Showing papers on "Broadband networks published in 2009"

The future of WiMAX: Multihop relaying with IEEE 802.16j

Abstract: Relaying and cooperation have re-emerged as important research topics in wireless communication over the past half-decade. Although multihop relaying for coverage extension in wireless networks is an old concept, it became practical only recently. Nowhere is this better illustrated than in the IEEE 802.16 working group, which has devoted a task group to incorporating relay capabilities in the foundation of mobile WiMAX-IEEE 802.16e-2005. Currently, this task group is in the process of finishing IEEE 802.16j, the multihop relay specification for 802.16. This amendment will be fully compatible with 802.16e-2005 mobile and subscriber stations, but a BS specific to 802.16j will be required for relays to operate. This article presents an introduction to the upcoming IEEE 802.16j amendment and provides insight about the obstacles that practical system designers face when incorporating relaying into a wireless broadband network.

Joint scheduling and resource allocation in uplink OFDM systems for broadband wireless access networks

Abstract: Orthogonal frequency division multiplexing (OFDM) with dynamic scheduling and resource allocation is a key component of most emerging broadband wireless access networks such as WiMAX and LTE (long term evolution) for 3GPP. However, scheduling and resource allocation in an OFDM system is complicated, especially in the uplink due to two reasons: (i) the discrete nature of subchannel assignments, and (ii) the heterogeneity of the users' subchannel conditions, individual resource constraints and application requirements. We approach this problem using a gradient-based scheduling framework. Physical layer resources (bandwidth and power) are allocated to maximize the projection onto the gradient of a total system utility function which models application-layer Quality of Service (QoS). This is formulated as a convex optimization problem and solved using a dual decomposition approach. This optimal solution has prohibitively high computational complexity but reveals guiding principles that we use to generate lower complexity sub-optimal algorithms. We analyze the complexity and compare the performance of these algorithms via extensive simulations.

Spectrum sharing between cellular and mobile ad hoc networks: transmission-capacity trade-off

Abstract: Spectrum sharing between wireless networks improves the efficiency of spectrum usage, and thereby alleviates spectrum scarcity due to growing demands for wireless broadband access. To improve the usual underutilization of the cellular uplink spectrum, this paper addresses spectrum sharing between a cellular uplink and a mobile ad hoc networks. These networks access either all frequency subchannels or their disjoint subsets, called spectrum underlay and spectrum overlay, respectively. Given these spectrum sharing methods, the capacity trade-off between the coexisting networks is analyzed based on the transmission capacity of a network with Poisson distributed transmitters. This metric is defined as the maximum density of transmitters subject to an outage constraint for a given signal-to-interference ratio (SIR). Using tools from stochastic geometry, the transmission-capacity trade-off between the coexisting networks is analyzed, where both spectrum overlay and underlay as well as successive interference cancellation (SIC) are considered. In particular, for small target outage probability, the transmission capacities of the coexisting networks are proved to satisfy a linear equation, whose coefficients depend on the spectrum sharing method and whether SIC is applied. This linear equation shows that spectrum overlay is more efficient than spectrum underlay. Furthermore, this result also provides insight into the effects of network parameters on transmission capacities, including link diversity gains, transmission distances, and the base station density. In particular, SIC is shown to increase the transmission capacities of both coexisting networks by a linear factor, which depends on the interference-power threshold for qualifying canceled interferers.

Key Technologies of WDM-PON for Future Converged Optical Broadband Access Networks [Invited]

Abstract: The wavelength-division-multiplexed passive optical network (WDM-PON) is considered to be the next evolutionary solution for a simplified and future-proofed access system that can accommodate exponential traffic growth and bandwidth-hungry new applications. WDM-PON mitigates the complicated time-sharing and power budget issues in time-division-multiplexed PON (TDM-PON) by providing virtual point-to-point optical connectivity to multiple end users through a dedicated pair of wavelengths. There are a few hurdles to overcome before WDM-PON sees widespread deployment. Several key enabling technologies for converged WDM-PON systems are demonstrated, including the techniques for longer reach, higher data rate, and higher spectral efficiency. The cost-efficient architectures are designed for single-source systems and resilient protection for traffic restoration. We also develop the integrated schemes with radio-over-fiber (RoF)-based optical-wireless access systems to serve both fixed and mobile users in the converged optical platform.

Hybrid wireless-broadband over power lines: A promising broadband solution in rural areas

Abstract: In rural areas, due to the low population density and the poor familiarization with new technologies, new projects related to broadband access are less profitable. In this article a hybrid wireless-broadband over power lines network, suitable for rural and remote areas is presented, offering smart grid applications and broadband access along a 107 km medium voltage power grid in Larissa, a rural area in central Greece. This hybrid solution exploits the ubiquitous presence of the power grid along with the adaptability and accessibility of wireless technology. Through the design and implementation of this hybrid network many aspects of BPL technology were successfully dealt with demonstrating that, in addition to enhancing the power grid performance, W-BPL technology may be considered as an alternative broadband solution in rural and/or sparsely populated areas.

EARTH — Energy Aware Radio and Network Technologies

Abstract: EARTH is a major new European research project starting in 2010 with 15 partners from 10 countries. Its main technical objective is to achieve a reduction of the overall energy consumption of mobile broadband networks by 50%. In contrast to previous efforts, EARTH regards both network aspects and individual radio components from a holistic point of view. Considering that the signal strength strongly decreases with the distance to the base station, small cells are more energy efficient than large cells. EARTH will develop corresponding deployment strategies as well as management algorithms and protocols on the network level. On the component level, the project focuses on base station optimizations as power amplifiers consume the most energy in the system. A power efficient transceiver will be developed that adapts to changing traffic load for an energy efficient operation in mobile radio systems. With these results EARTH will reduce energy costs and carbon dioxide emissions and will thus enable a sustainable increase of mobile data rates.

The next challenge for cellular networks: backhaul

Abstract: Growth in the number of mobile users, coupled with the strong uptake of wireless broadband services, is driving high transport capacity requirements among cellular networks. However, revenues are not scaling linearly with increases in traffic. Demand for optimizing the cost efficiency of backhaul is becoming as critical as investment in the radio infrastructure. As a result, new transmission technologies, topologies, and network architectures are emerging in an attempt to ease the backhaul cost and capacity crunch.

An overview of next-generation mobile WiMAX technology

Abstract: The growing demand for mobile Internet and wireless multimedia applications has motivated the development of broadband wireless access technologies in recent years. Mobile WiMAX has enabled convergence of mobile and fixed broadband networks through a common wide-area radio-access technology and flexible network architecture. Since January 2007, the IEEE 802.16 working group has been developing a new amendment of the IEEE 802.16 standard (i.e., IEEE 802.16m) as an advanced air interface to meet the requirements of ITU-R/IMT-advanced for 4G systems, as well as for the next-generation mobile network operators. Depending on the available bandwidth and multi-antenna mode, the next-generation mobile WiMAX will be capable of over-the-air data-transfer rates in excess of 1 Gb/s and of supporting a wide range of high-quality and high-capacity IP-based services and applications while maintaining full backward compatibility with the existing mobile WiMAX systems to preserve investments and continuing to support first-generation products. This tutorial describes the prominent technical features of IEEE 802.16m and the potential for successful deployment of the next generation of mobile WiMAX in 2011+.

Convergence of ethernet PON and IEEE 802.16 broadband access networks and its QoS-aware dynamic bandwidth allocation scheme

Abstract: IEEE 802.16 and Ethernet Passive Optical Network (EPON) are two promising broadband access technologies for high-capacity wireless access networks and wired access networks, respectively. They each can be deployed to facilitate connection between the end users and the Internet but each of them suffers from some drawbacks if operating separately. To combine the bandwidth advantage of optical networks with the mobility feature of wireless communications, we propose a convergence of EPON and 802.16 networks in this paper. First, this paper starts with presenting the converged network architecture and especially the concept of virtual ONU-BS (VOB). Then, it identifies some unique research issues in this converged network. Second, the paper investigates a dynamic bandwidth allocation (DBA) scheme and its closely associated research issues. This DBA scheme takes into consideration the specific features of the converged network to enable a smooth data transmission across optical and wireless networks, and an end-to-end differentiated service to user traffics of diverse QoS (Quality of Service) requirements. This QoS-aware DBA scheme supports bandwidth fairness at the VOB level and class-of-service fairness at the 802.16 subscriber station level. The simulation results show that the proposed DBA scheme operates effectively and efficiently in terms of network throughput, average/maximum delay, resource utilization, service differentiation, etc.

Multi-thread polling: a dynamic bandwidth distribution scheme in long-reach PON

Abstract: With the advances in optical technology, the span of a broadband access network using passive optical network (PON) technology can be increased from today's standard of 20 km to 100 km or higher, and thereby serve a lot more users. Such an extended-reach PON is known as SuperPON in the literature, and we call it a long-reach PON (LR-PON). A major challenge in LR-PON is that the propagation delay (for data as well as control signals) between the telecom central office (CO) and the end user is increased by a very significant amount. Now, traditional PON algorithms for scheduling the upstream transmission, such as dynamic bandwidth allocation (DBA) algorithms, may not be sufficient; actually, they may lead to degraded performance because of the long delay of the CO-to- Users "control loop." This challenge motivates us to propose and study a multi-thread polling algorithm to effectively and fairly distribute the upstream bandwidth dynamically. This algorithm exploits the benefits of having multiple polling processes running simultaneously and enabling users to send bandwidth requests before receiving acknowledgement from the CO. We compare the proposed algorithm with traditional DBA, and show its advantage on average packet delay. We then analyze and optimize key parameters of the algorithm, such as initiating and tuning multiple threads, inter-thread scheduling, and fairness among users. Numerical results demonstrate the algorithm's advantage to decrease the average packet delay and improve network throughput under varying offered loads.

Effect of Relaying on Coverage in 3GPP LTE-Advanced

Abstract: Current broadband wireless networks are characterized by large cell sizes. Yet, even in advanced networks that will be built using 3 GPP Long Term Evolution (LTE), also referred to as 3GPP LTE-Advanced, or mobile WiMAX radio interface, users on the cell edge will face relatively low signal-to-interference-plus-noise-ratio (SINR). An attractive solution for this problem is provided by multihop technologies. In this paper we consider the feasibility of Decode and Forward (DF) Relay Nodes (RNs) from 3GPP LTE-Advanced perspective. We propose a novel evaluation methodology that can be used to find a relation of RN transmission power, ratio between number of Base Stations (BSs) and RNs, and performance of the system. Evaluation of DF relays in 3GPP LTE-Advanced framework indicates a good performance gain.

A 60 GHz Radio-Over-Fiber Network Architecture for Seamless Communication With High Mobility

Abstract: We demonstrate a 60 GHz broadband picocellular Radio-over-Fiber network architecture that enables seamless connectivity for highly mobile end-users. Its seamless communication capabilities arise by the supported handover scheme that relies on a novel Moving Extended Cell (MEC) concept. MEC exploits user-centric virtual groups of adjacent cells that transmit the same data content to the user and utilizes a switch mechanism for restructuring the virtual multi-cell area according to the user's mobility pattern, so that a virtual antenna group moves together with the mobile user. We present the theoretical formulation for MEC and show that it can provide zero packet loss and call dropping probability values in high-rate wireless services for a broad range of mobile speeds up to 40 m/sec, independently of the fiber link distances. We also demonstrate the physical layer network architecture and switch mechanism both for a RoF network with a single 60 GHz radio frequency (RF) over each wavelength, as well as for a RoF configuration supporting simultaneous multi-RF channel transmission over each optical wavelength. The performance of the multi-RF-over-lambda network implementation is evaluated via simulations showing successful 100 Mb/s radio signal transmission over fiber links longer than 30 km. To this end, MEC can enable seamless connectivity and bandwidth guarantees in 60 GHz picocellular RoF networks being also capable of serving multiple users over the same wavelength in a RF frequency-division-multiplexed (FDM) approach.

The fourth generation broadband concept

Abstract: Fixed-broadband access technology is evolving from exclusively copper-based solutions to hybrid fiber-copper architectures. This article presents the expected next step in the evolution of broadband systems, which we call the fourth-generation broadband concept. It identifies a technical, infrastructural, and economical niche and describes how the fiber-access network is extended and forked to feed a last and ultimate generation of DSL systems, shown to have gigabit potential. The underlying infrastructural concept is presented, economic aspects are described and discussed, and achievable data rates are calculated.

Capacity and delay of hybrid wireless broadband access networks

Abstract: An optical network is too costly to act as a broadband access network. On the other hand, a pure wireless ad hoc network with n nodes and total bandwidth of W bits per second cannot provide satisfactory broadband services since the pernode throughput diminishes as the number of users goes large. In this paper, we propose a hybrid wireless network, which is an integrated wireless and optical network, as the broadband access network. Specifically, we assume a hybrid wireless network consisting of n randomly distributed normal nodes, and m regularly placed base stations connected via an optical network. A source node transmits to its destination only with the help of normal nodes, i.e., in the ad hoc mode, if the destination can be reached within L (L /spl geq/ 1) hops from the source. Otherwise, the transmission will be carried out in the infrastructure mode, i.e., with the help of base stations. Two transmission modes share the same bandwidth of W bits/sec. We first study the throughput capacity of such a hybrid wireless network, and observe that the throughput capacity greatly depends on the maximum hop count L and the number of base stations m. We show that the throughput capacity of a hybrid wireless network can scale linearly with n only if m = Omega(n), and when we assign all the bandwidth to the infrastructure mode traffics. We then investigate the delay in hybrid wireless networks. We find that the average packet delay can be maintained as low as Theta(1) even when the per-node throughput capacity is Theta(W).

Advanced System Technologies and Field Demonstration for In-Building Optical-Wireless Network With Integrated Broadband Services

Abstract: This work describes a concept of a hierarchical radio-over-fiber (RoF) network architecture that provides both intra- and inter-network connectivity for end user wireline and wireless terminals with high-bandwidth, in-building access applications. An intelligent gateway router (IGR) is proposed as a unified platform to accommodate multi-gigabit, millimeter-wave services at 60-GHz band as well as being backward compatible with all current wireless access technologies such as WiFi and WiMAX. In addition, we further present an advanced multi-band optical carrier generation technique that can simultaneously deliver independent 60-GHz mm-wave, 2.4-GHz WiFi, and 5.8-GHz WiMAX signals efficiently carried over the same wavelength, and is suitable for the proposed IGR. Finally, we report, for the first time to our knowledge, a campus-wide field trial demonstration of RoF system transmitting uncompressed 270-Mbps standard definition (SD) and 1.485-Gbps high definition (HD) real-time video contents carried by 2.4-GHz radio and 60-GHz millimeter wave signals, respectively, between two on-campus research buildings distanced over 2.5-km standard single mode fiber (SMF-28) through the Georgia Institute of Technology's (GT) fiber network.

Nemo-enabled localized mobility support for internet access in automotive scenarios

Abstract: This article surveys the major existing approaches and proposes a novel architecture to support mobile networks in network-based, localized mobility domains. Our architecture enables conventional terminals without mobility support to obtain connectivity either from fixed locations or mobile platforms (e.g., vehicles) and move between them, while keeping their ongoing sessions. This functionality offers broadband Internet access in automotive scenarios such as public transportation systems, where users spend time both in vehicles and at stations. The key advantage of our proposal, as compared with current alternatives, is that the described mobile functionality is provided to conventional IP devices that lack mobility functionality. We also performed an experimental evaluation of our proposal that shows that our architecture improves the quality perceived by the end users.

Hybrid wireless-optical broadband access network(woban) : prototype development and research challenges

Abstract: The hybrid wireless-optical broadband access network is emerging as a promising technology to provide economical and scalable broadband Internet access. In this cross-domain network architecture, end users receive broadband services through a wireless, mesh front end that is connected to the optical backhaul through gateway nodes. In this article, we present the architecture and functional characteristics of a WOBAN prototype built in the Networks Lab at UC Davis. We discuss research challenges for hybrid networks based on our experimental observations.

Bottom-up transfer function generator for broadband PLC statistical channel modeling

Abstract: We follow a bottom-up approach for modelling the channel transfer function aiming at realizing a fast statistical channel simulator. The simulator is derived from transmission line theory. It computes the transfer function via a fast procedure that calculates the voltage ratio between the receiver port and the transmitter port given a real or randomly generated network topology. The approach allows not only taking into account the cable characteristics, the number and length of branches, but also the effect of loads. In particular the effect of time-variant loads that cause the channel transfer function to be time-variant.

Adaptive subcarrier allocation schemes for wireless ofdma systems in wimax networks

Abstract: WiMax is one of the most important technologies for providing a broadband wireless access (BWA) in a metropolitan area. The use of OFDM transmissions has been proposed to reduce the effect of multipath fading in wireless communications. Moreover, multiple access is achieved by resorting to the OFDMA scheme. Adaptive subcarrier allocation techniques have been selected to exploit the multiuser diversity, leading to an improvement of performance by assigning subchannels to the users accordingly with their channel conditions. A method to allocate subcarriers is to assign almost an equal bandwidth to all users (fair allocation). However, it is well known that this method limits the bandwidth efficiency of the system. In order to lower this drawback, in this paper, two different adaptive subcarrier allocation algorithms are proposed and analyzed. Their aim is to share the network bandwidth among users on the basis of specific channel conditions without loosing bandwidth efficiency and fairness. Performance comparisons with the static and the fair allocation approaches are presented in terms of bit error rate and throughput to highlight the better behavior of the proposed schemes in particular when users have different distances from the BS.

On the state and guiding principles of broadband in India

Abstract: India, home to 1.2 billion people with a GDP growth of 9 percent, has been experiencing flat to modest growth of broadband services in the past decade despite the fact that the country continues to add 8-10 million cellular connections per month. In this article, we examine the reasons that affect the high cost of broadband in India and the steps required to reduce the cost. We also argue that the usage-based pricing model, which is used widely for billing retail customers, is hampering the growth of local content and services. In contrast, a flat-rate pricing model would spur demand for broadband services and enable content providers to target the local and emerging market. We study the Indian telecommunication scenario from a pricing and technology perspective to understand what the driving forces are for business to prosper. We then discuss the Indian landscape from a metro/access/core networks perspective. The technology choices and the methods of deployment are considered followed by an analysis of the service-centric model adopted by providers.

Hybrid wireless-optical broadband access network (WOBAN): network planning using Lagrangean relaxation

Abstract: The concept of a hybrid wireless-optical broadband access network (WOBAN) is a very attractive one. This is because it may be costly in several situations to run fiber to every home (or equivalent end-user premises) from the telecom central office (CO); also, providing wireless access from the CO to every end user may not be possible because of limited spectrum. Thus, running fiber as far as possible from the CO toward the end user and then having wireless access technologies take over may be an excellent compromise. How far should fiber penetrate before wireless takes over is an interesting engineering design and optimization problem, which we address in this paper. We propose and investigate the characteristics of an analytical model for network planning, namely optimum placements of base stations (BSs) and optical network units (ONUs) in a WOBAN (called the primal model, or PM). We develop several constraints to be satisfied: BS and ONU installation constraints, user assignment constraints, channel assignment constraints, capacity constraints, and signal-quality and interference constraints. To solve this PM with reasonable accuracy, we use ldquoLagrangean relaxationrdquo to obtain the corresponding ldquoLagrangean dualrdquo model. We solve this dual problem to obtain a lower bound (LB) of the primal problem. We also develop an algorithm (called the primal algorithm) to solve the PM to obtain an upper bound (UB). Via simulation, we compare this PM to a placement heuristic (called the cellular heuristic) and verify that the placement problem is quite sensitive to a set of chosen metrics.

Double-Phase Polling Algorithm Based on Partitioned ONU Subgroups for High Utilization in EPONs

Abstract: The Ethernet passive optical network (EPON) is an emerging technology for the next-generation broadband access networks and is considered an up-to-date candidate network for future fiber to the home. A crucial issue in EPONs is the sharing of uplink bandwidth among optical network units (ONUs). To manage resources efficiently, research on polling schemes based on multipoint control protocol has been conducted. We propose a novel polling algorithm to increase resource utilization by partitioning ONUs into two subgroups with some overlap. In the proposed scheme, after receiving frames from ONUs in one subgroup, the OLT performs dynamic bandwidth allocation for ONUs in the other. Hence, the OLT continuously receives frames from ONUs without significant interruptions. Comprehensive computer simulation results show that the proposed algorithm both defers saturation points of queues in ONUs and provides outstanding network throughput compared with previous work. It has up to 45% lower average packet delay and maximum performance improvement of 17% with respect to network throughput.

Is microwave backhaul up to the 4G task

Abstract: With the evolution toward the fourth generation of mobile networks, the backhaul network that portion of the network infrastructure that provides interconnectivity between the base stations and the core network is expected to come under intense pressure as capacity requirements increase to support new mobile broadband services. As a key technology used in backhaul networks around the world, point-to-point microwave is rapidly evolving to support this increasing capacity demand, improve network efficiency, and allow operators to reduce network operational costs. This article details how recent developments in the microwave industry support both the lowest cost per Mb/s transport and also the maximum Mb/s/MHz. These developments embrace the dramatic shift to support Internet protocol (IP) network convergence, including the key features to enable link capacities not previously seen in the industry, and the new methods developed to enable every last drop to be squeezed out of the finite resource that is the available frequency spectrum.

Interworked WiMAX-3G cellular data networks: An architecture for mobility management and performance evaluation

Abstract: This paper proposes an architecture for interworking heterogeneous all-IP networks with an in-depth analysis of its performance. The novelty of this framework is that it freely enables any 3G cellular technology, such as the Universal Mobile Telecommunications System (UMTS) or the CDMA 2000 system, to interwork with a given broadband wireless access (BWA) system, such as the Worldwide interoperability for microwave access (WiMAX) network or the wireless local area network (WLAN) via a common signaling plane. As a universal coupling mediator for real-time session negotiation and management between these dissimilar networks, the IP multimedia subsystem (IMS) has been exploited. The analytical evaluation investigates the behavior of handoff delay, transient packet loss, jitter, and signaling cost during a vertical handoff for the given framework. Finally, an OPNET based simulation platform has been introduced for the verification of the analytical model and results.

Broadband network access

Abstract: A method and Access Network Node for handling dissimilar protocols when a Host accesses a Broadband Network. The Access Network Node includes a protocol converter for interworking between the Neighbor Discovery (ND) protocol and the Dynamic Host Configuration Protocol (DHCP). When an ND Router Solicitation message is received from a Host that does not support DHCP, the converter converts the ND message to a DHCP Solicit message and forwards it to a Broadband Network Gateway (BNG) together with a port ID. When the Access Network Node receives a DHCP Reply message from the BNG destined for the same Host, the converter converts the DHCP Reply message to an ND Router Advertisement message before sending it to the Host.

A collision-free MAC scheme for multimedia wireless mesh backbone

Abstract: Wireless mesh networking is a promising wireless technology for future broadband Internet access. In this paper, a novel collision-free medium access control (MAC) scheme supporting multimedia applications is proposed for wireless mesh backbone. The proposed scheme is distributed, simple, and scalable. Benefiting from the fixed locations of wireless routers, the proposed MAC scheme reduces the control overhead greatly as compared with conventional contention-based MAC schemes (e.g., IEEE 802.11). In addition, the proposed scheme can provide guaranteed priority access to real-time traffic and, at the same time, ensure fair channel access to the routers with data traffic. Unlike most of the existing MAC schemes which focus on single-hop transmissions, the proposed MAC scheme takes the intra-flow correlations between up-stream and downstream hops of a multi-hop flow into consideration. To avoid buffer overflow at bottleneck routers, a simple but effective congestion control mechanism is proposed. Simulation results demonstrate that the proposed scheme significantly improves the delay performance of real-time traffic and the end-to-end data throughput, as compared with IEEE 802.11 and distributed packet reservation multiple access (DPRMA). The performance analysis of the proposed scheme is also presented. The accuracy of the analytical results is verified by computer simulations.

Adaptive Hybrid Transmission Mechanism for On-Demand Mobile IPTV Over WiMAX

Abstract: In this paper, we propose an Adaptive Hybrid Transmission (AHT) scheme for on-demand mobile IPTV service over broadband wireless access network (i.e. mobile WiMAX, 802.16e). Proposed algorithm utilizes hybrid mechanism which combines multi-channel multicasting and unicast scheme to enhance not only service blocking probability but also reduce overall bandwidth consumption of the wireless system which has very limited resources compared to wired networks. An adaptive resource allocation algorithm is also proposed, and is shown to achieve minimum blocking probability. In order to evaluate the performance, we compare proposed algorithm against traditional unicast and multicast schemes.

The need for speed: the importance of next-generation broadband networks

Abstract: This report from US think-tank ITIF argues that supporting the deployment of faster broadband networks will be crucial to enabling next-generation Web-based applications and services that will play important roles in improving quality of life and boosting economic growth. While getting broadband service to the Americans who lack it is an important policy target, next-generation broadband will deliver a wave of new benefits to consumers, society, businesses, and the economy.

3G/HSPA Performance in Live Networks from the End User Perspective

Abstract: Operators around the world are improving their 3G/UMTS networks by introducing HSPA (High Speed Packet Access) that includes both, enhanced uplink and downlink. The HSPA is expected to finally provide the mobile broadband access that is able to compete with the fixed connections in performance regarding popular applications such as web browsing, VoIP, and video. However, it has remained unclear how well the live networks fulfill the promises of performance. We contribute in filling this void by providing measurements in live 3G/HSPA networks. We compare TCP and UDP goodput performance in basic WCDMA, HSDPA-only, and HSPA. Moreover, one-way delay and jitter measurement results are presented in a stationary as well as in a mobile scenario. The results show that the enhanced network outperforms clearly its predecessor by offering considerably higher data rates, lower delay, and lower jitter. Also, because of the HARQ (Hybrid Automatic Repeat request), there are notably less delay spikes observed with HSPA than with WCDMA. However, the drive tests show that handovers result in high jitter and interruptions to the communications, which causes, e.g., decreased VoIP call quality. The uplink enhancement (HSUPA) improves the TCP performance beyond the HSDPA-only access, but it is still behind that of the fixed connections. In addition, the properties of the channel allocation mechanism still considerably deteriorate the data rates seen by the user. Nevertheless, the HSPA is an enabler for true mobile broadband internet access.

System for providing high speed communications service in an airborne wireless cellular network

Abstract: The present Broadband Link System supplements the existing Air-To-Ground Radio Frequency communications link with an additional, separate high speed Broadband Ground-To-Air Data Channel to provide additional data communication capacity for aircraft. This Broadband Ground-To-Air Data Channel is typically a uni-directional (Ground-To-Air) link directed via a focused beam to selected aircraft which are operational in the coverage area of the Broadband Ground-To-Air Data Channel. The routing of the various data transmissions on both the Air-To-Ground Radio Frequency communications link and the Broadband Ground-To-Air Data Channel are managed in a unified manner to maximize the utilization of the two transmission facilities.