Fahim Aziz Umrani

Analysis of effect of carrier frequency offset on performance of LTE uplink

Carrier frequency offset CFO is one of major issues effecting performance of Orthogonal Frequency Division Multiplexing OFDM based systems. It is basically caused due to oscillator instability and Doppler shift introduced in the channel. It seriously degrades the system performance. This problem becomes even worse in uplink case because of random nature of users, since each user experiences different offset. Single Carrier FDMA is also an OFDM based system which is actually DFT based OFDM. Long Term Evolution LTE uses SC-FDMA instead of OFDM in uplink due to problem of Peak to Average Power Ratio (PAPR) as mobile handsets have limited battery power. In this research work, we focus on analyzing effect of CFO on the performance of LTE uplink system. The simulation results in terms of constellation diagrams and Bit Error Rate graphs show that system performance is seriously degraded due to carrier offset and suppression techniques have to be employed in order to save the integrity of user data.

SONAR Based Obstacle Detection and Avoidance Algorithm

Autonomous robots are intelligent machines that arecapable of performing desired tasks by themselves, withoutexplicit human control. This paper presents a novel simplealgorithm based on ultrasonic sensors and simple calculationsfor real-time obstacle detection and avoidance that is intendedfor mobile robots. The design is implemented in air usingultrasonic sensors but can be adapted using sonar tounderwater environments where it has important applicationssuch as deep sea maintenance and reconnaissance tasks. Thepaper also presents performance results of a prototypedeveloped to prove the design concept.

Performance analysis of skin classifiers in RGB and YC b C r color space

Skin detection serves as a preliminary step for number of applications like face detection, gesture recognition, internet pornographic image filtering, and surveillance system. Number of artificial neural network (ANN) based skin detection algorithms have been presented in literature which are mostly based on back propagation (BP) ANNs. This paper attempts to analyze the performance of skin classifiers using AdaBoost learning algorithm in both RGB and YCbCr color space. Three RGB based classifiers (i.e., red, green, and blue) and one YCbCr based classifier is designed in order to analyze the performance of algorithm for each case. Set of weak heuristic rules are designed for the classifiers to reduce the false positive rate (FPR) without significantly affecting the correct detection rate (CDR). The results reveal that the best performance is achieved by RGB based classifiers with heuristic rules in terms of both accuracy and processing time. Without heuristic rules the best results have been provided by Y-classifier. The classifiers are trained and tested using SFA database. The classifiers are also tested by using images of FERET and CVL database.

A Novel Protocol with Patient and Node Identification for Optical WBAN with Inherent Security and Interference Rejection

The wireless body area network (WBAN) has emerged as a new technology for e-healthcare that allows real time monitoring of patients using miniaturized wearable and implantable sensors. An important concern in such networks is the secure transmission, without burdening the energy requirements. In this paper, a new energy efficient protocol is presented with enhanced inherent security, interference rejection and patient/node identification. The energy usage is low as there is no additional encryption circuitry required. Moreover, the nodes can sleep in the slots when they are not transmitting or receiving. The protocol implementation is experimentally demonstrated using low cost IR transceiver and Arduino Microcontroller. Experimental results reveal the successful transmission and reception of measured parameters over short ranges with sufficient accuracy. Furthermore, a MATLAB based mobile application is developed which helps to set up a database in distributed manner and subsequently allow the user to monitor, visualize and share the measured readings remotely.

Feedback method for estimation and compensation of carrier frequency offset in LTE uplink

Long Term Evolution (LTE) is getting popularity among cellular service providers throughout the World and it is going to dominate cellular systems in coming years. According to 3GPP specifications, LTE adopts Orthogonal Frequency-Division Multiplexing (OFDM) as modulation scheme in the downlink. The problem of systems based on OFDM is that they are prone to Carrier Frequency Offset (CFO). In uplink, LTE uses Single-Carrier Frequency Division Multiple Access (SC-FDMA) instead of OFDM. The main reason of its use is the better peak-to-average power ratio performance in comparison to OFDM, a property required in uplink to increase the duration of the battery of the user device. As OFDM, also SC-FDMA suffers with the problem of CFO. In this paper, a CFO estimation method for LTE uplink is analyzed and simulated by using MATLAB. The proposed method, termed feedback method, uses demodulation reference signals to estimate the CFO. After estimation of CFO, its effect is compensated in time-domain by multiplication with a linear phase.

Performance Analysis of Spectral Amplitude Coding Based OCDMA System with Gain and Splitter Mismatch

Abstract This paper presents the practical analysis of the optical code-division multiple-access (O-CDMA) systems based on perfect difference codes. The work carried out use SNR criterion to select the optimal value of avalanche photodiodes (APD) gain and shows how the mismatch in the splitters and gains of the APD used in the transmitters and receivers of network can degrade the BER performance of the system. The investigations also reveal that higher APD gains are not suitable for such systems even at higher powers. The system performance, with consideration of shot noise, thermal noise, bulk and surface leakage currents is also investigated.

Throughput of Coded Optical CDMA Systems with AND Detectors

Abstract Conventional detection techniques used in optical code-division multiple access (OCDMA) systems are not optimal and result in poor bit error rate performance. This paper analyzes the coded performance of optical CDMA systems with AND detectors for enhanced throughput efficiencies and improved error rate performance. The results show that the use of AND detectors significantly improve the performance of an optical channel.