Kostas Stamatiou

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From being a scientific curiosity only a few years ago, energy harvesting (EH) is well on its way to becoming a game-changing technology in the field of autonomous wireless networked systems. The promise of long-term, uninterrupted and self-sustainable operation in a diverse array of applications has captured the interest of academia and industry alike. Yet(More)
We consider a Poisson network of sources, each with a destination at a given distance and a buffer of infinite capacity. Assuming independent Bernoulli arrivals, we characterize the stability region when one or two classes of users are present in the network. We then derive a fixed-point equation that determines the success probability of the typical(More)
The goal of this paper is to explore the benefits of channel diversity in wireless ad hoc networks. Our model is that of a Poisson point process of transmitters, each with a receiver at a given distance. A packet is divided in blocks which are transmitted over different subbands that are determined by random frequency hopping. At the receiver, a(More)
This paper considers a wireless sensor powered by an energy harvesting device, which reports data of varying importance to its receiver. Modeling the ambient energy supply by a two-state Markov chain (“GOOD” and “BAD”), assuming a finite battery capacity constraint, and associating data transmission with a given energy cost, we propose low-complexity(More)
We design and implement a software-radio system for Superposition Coding (SC), a multiuser transmission scheme that deliberately introduces interference among user signals at the transmitter, using a library of off-the-shelf point-to-point channel codes. We experimentally determine the set of ratepairs achieved by this transmission scheme under a(More)
This paper considers the deployment of frequency-hopped OFDMA at the downlink of a cellular system. Each user in the cell is assigned a number of subcarriers by the base-station, which change every OFDM symbol according to deterministic hopping patterns. The construction of the hopping patterns is based on orthogonal Latin squares, that guarantee orthogonal(More)
We consider an ad hoc network where frequency hopping (FH), convolutional coding and multiple antennas are employed in order to combat fading and multiple access (MA) interference. The transmitters are distributed in space according to the Poisson distribution and the corresponding receivers are situated at a fixed distance. Under a channel model that(More)
We consider an ad hoc network where frequency hopping (FH) and coding are employed in order to mitigate multiple-access interference. In contrast to previous work, in our model hopping takes place at the symbol level. As a result, different interference levels are encountered across a codeword/packet, creating interference diversity which is exploited(More)
We evaluate the end-to-end delay of a multihop transmission scheme that includes a source, a number of relays, and a destination, in the presence of interferers located according to a Poisson point process. The medium access control (MAC) protocol considered is a combination of TDMA and ALOHA, according to which nodes located a certain number of hops apart(More)
Sensors powered by energy harvesting devices (EHD) are increasingly being deployed in practice, due to the demonstrated advantage of long-term, autonomous operation, without the need for battery replacement. This paper is concerned with the following fundamental problem: how should the harvested energy be managed to ensure optimal performance, if the(More)