Low Complexity Receiver Design Research Articles

Analysis and Design of Low Complexity Receiver for UWB Transmitted Reference Based on Wavelets Transform

The Rake receiver has become very popular in wireless communication in recent years, but it has a number of drawbacks, including complexity, high noise, poor performance, and a slow transmission rate. As a result, a system with high performance, low complexity, low noise, and high efficiency is required. In this article, the idea of a new discrete wavelet transform (DWT)-based system is called Low Complexity (LC) Transmitted Reference (TR) Ultra Wideband (UWB) that achieves high performance, low complexity, higher transmission rate, and lower noise than previous discrete wavelet transform systems. High frequencies that caused noise in the system were cut off using DWT. To remove these frequencies, DWT uses two types of FIR filters. To get a better result, use three levels in this system. The simulation results show that when three levels of noise reduction are used, the effect is to remove high frequencies that cause noise in the TR UWB received signal.

Orthogonal Time Sequency Multiplexing Modulation: Analysis and Low-Complexity Receiver Design

This paper proposes orthogonal time sequency multiplexing (OTSM), a novel single carrier modulation scheme that places information symbols in the delay-sequency domain followed by a cascade of time-division multiplexing (TDM) and Walsh-Hadamard sequence multiplexing. Thanks to the Walsh Hadamard transform (WHT), the modulation and demodulation do not require complex domain multiplications. For the proposed OTSM, we first derive the input-output relation in the delay-sequency domain and present a low complexity detection method taking advantage of zero-padding. We demonstrate via simulations that OTSM offers high performance gains over orthogonal frequency division multiplexing (OFDM) and similar performance to orthogonal time frequency space (OTFS), but at lower complexity owing to WHT. Then we propose a low complexity time-domain channel estimation method. Finally, we show how to include an outer error control code and a turbo decoder to improve error performance of the coded system.

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 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).

Frequency-Domain Joint Channel Estimation and Decoding for Faster-Than-Nyquist Signaling

Faster-than-Nyquist (FTN) signaling has attracted a lot of attentions for the fifth-generation (5G) cellular communication systems. However, low-complexity receiver design for FTN signaling becomes challenging. In this paper, we develop frequency-domain joint channel estimation and decoding methods for FTN signaling transmitting systems over frequency-selective fading channels. To deal with the colored noise inherent in FTN signaling, we propose to approximate the corresponding autocorrelation matrix by a circulant matrix, the special eigenvalue decomposition of which facilitates an efficient fast Fourier transform operation and decoupling the noise in frequency domain. Through a specific partition of the received symbols, many independent estimates are obtained and combined to further improve the accuracy of the channel estimation and data detection. Moreover, instead of assuming the data symbols to be Gaussian random variables, a generalized approximated message passing-based equalization is developed and embedded in the turbo iterations between the channel estimation and the soft-in soft-out decoder. Simulation results show that the proposed algorithm outperforms the cyclic prefix-based and overlap-based frequency-domain equalization methods. With the proposed algorithms, FTN signaling reaches up to 67% higher transmission rate compared to the Nyquist counterpart without substantially consuming more transmitter energy per bit, and the overall complexities grow logarithmically with the length of the observations.

ADMA: Amplitude-Division Multiple Access for Bacterial Communication Networks

In a communication network with extremely high processing delays, an efficient addressing and multiple-access control mechanism to improve the throughput performance of the system is a necessity. This paper focuses on source addressing in multiple-source single-receiver bacterial communication networks. We propose amplitude-division multiple access (ADMA), a method that assigns the amplitude of the transmitted signal as the address of the source. We demonstrate using genetically engineered Escherichia coli bacteria in a microfluidic device that using amplitude for addressing is feasible. We analyze the performance of the network with several addressing mechanisms and propose an amplitude sequence and a low-complexity receiver design that minimizes error in resolving the source addresses in the presence of collisions. Finally, we demonstrate that ADMA implicitly solves the problem of multiple-access control.

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.

Low-complexity iterative receiver design for mobile OFDM systems

Iterative receivers with minimum mean square error turbo equalization are computationally involved, as they require some form of matrix inversion. In this article, we propose a low complexity iterative receiver that implements successive interference cancelation-based MAP decoding (SIC-MAP) in doubly dispersive channels for orthogonal frequency division multiplexing systems. SIC-MAP leverages the soft feedback symbol estimates to remove the intercarrier interference from the received data. Numerical simulation results show that the proposed scheme achieves BER performance comparable to that of the equalization schemes proposed in Schniter et al. and Fang et al. but with significant computational savings. A low-complexity least squares-based iterative channel estimation scheme using soft feedback information is also proposed. This scheme is especially suitable when the number of significant channel taps is higher than the number of pilots, a phenomenon that is encountered by receivers in Single Frequency Networks (for example, DVB deployments in Europe).

Robust, Low-Complexity, and Energy Efficient Downlink Baseband Receiver Design for MB-OFDM UWB System

This paper presents optimized synchronization algorithms and architecture designs of a downlink baseband receiver for multiband orthogonal frequency division multiplexing ultra wideband (MB-OFDM UWB). The receiver system targets at low complexity and low power under the premise of good performance. At algorithm level, dual-threshold (DT) detection method is proposed for robust detection performance in timing synchronization; multipartite table method (MTM) is employed to implement arctangent and sin/cos functions in coarse frequency synchronization. MTM outperforms other state-of-the-art methods in power and area. A highly simplified phase tracking method is proposed with better performance in fine frequency synchronization. At architecture level, we focus on optimizing matched filter of packet detector, carrier frequency offset (CFO) corrector and FFT output reorder buffer. The proposed downlink baseband receiver is implemented with 0.13 /mi CMOS technology. The core area of layout is 2.66 × 0.94 mm2, which saves 45.1% hardware cost due to the low-complexity synchronization algorithms and architecture optimization. The postlayout power consumption is 170 mW at 132 MHz clock frequency, which is equivalent to 88 pJ/b energy efficiency at 480 Mbps data rate.

A Novel Uplink Multiple Access Scheme Based on TDS-FDMA

This contribution proposes a novel time-domain synchronous frequency division multiple access (TDS-FDMA) scheme to support multi-user uplink application. A unified frame structure for both single-carrier and multi-carrier transmissions and the corresponding low-complexity receiver design are derived. Compared with standard cyclic prefix based orthogonal frequency division multiple access systems, the proposed TDS-FDMA scheme improves the spectral efficiency by about 5% to 10% as well as imposes a similarly low computational complexity, while obtaining a slightly better bit error rate performance over Rayleigh fading channels.

Design and analysis of post-coded OFDM systems

This paper discusses the design and analysis of post coded OFDM (PC-OFDM) systems. Coded or precoded OFDM systems are generally employed to overcome the symbol recovery problem in uncoded OFDM systems. We show that PCOFDM systems are a special case of precoded OFDM systems that offer advantageous complexity-performance trade-offs. In particular, PC-OFDM systems introduce frequency diversity by manipulating the OFDM symbols in the time domain so that the computational complexity of the system can be significantly reduced. We discuss the design principles of PC-OFDM transmitter that uses upsampling operation and the spreading codes to introduce frequency diversity. We obtain the spreading code construction criterion for minimum error performance and give examples of spreading codes for PC-OFDM systems. We also describe the design of low-complexity receiver for PC-OFDM systems. In particular, our proposed partial spreading scheme results in a low complexity decoupled detector. The probability of error analysis of the receiver leads us to postulate different design criteria. We investigate different choices for detection algorithms suitable for PC-OFDM receiver and compare their performance through simulations over Rayleigh and IEEE UWB channels.

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.