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Today's IEEE 802.11 wireless local area network (WLAN) is an excellent solution for the broadband wireless networking. However, the legacy protocol lacks the capability to support real-time services such as Voice over IP (VoIP) properly because it depends on the best effort service. New IEEE 802.11e protocol can support QoS. This paper presents the VoIP stations capacity in IEEE 802.11 WLAN and IEEE...
In this paper an analytical model for GSM/EGPRS is developed. It is based on the performance of M/M/C/co/N queueing system with FCFS queue discipline. This model is adapted to guarantee GPRS/EGPRS system constraint and Internet traffic (ON/OFF traffic) over a single cell. The interaction of voice calls with GPRS/EGPRS connections is studied. Different performance parameters are calculated which are...
The cell planning problem concerns finding a set of sites for antennas from a set of pre-defined candidate sites, and for each selected site, to determine the number of antennas, as well as the associated values for each of the antenna parameters. All these choices must optimize a set of objectives. This paper presents a new approach for tackling this complex and highly combinatorial problem. The...
In this paper, we consider a mobile ad-hoc network (MANET) in which mobile nodes can access the Internet via a stationary gateway node or access point. These gateways act as bridges between a MANET and the Internet. Mobile nodes that are outside the transmission range of the gateway can continue to communicate with the gateway via a multi-hop connection with their neighboring nodes. Ad hoc on-demand...
We introduce microstrip patch antennas of simple shapes which can exhibit broadband operation and still enjoy relatively compact size. The circular and rectangular patches are considered when shorted to the ground plane via one or two shorting pins. The antenna is analyzed by finding the cavity modes of the structure in terms of their resonant frequencies and field distributions. Depending on the...
The adaptive array antenna is combined with OFDM "orthogonal frequency division multiplexing" as multicarrier technique to combat the flat and frequency selective fading effects at high speed wireless communication. In this paper an optimum weight sets beat informer at time and frequency domain were obtained based on LMS algorithm. Different aspects of these systems were investigated such...
In this paper, single-precision floating-point IEEE-754 standard Adder/Subtractor and Multiplier modules with high speed and area efficient are presented. These modules are designed, simulated, synthesized and optimized by using Mentor Graphics Tools, and they are implemented on an FPGA based system by using the Xilinx Tool (ISE). A comparison between the results of the proposed design and a previously...
In this paper we consider multi-user detection in CDMA systems. A modified recursive least squares (RLS) blind adaptive algorithm for multiuser detection in multipath channels is proposed. The proposed algorithm is shown to have a lower computational complexity than the conventional RLS algorithm while maintaining the same performance as the conventional RLS algorithm. Also, we propose a blind adaptive...
This paper presents a block based digital image watermarking that is dependent on the mathematical technique of singular value decomposition (SVD). Traditional SVD watermarking already exists for watermark embedding on the image as a whole. In the proposed approach, the original image is divided into blocks, and then the watermark is embedded in the singular values (SVs) of each block separately....
The effect of both shot noise and thermal noise on the performance of the optical code-division multiple- access (OCDMA) round robin receiver/transmitter (R3T) protocol is examined. Several performance measures, namely, the steady state system throughput, the protocol efficiency, and the average packet delay are evaluated. Our results reveal that the R3T is immune against both thermal and shot noise...
This paper presents a new combined acquisition scheme, known as "fast serial search sequential estimation" which is applicable to the direct sequence spread spectrum systems with a long period pseudo noise sequences. The proposed scheme is a combination of two basic acquisition schemes which are the serial search acquisition scheme and the rapid acquisition by sequential estimation (RASE)...
A proposed sensor for landmines detection consists of two parallel microstrip antennas placed on same ground plane with shorting pins between the patch and the ground plane has been investigated. The microstrip patch array with shorting pins has the advantage of a low coupling and size reduction compared with classic arrays. The finite-difference time-domain (FDTD) is used to simulate the senor for...
A stacked microstrip antenna with C-type feed is designed in order to enhance the bandwidth. The effect of the various parameters, such as the rotation feed angle (thetas), the variations of relative permittivity of parasitic patch (epsivr2), the distance of the feed point from the center (r), and the separation between two stacked patches (h2), have been discussed. Some designs give a good return...
Numerical solution of complex electromagnetic problems using hybrid techniques is presented in this paper. By combining the desirable features of the method of moments (MoM) and wavelet packet transform (WPT) to analyze large-scale electromagnetic problems. The computational domain is divided into smaller and manageable sub-domains, with coupling between these sub-domains is taken into account. As...
Diffie-Hellman key agreement protocol is the first and most famous protocol, but it has many flaws and drawbacks. Therefore, this paper proposes a new two-pass authenticated key agreement protocol (AK) provides assurance, randomization, and controlling of the key reception, this protocol is based on Dijfie-Hellman problem and also follows - up T. Matumoto, Y. Takashima and H. Imai two-pass Key Agreement...
A simple multi-wavelength laser source using, an erbium doped fiber (EDF) as a gain medium is proposed. The source is terminated by a chirped fiber Bragg grating (CFBG) on one side and cascaded FBGs on the other side. Different apodization profiles for the FBG are analyzed to improve the lasing wavelengths selectivity. The Blackman profile is found to be the best to reduce the reflection spectrum...
This paper presents a proposed algorithm for power control in CDMA system that is based on the powerful optimization technique known as particle swarm optimization (PSO). The algorithm finds a suitable power vector, i.e. the power levels that are determined in the base station and told to the mobile units so that if the mobile units adjust their transmitting levels to these power levels, they will...
The linearly constrained minimum variance (LCMV) algorithm fails to capture the signal if coherent copies (multipath signals) impinge on the array at the same time with the signal. The constant modulus algorithm (CMA) and the multi-modulus algorithm (MMA) techniques solved this problem with the disadvantage of more complicated behavior and the violation of some constraints about null directions staled...
This tutorial paper reports on the state-of-the-art of Monolithic Microwave Integrated Circuits (MMIC) technology. The paper gives an overview of available MMIC semiconductor materials, devices, processes and outlines the steps of a typical MMIC manufacturing process followed by a description of the different technologies used in MMIC assembly and packaging. MMIC design guidelines regarding performance...
Advanced antenna arrays at the base stations are one of the key techniques to reduce interference in WCDMA cellular systems. This paper presents the use of the beam steering method with circular arrays along with Chebyshev current distributions in order to reduce the value of the ratio of intercell interference to received intracell power in WCDMA cellular systems. The intercell to intracell interference...
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