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Traditional electro-optic modulators are not optimized for bandpass applications such as radio-on-fiber delivery systems due to their limited electro-optic response. This paper presents a resonant electrode structure that can be employed in optical modulator designs to enhance the electro-optic response of the modulator over a narrow frequency band, and improve the performance of optical radio systems...
A simple and efficient method for evaluation of near field of the GSM base station antennas in urban environment is presented in this paper. The method is based on the replacement of panel antenna with a discrete linear array. Moreover, the geometrical optics approach is used to consider the influence of environment. The approximate results are found to be in excellent agreement with the results obtained...
We present a systematic nonlinear procedure for designing microwave oscillators utilising a nonlinear PHEMT model, the negative resistance approach and the describing function concept. The procedure is applied in the design of a 24 GHz oscillator, which is then realised in hybrid technology. Measurement results show - 6% shift in the frequency but an acceptable agreement in the output power. A detailed...
A laser diode reliability test based on the measurements of the low-frequency optical and electrical noise, and their correlation factor changes during short-time ageing is presented. The noise characteristics reveal obvious differences between the stable and unreliable lasers operated near the threshold region. An excessive Lorentzian type noise with negative correlation factor at the threshold could...
The appropriate emitter database is one of the most important elements in the present electronic intelligence (ELINT) system. This paper provides an overview of the relational modelling, which is used to construct the emitter database for current ELINT systems. The method described, delivers the entities' relational diagram that is independent from the manner of the data storage in further process...
Theoretical and experimental study of using direct modulated vertical cavity surface emitting lasers in radio over fiber applications is presented. The nonlinear distortion and signal to noise ratio are investigated and evaluated in case of short-range multi-carrier transmission. Nonlinear characterization and comparison of the different kind of semiconductor lasers are also presented.
A gradient based optimization technique along with a new definition of cost function is applied to synthesis of coupled resonators filters. The cost function is defined using location of zeros and poles of the filter's transfer function. The topology of the structure is enforced on each step of optimization and its physical dimensions are used as independent variables.
New design method is presented for distributed amplifiers (DA). It is shown that by proper design of the applied transmission lines (TL) between the active devices the image impedance and the cut-off frequency (COF) of the input or output line of the DA can be independently tuned. As a consequence, the phase mismatch between the lines of the DA can be adjusted independently from the termination conditions...
The influence of optical radiation on the performance of the synchronized microwave Gunn-diode oscillator in the coherent signals subtraction mode has been described theoretically and investigated experimentally. The high sensitivity of the oscillator characteristics to the change of the optical intensity affecting the semiconductor diode structure has been shown. It is suggested to use this mode...
The paper presents output results of 3G network simulation software in the area of optimal site location as well as finding optimal values of antenna tilt. The loss of capacity is shown for a wide range of tilts and different antenna directions. Nonuniform distribution of base stations has been also included in the simulation scenarios influencing system performance. All of the described parameters...
The paper presents new method of integration home digital network with Bluetooth wireless communication system. In this new application Bluetooth is used as one of the main ways of communication and information exchange between elements of the system for integrated, centralized control of the digital devices in the multimedia home platform. Bluetooth enables communication between multimedia gateway...
The FDTD (Finite Difference Time Domain) method has proven to be effective in modeling high-frequency electromagnetic problems in telecommunications industry. Recently it has been successfully applied in microwave power engineering. In order to accurately model scenarios typical in this field one has to deal with the movement of objects placed inside cavities. This paper describes a simple algorithm...
Theory of scattering by lossy dielectric, ferrite and/or conducting cylinders is investigated using a combination of an iterative scattering procedure and the orthogonal expansion method. The addition theorems for vector cylindrical harmonics, which transform harmonics from one coordinate system to another, are presented.
In this paper, we propose a simple but efficient method for improving correlation properties of polyphase spreading sequences for asynchronous direct sequence code division multiple access (DS CDMA) applications. The proposed method can be used to reduce the mean square value of aperiodic crosscorrelation or the mean square value of aperiodic autocorrelation, the maximum value of aperiodic crosscorrelation...
This paper presents a new global positioning system (GPS)-based routing protocol, called location-based point-to-point adaptive routing (LPAR) for mobile ad hoc networks. This protocol utilises a 3-state route discovery strategy in a point-to-point manner to reduce routing overhead while maximising throughput in medium to large mobile ad hoc networks. In LPAR, data transmission is adaptable to changing...
We present a number of applications of Hadamard matrices to signal processing, optical multiplexing, error correction coding, and design and analysis of statistics.
This paper analyses the consistency of a set of MPEG-7 low level audio descriptors when the input audio stream has previously been compressed with a lossy compression algorithm. The analysis results show that lossy compression has a detrimental effect on the integrity of practical search and retrieval schemes that utilize the low level audio descriptors. Methods are then proposed to reduce the detrimental...
This paper presents a concept of IP Differentiated Services (DiffServ) architecture in conjunction with bandwidth brokerage and policy based network management, all aimed at efficient and flexible provision of the military oriented Quality of Service (M-QoS) features in the Australian Defence (strategic) wide area network and its satellite trunk interconnections with the tactical domain. Typical DiffServ...
Research on multi-path routing protocols to provide improved throughput and route resilience as compared with single-path routing has been explored in details in the context of wired networks. However, multi-path routing mechanism has not been explored thoroughly in the domain of ad hoc networks. In this paper, we analyze and compare reactive single-path and multi-path routing with load balance mechanisms...
In this paper, we propose framework for an adaptive handover control architecture (AHCA), which aims at enhancing overall IP handover performance while maximising utilisation of resources in wireless access networks. The IP handover procedures in the AHCA adapt dynamically to network conditions, as well as to a wide range of user profiles and application quality of service (QoS) requirements. To confirm...
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