Design and Analysis of a Dynamic Space-Code Multiple Access with Large Area Synchronous Scheme Using the Smart Antenna System

The most important property in wireless systems, when it comes to increase the system capacity and spectrum efficiency, is eliminating interference. Code Division Multiple Access (CDMA) is considered interference-limited system. Spatial filtering using smart antenna has emerged as a promising technique to improve the performance of cellular communication systems; hence, Space Division Multiple Access (SDMA) has recently received increasing interest in improving the performance of wireless systems. These interference-limited systems are susceptible to time of arrival (TOA) and angle of arrival (AOA) of individual user signals, thus, a non-uniform traffic can severely degrade the performance of CDMA and SDMA systems. In this thesis, new approach of the joint multiple access system arising from the combination of CDMA and SDMA systems is designed, and its system performances are then investigated. An innovative approach to eliminate the existing interferences in this joint multiple access system is proposed. The spreading sequences of Large Area Synchronous Even Ternary (LAS-ET) which exhibited an interference free window (IFW) in their correlation are exploited here. The spatial signature from smart antenna narrower beam is exploited to drive all the multipath propagation signals to arrive within the IFW in reverse link transmission. The size of IFW is adaptable with the size of smart antenna beamwidth through dynamic space code (DSC) algorithm. Hence, this double signatures scheme forms a novel multiple access scheme called Dynamic Space Code Multiple Access (DSCMA) system. From the nature of spatial filtering of smart antenna systems, a dynamic sequence reuse assignment is possible in DSCMA to increase its spectrum efficiency. The non-zero pulse intervals and sequence length of LAS-ET are arranged in even numbers which has demonstrated some performance improvements in ternary phase shift keying (TPSK) signalling. On the other hand, the combined spreading sequence and spatial signature scheme also prompts a possibility of developing a novel Space Division Duplexing (SDD) scheme. The reverse and forward links are transmitted within a narrower beam of smart antenna, and both links are distinguished by different LAS-ET sequences. The simulation results indicate that the reverse link system capacity in DSCMA using LAS-ET spreading sequences together with smart antenna system is increased dramatically compared to traditional binary spreading sequences. The results also showed that the spectrum efficiency of DSCMA is increased when the number of elements in smart antenna system is increased. Finally, it can be concluded that the system capacity and spectrum efficiency are increased significantly from DSCMA using smart antenna systems due to its perfect interference cancellation scheme

Design and Analysis of Phased Array Antenna Beam Steering For Satellite Tracking

Nowadays achievements on mobile satellite system (MSS) communication give a great concern for research in global wireless communication fields. This has prompted the development of several Non Geostationary Earth Orbit (Non-GEO) satellite systems that promises worldwide connectivity for real-time communications. The mobility of Non-GEO satellite systems require a high directivity satellite tracking technique and a reliable inter satellite handover algorithm to ensure that connectivity between two end users are not interrupted as a result of satellite movement. In this thesis, phased array antenna has been proposed to obtain high directivity beam for satellite tracking. In order to do this, the phased array antenna mathematical model has been developed. This mathematical model has demonstrated that a narrow beam with high directivity could be generated. By changing the phase of the exciting currents in each element of antenna array, the radiation pattern could be varied through space. Thus, the generation of multiple and steerable beams also could be depicted by varying the phase shift of phase shifter with appropriate spacing between each elements to be sufficiently large. It is also shown here that the generated radiation beamwidth can be controlled by varying the number of antenna elements. It was found that the beamwidth reduces exponentially with the increment of the number of antenna elements

A novel error correction scheme in quantum key distribution (QKD) protocol

Ideally, in any quantum key distribution (QKD) communication system, each sifted key is expected to be received without error. However in practice, due to infeasibility of generating pure single photon and device impairment problem, some of the sifted key may experience errors. This results to the increment of quantum bit error rate (QBER) that requires error reconciliation for correcting error. The main concept in error reconciliation is very much related to the capability of correcting all errors while minimizing eavesdrop information. The quantum error correcting code such as Hamming code which used in Winnow protocol is found to be more attractive. However the Winnow protocol can only correct one error out of seven bits. In this paper, a modified Hamming encoder/decoder to improve Winnow protocol by correcting two errors out of seven bits which leads to reducing the QBER is presented. This design utilizes a pair of forward and reverse order syndromes for error pattern recognition. A new reconciliation protocol has been developed to enhance the error correcting capability in BB84 protocol. It is carried out in a simple structure which can correct up to double erroneous bits and detect four erroneous bits for each seven bits

Expansion of a Y-shaped array antennas for radio astronomy

Observing celestial objects is common in radio astronomy. The Giant Meterwave Radio Telescope (GMRT) is one of the world's latest telescopes of its kind. The aim of this paper is to extend the number of array antennas and optimize configurations by changing the position of antennas for getting low sidelobes and high u-v plane coverage. Initially, the expansion along three arms configuration was studied and then expanding it to spiral shape. The results show about 98.5 percents less coverage of GMRT without expansion compare to the extended GMRT. The spiral expanded shows ability to cover the u-v plane more than expansion in three arms by sixteen percents

Finger triggered virtual musical instruments

With the current human movement tracking technology it is possible to build a real-time virtual musical instrument with a gestural interface which is similar to a real musical instrument. In this paper, a simple finger triggering based controller for virtual musical instruments is presented. The virtual musical instruments that can be operated by using this controller are piano and drum. This system consists of three main components; finger data glove system, musical notes recognition system, and data transceiver system. Finger triggering devices are mounted to each finger in a data glove. This finger data glove has the capability to get data from triggered devices and the attached microcontroller in the data glove system is used to receive the data before transmitted to the musical notes recognition system through wireless or wired transmission. The musical notes recognition system matches the received triggering signal data with the predefined musical notes data using matching algorithm. When the data is matched, the musical notes data will be playing the associated musical notes. The developed system has the ability to switch the virtual musical instruments between piano and drum. Nevertheless, this developed finger triggered virtual musical instruments has the real-time capability to analyze the sounds or musical notes that have yet encountered in the studio

Power Line Communication (PLC) Impulsive Noise Mitigation: A Review

Power Line Communication (PLC) is a technology which transforms the power line into pathways for the conveyance of broadband data. It has the advantage for it can avoid new installation since the current installation used for electrical power can also be used for data transmission. However, this power line channel presents a harsh environment for data transmission owing to the challenges of impulsive noise, high attenuation, selective fading and etc. Impulsive noise poses a severe challenge as its Power Spectral Density (PSD) is between 10–15dB above background noise. For good performance of the PLC system, this noise must be mitigated.  This paper presents a review of the techniques for the mitigation of impulsive noise in PLC which is classified into four categories, namely time domain, time/frequency domain, error correction code and other techniques. Time domain technique is a memoryless nonlinear technique where the signal's amplitude only changes according to a specified threshold without changing the phase.  Mitigation of impulsive noise is carried out on the received time domain signal before the demodulation FFT operation of the OFDM. Time/Frequency technique is a method of mitigating impulsive noise on the received signal at both before FFT demodulation and after FFT demodulation of the OFDM system. Error correction code technique is the application of forward error correction code by adding redundancy bits to the useful data bits for detection and possibly correction of error occurring during transmission.  Identifying the best performing technique will enhance the deployment of the technique while exploring the PLC channel capacity enhancement in the future. The best performing scheme in each of the category were selected and their BER vs SNR curves were compared with respect to the impulsive noise + awgn curve. Amongst all of these techniques, the error correction code technique had a performance that presents almost an outright elimination of impulsive noise in power line channel. Keywords: Impulsive noise, time domain, time/frequency domain, error correction code, sparse Bayesian learning, recursive detection and modified PLC-DMT

Melody to musical notation translating system

This paper presents a system that translates the captured or recorded melody into musical notations automatically and instantly into a developed stave whereby a musician can compose music directly without any extra process or procedure, in real-time environments. In this translating system, the frequency of a captured or recorded melody is first analyzed through a microphone or musical instrument for its fundamental frequency. The analyzed fundamental frequency is then compared with the predefined frequency of musical notes. The matched musical note frequency will be distinguished at the developed musical stave interface instantly. This developed system can facilitate a composer in automatically translate his melody to musical notes without having to manually writing it down based on the melody he plays

Path Reecovery in 6LoWPAN Routing Protocol

6LoWPAN has become a new technology to provide the Internetconnectivity to the traditional wireless sensor network (WSN). In order to route thedelivered packet from originator to destination nodes, the simplified Ad-hoc On-Demand Distance Vector (AODV) routing protocol for 6LoWPAN with 6LoWPANAd-Hoc On-Demand Distance Vector Routing (LOAD) has been introduced.However, the conceptual LOAD routing protocol has yet proposed any path recoverymechanism in 6LoWPAN. In this paper, an originator recognition (OR) path recoverymechanism is proposed for the 6LoWPAN LOAD-based routing protocol. In thisproposed mechanism, the participated nodes will memorize the originator addressattached within data packet during the data transmission. When a link break happenson destination path, the LOAD protocol message will be amended by inserting anidentity key, which is a memorial of originator address, in the generated route error(RERR) message before transmitted towards the originator for the failure notification.This identity key is then used by the originator to initialize path recovery in order toretransmit the failed data packet to the unreachable destination node. Instead of usingMAC address in the LOAD routing protocol, IP address is used in the proposedOriginator Recognition (OR) path recovery mechanism (OR-LOAD) routing protocolwhich is designed for the global routing. The proposed OR-LOAD routing protocolhas been examined under noisy 6LoWPAN environment in Qualnet simulator. Itsperformance is then evaluated and compared to AODV routing protocol in terms ofpacket delivery ratio and average energy consumption. The simulation results showthat the proposed OR-LOAD outperforms AODV with packet delivery ratio of 19.4%,and with comparable average energy consumption in both routing protocols

Enhanced Random Forest with Image/Patch-Level Learning for Image Understanding

Image understanding is an important research domain in the computer vision due to its wide real-world applications. For an image understanding framework that uses the Bag-of-Words model representation, the visual codebook is an essential part. Random forest (RF) as a tree-structure discriminative codebook has been a popular choice. However, the performance of the RF can be degraded if the local patch labels are poorly assigned. In this paper, we tackle this problem by a novel way to update the RF codebook learning for a more discriminative codebook with the introduction of the soft class labels, estimated from the pLSA model based on a feedback scheme. The feedback scheme is performed on both the image and patch levels respectively, which is in contrast to the state- of-the-art RF codebook learning that focused on either image or patch level only. Experiments on 15-Scene and C-Pascal datasets had shown the effectiveness of the proposed method in image understanding task.Comment: Accepted in ICPR 2014 (Oral