/output return loss higher than 12/10 dB, respectively The input P1 dB and input IP3 (IIP3) at 45 GHz are about −14 and −5 dBm, respectively The DC supply is 18 V

Access selection in WCDMA and WLAN multi-access networks

Abstract: This paper proposes and evaluates a set of access selection principles for data services in multi-access wideband code division multiple access (WCDMA) and wireless local area network (WLAN) networks. Access selection principles based on different input parameters are evaluated and compared in terms of their achieved bitrate characteristics. A heterogeneous user behavior with spatial traffic hotspots, covered by WLAN access points, is assumed. Results indicate that in many scenarios the simple access selection principle 'WLAN if coverage' yields satisfactory results. In scenarios with high traffic load concentrated to the hotspots or cellular access technologies offering bitrates in the same order as WLANs, better results may however be achieved with more sophisticated principles taking also traffic load into account.

A high-throughput MAC strategy for next-generation WLANs

Abstract: Today, IEEE 802.11 wireless LAN (WLAN) has emerged as a prevailing technology for broadband wireless networking. Along with many emerging applications and services, the demands for faster and higher-capacity WLANs have been growing fast. We propose a new medium access control (MAC) scheme for the next-generation high-speed WLANs, such as IEEE 802.11n. The proposed MAC, called multiuser polling controlled channel access (MCCA), is composed of two sub-schemes. The first is multiuser polling, in order to achieve higher network utilization. The second is a frame aggregation scheme, which performs aggregations at both MAC and physical (PHY) layers, and can achieve an even higher throughput gain as a result. From simulations, we confirm that the MCCA scheme enhances the aggregate throughput of non-quality-of-service (non-QoS) traffic by an order of magnitude from 17.4 Mbps to 129.9 Mbps, while the aggregate throughput and QoS requirements continue to be satisfied.

Performance of broadband multicarrier DS-CDMA using space-time spreading-assisted transmit diversity

Abstract: In this contribution multicarrier direct-sequence code-division multiple-access (MC DS-CDMA) using space-time spreading (STS)-assisted transmit diversity is investigated in the context of broadband communications over frequency-selective Rayleigh-fading channels. We consider the issue of parameter design for the sake of achieving high-efficiency communications in various dispersive environments. Furthermore, in contrast to conventional MC DS-CDMA schemes employing time (T)-domain spreading only, in this contribution we also investigate broadband MC DS-CDMA schemes employing both T-domain and frequency (F)-domain spreading, i.e., employing TF-domain spreading. The bit-error rate (BER) performance of STS-assisted broadband MC DS-CDMA is investigated for downlink transmissions associated with the correlation based single-user detector and the decorrelating multiuser detector. Our study demonstrated that when appropriately selecting the system parameters, broadband MC DS-CDMA using STS-assisted transmit diversity constitutes a promising downlink transmission scheme. This scheme is capable of supporting ubiquitous communications over diverse communication environments without BER performance degradation.

Obtaining channel knowledge for closed-loop multi-stream broadband MIMO-OFDM communications using direct channel feedback

Abstract: This paper introduces direct channel feedback in broadband multi-stream MIMO-OFDM communications as an efficient means for providing the base station with complete broadband channel information The mobile station first estimates the complete (frequency selective) downlink channel responses between all transmit and receive antenna combinations and then transmits these responses back to the base in the frequency domain in place of the usual data symbols The base station equalizes the received feedback signal and recovers the channel information by using standard channel estimation techniques Using some signal processing tricks, multiple channel responses can be encoded together and sent back in a single feedback message, making the feedback very bandwidth efficient Additional gains in bandwidth efficiency are provided by allowing multiple mobile stations to transmit their feedback on the same time-frequency resource in a spatial division multiple access (SDMA) fashion Simulation results demonstrate that in IEEE 80216 type systems, up to 16 complete broadband channels can be sent in one OFDM symbol period using the direct channel feedback method

Over The Air Programming Via A Broadband Access Gateway

Abstract: A system and method supporting over-the-air programming of access device such as, for example, a mobile multimedia handset and a wireless personal digital assistant (PDA) via a broadband access gateway, is disclosed. The broadband access gateway may receive identifying information from the access device via a personal area network and/or a wireless local area network, and may transfer the identifying information to a wide area network or a third party content provider, via a broadband network. The broadband access gateway may enable the registration of the access device with the wide area network, and may receive firmware/software updates and/or provisioning parameters via the broadband network. The gateway may then transfer the firmware/software update and/or provisioning parameters to the access device via the personal area network and/or wireless local area network.

Fair resource allocation with guaranteed statistical QoS for multimedia traffic in wideband CDMA cellular network

Abstract: A dynamic fair resource allocation scheme is proposed to efficiently support real-time and non-real-time multimedia traffic with guaranteed statistical quality of service (QoS) in the uplink of a wideband code-division multiple access (CDMA) cellular network. The scheme uses the generalized processor sharing (GPS) fair service discipline to allocate uplink channel-resources, taking into account the characteristics of channel fading and intercell interference. In specific, the resource allocated to each traffic flow is proportional to an assigned weighting factor. For real-time traffic, the assigned weighting factor is a constant in order to guarantee the traffic statistical delay bound requirement; for non-real-time traffic, the assigned weighting factor can be adjusted dynamically according to fading, channel states and the traffic statistical fairness bound requirement. Compared with the conventional static-weight scheme, the proposed dynamic-weight scheme achieves capacity gain. A flexible trade-off between the GPS fairness and efficient resource utilization can also be achieved. Analysis and simulation results demonstrate that the proposed scheme enhances radio resource utilization and guarantees statistical QoS under different fairness bound requirements.

Interference characteristics of broadband power line communication systems using aerial medium voltage wires

Abstract: The promise of broadband power line (BPL) communications - broadband access to virtually every home in the United States - remains unfulfilled if the radio emissions from these systems cause significant harmful interference to other users of the wireless spectrum. This article presents an elementary analysis of the physical mechanisms underlying these emissions, from which the interference characteristics of BPL systems can be derived. Numerical models are evaluated for idealized systems using overhead medium-voltage wires, a configuration that is of particular interest for U.S. deployments. The central conclusions of the analysis are: (i) BPL interference is governed primarily by two parameters: signal power and electrical balance of system excitation; (ii) interfering emissions are typically confined to the immediate vicinity of the BPL wire, but long-range effects cannot be neglected; and (iii) measurements on an installed BPL system suggest that it is operating within, but very close to, the limits set by rules recently adopted by the Federal Communications Commission.

Objective and subjective evaluation of QOAS video streaming over broadband networks

Abstract: This article presents objective and subjective testing results that assess the performance of the Quality-Oriented Adaptation Scheme (QOAS) when used for high quality multimedia streaming over local broadband IP networks. Results of objective tests using a QOAS simulation model show very efficient adaptation in terms of end-user perceived quality, loss rate, and bandwidth utilization, compared to existing adaptive streaming schemes such as LDA+, and TFRCP. Subjective tests confirm these results by showing high end-user perceived quality of the QOAS under various network conditions.