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- Professor (Associate)
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June 2009 - July 2013
Publications
Publications (58)
Documents in the Air is a middleware system that allows placing and retrieving virtual objects or documents at different indoor locations without requiring a positioning system. It consists of an Android application and an intranet or cloud server, and only makes use of existing WiFi or BLE infrastructure to produce location specific signatures. We...
Location privacy poses a critical challenge as the use of mobile devices and location-based services becomes more and more widespread. Proximity-detection data can reveal sensitive information about individuals, making it essential to preserve their location data. One way to achieve privacy protection is by adding noise to ground-truth data, which...
In this paper, we propose FlexTDOA, an indoor localization method and a system using ultra-wideband (UWB) radios. Our method uses time-difference of arrival (TDOA) localization so that the user device remains passive and is able to compute its location simply by listening to the communication between the fixed anchors, ensuring the scalability of o...
Future social networks will rely heavily on sensing data collected from users’ mobile and wearable devices. A crucial component of such sensing will be the full or partial access to user’s location data, in order to enable various location-based and proximity-detection-based services. A timely example of such applications is the digital contact tra...
Ultra-wideband (UWB) communications have gained popularity in recent years for being able to provide distance measurements and localization with high accuracy, which can enhance the capabilities of devices in the Internet of Things (IoT). Since energy efficiency is of utmost concern in such applications, in this work we evaluate the power and energ...
This paper presents a measurement-based analysis of the Received Signal Strength (RSS) of Bluetooth Low Energy (BLE) signals, under Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) scenarios, performed in tandem at two universities in Tampere, Finland, and Bucharest, Romania. We adopted the same hardware and methodology for measurements in both pla...
Ultra-wideband (UWB) communications have gained popularity in recent years for being able to provide distance measurements and localization with high accuracy, which can enhance the capabilities of devices in the Internet of Things (IoT). Since energy efficiency is of utmost concern in such applications, in this work we evaluate the power and energ...
Future wearable devices are expected to increasinglyexchange their positioning information with various Location-Based Services (LBSs). Wearable applications can includeactivity-based health and fitness recommendations, location-based social networking, location-based gamification, amongmany others. With the growing opportunities for LBSs, it isexp...
In this paper, we give a brief survey of the main research results in the area of wearable localization solutions, with a particular focus on the privacy constraints in the localization on wearable devices. We identify several open research challenges and define open questions for further research directions. It is shown that finding adequate metho...
Position and orientation information of individual nodes in ad hoc and sensor networks is useful for both service and application implementation. Ad hoc positioning system (APS) is a family of multihop positioning schemes using the basic idea of distance vector (DV) routing to find positions in an ad hoc network using only a fraction of landmarks,...
We propose the innovative architecture of Superfluidity, a Horizon 2020 project, co-funded by the European Union. Superfluidity targets 5G networks, by addressing key network operator challenges with a multi-pronged approach, based on the concept of a flexible, highly adaptive, superfluid network. Superfluidity supports rapid service deployment and...
Această lucrare propune un studiu aplicativ al funcțiilor și serviciilor care stau la baza operării stivei TCP/IP și a rețelei Internet “clasice” (ex. dirijare, rutare, conversia de adresa, configurare parametrii de rețea), fiind destinată în principal studenților Facultății de Electronică, Telecomunicații și Tehnologia Informației (ETTI/UPB), de l...
Mobile devices today rely on cellular (3G or LTE) connectivity because it has ubiquitous coverage. Unfortunately cellular links are energy hungry at low bit-rates and have high round-trip times after idle periods. These characteristics punish common mobile applications such as web browsing and streaming, decreasing battery life and user satisfactio...
Multihop wireless relays can extend the area of network connectivity instantly and efficiently. However, due to the spatial dependence of wireless link-quality, the deployment of relay nodes requires extensive, expensive measurement, and management efforts. This paper presents a mobile autonomous router system, (MARS) through which a relay router a...
This paper aims to exploit spectrum white spaces in time-domain via the Dynamic Spectrum Access (DSA) technology. DSA relies on opportunistic access of licensed spectrum by unlicensed devices. Any “unlicensed-with-licensed” coexistence must ensure “safe” (i.e., un-interfered) communications for the incumbents, while achieving high spectrum-use effi...
Optimizing distributed applications in the cloud requires network topology information, yet this information is kept confidential by the cloud providers. Today, applications can infer network properties and optimize accordingly but this is costly to get right. The cloud can optimize the network via load balancing, but the scope is limited to moving...
An architecture based on new concepts of Content Aware Networking (CAN) and Network Aware Applications (NAA) is proposed in FP7 ALICANTE research project as a better support for multimedia flows across the internet. A virtual CAN is a multi-domain overlay network based on light virtualization, provisioned to enable customized treatment of data flow...
Host mobility has traditionally been solved at the network layer, but even though Mobile IP has been standardised for 15 years, it hasn't been supported by operators. IP's double role as a location identifier and communication endpoint identifier brings a number of functional and performance problems. We argue that the best place to handle mobility...
Judiciou sly assigning channels to a wireless mesh network can substantially enhance capacity of the network. One particular flavor of mesh network is that with a tree topology, which has the property that all traffic passes through one central point. Usually the allocation problem is linked to problems of routing, load, and measurements of interfe...
When supporting both voice and TCP in a wireless multihop network, there are two conflicting goals: to protect the VoIP traffic, and to completely utilize the remaining capacity for TCP. We investigate the interaction between these two popular categories of traffic and find that conventional solution approaches, such as enhanced TCP variants, prior...
This paper proposes a new architectural solution to support Quality of Services (QoS) for real time media flows in a multi-domain system based on new concepts as Content-Aware Networks (CAN) and Network Aware Application (NAA). The system described, based on coupling between network and applications is focused, but not limited to, on multimedia ser...
ALICANTE is a recently proposed architecture that enables a lightweight form of virtualization for the purpose of offering QoS to media streams across the internet. A content aware network (CAN) is a cross domain overlay, which is provisioned in advance in order to provide preferential treatment to media streams. While it uses legacy infrastructure...
The capacity of wireless mesh networks can be enhanced with judicious channel assignment. This paper deals with one particular type of mesh network topology - the tree topology. The unique characteristics of this topology is that all the traffic to/from the mesh nodes goes through the root. This enables design of an efficient channel allocation alg...
Availability of multiple antennas enables increased capacity or increased resilience for modern radios. This advantage depends on the deployment of the antennas at the sender and receiver. But there is a performance gap between most simulated results and the actual performance obtained in practice. This is due to the rank of the channel obtained in...
When supporting both voice and TCP in a wireless multihop network, there are two conflicting goals: to protect the VoIP traffic, and to completely utilize the remaining capacity for TCP. We investigate the interaction between these two popular categories of traffic and find that conventional solution approaches, such as enhanced TCP variants, prior...
When supporting both voice and TCP in a wireless multihop network, there are two conflicting goals: to protect the VoIP traffic and to completely utilize the remaining capacity for TCP. We investigate the interaction between these two popular categories of traffic and find that many solution approaches, such as enhanced TCP variants, priority queue...
ABSTRACT The interference map,of an 802.11 network is a collection of data structures that can help heuristics for routing, channel assignment and call admission,in dense wireless networks. The map,can be obtained from detailed measurements, which are time consuming and require network down time. We explore methods,and models to produce the interfe...
In the recent past, there has been a tremendous increase in the popularity of VoIP services as a result of huge growth in broadband access. The same voice-over-Internet protocol (VoIP) service poses new challenges when deployed over a wireless mesh network, while enabling users to make voice calls using WiFi phones. Packet losses and delay due to i...
Performance in multihop wireless networks is known to degrade with the number of hops for both TCP and UDP traffic. For VoIP, the wireless network presents additio nal challenges as the perceived quality is dependent on both loss and delay. We investigate several methods to improve voice quality and present experimental results from an 802.11b test...
When compared with now classical MANETs, sensor networks have different characteristics, and present different design and engineering challenges. One of the main aspects of sensor networks is that the solutions tend to be very application-specific. For this reason, a layered view like the one used in OSI imposes a large penalty, and implementations...
Angle of arrival (AOA) has previously been used for outdoor positioning in aircraft navigation and for services like E911. For indoor positioning, the best schemes to date rely either on extensive infrastructure, or on sampling of the signal strength on a dense grid, which is subject to changes in the environment, like furniture, elevators, or peop...
Position and orientation of individual nodes in ad hoc sensor networks are useful for both service and application implementation. Services that can be enabled by availability of position include routing and querying. At application level, position is required in order to label the reported data in a sensor network, whereas position and orientation...
APS algorithms use the basic idea of distance vector routing to find positions in an ad hoc network using only a fraction of landmarks, for example GPS enabled nodes. All the nodes in the network are assumed to have the possibility of measuring: range, angle of arrival (AOA), orientation, or a combination of them. We give a lower bound for position...
APS algorithms use the basic idea of distance vector routing to find positions in an ad hoc network using only a fraction of landmarks, for example GPS enabled nodes. All the nodes in the network are assumed to have the possibility of measuring: range, angle of arrival (AOA), orientation, or a combination of them. We give a lower bound for position...
Position and orientation information of individual nodes in ad hoc networks is useful for both service and application implementation. Services that can be enabled by availability of position include routing and querying. At application level, position is required in order to label the reported data in a sensor network, whereas position and orienta...
Trajectory based forwarding (TBF) is a novel method to forward packets in a dense ad hoc network that makes it possible to route a packet along a predefined curve. It is a hybrid between source based routing and Cartesian forwarding in that the trajectory is set by the source, but the forwarding decision is based on the relationship to the trajecto...
Relentless progress in hardware technology and recent advances in sensor technology, and wireless networking have made it feasible to deploy large scale, dense ad-hoc networks. These networks together with sensor technology can be considered as the enablers of emerging models of computing such as embedded computing, ubiquitous computing, or pervasi...
Position centric approaches, such as Cartesian routing, geographic routing, and the recently proposed trajectory based forwarding (TBF), address scalability issues in large ad hoc networks by using Euclidean space as a complementary name space. These approaches require. that nodes know their position in a common coordinate system. While a GPS recei...
Position centric approaches, such as Cartesian routing, geographic routing, and the recently proposed trajectory based forwarding (TBF), address scalability issues in large ad hoc networks by using Euclidean space as a complementary name space. These approaches require that nodes know their position in a common coordinate system. While a GPS receiv...
Many ad hoc network protocols and applications assume the knowledge of geographic location of nodes. The absolute position of each networked node is an assumed fact by most sensor networks which can then present the sensed information on a geographical map. Finding position without the aid of GPS in each node of an ad hoc network is important in ca...
Position information of individual nodes is useful in implementing functions such as routing and querying in ad-hoc networks. Deriving position information by using the capability of the nodes to measure time of arrival (TOA), time difference of arrival (TDOA), angle of arrival (AOA) and signal strength have been used to localize nodes relative to...
We consider off-line versions of path provisioning and path protection problems for general circuit switched networks. Both problems deal with a given network topology and a list of integral demand flows. The objective is to route the flows and to allocate the bandwidth in a way that minimizes the total amount of bandwidth used for working and prot...
Providing quality of service(QoS) guarantees in mobile data networks is an inherently challenging task. Mobility of users imposes a spatial demand on resources resulting in overloaded regions that are entirely dependent on mobility pattern of the users, that is often unpredictable. Prior and ongoing work in this area of QoS relies on call admission...
Trajectory based forwarding (TBF) is a novel method to forward packets in a dense ad hoc network that makes it possible to route a packet along a predefined curve. It is a generalization of source based routing and Cartesian forwarding in that the trajectory is set by the source, but the forwarding decision is based on the relationship to the traje...
AoA(Angle of Arrival) is a well known method used for positioning in providing services such as E911, and for other military and civil radio-location applications, such as sonars and radars. Although devices such as GPS receivers and digital compasses provide good positioning and orientation outdoors, there are many applications requiring the same...
We consider off-line versions of path provisioning and path protection problems for general circuit switched networks. Both problems deal with a given network topology and a list of integral demand flows. The objective is to route the flows and to allocate the bandwidth in a way that minimizes the total amount of bandwidth used for working and prot...
Providing quality of service(QoS) guarantees in mobile data
networks is an inherently challenging task. Mobility of users imposes a
spatial demand on resources resulting in overloaded regions that are
entirely dependent on mobility pattern of the users, that is often
unpredictable. Prior and ongoing work in this area of QoS relies on call
admission...
Many ad hoc network protocols and applications assume the
knowledge of geographic location of nodes. The absolute location of each
networked node is an assumed fact by most sensor networks which can then
present the sensed information on a geographical map. Finding location
without the aid of GPS in each node of an ad hoc network is important in
ca...
Active networks address the problem of slow network evolution, when compared with the evolution of applications. The active approach builds programmability into the network, so that new protocols and functionalities may be added later. While classical, "passive" routers all implement the same functionality, the active routers all implement the same...
