|Title: Clipping Based PAPR Reduction Method for LTE OFDMA Systems|
|Author(s): M. M. Rana|
|Pages: 1-7||Paper ID: 10-96810-05-1212-IJECS-IJENS||Published: October, 2010|
Abstract: Long term evolution (LTE) is the last step toward the 4th generation (4G) of radio technologies designed to increase the capacity and speed of mobile telephone networks. LTE has adopted orthogonal frequency division multiplexing (OFDM) for the downlink transmission. OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for very wide carriers with high peak rates. However, the potentially large peak-to-average power ratio (PAPR) of the transmitting signals has limited its application. This high PAPR causes interference when the OFDM signals are passed through an amplifier which does not have enough linear range. Here, we investigate a clipping based PAPR reduction technique for LTE OFDMA systems. Simulation results show that the clipping method is reduced PAPR significantly which decreases as the number of clip and filtering level is increased. As a results, increase the mean transmit power, and improve the power amplifier efficiency.
|Keywords: 3GPP, CCDF, LTE, OFDMA, PAPR.|
|Full Text (.pdf) | 360 KB|
|Title: Design of a Simple CMOS Bandgap Reference|
|Author(s): Shopan din Ahmad Hafiz, Md. Shafiullah, Shamsul Azam Chowdhury|
|Pages: 6-9||Paper ID: 102505-6060-IJECS-IJENS||Published: October, 2010|
Abstract: This paper describes the design of a bandgap reference, implemented in 0.50 µm CMOS technology. The circuit generates a reference voltage of 1.2218V. It can operate between 20ºC & 70º C. Total variation of reference voltage within the temperature range is 2.6mV which is 0.213% of the reference voltage. This circuit works in a current feedback mode, and it generates its own reference current, resulting in a stable operation. A start-up circuit is required for successful operation of the system.
|Keywords: Analog Integrated Circuit, Bandgap eference, CMOS, Temperature Independence.|
|Full Text (.pdf) | 580 KB|
|Title: Tense and Aspect in the Context of Urdu|
|Author(s): A. Naseer, S. Hussain|
|Pages: 10-14||Paper ID: 103405-2727-IJECS-IJENS||Published: October, 2010|
Abstract: Tense represents the time information of the event while aspect defines repetition, duration, continuity and perfectness of the event, which is independent of time. In the time line an event occurs at some point on the timeline, or in a time interval. In this research paper both tense and aspect of Urdu language are explored and analyzed. Such features are explored which can represent a particular tense and aspect so that on the basis of these features a sentence can be parsed and generated.
|Keywords: Aspect, Reference Time, Time Line.|
|Full Text (.pdf) | 326 KB|
|Title: Gap Analysis between Ubiquitous Computing Requirements and Features of an Open Source Operating System (Openmoko) for Hand Held Devices|
|Author(s): Shahid Siddiq, Aasim Ali, Kamran Malik|
|Pages: 15-21||Paper ID: 103905-0404-IJECS-IJENS||Published: October, 2010|
Abstract: Ubiquitous Computing (UC) is an emerging technology of sharing the information by using large collection of computing devices. Sharing of information is in terms of availability of information at every time, every where and in invisible form. In Ubiquitous computing power of desktop paradigm is distributed to every day electronic devices in an invisible mode. Rather saying that we are living in the age of computers, using ubiquitous computing services, we can say that the computer is living in human beings. The implementation of requirements of ubiquitous computing is a real issue to address. It is considered that hand held devices’ operating systems are the best candidates to achieve implementation of Ubiquitous computing. In this paper, we present our analysis of gap present between the requirements of a virtual operating system of ubiquitous computing and a currently present open source operating system of hand held devices.
|Keywords: Ubiquitous Computing, Context Awareness, Security, Distributed Operating Systems, Pervasive Computing, Interface Heterogeneity.|
|Full Text (.pdf) | 400 KB|
|Title: Investigation of Multiple Faults Detection in Electric Machine Using Broken Rotor Bar and Eccentricity Fault Frequencies Techniques|
|Author(s): Intesar Ahmed, Manzar Ahmed, M. Shuja Khan, Kashif Imran|
|Pages: 22-30||Paper ID: 104605-9494-IJECS-IJENS||Published: October, 2010|
Abstract: The aim of this paper is to investigate and detect the multiple faults in machines using broken rotor bar and eccentricity fault frequencies techniques. It is proposed that using both current and instantaneous power signals simultaneously, will detect the multiple faults reliably, specifically using broken rotor bar fault frequencies and eccentricity fault frequencies under various load conditions. The analyses carried out in this paper show that the current spectra is able to detect multiple faults i.e. a combination of broken rotor bars and eccentricity faults either by using broken rotor bars fault frequency components (1±2s)f1 or using eccentricity fault frequency components (f1±fr) at any levels of loading. The results from the instantaneous power spectra using modified broken rotor bar fault frequency components (fp±4f2) show that it is preferable for estimating either the machines having multiple faults. It can be concluded from the results that flux signal is also not a useful source to detect multiple faults using both broken rotor bar and eccentricity fault frequency components.
|Keywords: Broken Rotor Bar, Eccentricity, Electric Machine, Multiple Faults.|
|Full Text (.pdf) | 566 KB|