This work presents a new approach on dynamic bandwidth allocation (DBA) for Ethernet Passive Optical Networks (EPONs). A brief introduction to the DBA area and major term definitions are given. The related research and standardization efforts are presented. Justification that EPONs can be used on the aggregation network is provided, based on their evolution and related research proposals. Focus is given to the Long Reach-Passive Optical Networks (LR-PONs) and their limitations which show the need for a non-polling, midterm DBA scheme for next-generation EPONs. The challenges arising, because of this new approach, are discussed along with possible solutions. Finally, this work proposes the EMDBA algorithm which is able to overcome the discussed issues. The correct operation of this algorithm is confirmed by a set of simulations using OMNet++ framework, and the outcome results show that EMDBA performance is satisfactory in terms of delay and service differentiation.

Mobile handsets have evolved a lot the last years and support numerous wireless interfaces for attaching to heterogeneous co-existing wireless networks. This raises new challenges and proposed solutions appear in the literature, which are listed in this work. The main focus is an extensible and robust system/framework that enables experimentation in such an environment. First seamless connectivity from the roaming on heterogeneous networks was achieved and tested using VPN tunnels. Then the system components for both network and terminal sides are presented, which provide multiple management and operation options in order to be adjustable to virtually any scenario. Additionally, a standalone and also extensible decision making framework was designed and implemented. Multi-Attribute Decision Making (MADM) methods and algorithms are used to select the preferred access network for the Mobile Nodes. Finally two set of experiments performed: (1) to validate the correct operation of the system in real-life scenarios and (2) to explore the performance of the handover technique used in this system. In both of the above sets, experiments were successive, proving the feasibility of the solutions proposed and the applicability of the proposed framework to any testbed environment.

With the growth of mobile handsets and services provided over wireless networks, the need of dynamically managed environments is obvious. Network providers have already moved from E1/T1 lines to more scalable technologies, including EPONs (Ethernet Passive Optical Networks) and WiMax. These new technologies support service differentiation and Quality of Service (QoS). This work presents an overlay, cross-technology, signaling protocol which allows information exchange, enabling convergence in terms of common resource management, between different types of networks. This behavior is desirable mainly in the fixed-mobile convergence (FMC) area. The benefits of such a common, distributed, resource management scheme are presented in this work. A set of simulations performed using OMNet++, show the advantages of its use in converged EPON-WiMax networks.

This research analyses the adoption of very high speed broadband (e.g. fiber to the home) and provides diffusion forecasts (i.e. yearly changes in subscription) for countries across the world. We present econometric models which estimate the diffusion rate according to a set of supply and demand characteristics. Based on data for 25 countries for the period of 1999-2009 we show that the demand- and supply-side factors such as income, monthly subscription price, and competition in broadband and television can explain 75% of the variance in the observed yearly change in subscription. Based on the econometric results we use a discrete form of the Logistic diffusion function and estimate the diffusion rate according to the above factors. We find that a country-specific diffusion model can substantially improve the forecast accuracy. Based on country specific models we show that 50% of households in most of the countries in Central and Eastern Europe will adopt high speed broadband through fiber to the home/building (i.e. FTTx) technology by 2015-2016. In contrast, we find that adoption rate in most countries in Western Europe is much slower and 50% of households will adopt FTTx broadband only after 2020.

The massive increase of mobile handsets in conjunction with the new and more demanding services deployed over wireless networks lead to huge bandwidth requirements for both the wireless and the backhaul networks. Ethernet Passive Optical Network deployment has already been started to replace E-1/T-1 lines. In addition wireless broadband access is taking place mostly with the use of WiMax. Integration and convergence of the above technologies had been proven to have many benefits. Due to the nature and the complexity though of the scenarios in this area, a large scale simulator, supporting multiple services and QoS is needed in order to validate new network and resource management algorithms. In this paper a simulator developed using OMNet++ framework is presented. The designed modules and their functionality are listed. A discussion on how these could be used to form different convergence architectures and the major outcome/results of such a simulation are explained.

Node consolidation and an all-passive (PON) infrastructure are important aspects to next-generation optical access (NGOA) networking. Wireless access is another important trend (WiFi, LTE/4G etc.) but requires active outside plant (base-stations). Once electrically-powered (e.g. via renewable energy) outside plant becomes a feature of an integrated NGOA architecture, the question of whether the NGOA network can be adapted and optimised still further (e.g. location of cognitive radio intelligence, vertical handover, locality, caching/content storage etc.) needs to be explored, as well as the additional energy-efficiency savings available with respect to optimising green radio technologies versus low-energy photonics. In this paper, we discuss the issues involved in the optimised design of a hierarchical and converged fixed-wireless access network, focussing on the handover possibilities associated with heterogeneous wireless technologies and the impact on the optimised design of an underlying fixed optical access infrastructure.

This research investigates the drivers and barriers to the adoption of FTTx broadband across the world. More specifically it explains the reason for wide disparity in adoption between countries of similar socio-economic structure. The barriers and drivers for both the demand for and the supply of FTTx broadband infrastructure is analysed using data for 25 countries for the period of 1999 to 2009. The results indicate that there is no adequate demand for FTTx broadband and as a consequence the investment in infrastructure is less in most countries. We find that regulation on unbundling and (inter-platform) competition in broadband market has no significant impact on the investment in infrastructure. In contrast, we find that higher penetration in paid television and competition in television market has a significant negative impact on the investment. Our results indicate that FTTx broadband has a positive impact on the growth of economy but the impact is not significant for countries in Europe.

Bloom filters have been recently proposed as an efficient multicast forwarding mechanism for the information centric topic-based publish/subscribe network proposed within the framework of the PSIRP project. Although such mechanism presents several advantages, as for instance very simple forwarding decisions and small forwarding tables, one of the limitations is the possibility of false positive occurrences during the forwarding decisions. This results in packets to be sent along unexpected links and the consequently wastage of network bandwidth among other effects. Therefore, its frequency must be minimized. One of the crucial points to reduce false positives in Bloom Filters is carefully select the number of hash functions utilized to create them. In this paper, we propose a mathematical analysis of the false positives in the whole network with respect to the number of hash functions. In particular, the number of hash functions correspondent to a minimum of false positive for the whole network is evaluated. Results from the mathematical analysis are compared with numerical analysis.

The current status of a campus research testbed that is being constructed to allow for the exploration of digital service delivery and smart networked environments using different networking technologies is presented.

A measurement study was conducted of video streaming across a testbed with routers typical of those found at bottlenecks on the wired Internet. During ‘bursty’ traffic packet loss was not always fairly distributed between background flows and a video stream. The paper shows that packet-by-packet end-to-end delay, an alternative metric, has the ability to closely track queuing delay, responding to available bandwidth in a timely manner. A wider issue considered by the paper is to what extent one-way delay across a network path that includes bottleneck links can act to detect congestion.

Presented is a fuzzy-logic-based scheduling algorithm for passive optical networks (PONs) that considers four different metrics to allocate an upstream bandwidth to optical network units (ONUs). The metrics considered are the delay of the head-of-the-line packets at the ONUs, the importance level of the packets, the relative ONU's buffer fullness, and the level of the power fluctuation from one ONU to another. One of the advantages of a fuzzy controller is the fact that, regardless of the design complexity, the controller can be implemented as a simple look-up table, which makes it ideal for high-speed operation. Further facilitation of implementation was achieved by realization of the fuzzy algorithm through a two-stage hierarchal architecture. Moreover, linear predictive filters have been used to predict the traffic arrival rate and the packet delay at the ONUs. Compared with the round-robin scheduling algorithm, the results show significant performance improvement in terms of the overall packets delay as well as jitter when the proposed algorithm in employed. Furthermore, using this algorithm would reduce the average level of power fluctuations in a PON system and will also provide high-level service differentiation between packets of different importance. (C) 2009 Optical Society of America

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.

This paper investigates the random channel access mechanism specified in the IEEE 802.16 standard for the uplink traffic in a point-to-multipoint (PMP) network architecture. An analytical model is proposed to study the impacts of the channel access parameters, bandwidth configuration and piggyback policy on the performance. The impacts of physical burst profile and non-saturated network traffic are also taken into account in the model. Simulations validate the proposed analytical model. It is observed that the bandwidth utilization can be improved if the bandwidth for random channel access can be properly configured according to the channel access parameters, piggyback policy and network traffic.

A dynamic bandwidth reservation (DBR) scheme for hybrid IEEE 802.16 wireless networks is investigated, in which 802.16 networks serve as the backhaul for client networks, such as WiFi hotspots and cellular networks. The DBR scheme implemented in the subscription stations (SSs) (co-locating with access pointers) consists of two components: connection admission controller (CAC), and bandwidth controller (BC). The CAC processes the received connection set-up requests from the client networks connected to the SSs. The BC manages the request and release of bandwidth from the base station (BS). It dynamically changes the reserved bandwidth between a small number of values. Hysteresis is incorporated in bandwidth release to reduce bandwidth request signalling load and connection blocking probability. An analytical model is proposed to evaluate the performances of reserved bandwidth, connection blocking probability and signalling load. The impacts of hysteresis mechanism and probability of reservation request blocking are taken into account. Simulation verifies the analytical model.

In the last 20 years, Synchronous Digital Hierarchy (SDH) has established itself as the predominant optical fiber transmission technique in European operator networks. The SDH format is very similar to the North American SONET format but with some modifications to accommodate the different legacy Plesiochronous Digital Hierarchy (PDH) transmission schemes used in Europe. Although this chapter focuses primarily on SDH, the fundamental principles of Next Generation SDH (NG-SDH) are identical to those of its SONET counterpart, except for the different multiplexing hierarchies between SDH and SONET, which are described in Chapter 10.

A measurement study is conducted of video streaming across a testbed with routers typical of those found at bottlenecks on the wired Internet. During dasiaburstypsila traffic packet loss is not always fairly distributed between background flows and a video stream. The paper shows that packet loss indications may be unreliable whereas packet-by-packet delay, an alternative metric, has the ability to closely track queue length, responding to available bandwidth in a timely manner.

Cellular networks have been widely used to support many new audio-and video-based multimedia applications. The demand for higher data rate and diverse services has driven the research on multihop cellular networks (MCNs). With its ad hoc network features, an MCN can offer many additional advantages, such as increased network throughput, scalability and coverage. However, providing ad hoc capability to MCNs is challenging as it may require proper wireless interfaces. In this article, the architecture of IEEE 802.16 network interface to provide ad hoc capability for MCNs is investigated, with its focus on the IEEE 802.16 mesh networking and scheduling. Several distributed routing algorithms based on network entry mechanism are studied and compared with a centralized routing algorithm. It is observed from the simulation results that 802.16 mesh networks have limitations on providing sufficient bandwidth for the traffic from the cellular base stations when a cellular network size is relatively large.

Business uptake of IP-centric services has been strong and necessitates reliable, highly-available, high-quality Internet access. Real time services such as mission-critical broadcast video, video conferencing and voice over IP (VoIP) have low tolerance for short-term network outages. However, applications like bulk data transfer maybe much more resistant to such events. Many different network resilience mechanisms can be offered to customers by service providers allowing for slower (or faster) recovery of network access. Yet in current networks, offering different resilience mechanisms for different services is complicated, involving multiple interfaces. In this work, we propose that services be offered differentiated resilience levels within a single physical interface. In order to do so, an application aware resilience mechanism is proposed based on using the supplementary IP header type of service (ToS) field to define arbitrary values in addition to the 6-bit differentiated services code points (DSCP). This mechanism allows different levels of resilience to be assigned to applications such as VoIP for emergency and mission critical services.

IEEE 802.16 standard specifies a contention based bandwidth request scheme for best-effort and non-real time polling services in point-to-multipoint (PMP) architecture. In this letter we propose an analytical model for the scheme and study how the performances of bandwidth efficiency and channel access delay change with the contention window size, the number of contending subscriber stations, the number of slots allocated for bandwidth request and data transmission. Simulations validate its high accuracy.