Majlesi Journal of Telecommunication Devices: 1 (1)

Open Access Article

1 - Crystal notch filter design for detecting clutter to low altitude radar
Habibollah Rezaei

On low altitude radar system heavy reflective clutter from earth case saturation receiver amplifier, for stoppage receiver saturation using a crystal notch filter on input of IF stage Crystal filter having high Q and selective frequency and band width, they have high re More

On low altitude radar system heavy reflective clutter from earth case saturation receiver amplifier, for stoppage receiver saturation using a crystal notch filter on input of IF stage Crystal filter having high Q and selective frequency and band width, they have high resistance for changing temperature so this filter suitable for radar receiver. In this paper we try to showing suitable method for increase Q and selective width of filter band width, to design a filter can attenuation 60dB selective band width of receiver by selective frequency. On crystal notch filter using trans for increasing circuit impedance and filter band width. Manuscript profile

Open Access Article

2 - Wide Tuning Range CMOS Colpitts VCO Based on Tunable Active Inductor

In this paper, a new differential Colpitts voltage-controlled oscillator (VCO) is presented. The VCO is based on the gm-boosted structure to relax the oscillation start-up current requirement and reduce the DC power consumption in comparison to conventional Colpitts str More

In this paper, a new differential Colpitts voltage-controlled oscillator (VCO) is presented. The VCO is based on the gm-boosted structure to relax the oscillation start-up current requirement and reduce the DC power consumption in comparison to conventional Colpitts structures. In the proposed VCO, a tunable active inductor is utilized as a part of LC tank instead of passive inductor with constant inductance. The proposed VCO is designed and simulated in ADS in a 0.18μm CMOS process. Simulation results indicate that the proposed VCO has a wide tuning range in comparison to other reported designs while consumes less DC power. Manuscript profile

Open Access Article

3 - High Performance Channel Decoders on CELL Broadband Engine for WiMAX System

Wireless baseband processing, which is characterized by high computational complexity and high data throughput, isregarded as the most challenging issue for software radio (SR) systems, especially for the General Purpose Processor(GPP)-based SR systems. To overcome this More

Wireless baseband processing, which is characterized by high computational complexity and high data throughput, isregarded as the most challenging issue for software radio (SR) systems, especially for the General Purpose Processor(GPP)-based SR systems. To overcome this implementation difficulty in SR systems, the multicore architecture hasbeen proposed as the GPP-based SR platform, for example, multicore Central Processing Unit (CPU), GraphicProcessing Unit (GPU) and Cell processors. In this paper, the Cell processor is considered as the core component inthe GPP-based SR platform. The channel decoding modules for convolutional, Turbo and Low-density parity-check(LDPC) codes of WiMAX systems are investigated and efficiently implemented on Cell processor. With a singleSynergistic Processor Element (SPE) running at 3.2GHz, the implemented channel decoders can throughput up to30Mbps, 1.36Mbps and 1.71Mbps for the above three codes, respectively. Moreover, the decoding modules can beeasily integrated to the SR system and provide a highly integrated SR solution Manuscript profile

Open Access Article

4 - Spectrum Sensor Hardware Implementation Based on Cyclostationary Feature Detector

Cognitive radios utilize spectrum sensors to provide information about the surrounding radio environment. Thisenables cognitive radios to communicate at the same frequency bands with existing (primary) radio systems, andthereby improve the utilization of spectral resour More

Cognitive radios utilize spectrum sensors to provide information about the surrounding radio environment. Thisenables cognitive radios to communicate at the same frequency bands with existing (primary) radio systems, andthereby improve the utilization of spectral resources. Furthermore, the spectrum sensor must be able to guarantee that the cognitive radio devices do not interfere with the primary system transmissions. This paper describes a hardwareimplementation of a spectrum sensor based on cyclostationary feature detector, which has an improved detectionperformance achieved by decimation of the cyclic spectrum. Decimation also provides a simple way to controldetection time and, therefore, allows trading the detection time to better probability of detection and vice versa.Implementation complexity in terms of power consumption and silicon area for a 65 nm CMOS process is evaluated.Measured detection performance is presented and detection of a 802.11g WLAN signal through air interface isdemonstrated. Manuscript profile

Open Access Article

5 - Rate Adaptive Resource Allocation and Utility-Based Packet

There are several approaches for Radio Resource Management (RRM) in multicarrier cellular systems. This work analyzes and compares two of them: rate-adaptive resource allocation (sub-carriers and power) based on instantaneous data rates, and utility-based packet More

There are several approaches for Radio Resource Management (RRM) in multicarrier cellular systems. This work analyzes and compares two of them: rate-adaptive resource allocation (sub-carriers and power) based on instantaneous data rates, and utility-based packet scheduling based on average data rates. A fundamental RRM problem in wireless cellular networks was chosen as a background to evaluate the aforementioned approaches: the trade-off between system spectral efficiency and fairness among the users when opportunistic allocation is used. Extensive system-level simulations were performed and important network metrics such as total cell throughput, mean user throughput, system fairness index and user satisfaction were assessed. It was concluded from the simulation results that it is possible to achieve an efficient trade-off between resource efficiency and fairness using any of the two RRM approaches. However, utility-based packet scheduling algorithms based on average data rates have the advantage of presenting higher user satisfaction with less computational complexity. Manuscript profile

Open Access Article

6 - Performance Evaluation of Decision Fusion

Cognitive radio is a promising solution to the problem of spectrum scarcity by means of allowing secondary radio networks access the spectrum opportunistically. One of the most important issues in cognitive radio is how to detect existing over-the-air signals reliably. More

Cognitive radio is a promising solution to the problem of spectrum scarcity by means of allowing secondary radio networks access the spectrum opportunistically. One of the most important issues in cognitive radio is how to detect existing over-the-air signals reliably. Not a few literatures have reported that signals could be detected via their inherent or embedded properties. However, this approach may not be reliable and flexible enough for all kinds of signals with different modulation types. In this paper, we propose a type of multitone beacon signal carrying cyclostationary signatures, which is able to enhance the reliability and efficiency of signal detection at low cost of spectrum overhead. This beacon not only can indicate the presence or absence of user signal but also can reveal some other information helpful to opportunistic spectrum access through the information bits carried on its cyclostationarysignatures. Manuscript profile

Open Access Article

7 - Application of Chaos Theory Mode Hannon in Optical Communication by Mach-Zehnder Interferometer for Chaotic Information Transference

This project investigates chaos theory as a method for information cryptography in optical communication. Information security and communicated information error reduction are the main communication issues. Different methods including chaos theory have been suggested fo More

This project investigates chaos theory as a method for information cryptography in optical communication. Information security and communicated information error reduction are the main communication issues. Different methods including chaos theory have been suggested for its analysis. In addition to introducing the theory, this article investigates whether it could be used in optical communication and suggests a method to use the theory in the communication. Manuscript profile

Open Access Article

8 - Investigation of the Carrier Concentration and Laser Peak Intensity on the Terahertz Pulse Generated by Photoconductive Antennas Based On LT-GaAs
Mohamad Ali Malakoutian Morteza Fathipour

The possibility of terahertz generation has been investigated from a photoconductive switch based on GaAs, gated by a femtosecond laser. The emission properties of photoconductive antenna (PCA) with low-temperature-grown (LT) GaAs have been studied. In such GaAs materia More

The possibility of terahertz generation has been investigated from a photoconductive switch based on GaAs, gated by a femtosecond laser. The emission properties of photoconductive antenna (PCA) with low-temperature-grown (LT) GaAs have been studied. In such GaAs materials presence of the charged defects induces a redistribution of the electric field between the antenna electrodes. This effect has a huge influence on the amplitude of the radiated terahertz field. In this work we demonstrate that carrier concentration enhances radiation power. Results obtained as a function of the laser excitation power (with 100 fs rise time and 1KHz repetition rate) and carrier concentration are discussed and a comparison of the performance of these devices with a conventional antenna-type (dipole) emitter is given. Manuscript profile

Open Access Article

9 - MVDR Beam Patterns of an Acoustic Vector Hydrophone Located Near a Reflecting Boundary

A vector hydrophone is composed of two or three spatially collocated but orthogonally oriented velocity hydrophones plus an optional collocated pressure hydrophone. A vector hydrophone may form azimuth-elevation beams that are invariant with respect to the sources’ freq More

A vector hydrophone is composed of two or three spatially collocated but orthogonally oriented velocity hydrophones plus an optional collocated pressure hydrophone. A vector hydrophone may form azimuth-elevation beams that are invariant with respect to the sources’ frequencies, bandwidths and radial locations. This paper characterizes the minimum variance distortionless response (MVDR) beam patterns associated with a single underwater acoustic vector hydrophone located near a reflecting boundary for the far-field underwater acoustic sources. Manuscript profile

Open Access Article

10 - Finger Printing Localization in WIMAX Network Based on RSS and Modulation
Meghdad Kaheh Mohammad farzan Sabahi Mohsen Ashourian

Among techniques based on power, fingerprinting method has the highest level of accuracy. In this method,error caused by the none line of sight (NLoS) between base station and user is compensable. However, some problems of the technique for implementation are: need to g More

Among techniques based on power, fingerprinting method has the highest level of accuracy. In this method,error caused by the none line of sight (NLoS) between base station and user is compensable. However, some problems of the technique for implementation are: need to gather high-capacity database and necessity of update and computational complexity to estimate the position. In this paper, The similar BCCH and Cell-ID and the used modulation and received signal strength (RSS) employed for filtering existing point in database to reduce computational complexity which is a novel technique. By executing the proposed algorithm in a part of Isfahan metropolis, the calculated average error of the suggested technique is 21 meters which its error is less than other techniques. Manuscript profile

Open Access Article

11 - OBF Radiation Behavior of Smart Antenna The Fourth Generation LTE Network on inter-city Express Railway
Amin Aliabadi Amin Heydari

communication systems of high-speed railway have inherent disadvantages and advantages. The estimation error of direction-of-arrival (DOA) of desired users caused by channel feedback delay and high moving speed make the common beamforming technique of smart antennas wor More

communication systems of high-speed railway have inherent disadvantages and advantages. The estimation error of direction-of-arrival (DOA) of desired users caused by channel feedback delay and high moving speed make the common beamforming technique of smart antennas work abnormally. Instead, the opportunistic beamforming (OBF) with dumb antennas which does not need channel feedback is proper for high-speed railway. As the system has linear topology, regular movement as well as predictable location and speed information, the OBF can be improved to adapt to this scenario. In this article, conventional OBF is first introduced to the communication systems of high-speed railway. By multiplying random complex on each transmit antenna, the channel fluctuation dynamic range is extended so that multiuser diversity can be exploited. And then location information is employed to assist the conventional one. Communication systems in high-speed railway have the advantage of predictable location and speed information. The improved OBF can perform closer to the performance of coherent beamforming. Numerical analysis and simulation results show that both two algorithms can improve the system performance significantly. Manuscript profile

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