Complexity Receiver Design Research Articles

Spectral Sampling and Signal Decomposition (SSSD) for Improved Spectral Efficiency

Spectrally Efficient Frequency Division Multiplexing (SEFDM) aims to enhance spectral efficiency by compressing subcarriers in the frequency domain, thereby reducing the required bandwidth. This approach primarily focuses on minimizing Inter-Carrier Interference (ICI), which typically necessitates a complex receiver design. We propose a simpler receiver design based on Spectral Sampling and Signal Decomposition (SSSD) technique. This technique facilitates the receiver to process Orthogonal Frequency Division Multiplexing (OFDM) signals outside the conventional orthogonality points in the frequency domain. Unlike traditional SEFDM approaches, the SSSD receiver utilizes interfering carriers as useful signals. Through simulations, we showcase the SSSD receiver’s performance in extracting SEFDM signals and accommodating various pulse shapes beyond the conventional sinc pulse. However, our results also highlight a significant challenge posed by severely ill-conditioned matrices, which can be mitigated by exploring alternative pulse types.

Design Strategies to Overcome EMI/EMC Issues of Airborne Receivers

Abstract This article describes various housing design strategies of a complex receiver system to overcome EMI/EMC challenges for airborne system applications. Isolation of leakage energy between various RF/DC-DC converters/Regulators/pulsing blocks are the key target of this design to keep conductive and radiative emission minimum. Hence, complex receiver design has been segregated into various modules. Block level design is carried out using 3D EM simulator to assess the leakage. Then they are stacked together very tactfully within the specified area without compromising inter-channel/module interference between them and the form factor respectively. The super compact stacks are further channelized for RF, DC supply, controls etc. and protected them from any kind of interferences. Low cost flexi interconnects are made to interface various stacks to arrest unwanted high/low frequency leakages. Finally, receiver module is developed and tested over temperature and EMI/EMC successfully to establish the methodology.

Improved Complex Receiver System Design Strategies to Overcome EMI/EMC Challenges

This article analyzes various strategies and implementation techniques in detail for complex receiver system design to qualify Environmental Stress Screening (ESS) especially EMI/EMC tests for airborne system applications. Isolation of leakage energy between various RF/DC-DC converters/regulators/pulsing blocks are the key target of this design to keep conductive and radiative emission to a minimum. Hence, complex receiver design has been segregated into various modules. Then they are stacked together very tactfully within the specified area without compromising inter-channel/module interference between them and the form factor, respectively. The super compact stacks are further channelized for RF, DC supply, controls etc. and protected from any kind of interference. Low cost flexi interconnects are made to interface various stacks to arrest unwanted high/low frequency leakages. Proper layout, component placement, layer specific signal routing, and wire shielding have been used to protect low/high frequency reference clock, control signals, switching pulses, etc. from mixing. Processor boards with a DC supply unit are also integrated into the receiver as another stack and have been isolated from each other to qualify emission tests. Finally, four modules are developed and tested over temperatures of -40°C to +71°C (ESS) and EMI/EMC successfully to establish the methodology for mass production.

Low complexity receiver design for time-varying Poisson molecular communication channels with memory

This paper introduces novel approaches for the design of the linear filter and the detection algorithms in unbounded advection diffusion-based molecular communication systems affected by inter-symbol interference. The received signal samples are modeled as Poisson random variables with memory where the effect of enzymatic reactions is also included. A main characteristic of the new filter design is to allow for a real-time computation of the filter's coefficients. For the detection of the transmitted symbols, we define an averaging method suitable for time-varying channels with finite memory length. In this paper the mean value of the Poisson channel is varying with time and we quantify the memory length with a finite number, from receiver point of view. The computational burden of the proposed approaches is evaluated in terms of number of required operations and their performance is evaluated in terms of bit error rate for different sets of parameters. We show that the proposed design of the filter and of the detection algorithms enables us to achieve a performance comparable to that of the state of the art approaches in relation to their simplicity.

Low Complex Receiver Design for Modified Inverse Source Coded Diffusion-Based Molecular Communication Systems

Diffusion Based Molecular Communication (DBMC) uses messenger molecules to transfer information between nanomachines. A major challenge for DBMC is Inter Symbol Interference (ISI), which is due to the diffusive nature of the molecular channel. By computing lower and upper bounds for the number of received molecules, in this letter we prove that ISI and Bit Error Rate (BER) of a DBMC system depend on a-priori probability of transmitted data. We derive the optimal value of the a-priori probability for which ISI and BER are minimized. A coding technique, called Modified Inverse Source Coding (MISC), is proposed to control the a-priori probability of the transmitted data. We also propose two low complexity receivers for MISC-DBMC. The first is a low complexity Reduced State Sequence Detector (RSSD) based on the Viterbi algorithm. The second is a computationally less intensive Decision Feedback based Maximum A-Posteriori (DF-MAP) threshold detector. Simulation results demonstrate that the DF-MAP receiver has a similar BER performance as that of the RSSD receiver in the ideal scenario, but practically it is limited by error propagation. Also, we show that the MISC-DBMC system using RSSD or DF-MAP receiver has better BER performance, increased range, and lower complexity compared to uncoded DBMC system.

Low Complexity Receiver Design Using Deep Neural Network Based on Compact Sparse AutoEncoder

In this letter, we demonstrate a novel strategy for designing a low complexity deep neural network (DNN) receiver. The compact-stacked Autoencoder (CSAE) receiver is designed based on the proposed neuron and layer numbers selection (NLNS) methodology. Compared with other DNN-based receiver, the CSAE receiver has low complexity but can achieve superior performance. Simulation results show that CSAE receiver can achieve or even outperform state of the art accuracy, and furthermore, the proposed receiver provides a robust performance against the phase offset, carrier frequency offset (CFO), and imperfect channel state information (ICSI).

A novel heat exchanger concept for latent heat thermal energy storage in solar power towers: Modelling and performance comparison

This study presents an innovative new alternative for utilizing phase change materials as energy storage media in solar power towers. The solar power tower prilling or granulation concept combines the existing molten salt design with a prilling tower incorporated into the central receiver. In this way heat transfer limitations normally associated with these systems can be overcome since only very small particles (diameter 1–2mm) are utilized. Three design cases were considered and a detailed model of the process was developed. The model demonstrates the design dependence on several key variables including particle diameter and the necessity of considering the system in conjunction with the steam generation cycle. Pinch considerations within this cycle and the tower itself determine the operational feasibility. It was found that the receiver design and prilling feed systems are crucial aspects which must be investigated further to refine the concept design and complete a full techno-economic assessment and optimization. The “best case scenario” resulted in a reduction of the circulating salt flow by one third compared to the base case. Preliminary indications are that this would result in a 20% reduction of the overall plant capital cost, but additional costs such as solids handling and a complex receiver design have to be taken into account.

Low Complexity Message Passing-Based Receiver Design for Wiener Phase-Noise Channels

This letter concerns low complexity receiver design for Wiener phase-noise channels, where the variance of the additive white Gaussian noise (AWGN) is unknown. By representing the system with a factor graph, both the variational message passing and the sum-product message passing are used to achieve efficient joint decoding, phase noise estimation, and AWGN precision (the reciprocal of AWGN variance) estimation. Compared with the state-of-the-art receiver, the proposed receiver is able to achieve the same performance with much lower complexity.

Prototype for 5G new air interface technology SCMA and performance evaluation

Sparse code multiple access (SCMA) is a novel non-orthogonal multiple access scheme proposed to meet the challenging demand of the future 5G communications, especially in support of the massive connections. The coded bits from each data stream will be directly mapped as multi-dimensional SCMA codeword in complex domain and then spread onto the physical resource elements in a sparse manner. The number of codewords that can be non-orthogonally multiplexed in one SCMA block can be made much larger than the number of orthogonal resource elements therein, resulting in an overloaded system. The sparsity in the spreading pattern and the design in the multidimensional modulator jointly ensure the SCMA codewords can be robustly decoded with low complexity. In this paper, we focus on the low complexity receiver design and verified the superior of an SCMA system via simulations and real-time prototyping. Lab tests and field tests all show that SCMA is a promising candidate for 5G non-orthogonal multiple access which can provide up to 300% overloading that triples the whole system throughput while still enjoying the link performance close to orthogonal transmissions.

SAW Filter Modelling in Matlab for GNSS Receivers

Satellite navigation has enabled a great amount of new application for many users, but a lot of limitations have been observed regarding precision and integrity of navigation signals. Overall signals of different navigation systems (GPS, GALILEO, GLONASS signals) compose Global Navigation Satellite Systems (GNSS) Signal. Each of the satellite system has separate signal characteristics, but each signal needs to be compatible with the others to prevent interferences and attenuations between signals. The processing of all the signals is performed in same receiver. Hence, complex receiver design is required. In GNSS signals different frequencies are used for different satellite navigation systems such as GPS, Galileo and Glonass. When the group delay response is observed in SAW filters it shows that the signals lie on different frequencies have different delays. Manufacturers carried out measurements with respect to carrier wave but they have ignored the spreading codes or modulation. In this research, we will design a model for GNSS SAW filter in Matlab. This model can be use to obserce the delay of the signals. This model will allow the manufacturers to address these problems in the SAW filter software to optimise slope and magnitude of the design which will benefit the users of GNSS all over the world to get more precise positioning. DOI: http://dx.doi.org/10.11591/ijece.v3i5.3643

A Novel Modulation Diversity Assisted Ultrawideband Communication System

In this paper, a novel modulation diversity assisted (MDA) ultrawideband (UWB) communication system is proposed. Pulse position modulation and pulse amplitude modulation are applied to successive transmitted pulses alternately. The resulting modulation diversity helps to overcome channel estimation difficulties in typical UWB channels and permits low complexity receiver design. If every two consecutive pulses are grouped together, some connections with a transmitted reference (TR) system are demonstrated. But significant advantages of the proposed system are observed in smooth spectrum and increased data rate. Utilizing statistical properties of the modulated signals and inherent diversity, different receivers are designed for such a system. A conceptual receiver performs symbol detection using neighboring received signal to construct the template, while an advanced receiver uses a block of received signals to obtain a better template. The advanced receiver may continue to improve the template as ongoing detected symbols are available. A maximum likelihood estimator is also derived as a performance benchmark. The conceptual receiver shows slightly better performance than a conventional TR receiver while the advanced receiver shows comparable performance of the receiver using a maximum likelihood template estimator. Performance of the advanced receiver is studied both analytically and numerically. In a case of severe multipath channel distortion that results in interference between received signals from consecutive transmitted pulses, a corresponding template estimator and different receivers are also presented with detection performance numerically studied.

Direct conversion receiver for radio communication systems

Direct conversion receiver (DCR) architecture, which has introduced the zero intermediate frequency (IF) approach, supports efficient wireless handset designs with a high level of integration. Transmission over wireless channels is subject to time dispersion due to multipath propagation and frequency dispersion due to Doppler effect, the design of wireless receivers are tremendously important in supporting reliable communication links. With wireless technology growing, the choice of optimal wireless receiver architecture that supports monolithic integration without performance degradation becomes an important dimension in modern handset design. The increasing demand for mobile terminals with smaller physical dimensions has led to the investigation of DCR, which supports single chip and multinode designs. Since DCR is a promising architecture for fourth generation mobile terminals, it is important to note that implementation of a certain dc offset technique does not compromise the benefits of low complexity receiver design.

A differential phase-shift keying multicarrier code division multiple access system with an equal gain combining receiver

Multicarrier code division multiple access (MC-CDMA) is a spread-spectrum technique which allows simple implementation of multiuser detection techniques. Combining this with differential phase-shift keying (DPSK) allows a low complexity receiver design which achieves the channel estimation implicitly. If only downlink communication is considered, performing the DPSK at a subcarrier level allows significant performance gains and employing a joint phase estimation approach for all users signals allows the implementation of an effective equal gain combining receiver. Theoretical predictions and simulations of the performance in additive white Gaussian noise are demonstrated. Comparison with similar systems is shown through simulations in a fast fading typical mobile channel.