A time-based admission control mechanism for IEEE 802.11 ad Hoc networks

This paper presents a time-based admission control mechanism (TAC) for IEEE 802.11 ad hoc networks. The proposed mechanism was adapted to the QoS AODV routing protocol, which takes the quality of service requirements of the data flow into account in the route discovery process. TAC-AODV estimates the idle time of the physical medium based on the frames listened. The incoming traffic is admitted according to the offered load as well as the intra-flow interference, calculated based on the number of hops in the forwarding chain. TAC-AODV is compared to AAC-AODV, another admission control mechanism found in the literature, and the simulation results show that TAC-AODV is in average 12.5% better in terms of the packet delivery rate.8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

A time-based admission control mechanism for IEEE 802.11 ad Hoc networks

This paper presents a time-based admission control mechanism (TAC) for IEEE 802.11 ad hoc networks. The proposed mechanism was adapted to the QoS AODV routing protocol, which takes the quality of service requirements of the data flow into account in the route discovery process. TAC-AODV estimates the idle time of the physical medium based on the frames listened. The incoming traffic is admitted according to the offered load as well as the intra-flow interference, calculated based on the number of hops in the forwarding chain. TAC-AODV is compared to AAC-AODV, another admission control mechanism found in the literature, and the simulation results show that TAC-AODV is in average 12.5% better in terms of the packet delivery rate.8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

A survey on wireless ad hoc networks

A wireless ad hoc network is a collection of wireless nodes that can dynamically self-organize into an arbitrary and temporary topology to form a network without necessarily using any pre-existing infrastructure. These characteristics make ad hoc networks well suited for military activities, emergency operations, and disaster recoveries. Nevertheless, as electronic devices are getting smaller, cheaper, and more powerful, the mobile market is rapidly growing and, as a consequence, the need of seamlessly internetworking people and devices becomes mandatory. New wireless technologies enable easy deployment of commercial applications for ad hoc networks. The design of an ad hoc network has to take into account several interesting and difficult problems due to noisy, limited-range, and insecure wireless transmissions added to mobility and energy constraints. This paper presents an overview of issues related to medium access control (MAC), routing, and transport in wireless ad hoc networks and techniques proposed to improve the performance of protocols. Research activities and problems requiring further work are also presented. Finally, the paper presents a project concerning an ad hoc network to easily deploy Internet services on low-income habitations fostering digital inclusion8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

Wireless ad hoc networks on underserved communities: an efficient solution for interactive digital TV

The Brazilian government intends to use the Digital TV technology as a vehicle of digital inclusion on underserved communities. The wireless ad hoc network is a low-cost, scalable and easy solution to implement the return channel. This work analyzes the performance of an ad hoc return channel using the wireless IEEE 802.11 technology in different Brazilian geographical scenarios. The results show that a high connectivity is achieved when more than 20% of the nodes are turned on, regardless of the position of the gateway. The influence of the number of hops and the number of transmitting nodes is also analyzed. A minimum throughput of 2 Mbps can be reached for increasing number of hops in the forwarding chain for a one-node transmission. Besides, when the number of transmitting nodes increases, the aggregated throughput can achieve 3.5 Mbps. The results show that the ad hoc network is a promising solution for the return channel of the interactive Digital TV.8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

A survey on wireless ad hoc networks

A wireless ad hoc network is a collection of wireless nodes that can dynamically self-organize into an arbitrary and temporary topology to form a network without necessarily using any pre-existing infrastructure. These characteristics make ad hoc networks well suited for military activities, emergency operations, and disaster recoveries. Nevertheless, as electronic devices are getting smaller, cheaper, and more powerful, the mobile market is rapidly growing and, as a consequence, the need of seamlessly internetworking people and devices becomes mandatory. New wireless technologies enable easy deployment of commercial applications for ad hoc networks. The design of an ad hoc network has to take into account several interesting and difficult problems due to noisy, limited-range, and insecure wireless transmissions added to mobility and energy constraints. This paper presents an overview of issues related to medium access control (MAC), routing, and transport in wireless ad hoc networks and techniques proposed to improve the performance of protocols. Research activities and problems requiring further work are also presented. Finally, the paper presents a project concerning an ad hoc network to easily deploy Internet services on low-income habitations fostering digital inclusion8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

SETDB2 and RIOX2 are differentially expressed among renal cell tumor subtypes, associating with prognosis and metastization

Increasing detection of small renal masses by imaging techniques entails the need for accurate discrimination between benign and malignant renal cell tumors (RCTs) as well as among malignant RCTs, owing to differential risk of progression through metastization. Although histone methylation has been implicated in renal tumorigenesis, its potential as biomarker for renal cell carcinoma (RCC) progression remains largely unexplored. Thus, we aimed to characterize the differential expression of histone methyltransferases (HMTs) and histone demethylases (HDMs) in RCTs to assess their potential as metastasis biomarkers. We found that SETDB2 and RIOX2 (encoding for an HMT and an HDM, respectively) expression levels was significantly altered in RCTs; these genes were further selected for validation by quantitative RT-PCR in 160 RCTs. Moreover, SETDB2, RIOX2, and three genes encoding for enzymes involved in histone methylation (NO66, SETD3, and SMYD2), previously reported by our group, were quantified (RT-PCR) in an independent series of 62 clear cell renal cell carcinoma (ccRCC) to assess its potential role in ccRCC metastasis development. Additional validation was performed using TCGA dataset. SETDB2 and RIOX2 transcripts were overexpressed in RCTs compared to renal normal tissues (RNTs) and in oncocytomas vs. RCCs, with ccRCC and papillary renal cell carcinoma (pRCC) displaying the lowest levels. Low SETDB2 expression levels and higher stage independently predicted shorter disease-free survival. In our 62 ccRCC cohort, significantly higher RIOX2, but not SETDB2, expression levels were depicted in cases that developed metastasis during follow-up. These findings were not apparent in TCGA dataset. We concluded that SETDB2 and RIOX2 might be involved in renal tumorigenesis and RCC progression, especially in metastatic spread. Moreover, SETDB2 expression levels might independently discriminate among RCC subgroups with distinct outcome, whereas higher RIOX2 transcript levels might identify ccRCC cases with more propensity to endure metastatic dissemination.This study was funded by research grants from Research Center of Portuguese Oncology Institute - Porto (CI-IPOP 4-2012 and CI-IPOP 27) and from Associacao Portuguesa de Urologia (APU-2010). ASP-L was supported by FCT-Fundacao para a Ciencia e a Tecnologia fellowship (SFRH/SINTD/94217/2013). CSG is supported by FCT- Fundacao para a Ciencia e Tecnologia PhD fellowships (SFRH/BD/92786/2013) and BMC is funded by FCT-Fundacao para a Ciencia e a Tecnologia (IF/00601/2012).info:eu-repo/semantics/publishedVersio

Wireless ad hoc networks on underserved communities: an efficient solution for interactive digital TV

The Brazilian government intends to use the Digital TV technology as a vehicle of digital inclusion on underserved communities. The wireless ad hoc network is a low-cost, scalable and easy solution to implement the return channel. This work analyzes the performance of an ad hoc return channel using the wireless IEEE 802.11 technology in different Brazilian geographical scenarios. The results show that a high connectivity is achieved when more than 20% of the nodes are turned on, regardless of the position of the gateway. The influence of the number of hops and the number of transmitting nodes is also analyzed. A minimum throughput of 2 Mbps can be reached for increasing number of hops in the forwarding chain for a one-node transmission. Besides, when the number of transmitting nodes increases, the aggregated throughput can achieve 3.5 Mbps. The results show that the ad hoc network is a promising solution for the return channel of the interactive Digital TV.8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI