A TDMA-based cooperative MAC protocol for cognitive networks with opportunistic energy harvesting

In this article, a cooperative medium access control (MAC) protocol called cooperative cognitive TDMA (CC-TDMA) for cognitive networks is proposed, which is based on time division multiple access (TDMA). The proposed protocol guarantees the quality of service (QoS) required by the primary network. In this regard, licensed users lease part of their spectrum to unlicensed users to retransmit the failed packets on the licensed users' behalf. By doing so, the unlicensed users obtain greater opportunity for data transmission, thus increasing their performance. The simulation and analytical results indicate that the CC-TDMA significantly improves the throughput and packet drop rate (PDR) of both licensed and unlicensed users compared to conventional TDMA

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

Internet utility evaluation of a multi-start particle swarm optimization beamformer in a partial joint processing cellular network

Joint processing (JP) is a powerful mechanism in alleviating inter-cell interference (ICI) and maximizing data rate of cell-edge users. However, JP puts tremendous load on both feedback and backhaul overhead, thus partial JP was proposed to overcome high overhead signaling. Unlike linear techniques such as zero-forcing (ZF), achieving an equivalent backhaul reduction and presenting a totally free ICI system based on limited feedback channel state information can be done by designing and implementing a multi-start particle swarm optimization algorithm (MSPSOA) as a beamforming (BF) mechanism. The performance of the proposed MSPSOA and ZF BF is evaluated based on the acquired spectral efficiency and utility of internet application such as hard real-time, adaptive and elastic applications. The simulation results shows that, the proposed MSPSOA BF achieves spectral efficiency up to 69.5% compared to ZF BF, and it maintains total utility for high data rate requirements of three common internet traffic such as hard real-time, adaptive and elastic applications

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

A lower complexity K best algorithm for multiple input and multiple output detection

This paper presents Multiple Input Multiple Output (MIMO) detection steps using tree search based method known as the ‘K’ best algorithm. This low complexity algorithm is based on probabilistic approach of sphere decoding with self adjustable capability depending on the levels (root, branch, leaf etc.) of a tree. While the tree was searched to estimate the transmitted symbols level by level, the algorithm took into account the effect of the undetected symbols in the search criteria. Simulation results showed that the proposed method reduced complexity (in terms of the average number of visited nodes) about 10% for higher (medium to high) signal to noise ratio (SNR) values without degrading the system BER performance

A full rate concatenated space-frequency and space-time OFDM over Naftali fading channels

In this paper we investigate 2 transmit and 1 receive (2Tx:1Rx) space-frequency orthogonal frequency division multiplexing (SF-OFDM) and space-time OFDM (ST-OFDM) concatenated with convolutional channel coding as a redundancy method to combat channel impairments. We built our SF and ST-OFDM on top of our coded OFDM (COFDM) with coding rate of 1/4 and constraint length of 10. We simulate our concatenated SF-OFDM and ST-OFDM over a multipath fading channel using Naftali 802.11 channel model under different delay spreads in relation to outdoor environment. Concatenated SF- OFDM performs slightly better than ST-OFDM at delay spread of 2.0 microseconds, but both are almost comparable at all other delay spreads. These two schemes outperforms other schemes such as single antenna coded OFDM and Alamouti's Space-Time Block Code (STBC) under these conditions by as much as 10 dB at BER of 104

A simplified sphere decoding algorithm for MIMO transmission system

In sphere decoding the choice of sphere radius is crucial to excellent performance. In Chan-Lee sphere decoding -based algorithm, the problem of choosing initial radius has been solved by making the radius sufficiently large, thus increasing the size of the search region. In this paper we present maximum likelihood decoding using simplified sphere decoder as apposed to the original sphere decoder for the detection of cubic structure quadrature amplitude modulation symbols. This simple algorithm based on Chan-Lee sphere decoder allows the search for closest lattice point in a reduced complexity manner compared to original sphere decoder for multiple input multiple output system with perfect channel state information at the receiver. Results show symbol error rate has stabilized even at very low initial value of the square radius

A new cooperative spectrum sensing scheme based on discrete cosine transform

Recently, the need to extra frequency bands is increasing significantly due to modern devices and applications. This problem can be addressed by exploiting the idle spectra. Thus, the spectrum exploiting is performed using the technique of spectrum sensing. In this paper, a new cooperative spectrum sensing scheme is proposed based on discrete cosine transform periodogram. This scheme is applied on both DVB models for AWGN channel and various S NR values. The obtained results reveal that the proposed scheme has a good performance for ten secondary users and low SNR