Karina Gomez - Academia.edu (original) (raw)
Papers by Karina Gomez
PLOS Neglected Tropical Diseases, 2011
Patients with Chronic Chagas' Heart Disease possess high levels of antibodies against the carboxy... more Patients with Chronic Chagas' Heart Disease possess high levels of antibodies against the carboxyl-terminal end of the ribosomal P2ß protein of Trypanosoma cruzi (TcP2ß). These antibodies, as well as the murine monoclonal antibody (mAb) 17.2, recognize the last 13 amino acids of TcP2ß (called the R13 epitope: EEEDDDMGFGLFD) and are able to cross-react with, and stimulate, the ß1 adrenergic receptor (ß1-AR). Indeed, the mAb 17.2 was able to specifically detect human b1-AR, stably transfected into HEK cells, by flow cytometry and to induce repolarisation abnormalities and first degree atrioventricular conduction block after passive transfer to naïve mice. To study the structural basis of this cross-reactivity, we determined the crystal structure of the Fab region of the mAb 17.2 alone at 2.31 Å resolution and in complex with the R13 peptide at 1.89 Å resolution. We identified as key contact residues on R13 peptide Glu3, Asp6 and Phe9 as was previously shown by alanine scanning. Additionally, we generated a model of human b1-AR to elucidate the interaction with anti-R13 antibodies. These data provide an understanding of the molecular basis of cross-reactive antibodies induced by chronic infection with Trypanosoma cruzi.
Journal of Virological Methods, 2002
The observation that mice infected with mouse hepatitis virus (MHV) develop autoantibodies direct... more The observation that mice infected with mouse hepatitis virus (MHV) develop autoantibodies directed mainly to liver fumarylacetoacetate hydrolase (FAH) enabled the development of an ELISA applicable to the detection of MHV-infection. The method, based on the titration of antibodies to semipurified FAH from rat liver, is easy, economical, and does not require the isolation of viral proteins from large MHV stocks. Furthermore, since sera from mice immunized with a purified fraction of the rat liver enzyme do react with its homologous protein, this antiserum can be used as a positive control avoiding the manipulation of samples from MHV-infected animals.
International Journal for Parasitology, 2011
High levels of antibodies (Abs) against the C-terminal end of the Trypanosoma cruzi ribosomal P2b... more High levels of antibodies (Abs) against the C-terminal end of the Trypanosoma cruzi ribosomal P2b protein, defined by the R13 peptide, are detected in sera from patients with chronic Chagas heart disease (cChHD). These Abs can cross-react with the b1-adrenergic receptor (b1-AR), inducing a functional response in cardiomyocytes. In this study, we report that a monoclonal Ab against the R13 peptide, called mAb 17.2, and its single-chain Fv fragment (scFv), C5, caused apoptosis of murine adult cardiac HL-1 cells, and this effect was inhibited by pre-incubation with the b-blocker, propranolol. In addition, apoptosis induced by mAb 17.2 might involve the mitochondrial pathway evidenced by an increase in pro-apoptotic molecule, Bax/anti-apoptotic molecule, Bcl XL , mRNA levels. HL-1 cells also underwent apoptosis after incubation with nine of 23 IgGs from cChHD patients (39.1%) that presented reactivity against R13 peptide and b1-AR. The apoptotic effect caused by these IgGs was partially abolished by pre-incubation with R13 peptide or propranolol, suggesting the involvement of the C-terminal end of ribosomal P proteins and the b-adrenergic pathway. Moreover, we observed high rates of cardiomyocyte apoptosis in two tissue samples from cChHD patients by using a TUNEL assay and staining of active caspase-3. Our data demonstrate that Abs developed during T. cruzi infection have a strong cardiomyocyte apoptosis inducing ability, which could contribute to the heart disease developed in patients with cChHD.
Growth Hormone & Igf Research, 1999
Anti-human growth hormone (hGH) polyclonal and monoclonal antibodies (MAb) failed to recognize ov... more Anti-human growth hormone (hGH) polyclonal and monoclonal antibodies (MAb) failed to recognize ovine placental lactogen (oPL), indicating that the antigenic topographies of both hormones are different. Binding assays showed that oPL completely inhibited hGH binding to lactogenic receptors from Nb2-cells and to somatogenic receptors from rabbit or sheep liver; in contrast, oPL only bound to a subpopulation of rat liver receptors. Zinc ion increased hGH and oPL binding to Nb2-cell receptors and slightly inhibited both hormones' recognition by somatogenic receptors. However, ZnCl 2 increased hGH binding to rat liver microsomes but prevented that of oPL. Furthermore, MAb R7B4, recognizing lactogenic as well as somatogenic receptors, entirely blocked hGH binding to the various receptor systems but not affected oPL binding. Therefore, results presented in this paper suggest that oPL and hGH bind to different regions of the same receptors.
PLOS One, 2012
The ribosomal P proteins are located on the stalk of the ribosomal large subunit and play a criti... more The ribosomal P proteins are located on the stalk of the ribosomal large subunit and play a critical role during the elongation step of protein synthesis. The single chain recombinant antibody C5 (scFv C5) directed against the C-terminal region of the Trypanosoma cruzi P2b protein (TcP2b) recognizes the conserved C-terminal end of all T. cruzi ribosomal P proteins. Although this region is highly conserved among different species, surface plasmon resonance analysis showed that the scFv C5 possesses very low affinity for the corresponding mammalian epitope, despite having only one single aminoacid change. Crystallographic analysis, in silico modelization and NMR assays support the analysis, increasing our understanding on the structural basis of epitope specificity. In vitro protein synthesis experiments showed that scFv C5 was able to specifically block translation by T. cruzi and Crithidia fasciculata ribosomes, but virtually had no effect on Rattus norvegicus ribosomes. Therefore, we used the scFv C5 coding sequence to make inducible intrabodies in Trypanosoma brucei. Transgenic parasites showed a strong decrease in their growth rate after induction. These results strengthen the importance of the P protein C terminal regions for ribosomal translation activity and suggest that trypanosomatid ribosomal P proteins could be a possible target for selective therapeutic agents that could be derived from structural analysis of the scFv C5 antibody paratope.
Scandinavian Journal of Immunology, 2003
An immunization protocol that induces antibodies (Abs) directed to cryptic epitopes of a protein ... more An immunization protocol that induces antibodies (Abs) directed to cryptic epitopes of a protein antigen (Ag) reduces the efficacy of vaccines that ideally should induce Abs against native epitopes. We have shown earlier that viral infections concomitant with immunization against a protein tend to shift the Ab specificity toward cryptic epitopes and tend to induce the production of autoantibodies (autoAbs). Here, we show the effects of three adjuvants on the Ab specificity in the absence or presence of a viral infection (lactate dehydrogenaseelevating virus or LDV), with human growth hormone (hGH) being, as before, the protein Ag.
... Laser Beam Induced Dielectric Cracks in VLSI Devices Alvaro Maury1, a, John Schaller1, Goh Ch... more ... Laser Beam Induced Dielectric Cracks in VLSI Devices Alvaro Maury1, a, John Schaller1, Goh Chia Lan1, 2, Iskandar Idris Yaacob2, Chua Choon Meng3, Tan Soon Huat3, Alexei Maznev4 and Kenneth Gomez5. 1Silterra (M) Sdn. ... SRO Ti/TiN TiN ARC Aluminum W Plug ILD ...
... In such a scenario, the FirstCome FirstServed scheduling policy implemented in most commerc... more ... In such a scenario, the FirstCome FirstServed scheduling policy implemented in most commercial WiFi devices, combined with the finite size transmission buffer, may negatively impact both fairness and session delay. ... 101 102 103 104 10−6 10−4 10−2 Session Size [Kbytes] ...
Aerial telecommunications networks based on Low Altitude Platforms (LAPs) are expected to optimal... more Aerial telecommunications networks based on Low Altitude Platforms (LAPs) are expected to optimally meet the urgent needs of emergency relief and recovery operations for tackling large scale natural disasters. The energy efficient operation of such networks is important given the fact that the entire network infrastructure including the battery operated ground terminals, exhibit requirements to operate under power constrained situations. In this paper, we show that the cooperation between mobile terrestrial terminals on the ground could improve the energy efficiency in the uplink depending on the temporal behavior of the terrestrial and the aerial uplink channels. We consider cognitive context aware capabilities that could be utilized to improve the overall lifetime of the mobile ground terminals by dynamically adapting between direct and cooperative relay links. We also discuss a novel network architecture constituted of an integrated and highly dynamic multi-purpose aerial-terrestrial communications infrastructure that can be contextually extended with fast-deploying aerial platforms for emergency communications.
The extended radio coverage provided by wireless mesh networking (WMN) technologies represents a ... more The extended radio coverage provided by wireless mesh networking (WMN) technologies represents a key advantage compared to the last mile solutions based on standard IEEE 802.11 hot spots. Nevertheless, modern requirements to wireless connectivity include mandatory QoS guarantees for a wide set of real-time applications. In this paper, we first propose a methodology for evaluating multimedia applications over real world WMN deployments and then we report the results of an extensive measurement campaign performed exploiting IEEE 802.11-based WMN testbed. Later, we evaluate the QoS performance of the reference multimedia applications exploiting three different link scheduling disciplines. Results show that, using opportunistic scheduling techniques capable of providing performance isolation among competing flows can significantly improve system capacity.
In this paper, we present the Airtime Deficit Round Robin (ADRR), a novel scheduling algorithm fo... more In this paper, we present the Airtime Deficit Round Robin (ADRR), a novel scheduling algorithm for IEEE 802.11-based wireless networks. The ADRR mechanism enhances the Deficit Round Robin scheduling discipline by taking into account the channel quality experienced by the transmitting node. The devised algorithm addresses the IEEE 802.11 performance anomaly, preventing a node which experiences poor channel conditions from monopolizing the wireless medium, lowering the performance of the whole system. The proposed approach combines link scheduling with measurable routing metrics. Simulation analyses have shown that the proposed scheme can achieve performance isolation among links characterized by heterogeneous channel conditions. A real prototype has been implemented and evaluated over a small scale testbed confirming the simulation results.
A customary solution to reduce the energy consumption of wireless communication devices is to per... more A customary solution to reduce the energy consumption of wireless communication devices is to periodically put the radio into low-power sleep mode. A relevant problem is to schedule the wake-up of nodes in such a way as to ensure proper coordination among devices, respecting delay constraints while still saving energy. In this paper, we introduce a simple algebraic characterization of the problem of periodic wake-up scheduling under both energy consumption and delay constraints. We demonstrate that the general problem of wake-up times coordination is equivalent to integer factorization and discuss the implications on the design of efficient scheduling algorithms. We then propose simple polynomial time heuristic algorithms that can be implemented in a distributed fashion and present a message complexity of the order of the number of links in the network. Numerical results are provided in order to assess the performance of the proposed techniques when applied to wireless sensor networks.
We show how the TUNEGreen real-time energy consumption monitoring capabilities can be used to und... more We show how the TUNEGreen real-time energy consumption monitoring capabilities can be used to understand how and where power is consumed in a simple star-shaped network based on IEEE 802.11. Different traffic patterns will be generated in order to demonstrate the correlation between traffic and energy consumption.
Abstract The extended radio coverage provided by wireless mesh networking (WMN) technologies repr... more Abstract The extended radio coverage provided by wireless mesh networking (WMN) technologies represents a key advantage compared to the last mile solutions based on standard IEEE 802.11 hot spots. Nevertheless, modern require- ments to wireless connectivity include mandatory QoS guarantees for a wide set of real-time applications. In this paper, we first propose a methodology for evaluating multimedia applications over real world WMN deployments and then we report the results of an extensive measurement campaign performed exploiting IEEE 802.11-based WMN testbed. Later, we evaluate the QoS per- formance of the reference multimedia applications exploiting three different link scheduling disciplines. Results show that, using opportunistic scheduling techniques capable of providing performance isolation among competing flows can significantly improve system capacity. KEYWORDS: wireless networks, IEEE 802.11, mesh architecture, multime-
Aerial telecommunications networks based on Low Altitude Platforms (LAPs) are expected to optimal... more Aerial telecommunications networks based on Low Altitude Platforms (LAPs) are expected to optimally meet the urgent needs of emergency relief and recovery operations for tackling large scale natural disasters. The energy efficient operation of such networks is important given the fact that the entire network infrastructure including the battery operated ground terminals, exhibit requirements to operate under power constrained situations. In this paper, we propose and evaluate a real-time adaptive transmission strategy for dynamic selection of direct and cooperative links based on the channel conditions for improved energy efficiency. We show that the cooperation between mobile terrestrial terminals on the ground could improve the energy efficiency in the uplink depending on the temporal behavior of the terrestrial and the aerial uplink channels. The simulation analysis corroborates that the adaptive transmission technique improves the overall energy efficiency of the network.
WING is an experimental multi-radio WMN testbed designed and built exploiting commodity hardware ... more WING is an experimental multi-radio WMN testbed designed and built exploiting commodity hardware and opensource software components. WING implements a flexible and scalable WMN architecture capable of supporting nextgeneration Internet services with a particular focus on multimedia applications. The WING project aims at providing an open-platform on top of which innovative solution can be implemented and tested in a realistic environment. WING's design has be driven by our previous work on the stateof-the-art solutions for engineering a WMN testbed [1] by applying the observed guidelines to a real-world scenario. All the developed software has been released under a BSD License and is made fully available to the research community 1 .
... In such a scenario, the FirstCome FirstServed scheduling policy implemented in most commerc... more ... In such a scenario, the FirstCome FirstServed scheduling policy implemented in most commercial WiFi devices, combined with the finite size transmission buffer, may negatively impact both fairness and session delay. ... 101 102 103 104 10−6 10−4 10−2 Session Size [Kbytes] ...
Aerial telecommunications networks based on Low Altitude Platforms (LAPs) are expected to optimal... more Aerial telecommunications networks based on Low Altitude Platforms (LAPs) are expected to optimally meet the urgent needs of emergency relief and recovery operations for tackling large scale natural disasters. The energy efficient operation of such networks is important given the fact that the entire network infrastructure including the battery operated ground terminals, exhibit requirements to operate under power constrained situations. In this paper, we show that the cooperation between mobile terrestrial terminals on the ground could improve the energy efficiency in the uplink depending on the temporal behavior of the terrestrial and the aerial uplink channels. We consider cognitive context aware capabilities that could be utilized to improve the overall lifetime of the mobile ground terminals by dynamically adapting between direct and cooperative relay links. We also discuss a novel network architecture constituted of an integrated and highly dynamic multi-purpose aerial-terrestrial communications infrastructure that can be contextually extended with fast-deploying aerial platforms for emergency communications.
PLOS Neglected Tropical Diseases, 2011
Patients with Chronic Chagas' Heart Disease possess high levels of antibodies against the carboxy... more Patients with Chronic Chagas' Heart Disease possess high levels of antibodies against the carboxyl-terminal end of the ribosomal P2ß protein of Trypanosoma cruzi (TcP2ß). These antibodies, as well as the murine monoclonal antibody (mAb) 17.2, recognize the last 13 amino acids of TcP2ß (called the R13 epitope: EEEDDDMGFGLFD) and are able to cross-react with, and stimulate, the ß1 adrenergic receptor (ß1-AR). Indeed, the mAb 17.2 was able to specifically detect human b1-AR, stably transfected into HEK cells, by flow cytometry and to induce repolarisation abnormalities and first degree atrioventricular conduction block after passive transfer to naïve mice. To study the structural basis of this cross-reactivity, we determined the crystal structure of the Fab region of the mAb 17.2 alone at 2.31 Å resolution and in complex with the R13 peptide at 1.89 Å resolution. We identified as key contact residues on R13 peptide Glu3, Asp6 and Phe9 as was previously shown by alanine scanning. Additionally, we generated a model of human b1-AR to elucidate the interaction with anti-R13 antibodies. These data provide an understanding of the molecular basis of cross-reactive antibodies induced by chronic infection with Trypanosoma cruzi.
Journal of Virological Methods, 2002
The observation that mice infected with mouse hepatitis virus (MHV) develop autoantibodies direct... more The observation that mice infected with mouse hepatitis virus (MHV) develop autoantibodies directed mainly to liver fumarylacetoacetate hydrolase (FAH) enabled the development of an ELISA applicable to the detection of MHV-infection. The method, based on the titration of antibodies to semipurified FAH from rat liver, is easy, economical, and does not require the isolation of viral proteins from large MHV stocks. Furthermore, since sera from mice immunized with a purified fraction of the rat liver enzyme do react with its homologous protein, this antiserum can be used as a positive control avoiding the manipulation of samples from MHV-infected animals.
International Journal for Parasitology, 2011
High levels of antibodies (Abs) against the C-terminal end of the Trypanosoma cruzi ribosomal P2b... more High levels of antibodies (Abs) against the C-terminal end of the Trypanosoma cruzi ribosomal P2b protein, defined by the R13 peptide, are detected in sera from patients with chronic Chagas heart disease (cChHD). These Abs can cross-react with the b1-adrenergic receptor (b1-AR), inducing a functional response in cardiomyocytes. In this study, we report that a monoclonal Ab against the R13 peptide, called mAb 17.2, and its single-chain Fv fragment (scFv), C5, caused apoptosis of murine adult cardiac HL-1 cells, and this effect was inhibited by pre-incubation with the b-blocker, propranolol. In addition, apoptosis induced by mAb 17.2 might involve the mitochondrial pathway evidenced by an increase in pro-apoptotic molecule, Bax/anti-apoptotic molecule, Bcl XL , mRNA levels. HL-1 cells also underwent apoptosis after incubation with nine of 23 IgGs from cChHD patients (39.1%) that presented reactivity against R13 peptide and b1-AR. The apoptotic effect caused by these IgGs was partially abolished by pre-incubation with R13 peptide or propranolol, suggesting the involvement of the C-terminal end of ribosomal P proteins and the b-adrenergic pathway. Moreover, we observed high rates of cardiomyocyte apoptosis in two tissue samples from cChHD patients by using a TUNEL assay and staining of active caspase-3. Our data demonstrate that Abs developed during T. cruzi infection have a strong cardiomyocyte apoptosis inducing ability, which could contribute to the heart disease developed in patients with cChHD.
Growth Hormone & Igf Research, 1999
Anti-human growth hormone (hGH) polyclonal and monoclonal antibodies (MAb) failed to recognize ov... more Anti-human growth hormone (hGH) polyclonal and monoclonal antibodies (MAb) failed to recognize ovine placental lactogen (oPL), indicating that the antigenic topographies of both hormones are different. Binding assays showed that oPL completely inhibited hGH binding to lactogenic receptors from Nb2-cells and to somatogenic receptors from rabbit or sheep liver; in contrast, oPL only bound to a subpopulation of rat liver receptors. Zinc ion increased hGH and oPL binding to Nb2-cell receptors and slightly inhibited both hormones' recognition by somatogenic receptors. However, ZnCl 2 increased hGH binding to rat liver microsomes but prevented that of oPL. Furthermore, MAb R7B4, recognizing lactogenic as well as somatogenic receptors, entirely blocked hGH binding to the various receptor systems but not affected oPL binding. Therefore, results presented in this paper suggest that oPL and hGH bind to different regions of the same receptors.
PLOS One, 2012
The ribosomal P proteins are located on the stalk of the ribosomal large subunit and play a criti... more The ribosomal P proteins are located on the stalk of the ribosomal large subunit and play a critical role during the elongation step of protein synthesis. The single chain recombinant antibody C5 (scFv C5) directed against the C-terminal region of the Trypanosoma cruzi P2b protein (TcP2b) recognizes the conserved C-terminal end of all T. cruzi ribosomal P proteins. Although this region is highly conserved among different species, surface plasmon resonance analysis showed that the scFv C5 possesses very low affinity for the corresponding mammalian epitope, despite having only one single aminoacid change. Crystallographic analysis, in silico modelization and NMR assays support the analysis, increasing our understanding on the structural basis of epitope specificity. In vitro protein synthesis experiments showed that scFv C5 was able to specifically block translation by T. cruzi and Crithidia fasciculata ribosomes, but virtually had no effect on Rattus norvegicus ribosomes. Therefore, we used the scFv C5 coding sequence to make inducible intrabodies in Trypanosoma brucei. Transgenic parasites showed a strong decrease in their growth rate after induction. These results strengthen the importance of the P protein C terminal regions for ribosomal translation activity and suggest that trypanosomatid ribosomal P proteins could be a possible target for selective therapeutic agents that could be derived from structural analysis of the scFv C5 antibody paratope.
Scandinavian Journal of Immunology, 2003
An immunization protocol that induces antibodies (Abs) directed to cryptic epitopes of a protein ... more An immunization protocol that induces antibodies (Abs) directed to cryptic epitopes of a protein antigen (Ag) reduces the efficacy of vaccines that ideally should induce Abs against native epitopes. We have shown earlier that viral infections concomitant with immunization against a protein tend to shift the Ab specificity toward cryptic epitopes and tend to induce the production of autoantibodies (autoAbs). Here, we show the effects of three adjuvants on the Ab specificity in the absence or presence of a viral infection (lactate dehydrogenaseelevating virus or LDV), with human growth hormone (hGH) being, as before, the protein Ag.
... Laser Beam Induced Dielectric Cracks in VLSI Devices Alvaro Maury1, a, John Schaller1, Goh Ch... more ... Laser Beam Induced Dielectric Cracks in VLSI Devices Alvaro Maury1, a, John Schaller1, Goh Chia Lan1, 2, Iskandar Idris Yaacob2, Chua Choon Meng3, Tan Soon Huat3, Alexei Maznev4 and Kenneth Gomez5. 1Silterra (M) Sdn. ... SRO Ti/TiN TiN ARC Aluminum W Plug ILD ...
... In such a scenario, the FirstCome FirstServed scheduling policy implemented in most commerc... more ... In such a scenario, the FirstCome FirstServed scheduling policy implemented in most commercial WiFi devices, combined with the finite size transmission buffer, may negatively impact both fairness and session delay. ... 101 102 103 104 10−6 10−4 10−2 Session Size [Kbytes] ...
Aerial telecommunications networks based on Low Altitude Platforms (LAPs) are expected to optimal... more Aerial telecommunications networks based on Low Altitude Platforms (LAPs) are expected to optimally meet the urgent needs of emergency relief and recovery operations for tackling large scale natural disasters. The energy efficient operation of such networks is important given the fact that the entire network infrastructure including the battery operated ground terminals, exhibit requirements to operate under power constrained situations. In this paper, we show that the cooperation between mobile terrestrial terminals on the ground could improve the energy efficiency in the uplink depending on the temporal behavior of the terrestrial and the aerial uplink channels. We consider cognitive context aware capabilities that could be utilized to improve the overall lifetime of the mobile ground terminals by dynamically adapting between direct and cooperative relay links. We also discuss a novel network architecture constituted of an integrated and highly dynamic multi-purpose aerial-terrestrial communications infrastructure that can be contextually extended with fast-deploying aerial platforms for emergency communications.
The extended radio coverage provided by wireless mesh networking (WMN) technologies represents a ... more The extended radio coverage provided by wireless mesh networking (WMN) technologies represents a key advantage compared to the last mile solutions based on standard IEEE 802.11 hot spots. Nevertheless, modern requirements to wireless connectivity include mandatory QoS guarantees for a wide set of real-time applications. In this paper, we first propose a methodology for evaluating multimedia applications over real world WMN deployments and then we report the results of an extensive measurement campaign performed exploiting IEEE 802.11-based WMN testbed. Later, we evaluate the QoS performance of the reference multimedia applications exploiting three different link scheduling disciplines. Results show that, using opportunistic scheduling techniques capable of providing performance isolation among competing flows can significantly improve system capacity.
In this paper, we present the Airtime Deficit Round Robin (ADRR), a novel scheduling algorithm fo... more In this paper, we present the Airtime Deficit Round Robin (ADRR), a novel scheduling algorithm for IEEE 802.11-based wireless networks. The ADRR mechanism enhances the Deficit Round Robin scheduling discipline by taking into account the channel quality experienced by the transmitting node. The devised algorithm addresses the IEEE 802.11 performance anomaly, preventing a node which experiences poor channel conditions from monopolizing the wireless medium, lowering the performance of the whole system. The proposed approach combines link scheduling with measurable routing metrics. Simulation analyses have shown that the proposed scheme can achieve performance isolation among links characterized by heterogeneous channel conditions. A real prototype has been implemented and evaluated over a small scale testbed confirming the simulation results.
A customary solution to reduce the energy consumption of wireless communication devices is to per... more A customary solution to reduce the energy consumption of wireless communication devices is to periodically put the radio into low-power sleep mode. A relevant problem is to schedule the wake-up of nodes in such a way as to ensure proper coordination among devices, respecting delay constraints while still saving energy. In this paper, we introduce a simple algebraic characterization of the problem of periodic wake-up scheduling under both energy consumption and delay constraints. We demonstrate that the general problem of wake-up times coordination is equivalent to integer factorization and discuss the implications on the design of efficient scheduling algorithms. We then propose simple polynomial time heuristic algorithms that can be implemented in a distributed fashion and present a message complexity of the order of the number of links in the network. Numerical results are provided in order to assess the performance of the proposed techniques when applied to wireless sensor networks.
We show how the TUNEGreen real-time energy consumption monitoring capabilities can be used to und... more We show how the TUNEGreen real-time energy consumption monitoring capabilities can be used to understand how and where power is consumed in a simple star-shaped network based on IEEE 802.11. Different traffic patterns will be generated in order to demonstrate the correlation between traffic and energy consumption.
Abstract The extended radio coverage provided by wireless mesh networking (WMN) technologies repr... more Abstract The extended radio coverage provided by wireless mesh networking (WMN) technologies represents a key advantage compared to the last mile solutions based on standard IEEE 802.11 hot spots. Nevertheless, modern require- ments to wireless connectivity include mandatory QoS guarantees for a wide set of real-time applications. In this paper, we first propose a methodology for evaluating multimedia applications over real world WMN deployments and then we report the results of an extensive measurement campaign performed exploiting IEEE 802.11-based WMN testbed. Later, we evaluate the QoS per- formance of the reference multimedia applications exploiting three different link scheduling disciplines. Results show that, using opportunistic scheduling techniques capable of providing performance isolation among competing flows can significantly improve system capacity. KEYWORDS: wireless networks, IEEE 802.11, mesh architecture, multime-
Aerial telecommunications networks based on Low Altitude Platforms (LAPs) are expected to optimal... more Aerial telecommunications networks based on Low Altitude Platforms (LAPs) are expected to optimally meet the urgent needs of emergency relief and recovery operations for tackling large scale natural disasters. The energy efficient operation of such networks is important given the fact that the entire network infrastructure including the battery operated ground terminals, exhibit requirements to operate under power constrained situations. In this paper, we propose and evaluate a real-time adaptive transmission strategy for dynamic selection of direct and cooperative links based on the channel conditions for improved energy efficiency. We show that the cooperation between mobile terrestrial terminals on the ground could improve the energy efficiency in the uplink depending on the temporal behavior of the terrestrial and the aerial uplink channels. The simulation analysis corroborates that the adaptive transmission technique improves the overall energy efficiency of the network.
WING is an experimental multi-radio WMN testbed designed and built exploiting commodity hardware ... more WING is an experimental multi-radio WMN testbed designed and built exploiting commodity hardware and opensource software components. WING implements a flexible and scalable WMN architecture capable of supporting nextgeneration Internet services with a particular focus on multimedia applications. The WING project aims at providing an open-platform on top of which innovative solution can be implemented and tested in a realistic environment. WING's design has be driven by our previous work on the stateof-the-art solutions for engineering a WMN testbed [1] by applying the observed guidelines to a real-world scenario. All the developed software has been released under a BSD License and is made fully available to the research community 1 .
... In such a scenario, the FirstCome FirstServed scheduling policy implemented in most commerc... more ... In such a scenario, the FirstCome FirstServed scheduling policy implemented in most commercial WiFi devices, combined with the finite size transmission buffer, may negatively impact both fairness and session delay. ... 101 102 103 104 10−6 10−4 10−2 Session Size [Kbytes] ...
Aerial telecommunications networks based on Low Altitude Platforms (LAPs) are expected to optimal... more Aerial telecommunications networks based on Low Altitude Platforms (LAPs) are expected to optimally meet the urgent needs of emergency relief and recovery operations for tackling large scale natural disasters. The energy efficient operation of such networks is important given the fact that the entire network infrastructure including the battery operated ground terminals, exhibit requirements to operate under power constrained situations. In this paper, we show that the cooperation between mobile terrestrial terminals on the ground could improve the energy efficiency in the uplink depending on the temporal behavior of the terrestrial and the aerial uplink channels. We consider cognitive context aware capabilities that could be utilized to improve the overall lifetime of the mobile ground terminals by dynamically adapting between direct and cooperative relay links. We also discuss a novel network architecture constituted of an integrated and highly dynamic multi-purpose aerial-terrestrial communications infrastructure that can be contextually extended with fast-deploying aerial platforms for emergency communications.