Vangelis Angelakis

Learn More
The IEEE 802.11a standard amendment describes an OFDM-based physical layer for 802.11 wireless stations operation in the 5 GHz band. Due to the poor channelization of 802.11b/g that left only three of the available channels non-overlapping, the channelization scheme of 802.11a was over-advertised to offer 19 non-overlapping channels in the European(More)
In this work we utilize the model for calculation of the interference power by partially overlapping channels introduced in [1] and combine it with the Signal to Interference plus Noise (SINR) criterion for signal capture to quantify the effect of adjacent channel interference (ACI) in 802.11a. We validate the results from our theoretical model by applying(More)
A fundamental aspect in performance engineering of wireless networks is optimizing the set of links that can be concurrently activated to meet given signal-to-interference-and-noise ratio (SINR) thresholds. The solution of this combinatorial problem is the key element in scheduling and crosslayer resource management. Previous works on link activation assume(More)
In typical resource allocation for Orthogonal Frequency Division Multiple Access (OFDMA), assigning subcarriers to the more favorable users provides beneficial diversity and increased system performance. It is however relevant to consider OFDMA resource allocation with a subcarrier adjacency restriction, grouping a number of adjacent subcarriers into a(More)
Opportunistic routing has recently been proposed to take advantage of the broadcast nature and spatial diversity of the wireless medium and cope with unreliable transmissions. Within this "opportunistic routing hype", complex routing schemes with opportunistic features have been proposed, but their performance gains can not be clearly attributed to their(More)
We consider N transmitter-receiver pairs that share a wireless channel and we address the problem of obtaining a schedule for activating subsets of these links so as to empty the transmitter queues in minimum time. Our aim is to provide theoretical insights for the optimality characterization of the problem, using both a cross-layer model formulation, which(More)
The Internet of Things (IoT) provides a platform for the interconnection of a plethora of smart objects. It has been widely accepted for providing Information and Communication Technologies (ICT) applications in many “smart” environments, such as cities, buildings, metering, and even agriculture. For several reasons though such applications(More)
In this work we utilize Signal to Interference-plusNoise (SINR) criterion for reception, and combine it with the model for partial channel overlap presented in [1] and extended for 802.11a/g, to quantify the impact of Adjacent Channel Interference (ACI) in multi-radio 802.11a/g based wireless nodes designed for mesh networking. The nodes we consider are(More)
We present the design and initial experience from an experimental metropolitan multi-radio mesh network that covers an area of approximately 60 Km<sup>2</sup> in the city of Heraklion, Crete. The network consists of 14 nodes, among which six are core nodes with up to four 802.11a wireless interfaces each, and one wireless interface for management and(More)