Daniel Corujo | University of Aveiro (original) (raw)

Papers by Daniel Corujo

Envisioning a future where mobile terminals equipped with one or more network 9 devices are able ... more Envisioning a future where mobile terminals equipped with one or more network 9 devices are able to roam across wireless or wired networks, in a multi-diverse macro and micro wireless cells environment, requires the development of enhanced methods 11 to control IP based mobility. These methods should consider traditional terminal 12 mobility (mainly due to user movement) as well as mobility across heterogeneous 13 networks in the presence of semi-static users. For this to become reality, a cross 14 layer interaction starting from a potential large diversity of layer two access net-15 works up to the common IP layer is required, allowing the exchange of messages 16 between terminals and network components. Therefore, traditional host mobility 17 driven concepts need to meet more stringent mobile operator requirements in con-18 text of fully driven network controlled mobility. This paper presents and evaluates 19 a novel framework design, based on the IEEE 802.21 future standard, encompassing 20 network driven as well as host driven mobility 1 . 21 IP Mobility has been widely explored in the research community. IETF 2 pro-25 tocols, such as [1], [2], [3], [4] and their extensions or optimizations [5], [6], 26 are becoming mature and already first implementations are available for de-27 ployment. This is being paralleled by large scale ambitions, which will require 28 synergy across multiple technology aspects [7]. Liaisons between standardiza-29 tion bodies are happening with increasing frequency. As examples, 3GPP 3 30 (defining architecture reference scenarios for next generation Mobile Oper-31 ators networks), the WiMax forum 4 (defining the WiMax mobile reference 32 architecture) and the IEEE 5 802.21 working group (defining the standard 33 for enhanced vertical handover strategies) are actively discussing liaisons with 34 IETF to agree on a common set of requirements to ensure the compatibility 35 between architectures and protocols for mobility [8], [9], [10]. In other words, 36 while IETF mobility protocols use the IP layer as convergence layer, it still has 37

In the future mobile Internet, a key challenge is how the content is delivered to the mobile user... more In the future mobile Internet, a key challenge is how the content is delivered to the mobile user, especially when there are multiple networks belonging to distinct operators. Knowing the network services and conditions available at each one becomes crucial. In order to store information from several networks and operators, the new IEEE 802.21 standard specifies a Media Independent Information Service (MIIS) supporting various information elements (IEs) that provide network information within a geographical area, with the aim of optimising the handover process. Since next-generation wireless devices are expected to support multiple radio access networks, users will be able to maintain connections when switching from one network to another. This article addresses a general approach towards the deployment of a Hierarchical 802.21 Information Service management infrastructure in a heterogeneous mobile environment. Through an NS-2-based simulation, it is shown that the proposed scheme improves the user experience in terms of MIIS server access time and number of optimal handovers in a random mobility scenario.

The FP7 M EDIEVAL project, which started in 2010, has been defining the necessary evolutions over... more The FP7 M EDIEVAL project, which started in 2010, has been
defining the necessary evolutions over today’s mobile Internet architecture, in
order to more efficiently support the upcoming growth of video services, in
mobile wireless environments. This paper evolves from these initial definitions, by taking into consideration the requirements placed by a core set of next generation video services and defining a global architecture. We describe its main functionalities and subsystems as well as the necessary interfaces, towards the operation of these services in different use cases.

The evolution of telecommunications has allowed the coupling of networking features to an ever-in... more The evolution of telecommunications has allowed the
coupling of networking features to an ever-increasing plethora
of devices, enabling their connectivity and berthing of an
Internet of Things (IoT). However, the assorted nature of such
“things” implies disparate specifications, requirements and
interfacing, for interaction with high-level decision modules,
services and agents involved in the most distinct kind of
scenarios. The joint operation of all networkable things in a
truly integrated IoT vision requires a flexible framework able to
facilitate interfacing with different elements and concepts. In
this paper we present a framework that builds over the concept
of Media Independence, further enhancing it to encompass the
abstraction of different “things”, by providing the means for
accessing their different interfacing procedures. We highlight
the feasibility and flexibility of this framework by introducing it
into an IoT scenario, enabling a flexible way for interface
retrieval and control of different entities, paving the way for a
truly universal and dynamic connectivity vision.

IEEE Communications Magazine, Jan 1, 2011

Taking advantage of the multi-mode ability of modern mobile terminals, cellular operators are inv... more Taking advantage of the multi-mode ability of modern mobile terminals, cellular operators are investing in alternate access networks (such as IEEE802.11 and IEEE802.16) complementing the increasingly overloaded cellular accesses. Complementing this, IP mobility support is gradually being introduced into network architectures, providing session continuity. To facilitate and optimize handover procedures between different access technologies in a seamless way, the IEEE802.21 Media Independent Handover Services standard provides technology agnostic mechanisms to obtain information and control link layers. Implementations of the standard are appearing, but since the support of IEEE802.21 primitives directly at link driver level is not yet realized, they have to revert to proprietary wrapping mechanisms, or use specific operating system solutions, to circumvent this issue. In this paper we present ODTONE, an IEEE802.21 implementation that is operating-system independent and open-source, and offers a novel approach towards interfacing with different link layers which facilitates the deployment of IEEE802.21 mobility mechanisms in multiple scenarios. We present a scenario where we integrate our middleware with an IP mobility management protocol, Proxy MIP IPv6, highlighting ODTONE’s supporting features and impact while providing an open handover control architecture for network based localized mobility management.

The evolution on ambient intelligence technologies, such as sensor networks, propelled a universe... more The evolution on ambient intelligence technologies, such as sensor networks, propelled a universe of very diverse types of both data and hardware equipment creating one of the most heterogeneous network environments. This diversity brings to light the main issue we aim to address in this paper: the need for a common ground that enables communications between the different heterogeneous equipments and technologies. Starting from the well-established IEEE 802.21 Media Independent Handover standard, we propose its mechanisms and structure to
be extended to provide the needed common ground for communication in ambient intelligence scenarios. In this work, we extend 802.21 to include sensor information, enabling different types of equipment and network technologies to
communicate with each other under a common standard contributing to a truly heterogeneous network framework. To conclude, we address its viability through a comparison with other known solutions for communication on sensing devices.

The wide deployment of Wireless Local Area Networks (WLAN) we are witnessing today increases conn... more The wide deployment of Wireless Local Area
Networks (WLAN) we are witnessing today increases
connectivity opportunities for mobile terminal devices, such as
smartphones. However, continuous scanning for WLAN points of
attachment can be a power exhausting mechanism for such
battery-powered devices. These mobile devices, besides being
equipped with different wireless access interfaces, are also
coupled with sensors such as accelerometer, GPS , luminance
and magnetic compass. In fact, sensors are increasingly being
coupled into different devices and environments and are able to
convey sensing information through networks into decision
entities able to optimize different processes. In this paper we
propose a framework where media independent sensing
information is used to enhance wireless link management
towards energy-efficiency. This framework enables the
dissemination of sensing information towards local and remote
decision entities, enhancing other processes (e.g. mobility) with
sensing information in order to provide true Ambient
Intelligence scenarios. We introduce this framework into a
wireless management scenario able to provide energy-efficient
optimal network connectivity.

Deploying Smart Environments often implies a plethora of co-existing devices and services, each w... more Deploying Smart Environments often implies a plethora of co-existing devices and services, each with their own set of features, requirements and interfacing characteristics. These intricate scenarios are further exacerbated when such devices are coupled with networking capabilities, globalizing their interaction opportunities to create the so-called Internet of Things. In such interconnected heterogeneous environments, the joint operation of entities requires a flexible framework that enables and simplifies interfacing between elements. In this paper, we propose MINDiT, a framework that provides a common abstract interface towards the communication support with different entities. It incorporates cross-layer mechanisms inspired on the existing IEEE 802.21 technology, suitably modified to facilitate and optimize deployment in scenarios featuring both high-level, and low-powered network-restricted entities. MINDiT was validated through a prototype built over an open-source IEEE 802.21 implementation. We further compared its signaling impact against other solutions, and evaluated its performance over a smart environment featuring a multimedia scenario with multiple devices and services.

The utilization of Media Independent Handover (MIH) mechanisms, such as the ones provided by the ... more The utilization of Media Independent Handover (MIH) mechanisms, such as the ones provided by the IEEE802.21 standard, allow the abstraction of control and information querying primitives of different wireless access technologies, using a common interface. This not only simplifies the design of high-level entities interfacing with said technologies, but by providing a transport protocol for that interface, such primitives can be used to extend controlling mechanisms towards remote entities. However, the standard only employs such flexible and abstraction capabilities towards handover optimization and facilitation scenarios. In this paper, we take advantage of the flexible design of the MIH mechanisms, and propose evolutions over their base design, allowing their integration into the areas of Internet Multimedia Optimization and the Internet of Things.

The proliferation of mobile terminals coupled with multiple wireless interfaces has created compl... more The proliferation of mobile terminals coupled with multiple wireless interfaces has created complex scenarios where network operators need to provide connectivity in heterogeneous environments. To facilitate handover procedures in these scenarios, the 802.21 standard has been specified, providing Media Independent Handover (MIH) services allowing control and information gathering from different access interfaces. However, accessing these procedures requires the discovery of supporting nodes and their capabilities. This paper provides a description and performance comparison of different available MIH discovery schemes and proposes a novel local discovery procedure for automatically detecting link interfaces in MIH-enabled entities, showing by evaluation that its deployment increases performance and requires less information exchange.

The increase will of ubiquitous access of the users to the requested services points towards the ... more The increase will of ubiquitous access of the users to the requested services points towards the integration of heterogeneous networks. In this sense, a user shall be able to access its services through different access technologies, such as WLAN, Wimax, UMTS and DVB technologies, from the same or different network operators, and to seamless move between different networks with active communications. In this paper we propose an end-to-end QoS architecture able to support this users' ubiquitous access and seamless movement. This architecture is able to support QoS on unicast and multicast services, as well as in unicast and broadcast unidirectional networks, in multihomed environments. The integration of measurements for aid in admission control, inter-domain QoS approach, and integration with mobility is also presented.

Next Generation Networks (NGN) will be based upon the “all IP” paradigm. The IP protocol will glu... more Next Generation Networks (NGN) will be based upon the “all IP”
paradigm. The IP protocol will glue multiple technologies, for both
access and core networks, in a common and scalable framework that
will provide seamless communication mobility not only across those
technologies, but also across different network operators. In this
article we describe a framework for QoS support in such NGNs,
where multi-interface terminals are given end-to-end QoS
guarantees regardless of their point of attachment. The framework
supports media independent handovers, triggered either by the user
or by the network, to optimize network resources’ distribution. The
framework integrates layer two and layer three handovers by
exploiting minimal additions to existing IETF and IEEE standards.

The availability of multiple technologies, with micro and macro wireless cells, for network acces... more The availability of multiple technologies, with
micro and macro wireless cells, for network access combined
with terminals capable of exploiting such diversity in wireless
access requires the development of new mechanisms for
optimized handover procedures. Appealing solutions should
support network controlled handovers through heterogeneous
technologies, preferably combined with a cross-layers two/three
design. The IEEE 802.21 working group is currently
standardizing the methods and the protocol potentially able to
provide such a solution. In this paper we analyze the impact of
signaling timing on network controlled handovers execution and
performance in this environment. Through an extensive
simulation study, we obtain results, that can be exploited in both
terminal and handover procedure designs.

This paper describes and evaluates the aplication of the IEEE 802.21 standardto an heterogeneous ... more This paper describes and evaluates the aplication
of the IEEE 802.21 standardto an heterogeneous networks
IP mobility environment, where handovers are network-
controlled. The mobility management complexity, increased
by the different tecnologies the terminal is able to connect
to, requires the interaction of information pertaining to the
link devices at the terminal (detected links and received signal
strength) as well as network information (user load at a certain
cell, user preferences). For this paper, a framework was devel-
oped where the IEEE 802.21 allows this information sharing in
a media independent way, which was evaluated through simu-
lation.

Wireless network access and the exchange of multimedia flows over the Internet are becoming more ... more Wireless network access and the exchange of multimedia flows
over the Internet are becoming more and more pervasive in the
everyday life. However, simple technological advances in terms
of improved network capacity cannot satisfy the increasing
demand of such services, since a paradigm shift from the
current Internet architecture is required. The EU FP7 MEDIEVAL
project tackles this issue by addressing novel architectural
frameworks and viable strategies to efficiently deliver video
services in a wireless Internet context. This paper reviews the
currently ongoing activities of the project for what concerns
wireless access, in particular the identification of useful
techniques for the considered access technologies (WLAN and
LTE-A) and the general definition of architectural schemes to
efficiently support video flows.

The integration of the digital world into every aspect of our lives is becoming more and more pre... more The integration of the digital world into every aspect of our lives is becoming more and more preeminent. Nowadays, not only humans but also devices and the environments where we dwell are also able to provide their own information, through the usage of sensors. Through their interconnection over communication networks, sensors enable Ambient Intelligent scenarios achieving a true Internet of Things, and crossing the gap between computer systems and the real world. However, the different sensing devices and information generated by them, are of such disparate nature that it becomes increasingly difficult to access and make use of such heterogeneous data. In this paper, we propose a framework which not only considers a media independent information access to sensors and their supplied data, but is also flexible enough to configure and provide different means to best transport collected sensor information via wireless gateways, facilitating its deployment in different scenarios. We demonstrate its usefulness by providing a throughput efficient approach towards the collection and dissemination of sensing data, through sensing information compression and aggregation of multiple sources.

With the foreseen major increase in video traffic over the coming years, the current Internet’s d... more With the foreseen major increase in video traffic over the coming years, the current Internet’s design is being perceived as inefficient for handling the demanding flow of video over wireless access networks, populated by an ever increasing number of mobile terminals. The MEDIEVAL project aims to evolve the current Internet architecture to provide an optimized video support in all layers of the protocol stack. With its cross-layer approach, abstraction mechanisms such as IEEE802.21 will work as enablers between the different architecture modules. With the widespread diffusion of video being realized over multicast and broadcast channels for resource optimization, using 802.21 signalling to optimize handovers affecting groups of users will generate multiple messages to each individual terminal. In this article, we extend 802.21 to support multicast transport of its signalling, enabling more efficient group handover scenarios.

Sensor networks, along with the sensorial output from their nodes, provide an information source ... more Sensor networks, along with the sensorial output from their nodes, provide an information source to enhance and enrich upper layers mechanisms. The 802.21 MIH protocol provides a cross layer framework that can be extended for sensor information transport. At the same time, it creates an abstraction layer that removes hardware and software specificity from sensor nodes. On a higher level of the network stack, the XMPP protocol also provides an upper layer solution for content syndication on a platform with global access availability. We present a framework which integrates a cross-layer abstraction approach towards sensor devices of different families, while enabling the integration of media-independent sensor information into context consumers with the aim of optimizing network management, as well as application operation and usability. The work presented was also part of the first author’s MsC dissertation.

Computer Networks, Jan 1, 2007

Envisioning a future where mobile terminals equipped with one or more network devices are able to... more Envisioning a future where mobile terminals equipped with one or more network devices are able to roam across wireless or wired networks, in a diverse macro and micro wireless cells environment, requires the development of enhanced methods to control IP-based mobility. These methods should consider traditional terminal mobility (mainly due to user movement) as well as mobility across heterogeneous networks in the presence of semi-static users. For this to become reality, a cross layer interaction is required starting from a potentially large diversity of layer two access technologies up to the common IP layer, allowing the exchange of messages between terminals and network components. Furthermore, traditional host mobility driven concepts need to evolve, and include more stringent mobile operator requirements in context of fully driven network controlled mobility. This paper presents and evaluates a novel framework design, based on the IEEE 802.21 future standard, encompassing network driven as well as host driven mobility. This paper evaluates signalling aspects, algorithm design and performance issues.

… , 2007. ISCC 2007. …, Jan 1, 2007

In the future, mobile terminals will be equipped with several interfaces to different technologie... more In the future, mobile terminals will be equipped with
several interfaces to different technologies - such as
UMTS, IEEE 802.11, DVB and WiMAX- and will be
able to connect simultaneously to the most appropriate
access networks. This paper presents a mobility and
QoS architecture aiming at supporting intelligent
handovers. We introduce the concept of Network-
Assisted Mobile terminal Initiated HandOver
(NAMIHO), where the handover decision is negotiated
between the network and the user, taking into account
inputs and decision algorithms running both on the
terminal and network. We also present an instantiation
of the architecture using IEEE 802.21 and concepts of
locallglobal mobility. We further propose extensions to
IEEE 802.21 standard.

IEEE Communications Magazine, Jan 1, 2011

Computer Networks, Jan 1, 2007

… , 2007. ISCC 2007. …, Jan 1, 2007