Manuel Alvarez-Campana

A Simulation Tool for Dimensioning and Performance Evaluation of the UMTS Terrestrial Radio Access Network

The efficient support of multiple traffic classes with different quality of service requirements (end-to-end delay, jitter, loss) poses an extraordinary complexity in the design of third-generation mobile networks. This task becomes especially critical for the access network, where radio and transmission resources are usually scarce. In this paper we present a simulation model of the ATM-based UMTS (Universal Mobile Telecommunications System) terrestrial radio access network. The simulator aims to provide a test bed for conducting further research studies on several topics of potential interest. In particular, we intend to use the tool for dimensioning ATM links, for evaluating performance under different mixes of traffic classes, and for investigating quality of service mechanisms. This wide range of applications has led us to develop a very flexible simulation model that captures many low level details. Some preliminary results obtained with the simulator are presented in order to illustrate its capabilities.

MEHARI: a system for analysing the use of the internet services

Abstract This paper describes the MEHARI system for monitoring and analysing the traffic on National R&D Networks (NRN). The main design requirement of the MEHARI system was to cope with the main challenges currently faced by most of these networks: Service usage, charging schemes, network dimensioning and auditing procedures according to a given Acceptable Use Policy (AUP). The resulting MEHARI system consists of a low cost hardware traffic capture platform, and several traffic analysis software modules running on top of this platform. These modules can report information on the usage of the Internet services, the main traffic origin and destinations, etc. The MEHARI system has been tested by running a field trial on the Spanish NRN (RedIRIS). Some relevant data on the performance and efficiency of the system configuration used in the field trial is presented in this paper.

Simulation of quality of service mechanisms in the UMTS terrestrial radio access network

Supporting multiple traffic classes with different QoS (quality of service) constraints in third generation mobile systems is not a straightforward problem. This issue becomes critical at the access network interfaces, where transmission resources are usually expensive. One of the most important interfaces is the one that connects each base station with its controller, because there can be many instances of it. We have approached the dimensioning of this interface from the perspective of simulation, concretely for the UMTS (Universal Mobile Telecommunications System) access network. We have developed a simulation model capable of representing multi-service scenarios inside this particular UTMS interface. This tool can be fed with traffic of different types, representing the different traffic classes defined for UMTS, and is able to simulate traffic differentiation both at the ATM (Asynchronous Transfer Mode) and the AAL2 (ATM Adaptation Layer 2) level. We present simulation results showing how the simulator can aid us in the task of access network dimensioning with QoS constraints.

Performance modeling of web access over HSPA networks

HSPA (High Speed Packet Access) technologies have become an attractive solution for broadband wireless Internet access. This article evaluates the quality of service experimented by one HSPA user in the presence of multiple terminals sharing the cell capacity. The study focuses on Web traffic and includes analytical and simulation results, providing a basis for dimensioning and admission control in HSPA networks given the intended user quality of experience. The results show that the downlink channel capacity can be shared by several tens of Web users with a satisfactory quality. This is possible because the activity factor of this application (i.e. the time spent in downloading pages compared to the time spent in reading them) is low. However, the results also indicate that the page download time is penalized by the delay associated with the initial procedure for allocating resources on the traffic channels. This problem can be alleviated by an adequate configuration of the timers associated to the resource allocation procedures in HSPA.

Smart CEI Moncloa: An IoT-based Platform for People Flow and Environmental Monitoring on a Smart University Campus

Internet of Things platforms for Smart Cities are technologically complex and deploying them at large scale involves high costs and risks. Therefore, pilot schemes that allow validating proof of concepts, experimenting with different technologies and services, and fine-tuning them before migrating them to actual scenarios, are especially important in this context. The IoT platform deployed across the engineering schools of the Universidad Politécnica de Madrid in the Moncloa Campus of International Excellence represents a good example of a test bench for experimentation with Smart City services. This paper presents the main features of this platform, putting special emphasis on the technological challenges faced and on the solutions adopted, as well as on the functionality, services and potential that the platform offers.

Network Convergence over MPLS

Multiprotocol Label Switching (MPLS) is emerging as a flexible technology that can transport voice, IPv4, IPv6, layer 2 services (Frame Relay, ATM, Ethernet, etc.), and even PDH and SDH/SONET circuits over a single packet infrastructure, in a new attempt to solve the old problem of network convergence. MPLS traffic engineering, quality of service support (in combination with DiffServ), and fast restoration capabilities can be used to provide each service with strict service-level agreements (SLAs) in a cost- efficient way. Several standardization and industry organizations are contributing to this goal. This article reviews current activities in the IETF, MPLS/Frame Relay Alliance, and ITU-T related to transport over MPLS, comparing their approaches, identifying overlaps, and open issues.

Reliable signalling transport in next generation networks

Next-generation network architectures aim at the convergence of services (e.g. telephony, television, Web access, online games, and new services) over a common IP core. Additionally, the integration of wired and wireless access technologies will offer users ubiquitous access to all those services. Telecommunications networks rely on signalling protocols to perform key service control functions such as locating and authenticating users, establishing communication sessions, reserving resources, charging, etc. Signalling is crucial for network operators and so requires a transport service with very high availability and low delay. Traditionally, operators have deployed dedicated and highly redundant signalling networks following ITU-T standards. More recently, and motivated by the current evolution towards IP, the IETF has defined SIGTRAN, a new protocol suite intended to transport signalling protocols over IP. This paper addresses the problem of configuring the protocol mechanisms existing at different layers of the SIGTRAN architecture in a coordinated way, with the goal of creating a redundant network topology able to meet the stringent availability levels required for signalling in carrier-grade networks. The proposed solution is described and evaluated numerically.

Measuring Quality of Experience of Internet Access over HSDPA

High-Speed Downlink Packet Access (HSDPA) is being introduced by mobile operators as a solution both for increasing the downlink throughput and for achieving a more efficient usage of the radio resources. This work analyses the quality of experience of HSDPA users, based on experiments and measurements over a commercial network. The effect of multiple users sharing the overall capacity of the cell is explicitly evaluated. The results show that the HSDPA user experience for Internet access is satisfactory and in some cases comparable to that achievable over fixed access technologies such as ADSL. In addition, we explore the impact of TCP configuration on the HSDPA performance and suggest suitable parameter values.

Efficiency and quality of service issues in MPLS transport for the UMTS access network

Multiprotocol Label Switching (MPLS) offers a simple and flexible transport solution for multiservice networks, and many operators are currently using or considering the use of an MPLS backbone. In UMTS networks, MPLS can be used both in the access part (i.e. the links that provide connectivity to each base station) and in the core. However, the efficient transport of short voice and data packets in the UMTS access network requires multiplexing and segmentation functions not provided by MPLS. This paper investigates the use of ATM Adaptation Layer 2 (AAL2) over MPLS to perform both functions. The efficiency of AAL2/MPLS is analyzed for different traffic types and compared with other transport options. The results indicate that significant capacity savings can be obtained with this solution.

Efficiency Issues in MPLS Transport for the UMTS Access Network

Multiprotocol Label Switching (MPLS) offers a simple and flexible transport solution for multiservice networks. Therefore, many UMTS operators are currently considering the use of a MPLS backbone. However, the efficient transport of short voice and data packets in the UMTS access network requires multiplexing and segmentation functions not provided by MPLS. This paper investigates the use of ATM Adaptation Layer 2 (AAL2) over MPLS to perform both functions. The efficiency of AAL2/MPLS is analyzed for different traffic types and compared with other transport options. The results indicate that significant capacity savings can be obtained with this solution.