Miquel Oliver

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The limited energy resources of sensor nodes are among the most important constraints in Wireless Sensor Networks (WSNs). Consequently, the Medium Access Control (MAC) layer design is crucial, due to its influence on the transceiver,which is themost energy-consuming component of a sensor node. Among the differentMAC protocols designed forWSNs, preamble(More)
M2M communications are projected to be one of the fastest growing technology segments of the IT sector in the next years. Sensor and actuator networks connect communication machines and devices so that they automatically transmit information, serving the growing demand for environmental data acquisition. IEEE 802.11ah Task Group addresses the creation of a(More)
As wireless devices boom, and bandwidth-hungry applications (e.g., video and cloud uploading) get popular, today’s Wireless Local Area Networks (WLANs) become not only crowded but also stressed at throughput. Multi-user Multiple-Input and Multiple-Output (MU-MIMO), an advanced form of MIMO, has gained attention due to its huge potential in improving the(More)
The antitumor antibiotics mithramycin A and chromomycin A(3) bind reversibly to the minor groove of G/C-rich regions in DNA in the presence of dications such as Mg(2+), and their antiproliferative activity has been associated with their ability to block the binding of certain transcription factors to gene promoters. Despite their biological activity, their(More)
A model of the IEEE 802.11e EDCA function is presented. The model is built to be simple, but providing a clear description of the inter-relations between the EDCA MAC parameters (AIFS, CWmin, CWmax and TXOP values) and the traffic flow characteristics (packet arrival rate and packet length). The model is intended to be used as an abstraction of the IEEE(More)
In multi-rate WLANs, users can suffer transmission rate changes due to the link adaptation mechanism. This results in a variable capacity channel, which is very hostile for VoIP and can cause serious quality of service (QoS) degradation in all active calls. Various codec adaptation mechanisms have been proposed as a solution to this, as well as to solve(More)
Multi-user spatial multiplexing combined with packet aggregation can significantly increase the performance of Wireless Local Area Networks (WLANs). In this letter, we present and evaluate a simple technique to perform packet aggregation in IEEE 802.11ac MU-MIMO (Multi-user Multiple Input Multiple Output) WLANs. Results show that in non-saturation(More)
Carrier sense multiple access with enhanced collision avoidance (CSMA/ECA) is a distributed MAC protocol that allows collisionfree access to the medium in WLANs. The only difference between CSMA/ECA and the well-known CSMA/CA is that the former uses a deterministic backoff after successful transmissions. Collision-free operation is reached after a transient(More)
Focusing on the increasing market of the sensors and actuators networks, the IEEE 802.11ah Task Group is currently working on the standardization of a new amendment. This new amendment will operate at the sub-1GHz band, ensure transmission ranges up to 1 Km, data rates above 100 kbps and very low power operation. With IEEE 802.11ah, the WLANs will offer a(More)
This paper presents CSMA/ECA, which combines the efficiency of reservation-based protocols and the simplicity of random access mechanisms. The maximum efficiency of CSMA/CA with optimal parameter adjustment is easily exceeded by CSMA/ECA, even when fixed parameters are used by the latter. CSMA/ECA stations fairly coexist with legacy CSMA/CA and increase the(More)