Microstrip antenna array for mobile communications

Several challenges remain however in the development of antenna array for mobile communications and one of these is the availability of efficient radiating elements interfacing with the beamformer. This paper presents therefore a development effort for a novel printed array antenna. In this paper we presents a modification version of such antennas by adding a series capacitance to the patch equivalent circuit, implemented by electromagnetic coupling and varying the distance between the successive elements in a non linear way. It was found through experiments that the bandwidth of such antennas is increased to 1.5 GHz. The comparaison of the theoretical results montionned above and the measured values showed a good agreement. The design and realization of this log-periodic arrays at 30 GHz, are implemented on a high dielectric constant substrate (epsilon(tau) = 9.9), which is close to the dielectric constant of GaAs. The feasibility of integration of such an antenna strucuture into a monolithic circuits is demonstrated

Power savings and performance analysis in wireless networks

This paper investigates the effects of power saving strategies on the performance of wireless local area networks (WLANs). More specifically, a power management model is formulated as an integer linear program that the network planner can use in order to achieve power savings while maintaining an acceptable quality of service (QoS), measured by the signal to interference ratio (SIR) for interference limited WLAN. Furthermore, through a network simulation implemented in NS-2, it is shown that the adaptive power saving scheme can guarantee the same average throughput as the non-adaptive counterpart, while significantly reducing the total transmitted power. Considering a realistic scenario, we show that, using the proposed power management model, one can save about 55% of the transmitted power while the SIR is increased by 6 dB thus improving the QoS. Also, using a simple experiment with two access points it is shown that, in the case of users within the overlap of the two coverage areas, the throughput remains constant when the transmit power is changed from a low value to a high value although a minor degradation of the average delay is noticed. As a conclusion, the commonly assumed fact that increasing the transmit power results in better network performance is not necessarily true and can result as shown in this paper in energy waste

Traffic analysis for GSM networks

When GSM was introduced in the early 90's, it was considered an over specified system. Nowadays, it is obvious that the whole range of services is widely in use. In addition, performance is degrading due to the rapidly increasing number of mobile subscribers, numbering over 2.9 billion subscribers around the world. The performance of cellular networks is the most important issue concerning their operators. The main goal is to keep subscribers satisfied with the delivered quality of service (QoS). In order to achieve the best performance, service providers have to monitor and optimize their network continuously. A Network Management System (NMS) with an online database is responsible for the collection of data on live networks. For greater effectiveness, operators install systems that do a lot more than collect and store raw data. These systems are easier to use and take advantage of all the data provided by the NMS. In this paper, we summarize measurements that were carried out on an operative GSM-1900 network to evaluate the performance of the GSM's Air-Interface (Um), during eight months. In this paper we have established statistically the following facts: (i) The peak hour in North America is between 4:00 and 5:00 PM. (ii) During week days the duration of calls increases from Monday through Friday. (iii) Weekend traffic is different from week-days traffic. Using a regression analysis we forecast traffic over time. The presented KPIs along with the derived statistical facts are crucial for operators who are concerned with maintaining a reliable and stable network, while maintaining an acceptable QoS

A Middleware Architecture for RFID-enabled traceability of air baggage

International audience1980 marked the start of a boom in radiofrequency identification (RFID) technology, initially associated with a growing need for traceability. In view of the technological progress and lower costs, RFID's area of application became much broader and, today, multiple business sectors take advantage of this technology. However, in order to achieve the maximum benefits of RFID technology, the data collected should be delivered in the best conditions to the whole applications that have need of its exploitation. For that, a dedicated middleware solution is required to ensure the collection of RFID data and their integration in information systems. The issues and key points of this integration as the description of the RFID technology will be summarized in the present paper, with a new middleware architecture. We focus mainly on components and the design of our middleware MedRFID, solution developed in our Lab, and which integrates mobility and provides extensibility, scalability, abstraction, ease of deployment and compatibility with IATA standards and EPCglobal standards. Moreover, we have developed an application (FindLuggage) allowing a real time tracking of luggage in the airport, based on the proposed middleware MedRFID

A Middleware Architecture for RFID-enabled traceability of air baggage

1980 marked the start of a boom in radiofrequency identification (RFID) technology, initially associated with a growing need for traceability. In view of the technological progress and lower costs, RFID’s area of application became much broader and, today, multiple business sectors take advantage of this technology. However, in order to achieve the maximum benefits of RFID technology, the data collected should be delivered in the best conditions to the whole applications that have need of its exploitation. For that, a dedicated middleware solution is required to ensure the collection of RFID data and their integration in information systems. The issues and key points of this integration as the description of the RFID technology will be summarized in the present paper, with a new middleware architecture. We focus mainly on components and the design of our middleware MedRFID, solution developed in our Lab, and which integrates mobility and provides extensibility, scalability, abstraction, ease of deployment and compatibility with IATA standards and EPCglobal standards. Moreover, we have developed an application (FindLuggage) allowing a real time tracking of luggage in the airport, based on the proposed middleware MedRFID

A lightweight middleware for an e-health WSN based system using android technology

With the rapid development of Wireless Sensors Network (WSN) technology, together with its growing market due to the variety of applications in which this technology can be used, sensors are now available at very cheap prices, and relatively high quality. The medical field among other fields is one of the most promising fields in which sensors technology is undergoing great improvements. With the constant and continuing advances on the wireless sensor networks and applications, lots of medical applications that use sensors are emerging. Varying from pre-hospital, in-hospital applications to post-hospital and rehabilitation applications, sensors are used in a wide range of applications such as patient's drug administration to elderly remote supervision. With the lake of standardization, a framework that would govern the interaction between the applications and the network is a must to be capable of sensing, processing, and communicating vital health signs. In this research we proposed layered approach architecture for a lightweight portable middleware with the Android technology. Our system takes into consideration the design principles and issues related to medical applications. A prototype of the lightweight middleware for an e-Health WSN based System was designed and tested and we showed that the results are very promising

A Comparative Study on Security implementation in EPS/LTE and WLAN/802.11

Security in the wireless access network gained increasing interest over the last years. Its implementation varies from one access network to another. The current trend in wireless access network is towards implementing mechanisms for mobility management namely handoff process and quality of service control. Consequently, security should be taken into consideration at each handoff process which may occur between different technologies (inter-technology) or within the same (intra-technology). At the same time, security provisioning impact on network performances (e.g. end-to-end delay, throughput) should be controlled. This chapter aims to give a better understanding of security measures and protocols available in two distinct wireless network families, namely the Wireless Wide Area Network (WWAN) and the Wireless Local Area Network (WLAN). WWAN family includes the wide coverage area technologies such as the Long-term Evolution (LTE), also named as Evolved Packet System (EPS). On the other hand, WLAN are characterized by having a small coverage area. It includes the WiFi (802.11) technology. Each time, the chapter highlights the mechanisms employed by access network to ensure the trade-off between secured mobility and application requirements in terms of delay and throughput