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Secondary User (SU) has a responsibility to seek opportunities of spectrum access through spectrum sensing continuously. Spectrum sensing is a main task in Cognitive Radio (CR) that must be performed to avoid collision with Primary User (PU) and having seamlessly data transmission via license channel. To achieve sensing outcome correctly with tolerable error rate, SU requires sufficient time for sensing...
This paper studies the design of two stage microwave low noise amplifier (LNA) for coastal radar application at S-band operation. The cascade amplifier configuration and double stub matching networks are applied in this design which is aimed to obtain high gain with minimum reflected RF power. The first stage uses E-pHEMT GaAs FET of ATF-551M4 type and the second one uses RF transistor of BFP740FESD...
Prior to access license channel, secondary user (SU) is supposed to sense available channel to confirm that channel spectrum is unoccupied by primary user (PU) in cognitive radio (CR). Secondary user necessarily performs spectrum sensing at a certain time. Longer time allocation for spectrum sensing is expected can increase the fidelity of sensing outcome that leads to improve detection performance...
Energy Detection is a popular technique to detect primary user (PU) in cognitive radio (CR) compared with others. Due to less complexity and easier to be implemented makes energy detector (ED) is a common technique in use for signal detection. This paper studies detection performance of primary signal under Additive White Gaussian Noise (AWGN) with low signal to noise ratio (SNR). The performance...
High sensitivity environmental sensors with a simple and compact structure are required to monitor unwanted pollution such as liquid waste. In this paper an environmental sensor liquid waste using a polymer multi-coupled ring resonator (MCRR) structure is proposed. The proposed structure consists of polymeric materials on silicon substrate. Also discussed the influence of different refractive index...
Regional Integrated Border Surveillance System, is a system that is capable to providing a wide range of data and actual informations. This system is very suitable to support efforts to control the border area by the government. Basically this system is the result of the integration between sub-system monitors. In this research activity has built models of Integrated Surveillance Systems Border Region,...
Cooperative sensing is one solution for fading, hidden node problems, and uncertainty noises in primary signal detection. In this case, each secondary user (SU) senses available channel and exchanges their local sensing results to decide which channel can be accessed. Subsequently, this technique is capable to reduce sensing errors and lead to the throughput improvement. In this paper, we investigate...
The IMT-2000 standard UMTS of (Universal Mobile Telecommunications System) is based on Wideband CDMA (Code Division Multiple Access). To access a shared transmission channel for multiple users, UMTS exploit Code Division Multiple Access (CDMA). Multi-user interference is a critical issue in CDMA, limited user, cell Capacity and limiting spectral efficiency dramatically. The manner of used multiple...
Opportunistic Spectrum Access (OSA) brings new research challenges in MAC protocol design. It allows unlicensed users to share licensed spectrum in space and time with no or little interference to Primary Users (PUs). When designing an OSA MAC protocol, one of the most difficult but important problem is how the unlicensed users decide when and which channel they should sense and access without conflicting...
Cognitive radio (CR) is expected to be the key enabling technology for increased spectrum utilization. As primary user activity is not spatially localized, a collaborative measure amongst multiple cognitive radio nodes has been suggested as a more accurate model of activity. This scheme was proposed to combat noise fading and shadowing as well as improves the probability of detection by collaborating...
Energy efficiency is the major point of consideration in Wireless Sensor Networks (WSN). The protocols of Media Access Control (MAC) layer provide the most effective energy utilization. Idle listening is a major source of energy wastage in wireless sensor networks; the nodes do not remain in the idle listening state when no data is available to them. Lowering the duty cycle reduces the active period...
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