José Luis Valenzuela

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In this paper the performance of the IEEE 802.11 wireless local area networks in combination with Hierarchical Tocken Bucket traffic shaper is assessed. The analysis allows to show the basic advantages of the proposed scheduler. Results are obtained on a real IEEE 802.11b testbed to gain insight into HTB practical implementation issues. The HTB concept(More)
This paper studies the feasibility of using low-power wireless technologies such as Bluetooth, IEEE 802.15.4 and ZigBee in high-speed railway scenarios that involve bidirectional ground-to-train communication. The presented results have been obtained through experimental tests conducted at the MadridBarcelona high-speed rail line. A multiplatform(More)
This paper presents an efficient multipolling scheme that improves the IEEE 802.11 MAC protocol efficiency and does not suffer from the hidden terminal problem or inefficient channel usage problems. To design an efficient polling scheme, the access point (AP) needs to obtain information about the current transmission status and channel state for each(More)
The purpose of this paper is to evaluate from a real perspective the performance of Bluetooth Low Energy (BLE) as a technology that enables fast and reliable discovery of a large number of users/devices in a short period of time. The BLE standard specifies a wide range of configurable parameter values that determine the discovery process and need to be set(More)
The use of hypothermia after cardiac arrest caused by ventricular fibrillation is a standard clinical practice, however its use for neuroprotection has been extended to other conditions. We report a 23-year-old male with intracranial hypertension secondary to a parenchymal hematoma associated to acute hydrocephalus. An arterial malformation was found and(More)
The device discovery process is one of the most crucial aspects in real deployments of sensor networks. Recently, several works have analyzed the topic of Bluetooth Low Energy (BLE) device discovery through analytical or simulation models limited to version 4.x. Non-connectable and non-scannable undirected advertising has been shown to be a reliable(More)
In this paper we present a hybrid Physical and Medium Access Control protocol for a Wireless LAN which is designed to support both synchronous (voice) and asynchronous (data) traffic. The protocol is designed using a modified Bluetooth core and 802.11e radio access, where the voice service is supported by Bluetooth whereas data and video services are(More)