Driss Benhaddou

Orthogonal frequency division multiplexing for indoor optical wireless communications using visible light LEDs

Visible light LEDs are being used for indoor optical wireless systems as well as room lighting. In indoor diffuse optical wireless links multipath dispersion limits the maximum transmission data rates. In this paper we investigate OFDM system where multipath induced intersymbol interference (ISI) is reduced, enabling higher data rates. Pilot signals are uniformly inserted into data symbols (subcarriers) and are extracted at the receiver for channel estimation. Predicted and simulated results for the symbol error rate (SER) for an OFDM employing BPSK, QPSK and M-QAM for line of sight (LOS) and diffuse links are presented for a range of pilot signal.

Remote Laboratories for Optical Circuits

This paper presents a remote laboratory implementation for an optical circuits course. The process from design and implementation towards assessment and continuous improvement phase is outlined. The design of the experiments involved the research on remote access technology and the investigation of best practices for an experimental setup. The first pilot implementations were used to determine the possible shortfalls during an ldquoIntroduction to an Optical Communicationsrdquo course in fall 2004 at the University of Colorado, Boulder, and an ldquoOptical Circuitsrdquo course in fall 2005 at the University of Houston, Houston, TX. After improvements, two experiments were pilot tested during spring 2006 at the University of Houston. Assessment of learning outcomes and teaching methods were performed. The remote access methods, in addition to the delivery of the class and lectures, are presented in the paper. Delivery of a class with remote laboratories and videotaped lectures are also outlined under future directions of this project.

Wireless sensors networks for Internet of Things

The Internet is smoothly migrating from an Internet of people towards an Internet of Things (IoT). By 2020, it is expected to have 50 billion things connected to the Internet. However, such a migration induces a strong level of complexity when handling interoperability between the heterogeneous Internet things, e.g., RFIDs (Radio Frequency Identification), mobile handheld devices, and wireless sensors. In this context, a couple of standards have been already set, e.g., IPv6, 6LoWPAN (IPv6 over Low power Wireless Personal Area Networks), and M2M (Machine to Machine communications). In this paper, we focus on the integration of wireless sensor networks into IoT, and shed further light on the subtleties of such integration. We present a real-world test bed deployment where wireless sensors are used to control electrical appliances in a smart building. Encountered problems are highlighted and suitable solutions are presented.

Remote Healthcare Monitoring System Architecture using Sensor Networks

Ubiquitous processing is impacting several applications affecting our lives. In this paper we propose a remote health care monitoring system that uses sensor networks to extend the coverage of medical application to underserved area. We delineate the challenges that face researchers in this area. In addition, the paper describes the general architecture and proposes a MAC scheme for healthcare sensor networks (MACH) that adapts channel provisioning based on the information criticality. MACH enables emergency traffic to meet its quality of service (QoS) requirements. Performance evaluation using analytical modeling shows that our proposed MAC give preference to emergency traffic which is crucial for medical applications.

Energy efficient cross-layer routing protocol in Wireless Sensor Networks based on fuzzy logic

Resources are scarce in Wireless Sensor Networks (WSN) and one of the challenges is to design a lightweight communication protocol to support efficient and uniform power consumption among nodes. In this paper, we propose an energy aware routing scheme based on a cross-layer approach for WSNs with the objective to minimize the overall consumed energy; thus, maximizing the network lifetime. The remaining battery reserve capacity, link quality and transmission power for nodes within the local communication range are taken into consideration to determine the next hop relay node to reach the network sink. Parameters from different stack layers (i.e., physical, MAC, and network) are presented to a fuzzy logic system controller which makes a next hop routing decision. The performance of the proposed cross-layer algorithm is evaluated using discrete event simulation (OMNET++ Modeler).

Value-added services in next-generation SONET/SDH networks

Advances in next-generation SONET/SDH have introduced novel features for generic protocol framing/encapsulation, virtual concatenation, inverse multiplexing, dynamic circuit adjustment, and so on. In turn, these provisions have enabled much improved multi-tiered service provisioning and are viewed very favorably by carriers, particularly incumbents. This article looks at this evolved framework with a particular focus on value-added services creation. Results from a sample performance evaluation study also are presented to quantify some of the achievable gains.

Temporal data representation, normalization, extraction, and reasoning

BACKGROUND AND OBJECTIVE We live our lives by the calendar and the clock, but time is also an abstraction, even an illusion. The sense of time can be both domain-specific and complex, and is often left implicit, requiring significant domain knowledge to accurately recognize and harness. In the clinical domain, the momentum gained from recent advances in infrastructure and governance practices has enabled the collection of tremendous amount of data at each moment in time. Electronic health records (EHRs) have paved the way to making these data available for practitioners and researchers. However, temporal data representation, normalization, extraction and reasoning are very important in order to mine such massive data and therefore for constructing the clinical timeline. The objective of this work is to provide an overview of the problem of constructing a timeline at the clinical point of care and to summarize the state-of-the-art in processing temporal information of clinical narratives. METHODS This review surveys the methods used in three important area: modeling and representing of time, medical NLP methods for extracting time, and methods of time reasoning and processing. The review emphasis on the current existing gap between present methods and the semantic web technologies and catch up with the possible combinations. RESULTS The main findings of this review are revealing the importance of time processing not only in constructing timelines and clinical decision support systems but also as a vital component of EHR data models and operations. CONCLUSIONS Extracting temporal information in clinical narratives is a challenging task. The inclusion of ontologies and semantic web will lead to better assessment of the annotation task and, together with medical NLP techniques, will help resolving granularity and co-reference resolution problems.

Nonintrusive Occupant Identification by Sensing Body Shape and Movement

The ability to identify people has numerous applications including in smart buildings where the building can be customized to the needs of its occupants or for other applications such as in assisted living and customer behavior analysis in commercial settings. There are different methods used for occupant identification. Some are intrusive such as using cameras or microphone and others require the users to carry mobile gadgets to be identified. In this paper, we present a nonintrusive method to identify people by sensing their body shape and movement. Such information is derived from using ultrasonic sensors to measure the height and width as the occupant walks through the instrumental doorway. In fact, height and width are not unique to every occupant, but extracting a set of features from the variations in height and width makes identification possible. In this study, our system senses a stream of height and width data, recognizes the walking event when a person walks through the door, extracts features that capture a persons movement as well as physical shape. These features are fed to our clustering algorithm that associates each occupant with a distinct cluster. We deployed our system for 1 month. We found out that our approach achieves 95% accuracy with 20 occupants suggesting the suitability of our approach in commercial building settings. In addition, we found out that using girth to distinguish between occupants is more successful than using height.

Preemptive emergency medium access for wireless sensor networks: performance under realistic network conditions

The proliferation of Wireless Sensor Network (WSN) deployment in threat monitoring applications requires support for emergency-class services with tight Quality-of-Service (QoS) bounds. The CP-EDCA protocol was designed to achieve deterministic delay bounds for emergency-class traffic during distributed wireless network operation. The CP-EDCA scheme could be an ideal choice for prioritised channel access in WSNs, if the performance is demonstrated to be effective under WSN conditions. Here, we evaluate the effectiveness of CP-EDCA protocol under erroneous channel conditions and multi-hop data flow scenarios, which are distinctive features of WSNs. Mathematical and simulation analysis depicts that under typical WSN conditions, distributed preemptions accomplish deterministic delay bounds for emergency traffic even with heavy network loads. Under severe packet losses, CP-EDCA depicted perceivable improvements, relative to IEEE 802.11e standards. Analysis in multi-hop scenarios validates that the channel access preemptions have a significant impact on the end-to-end data flow performance.

Channel estimation for indoor diffuse optical OFDM wireless communications

Pilot insertion for channel estimation in orthogonal frequency division multiplexing (OFDM) is a promising technique for broadband/high data rate wireless communications. In indoor diffuse optical wireless links, channel impulse response depends on the location of the receiver. For links to offer mobility tracking is essential which can be complex to implement. In this paper we propose channel estimation to allow receiver mobility. We have examined channel estimation with different interpolation methods for OFDM system and have compared the symbol error rates (SER) performance.