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The European research project DICONET proposed and implemented a multi-plane impairment-aware solution for flexible, robust and cost-effective core optical networks. The vision of DICONET was realized via a set of cross-layer optimization algorithms designed to serve the network during planning and operation. The cross-layer modules were incorporated in a common software platform forming a planning and operation tool that takes into account physical-layer impairments in the decision making. The overall solution relies on a GMPLS-based control plane that was extended to disseminate the physical layer information required by the cross-layer modules. One of the key activities in DICONET concerns the routing and wavelength assignment of traffic demands that arrive dynamically during the network operation. Identifying the important role of dynamic lightpath provisioning, in this work we focused on the performance of routing algorithms in dynamic optical networks. We tested the suitability and performance of two different online IA-RWA algorithms in a 14-node experimental test-bed that employed centralized control-plane architecture under the same network and traffic conditions. The parameters used to evaluate the two routing engines included the lightpath setup time and the blocking ratio in a traffic scenario where connections arrive and depart from the network dynamically. Results for different traffic loads showed that optimum impairment-aware decisions are made at the expense of higher lightpath setup times., Postprint (published version)

En los últimos años la adopción de MPLS se ha incrementado debido a las ventajas y la cantidad de aplicaciones que ofrece. En una red MPLS se asignan etiquetas a los paquetes según entran al dominio y son conmutados en base a ellas hasta que lo abandonan. Al igual que ocurre en redes IP convencionales, la ruta seguida por los paquetes (denominada LSP o Label Switched Path) puede variar debido a la naturaleza de los protocolos de encaminamiento y a la existencia de fallos en la red. Por lo tanto, conocer la ruta que seguirá el tráfico resulta interesante desde un punto de vista de gestión de red. Este proyecto tiene como objetivo el diseño e implementación de un sistema capaz de determinar el camino que seguirá un cierto patrón de tráfico a través de una red IP con funcionalidades MPLS. A alto nivel, la aplicación trata de reproducir la ruta que seguiría el tráfico. Para ello emula el proceso de decisión que realiza cada router a partir de las características del paquete y la información de encaminamiento de la que dispone. Esto requiere la adquisición de dicha información la cual se almacenará y procesará de forma eficiente. Por último, se necesitará un algoritmo que realice el cómputo de las trayectorias.

Differentiated services provision according to clients or applications is an added feature that network operators ambition to fully provide. One of the possible approaches is to map DiffServ into MPLS based network. However in an IP over WDM (Wavelength Division Multiplexing) network data flow traverse multiple layers and, therefore, Class-Type information from the MPLS DiffServ layer is eventually lost. Besides, with the implement of a Path Computation Element (PCE) on multi-layer and multi-domain networks, the bandwidth constraints used to differentiate services are no longer applied. This paper presents a proposal for a QoS DiffServ approach applied on PCE as a traffic grooming technique for WDM core networks and the problematic involved on the application of this technology on multilayer and multi-domain networks., Postprint (published version)

© 2011 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., Channel assignment has been extensively researched for multi-radio wireless mesh networks, but it is still very challenging when it comes to its implementation. In this paper we propose a semi-dynamic and distributed channel assignment mechanism called SICA that uses game theory. To the best of our knowledge this is the first game formulation of channel assignment which takes the co-channel interference into account. SICA is an interference aware, distributed channel assignment which preserves the network connectivity without relying on a common channel nor central node for coordination between mesh routers. SICA applies an on-line learner algorithm which assumes that nodes do not have perfect information. We have simulated SICA and compared against another interference-aware channel assignment mechanism proposed in the literature called Urban-X. Simulation results show that SICA outperforms Urban-X, even using fewer radio interfaces per node., Peer Reviewed, Postprint (author's final draft)

A one-to-one association between data and control channels has traditionally existed in transport networks. Being the control plane embedded in the data plane, the design of the former, as well as its resilience, has been addressed in the latter’s one. However, a main GMPLS architectural requirement is to provide a clean separation between control and data planes. In this sense, the control plane in GMPLS networks may describe a different topology than the data plane, even realized over a separated IP network. As a consequence of this, data and control network design become no more linked in such scenarios. To the best of our knowledge, no works in the literature have addressed an independent design of the control plane in GMPLS-enabled networks regardless of the data plane. In this paper, we provide a method to obtain the optimal GMPLS control plane design, minimizing the network Capital Expenditures (CAPEX) while matching specific resilience requirements. To this goal, the problem of finding an optimal control plane topology that ensures a certain resilience level is formulated as a non-linear combinatorial model. This model, however, does not scale properly for large backbone networks. In view of this, a constructive linear method is also presented and its optimality validated through simulations on several reference network scenarios. Furthermore, its benefits in terms of total execution time are also highlighted., Postprint (published version)

The impact of the regenerator placement strategies when dynamically provisioning connections in translucent WSON is studied. The evaluation is experimentally conducted in the ADRENALINE testbed in terms of the connection blocking., Postprint (published version)

Compact routing schemes address the fundamental tradeoff between the memory space required to store the routing table entries and the length of the routing paths that these schemes produce. This paper introduces the first known name-independent, leaf-initiated dynamic compact routing scheme that allows the distribution of traffic from any source to any set of leaf nodes along a multicast routing path that defines a distribution tree. By means of the proposed scheme, a multicast distribution tree dynamically evolves according to the arrival of leaf-initiated join/leave requests. To evaluate the performance we consider the following metrics: the stretch of the produced routing paths, the size and the number of routing table entries, and the communication cost. The results obtained by simulation on synthetic power law graphs (modeling the Internet topology) show that our scheme can successfully handle leaf-initiated dynamic setup of multicast distribution trees. Two reference multicast routing schemes (the Shortest Path Tree and the Steiner Tree algorithm) are used to compare the performance of the proposed scheme. While increasing the communication cost compared to the Shortest Path Tree, the proposed scheme achieves considerable reduction of the routing table size compared to both reference schemes. Moreover, the stretch of the resulting multicast routing paths show limited deterioration compared to the minimum value obtained with Steiner Trees., Peer Reviewed, Postprint (published version)

Network performance measurements have been broadly used in order to debug and to assess the reliability of the network. In general performance measurement is a resource consuming process, which in practice derives in hardly scalable systems. However, in order to control and monitor network resource usage and to assess the quality of multimedia traffic, it is broadly accepted that efficient and scalable network performance evaluation infrastructures must be present in nowadays networks. Nevertheless, most of current research is focused on the assessment of the different performance metrics in order to determine if the quality of the delivered service is correct. Differently, the main contribution presented in this paper, relies on the fact that the accurate estimation of the network metrics is generally not necessary, given that it is much more efficient to directly detect service disruptions. To this end, we propose an algorithm to detect anomalies on the service level delivered to the users. Our solution is based on the distance measurement between acquired reference distributions on the Inter-Packet Arrival Times. This simple to measure time-series permit to detect very efficiently QoS disruptions, making of the solution a very good candidate to be used on Service Level Agreement assessment systems, as we prove in our experimental set up, where we evaluate the performance and accuracy of the proposal in a real scenario., Peer Reviewed, Postprint (published version)

This paper presents a Cross-layer Network Management System (NMS) that allows Service Providers (SPs) to perform cost-effective network resource reservations with their Network Operators (NOs). The novelty of our NMS is that it offers a fresh and promising approach to use the endusers satisfaction level as the metric to perform the resource management. We show that our system is capable of achieving considerable reductions in the operational costs of SPs, while keeping proper bounds in the end-user satisfaction for the offered multimedia services., Peer Reviewed, Postprint (published version)

This paper introduces and evaluates a hybrid OBS/OCS switch for Quality of Service (QoS) differentiation in next-generation all-optical transport networks. Depending on their QoS requirements, incoming IP packets are collected in delay-sensitive or loss-sensitive assembly queues. Once assembled, those departing delay or losssensitive bursts are sent to the destination over a parallel all-optical hybrid network, where a set of switch ports and wavelengths are dedicated to delay-sensitive OBS-like transmission based on Just Enough Time (JET), whereas the remainder are dedicated to loss-sensitive OCS-like transmission. The obtained results validate the differentiated transport services in the deployed reference network scenario. Moreover, they show that circuit set-up retries are mandatory in OCS to carry loss-sensitive traffic efficiently., Postprint (published version)

In transparent optical networks, the signal experiences the impact of various phenomena that degrade its quality. Considering the impact of physical layer impairments (PLIs) on transparent [1] and highly dynamic optical networks [2] has received much attention recently. The main innovation of the DICONET project [3] is the development of a dynamic Network Planning and Operation Tool (NPOT) that incorporates real-time assessments of the optical layer performance into Impairment Aware Routing and Wavelength Assignment (IA-RWA) algorithms. The NPOT is integrated into a unified extended Generalized Multi-Protocol Label Switching (GMPLS)-based control plane. The work in [1] reported the result of a centralized integration scheme for transparent networks considering various PLIs, while [4] only investigated a distributed GMPLS integration for translucent networks. This paper demonstrates the performance of centralized and distributed impairment-aware control plane approaches over a realistic 14-node experimental test-bed under dynamic traffic conditions.Initial simulation results were reported in [5] and experimental results are reported here. The test-bed integrates the developed NPOT engine, the extended GMPLS control protocols required for supporting the innovative DICONET solutions and the various communication protocols to allow all DICONET building blocks run in an orchestrated fashion. To the best of our knowledge, for the first time, impairment-aware control plane schemes with integrated real-time Quality of Transmission (QoT) estimator are demonstrated., Postprint (published version)

The architecture definition, design, and validation of the interconnect networks is a key step in the design of modern on-chip systems. This paper proposes a mathematical formulation of the problem of simultaneously defining the topology of the network and the message routes for the traffic among the processing elements of the system. The solution of the problem meets the physical and performance constraints defined by the designer. The method guarantees that the generated solution is deadlock free. It is also capable of automatically discovering topologies that have been previously used in industrial systems. The applicability of the method has been validated by solving realistic size interconnect networks modeling the typical multiprocessor systems., Peer Reviewed, Postprint (published version)

A Mobile Ad hoc Network (MANET) is a collection of wireless mobile terminals that are able to dynamically form a temporary network without any aid from fixed infrastructure or centralized administration. In recent years, MANETs are continuing to attract the attention for their potential use in several fields such as military activities, rescue operations and time-critical applications. In this paper, we present the implementation and analysis of our implemented wireless multi-hop network testbed considering the Optimized Link State Routing (OLSR) protocol for wireless multi-hop networking. We investigate the effect of mobility and topology changing in MANET. We study the impact of best-effort traffic for non line of sight communication. In this work, we consider three models: stationary, mobility and non line of sight communication models. We assess the performance of our testbed in terms of throughput and packet loss. From the experimental results, we found that OLSR has not a good performance when the relay node is moving. Also, the performance deteriorates when the CBR is higher., Peer Reviewed, Postprint (published version)

A connection spanning, for example, several countries crosses multiple optical backbone networks, each one controlled by different administrators or operators. In this context, the interworking of these networks is thus necessary to set up end-to-end optical connections. A key issue when delivering such optical services is the use of efficient and fast restoration strategies to recover a connection disruption. To this end, there are several issues and policies that a network operator should address, such as interdomain failure information exchange and the point of repair (PoR) placement problem. Upon a failure’s occurrence, exchanging interdomain failure information results is essential to attain both an efficient use of the network resources (i.e., wavelength channels) and a fast restoration time. In this regard, within the GMPLS (Generalized Multi-Protocol Label Switching) framework, interdomain information exchange remains unstandardized. Three network operator policies are proposed to yield different restoration mechanisms according to different interdomain failure exchanges. Additionally, three PoR strategies are pointed out and are qualitatively compared. Finally, selected policies and restoration strategies are experimentally validated and compared in terms of the restoration time. Experiments have been carried out over a multidomain optical network infrastructure connecting the GMPLS-based control planes of the UPC CARISMA and the CTTC ADRENALINE test beds., Postprint (published version)

The mobile cellular systems are expected to support multiple services with guaranteed Quality of Service(QoS). But, the ability of wireless systems to accommodate expected growth of traffic load and broadband services is limited by available radio frequency spectrum. Call Admission Control (CAC) is one of the resource management functions, which regulates network access to ensure QoS provisioning. However, the decision for CAC is very challenging issue due to user mobility, limited radio spectrum, and multimedia traffic characteristics. To deal with these problems, we implemented a Fuzzy Admission Control System (FACS). We compared the performance of FACS with Shadow Cluster Concept (SCC). In another work, we extended FACS by considering the priority of the on-going connections. We called this system FACS-P. As priority parameter, we considered only one parameter (service request). In this work, we improve our previous system by adding different priorities. We call this system FACS-MP. We evaluate and compare the performance of implemented systems by simulations. From the simulations results, we conclude that the FACS-MP can differentiate better different services compared with previous systems., Peer Reviewed, Postprint (published version)

The mobile cellular systems are expected to support multiple services with guaranteed Quality of Service(QoS). But, the ability of wireless systems to accommodate expected growth of traffic load and broadband services is limited by available radio frequency spectrum. Call Admission Control (CAC) is one of the resource management functions, which regulates network access to ensure QoS provisioning. However, the decision for CAC is very challenging issue due to user mobility, limited radio spectrum, and multimedia traffic characteristics. In our previous work, we proposed a fuzzy-based CAC system by considering the priority of the on-going connections. As priority parameter, we considered only one parameter (service request). In this work, we extend our work by adding different priorities. We call this system FACS-MP. We evaluate by simulations the performance of the proposed system. From the simulations results, we conclude that the FACS-MP can differentiate better different services compared with previous system., Peer Reviewed, Postprint (published version)

In this paper, we present the implementation and analysis of our implemented testbed considering the Optimized Link State Routing (OLSR) protocol for Mobile Ad hoc Networks (MANET). We investigate the effect of mobility and topology changing in the throughput of MANETs. We study the impact of best-effort traffic for Mesh Topology. Experimental time is 150 seconds. In this work, we consider 6 experimental models and we assess the performance of our testbed in terms of throughput, round trip time and packet loss. From our experiments, we found that the OLSR protocol has a good performance when the source node is moving. However, the performance is not good when the three relay nodes are moving., Peer Reviewed, Postprint (published version)

On-line end-to-end Service Level Agreement (SLA) monitoring is of key importance nowadays. For this purpose, past recent researches focused on measuring (when possible) or estimating (most of the times) network QoS or performance parameters. Up to now, attempts to provide accurate techniques for estimating such parameters have failed. In addition, live reporting of the estimated network status requires a huge amount of resources, and lead to unscalable systems. The originality of the contribution presented in this paper, relies on the statement that the accurate estimation of network QoS parameters is absolutely not required in most cases: specifically it is sufficient to be aware of service disruptions, i.e. when the QoS provided by the network collapses. For this purpose, we propose an algorithm for disruption detection of network services. The proposed solution is based on the use of the wellknown Kullback-Leibler Divergence algorithm. More specifically, we work on simple to measure time series, i.e. received interpacket arrival times. In addition of efficiently detecting network QoS disruptions, the algorithm, also drastically reduces the required resources, and the overhead produced by the traffic collection for scalable SLA monitoring systems. The validity of the proposal is verified both in terms of accuracy and consumed resources in a real testbed, using different traffic profiles., Peer Reviewed, Postprint (published version)

Recently, performance evaluation of ad hoc network protocols is done using realistic mobility and traffic models, thus improving the validity and credibility of wireless simulation studies. In this paper we design and implement MixMobGen, a mobility generator for ad hoc vehicular applications, which takes into account mixed vehicular conditions. This is the first mobility model that takes into account, both, slow and fast vehicles. While speed for highway traffic has been modeled following a normal distribution, two studies on the mixed traffic show that speed follows a multimodal or bimodal distribution, instead. In this paper we a) design and implement MixMobGen, a realistic mobility generator that models mixed traffic conditions. b) evaluate protocol performance in 802.11 network protocols using NS 2 simulator., Peer Reviewed, Postprint (published version)

Wireless mobile networks and devices are becoming increasingly popular to provide users the access anytime and anywhere. We are witnessing now an unprecedented demand for wireless networks to support both data and real-time multimedia traffic. The wireless mobile systems are based on cellular approach and the area is covered by cells that overlap each other. In mobile cellular systems the handover is a very important process. Many handover algorithms are proposed in the literature. However, to make a better handover and keep the QoS in wireless networks is very difficult task. For this reason, new intelligent algorithms should be implemented to deal with this problem. In this paper, we carried out a comparison study of two handover systems based on fuzzy logic. We implement two Fuzzy-Based Handover Systems (FBHS) called FBHS1 and FBHS2. The performance evaluation via simulations shows that FBHS2 has better behavior than FBHS1 and can avoid ping-pong effect in all simulation cases., Peer Reviewed, Postprint (published version)

Current service-level agreements (SLAs) offered by cloud providers make guarantees about quality attributes such as availability. However, although one of the most important quality attributes from the perspective of the users of a cloud-based Web application is its response time, current SLAs do not guarantee response time. Satisfying a maximum average response time guarantee for Web applications is difficult due to unpredictable traffic patterns, but in this paper we show how it can be accomplished through dynamic resource allocation in a virtual Web farm. We present the design and implementation of a working prototype built on a EUCALYPTUS-based heterogeneous compute cloud that actively monitors the response time of each virtual machine assigned to the farm and adaptively scales up the application to satisfy a SLA promising a specific average response time. We demonstrate the feasibility of the approach in an experimental evaluation with a testbed cloud and a synthetic workload. Adaptive resource management has the potential to increase the usability of Web applications while maximizing resource utilization., Postprint (published version)

The mobile cellular systems are expected to support multiple services with guaranteed Quality of Service (QoS).But, the ability of wireless systems to accommodate expected growth of traffic load and broadband services is limited by available radio frequency spectrum. Call Admission Control (CAC) is one of the resource management functions, which regulates network access to ensure QoS provisioning. However, the decision for CAC is very challenging issue due to user mobility, limited radio spectrum, and multimedia traffic characteristics. In our previous work, we proposed a fuzzy-based CAC system and compared the performance of the proposed system with Shadow Cluster Concept (SCC). In this work, we extend our work by considering the priority of the on-going connections. We evaluate by simulations the performance of the proposed system and compare its performance with our previous work. The performance evaluation shows that the proposed system has a good behavior in keeping the QoS of on-going connections, Peer Reviewed, Postprint (published version)

Simulation is a common approach for designing ad hoc network applications, due to the slow deployment of these networks. The main building blocks of ad hoc network applications are the routing protocols, mobility, and traffic models. Several studies, which use synthetic models, show that mobility and traffic have a significant effect on protocol performance. Synthetic models do not realistically reflect the environment where the ad hoc networks will be deployed. In addition, mobility and traffic tools are designed independently of each other, however real trace data challenge that assumption. Indeed, recent protocol performance evaluation using real testbeds show that performance evaluations under real testbeds and simulations that use synthetic models differ significantly. In this paper we consider jointly both real mobility and traffic for protocol performance evaluation. The contributions of this work are as follows: (1) demonstrates that real mobility and traffic are interconnected; (2) announces the design and implementation of WIT –Wireless Integrated Traffic–, which includes the design of a real traffic generator; (3) shows that under real mobility and integrated traffic the performance metrics need to be re-thought, thus we propose availability as a new ad hoc network protocol performance metric; and, finally, (4) evaluates protocol performance under synthetic and real mobility models with integrated traffic. We believe that the results of our work constitute a step forward toward benchmarking of ad hoc network performance evaluations., Peer Reviewed, Postprint (published version)

Broadband satellite constellation networks will be required to carry all types of IP traffic, real time interactive traffic as well as non-real time traffic, warranting the need for appropriate QoS for these different traffic flows. In this paper we investigate the need for MPLS traffic engineering in GEO/MEO/LEO satellite networks to address QoS issues. We compare the service received by TCP and UDP flows when they share a link and when they are routed on explicit MPLS traffic trunks. Since MPLS traffic trunks allow non-shortest path links also to be used, the total network throughput goes up with proper traffic engineering. If UDP and TCP flows are mixed in a trunk, TCP flows receive reduced service as the UDP flows increase their rates. Also, we found that with MPLS traffic engineering we can protect real time traffic and VoIP traffic from packet loss and excessive jitter by separating them from other congestion unresponsive flows, Peer Reviewed, Postprint (published version)

In order to support multimedia communication, it is necessary to develop routing algorithms which use for routing more than one QoS parameters. This is because new services such as video on demand and remote meeting systems require better QoS. Also, for admission control of multimedia applications different QoS parameters should be considered. In our previous work, we proposed an intelligent routing and CAC strategy using cooperative agents. In this paper, we propose and evaluate the performance of SSRA algorithm and a GA-based InterD agent. Performace evaluation shows that proposed agents have a good behavior, Peer Reviewed, Postprint (published version)

The mobile cellular systems are expected to support multiple services with guaranteed quality of service (QoS). However, the ability of wireless systems to accommodate expected growth of traffic load and broadband services is limited by available radio frequency spectrum. Call admission control (CAC) is one of the resource management functions, which regulates network access to ensure QoS provisioning. However, the decision for CAC is very challenging issue due to user mobility, limited radio spectrum, and multimedia traffic characteristics. To deal with these problems, in this paper, we propose a fuzzy CAC system. We compare the performance of the proposed system with shadow cluster concept (SCC). We evaluate by simulation the performance of the proposed system. The proposed system has a good behavior on deciding the number of accepted connections while keeping the QoS for serving connections., Peer Reviewed, Postprint (published version)

In this paper we study the properties of a new packet trace compression method based on clustering of TCP flows. With our proposed method, the compression ratio that we achieve is around 3%, reducing the file size, for instance, from 100 MB to 3 MB. Although this specification defines a lossy compressed data format, it preserves important statistical properties present into original trace. In order to validate the method, memory performance studies were done with the Radix Tree algorithm executing a trace generated by our method. To give support to these studies, measurements were taken of memory access and cache miss ratio. For the time, the results have showed that our proposed method provides a good solution for packet trace compression., Peer Reviewed, Postprint (published version)

This paper analyzes the performance of a base station layout for a UMTS network in a densely populated city. The study is carried out using snapshot simulations of an actual city (Barcelona, Spain) with specific traffic and propagation profiles. A first layout is proposed in order to guarantee good coverage with a minimum number of base stations. This layout is approached taking into account the link budget analytical calculations and the first simulation results for a single-cell environment. A second layout is then presented in an attempt to solve the problems that arise in the first (e.g. shadows, blind zones, etc.). This is carried out by finely tuning parameters from the first layout, adding new base stations and changing the locations of the existing ones.

We address the design of a packet buffer for future high-speed routers that support line rates as high as OC-3072 (160 Gb/s), and a high number of ports and service classes. We describe a general design for hybrid DRAM/SRAM packet buffers that exploits the bank organization of DRAM. This general scheme includes some designs previously proposed as particular cases. Based on this general scheme, we propose a new scheme that randomly chooses a DRAM memory bank for every transfer between SRAM and DRAM. The numerical results show that this scheme would require an SRAM size almost an order of magnitude lower than previously proposed schemes without the problem of memory fragmentation., Peer Reviewed, Postprint (published version)

This document considers the performance of multiantenna transmit/receive techniques in high-speed downlink and uplink packet access. The evaluation is done using both link and system level simulations by taking into account link adaptation and packet retransmissions. The document is based on the initial studies carried out in deliverables D3.1 and D3.2., Preprint

In order to support the enormous growth of the Internet, innovative research in every router subsystem is needed. We focus our attention on packet buffer design for routers supporting high-speed line rates. More specifically, we address the design of packet buffers using virtual output queuing (VOQ), which are used in most modern router architectures. The design is based on a previously proposed scheme that uses a combination of SRAM and DRAM modules. We propose a storage scheme that achieves a conflict-free memory bank organization. This leads to a reduction of the granularity of DRAM accesses, resulting in a decrease of storage capacity needed by the SRAM. In the DRAM/SRAM scheme, SRAM memory bandwidth needs to fit the line rate. Since memory bandwidth is limited by its size, searching for memory schemes having a small SRAM size arises as an essential issue for high speed line rates (e.g. OC768, 40 Gbps and OC3072, 160 Gbps)., Peer Reviewed, Postprint (published version)

This activity evaluates the extension of the bandwidth of the UTRA MIMO HSDPA concept to 20 MHz, which is precisely the bandwidth of HIPERLAN/2. This would allow a fair comparison between the performance of UTRA MIMO HSDPA and the enhanced HIPERLAN/2. The bandwidth expansion would be the consequence of multiplying the chip rate of the W-CDMA spreading by four, i.e., 3.84 x 4 = 15.36 Mcps. A higher bandwidth MIMO channel model is necessary and this will be developed based on the channel model already developed in WP2. High data rates are required to satisfy the ever-increasing application requirements in future wireless communication systems. Recent investigations have indicated that a peak data rate of up to 20Mbps per user in the DL may be required for satisfactory reception of bursty traffic. As the transmission powers (of both mobile terminals and base stations) are limited, higher data rates lead to the reduction of the effective coverage area of a cell. That is, only users that are close to the base station will be able to communicate with high data rates, while users far away from the base station will only be able to use low data rates., Preprint

In this activity MIMO HSDPA is evaluated as the UMTS evolution that could allow a combination of high bit rate services, coverage and mobility with a good trade-off between cost and performance. This evaluation requires the definition of an objective framework for comparison between competing air interface technologies for Systems beyond 3G, and should be carried out in cooperation with other IST projects. The deliverable is complemented by analytically assessing channel capacity in flat Rician- and Rayleigh fading when ideal proportional fast scheduling, optimal rate adaptation, and various transmit diversity techniques are used., Preprint

This deliverable contains a description of the space-time coding algorithms to be simulated within the I-METRA project. Different families of algorithms have been selected and described in this document with the objective of evaluating their performance. One of the main objectives of the I-METRA project is to impact into the current standardisation efforts related to the introduction of Multiple Input Multiple Output (MIMO) configurations into the High Speed Downlink and Uplink Packet Access concepts of UMTS (HSDPA and HSUPA). This required a review of the current specifications for these systems and the analysis of the impact of the potential incorporation of the selected MIMO schemes., Preprint

This deliverable provides a high level description of the software developed within the I-METRA project following the selection reported in D3.1 "Design, Analysis and Selection of Suitable Algorithms"., Preprint

The Available Bit Rate service (ABR) is a "best effort" service intended for traffic which imposes no bound on delay or delay variation. The network guarantees a Minimum Cell Rate (MCR) for an ABR source, which is negotiated at the connection set up, and commits to fairly divide the unused bandwidth among all ABR sources., This work was partly supported by the Ministry of Education of Spain under grant TIC95-09-82 and by project ACTS 094 "EXPERT"., Peer Reviewed, Postprint (published version)

The transmission of multimedia contents through broadband networks is constrained by a certain Quality of Service (QoS) that must be guaranteed. Textual contents need few network resources and no real time constraints are required. However, the new audio and video services (such as video on demand) need better network performance., Peer Reviewed, Postprint (published version)

The purpose of this paper is to show that using decoupling techniques in a vector processor, the performance of vector programs can be greatly improved. Using a trace driven approach, we simulate a selection of the Perfect Club programs and compare their execution time on a conventional vector architecture and on a decoupled vector architecture. Decoupling provides a performance advantage of more than a factor of two for realistic memory latencies, and even with an ideal memory system with no latency, there is still a speedup of as much as 50%. A bypassing technique between the load/store queues is introduced and we show how it can give up to an extra speedup of 22% while also reducing total memory traffic by an average of 20%. An important part of this paper is devoted to study the tradeoffs involved in choosing an adequate size for the different queues of the architecture, so that the hardware cost of the queues can be minimized while still retaining most of the performance advantages of decoupling., Peer Reviewed, Postprint (published version)