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In digital communication systems the use of filters that fulfill the first Nyquist criterion (Nyquist-I), guarantees that a sequence of pulses will not be affected by inter-symbol interference (ISI) if the receiver samples signals at optimum and uniformly spaced instants. In this manuscript the Nyquist-I pulse, called exponential linear pulse (ELP), is evaluated in the time and frequency domain using...
In this review, we summarise methods towards achieving 10 Mb/s connectivity for visible light communications links utilising organic polymer based light-emitting diodes as the transmitter. We present two different methods; on-off keying supported by least mean squares equalisation and orthogonal frequency division multiplexing without equalisation.
This paper describes a method to increase the sensitivity of a digital radio receiver based on the time synchronous averaging (TSA). The data to be send are grouped into a block and the block is retransmitted multiple times. Received blocks are synchronously averaged thus increasing the signal-to-noise ratio. The TSA can be performed on the analog signal at the demodulator output (soft TSA) or on...
This article discusses the implementation of a wide band vectorial digital modulator and a tool to evaluate the Bit Error Rate. This modulator is capable of generate a wide band (up to 6.3 MHz) 16-QAM modulation in baseband. A second functionality programmed in the tool and reported in this article evaluates the Bit Error rate in order to measure the received signal quality. Results are validated...
FH (frequency hopping) technique is widely used in underwater acoustic communication due to its good performance on anti-interference and anti-fading. In addition, communication might encounter intentionally destruction such as jamming. So it is necessary to make an effect evaluation on FH communication under jamming. Firstly, FH communication system with three typical jamming styles including partial...
We propose and experimentally demonstrate a novel channel-independent multi-band orthogonal circulant matrix transform (MB-OCT) precoding, to efficiently combat the severe frequency-selective fading induced by the limited modulation bandwidth of visible light communication (VLC). The proposed MB-OCT precoding exhibits ladder-like signal-to-noise-ratio (SNR) profile, thus significant BER reduction...
Monitoring the physical layer is key to detect bit error rate (BER) degradation caused by failures and to identify the cause of the failure and localize the failed elements. Once the failure has been detected, actions can be taken to reduce as much as possible its impact on the network. Commercially available optical equipment are able to correct degraded optical signals by means of Forward Error...
We present a robust adaptive digital pre-distortion technique to mitigate the linear and non-linear degradation of optical communication transmitter components. The proposed method is based on the principles of memory polynomial based pre-distortion and indirect learning architecture. Effectiveness of the presented algorithm is assessed across various higher order modulation formats and higher baud...
Frequency bands above 6GHz are receiving great attention for 5G mobile radio communications due to the potential availability of enormous channel bandwidths. Various multi-carrier and single-carrier waveforms are being considered as potential candidates for 5G radio interface. When evaluating the waveform performance at high carrier frequency and large bandwidths, the inclusion of realistic hardware...
The integration of radar and communication has attracted general interest with its advantage of equipment miniaturizing and high efficiency of spectrum, especially in intelligent transportation systems because of the need for transmitting and detecting simultaneously and the lack of room for various devices. Among various integration schemes, the integrated waveform which realizes transmitting and...
We introduce a model of a combination of particular low density parity check (LDPC) code and quadrature-quadrature phase shift keying (Q2PSK) constellation for the application of the downlink of the unmanned aerial vehicle (UAV) data chain. This model is a modification of the combination of LDPC code and constant envelope Q2PSK (CEQ2PSK) constellation. It achieves higher bandwidth efficiency of 4/3...
We propose and experimentally demonstrate for the first time, M-PAM transmission through a hybrid POF/VLC downlink using off-the-shelf components. The link consists of 60 m SI-POF and 1 m VLC and with the aid of a blue filter, the link has an effective bandwidth of 17 MHz. Conventional adaptive decision feedback equaliser (DFE) and multi-layer perceptron DFE (MLP-DFE) are also implemented and their...
Orthogonal Frequency division multiplexing is the modulation technique used for the fourth generation wireless communication system. In OFDM, Signals can be modulated by multiple carriers. OFDM uses the bandwidth of the spectrum efficiently. But the limitation of the OFDM system is the high Peak to Average Power Ratio (PAPR) which results in the degradation of the signal quality. Hence reducing the...
An analytical approach is presented to evaluate the bit error rate performance of a wavelength division multiplexing (WDM) fiber-optic transmission link with distributed Raman amplifier taking into account the combined effect of Amplified Spontaneous Emission (ASE) and Raman scattering induced crosstalk for direct detection receiver. The analysis is developed to find the photodetector output due to...
In ongoing efforts, our team has developed DISCO (Distributed Cross-layer Architecture for Network Awareness and Opportunistic Transport), a cross-layer framework to enable network awareness and automated adaptation of transport, network and application parameters in a MANET. DISCO automates discovery of new applications and services, and applies rule-based logic and machine learning to enable the...
This paper proposes a novel uncoded digital modulation scheme with high spectral and power efficiency, denominated 32P-3D. This scheme has a symbol constellation that consists of 32 points symmetrically distributed in a threedimensional space. The theoretical analysis and the simulations show a considerably high performance against the noise in comparison to 16-ary Quadrature Amplitude Modulation...
Digital baseband communication systems are characterized by having a filter at the transmitter and receiver side to band limit the transmitted signals and diminish the effects to intersymbol interference (ISI). The impulse response of the sinc parametric linear combination pulse (SPLCP) is derived in the time domain, whereas its frequency response is also evaluated. The SPCLP is evaluated at the transmitter...
Beamforming is used to correct for phase or time delay in signals received at multiple antennas in mm-wave receivers. The correction is meant to improve the signal-to-noise ratio and the bit-error-rate (BER) by filtering away the effect of noise and interferences. Typically, phase-corrected beamformers are used for lower fractional bandwidth applications, where the symbols are well spaced. In wideband...
For some scenarios where high received power cannot be guaranteed due to user moving, the OFDM system with low order M-QAM such as BPSK/QPSK is promising. This paper will propose an orthogonal parallel combinatory ASK modulated multicarrier system to achieve flexible bandwidth efficiency (BWE) using low order ASK modulation and parallel combinatory (PC) code. PC code has been shown that it can achieve...
In this paper, we investigate the achievable rate and the average sum capacity of an underlay cognitive radio (CR) (also known as a secondary) system. We consider single user (SU) and multiple users (MU) secondary systems that deploy spread spectrum as the signaling technique which utilizes the whole available spectrum. The objective is to maximize the achievable rate and the average sum capacity...
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