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Wireless sensor networks (WSN) consists of unattended sensors with limited storage, energy (battery power) and computational and communication capabilities. Since battery power is the most crucial resource for sensor nodes and delay time is a critical metric for certain WSN applications, data diffusion between source sensors and sink should be done in an energy efficient and timely manner. We characterize...
Dual-Tone Multi-Frequency (DTMF) Signals are used in touch-tone telephones as well as many other areas. Since analog devices are rapidly being replaced with digital devices, digital DTMF decoders with superior quality have become the ideal replacement. In this paper a comparative analysis on the four DTMF detector designs are studied. They are namely, filter design approach, Discrete Fourier Transform(DFT),...
Video and audio communications like video conference, news, and chat applications are candidates to be the greater portion of Internet traffic. Thus, using compressed video and audio traffic seems to be compulsory to reduce the costs of transmission and storage. Variable bit rate (VBR) compressed video and audio traffic have been receiving considerable attention due to their compression algorithms...
In this work, we investigate the characteristics of the 2004 major storm events based on GPS-TEC measurement at Scott Base station Antarctica (77.9degS, 166.8degE). The F2 layer critical frequencies and peak height during the storm from the ionosonde measurement at the station are also investigated. Our main emphasis was on the characteristics and response during major storms events. Our results include...
In this paper we demonstrate experimental results of a double-pass erbium-doped fiber amplifier with built-in variable optical Bragg grating (DPF- EDFA) to enhance the performance of the transmission system. The system has achieved power gain of 6 dB which can be translated into an improvement to the distance of about 24 km compared to the conventional double-pass EDFA (DP-EDFA).
In this paper, we present a novel method based on Electromagnetically Induced Transparency (EIT) and ring resonator for description of all-optical controllable filters that is so necessary for development of all-optical networks and systems. Impurities including 4-level atoms or nanocrystals added to ring resonator for control of the absorption and the index of refraction. Parameters of the control...
Modeling and simulation are traditional methods used to evaluate wireless network design, this paper provides a discrete event simulation modeling tool built using Borland c++ builder 6 to modeling a GPSR protocol routing process in ad hoc wireless network, this paper describe the main components of discrete event simulation tool used in building any discrete event simulation model such as processes,...
In this paper an asymmetric structure for enhancement of second-order nonlinear optical susceptibilities in the strained asymmetric GaN-AlGaN- A1N QW is proposed. In this structure, the strain-induced spontaneous and piezoelectric effects have been taken into account, and the second-order optical susceptibility of the delta -doped step QW structure have been analyzed by considering the Shrodinger-Poisson...
In multi-hop mobile ad hoc networks (MANETs), mobile nodes cooperate with each other without using any infrastructure such as access points or base stations. Security remains a major challenge for these networks due to their features of open medium, dynamically changing topologies, reliance on cooperative algorithms, absence of centralized monitoring points, and lack of clear lines of defense. Among...
This paper proposes a bandwidth sharing scheme for DiffServ-aware MPLS networks based on the Russian Dolls bandwidth allocation model. Three DiffServ traffic class types were used in the DiffServ-aware MPLS network under study, i.e. real time constant bit rate premium, real time variable bit rate assured and non-real time best effort traffic. We propose a preemption scheme based on rerouting or resizing...
In this paper, we analyze the effect of applying leaky bucket as a well known traffic shaper on data users in a variable spreading gain CDMA (VSG-CDMA) uplink wireless cellular network. To this end, we model the effect of leaky bucket mechanism on a typical data user, with a closed product form queueing network. Each node in this queueing network corresponds to a specific processing gain or equivalently...
IEEE 802.15.4 is a wireless personal area network (WPAN) for low data-rate and duty-cycle applications. How this simple network can also be used for high quality, secure speech communication is described in this paper. The key to achieve this lies in how the various features can be packed into the low bandwidth structure that has been allocated in this protocol. A low bandwidth high quality speech...
This paper presents a new approximate calculation method of the occupancy distribution and the blocking probability in switching networks which are offered multi-service traffic streams generated by a finite population of two-state sources. The proposed method belongs the class of methods known as the effective availability methods. The basis of the proposed calculation algorithm is the occupancy...
Providing quality of service (QoS) and traffic engineering (TE) capabilities in the Internet is essential, especially in supporting the requirement of real- time traffic, as well as mission critical applications. differentiated services (DiffServ) is an emerging technology that provides QoS and traffic engineering features in IP network by programming the IXP2400 Intel Network Processor. Since the...
During communication between wireless users, disconnection may occur during the handover process. The high handover latency during the process of handover degrades the service quality of the wireless communications. This problem becomes more crucial if the operation network is transmitting real-time multimedia applications. This paper presents our work on the interworking of protocols in IPv6 mobility...
SSB (Simplified Switched Beam) was originally motivated by a simple beamforming technique. It is expected to increase the performance of Mobile Ad Hoc Networks (MANETs) by associating with the dedicated MAC protocol [12]. However, we further find that it is a variation of the antenna diversity scheme, which is called GSC in [6] and H-S/MRC in [11]. SSB only requires one RF front-end and a simple additional...
Wideband Code Division Multiple Access (WCDMA) system simulators are commonly used as a design and research tool to aid the deployment of 3G as well as forthcoming wireless communication systems. High data rates, reliability, security and Bit Error Rate (BER) performance are key requirements of a 3G system. If realistic simulations are to be performed, these requirements have led to unacceptably long...
This paper presents a study into different decoders for the new Rotation Spreading Matrix proposed for Block Spread OFDM (BSOFDM). It presents simulation results for the Maximum Likelihood (ML), Minimum Mean Square Error (MMSE), Zero Forcing (ZF), Maximal Ratio Combining (MRC) and Equal Gain Combining (EGC) decoders across the four IEEE defined Ultra-Wideband (UWB) channels CM1 to CM4. While it is...
In the last few years, some measurement infrastructures have been proposed as a form of efficiently evaluating the performance of computer networks. Despite the advantages of these infrastructures, their usage in large scale scenarios has been presenting critical problems, preventing their wider adoption. One of the reasons for this situation is the lack of management support for the monitoring devices...
This paper continues the work on the new rotation matrix developed for BSOFDM which showed improvement in frequency selective channels such as the UWB IEEE defined CM1 to CM4 and overall system performance. This paper presents a method by which higher order Rotation matrix can be derived and simulation results are used to show that the higher order Rotation matrix outperforms the Hadamard matrix in...
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