Software Defined Radio Implementation Research Articles

SDR implementation of wideband spectrum sensing using machine learning

SummaryNew cognitive radio (CR) systems require high throughput and bandwidth. Hence, CR users need to detect wide frequency bands of the radio spectrum to exploit unused frequency channels. This paper proposes a new wideband spectrum sensing (WBSS) detection approach based on machine learning (ML) for scanning subchannels. The originality of the proposed approach is to detect spectrum opportunities using a narrowband spectrum sensing (NBSS) method‐based support vector machine (SVM) classification and two features: energy and goodness of fit (GoF). The simulation results show that the proposed WBSS approach‐based ML presents a higher probability of detection than the WBSS approach‐based conventional detectors, even at low signal‐to‐noise ratio (SNR). Finally, the software defined radio (SDR) implementation validates the proposed WBSS approach for real detection scenarios.

Design and implementation of SDR (software-defined radio) systems for enhanced signal processing: An experimental study

Design and implementation of SDR (software-defined radio) systems for enhanced signal processing: An experimental study

SDR implementation and real-time performance evaluation of 5G channel coding techniques

This article presents a study on the real-time performance and practical implementation of several 5G channel coding candidates including low-density parity check (LDPC), polar, turbo, and convolutional channel codes. The experiment was conducted using a wireless communication transceiver system implemented on a software defined radio (SDR) platform called Universal Software Radio Peripheral (USRP). The system was implemented using Matlab software and included scrambling, channel coding, interleaving, and required synchronization and estimation blocks. Various sets of system and channel parameters were tested, including the impact of information block sizes, code lengths, and modulation orders on the performance of each channel coding technique. The study also evaluated the impact of hardware impairments and the required blocks to mitigate them. The results indicated that polar codes had the best performance, while other codes had trade-offs for various system parameters. The study concludes that polar codes with cyclic redundancy check-successive cancellation list (CRC-SCL) are the most reliable 5G channel coding candidates.

Proposed SAR range focusing algorithm based on simulation analysis and SDR implementation

Synthetic aperture radar (SAR) imaging systems use pulse focusing techniques for achieving fine range resolution and large range detection. Stretch processing and correlation pulse focusing techniques are the most popular algorithms used in the radar signal processing stage. The architecture of the stretch processing technique makes it commonly used in frequency modulated continuous wave (FMCW) radar systems due to its simple architecture, low sampling rate, and inexpensive hardware. This paper discusses how the stretch range focusing approach can be used instead of the matched filter technique in the processing stage of the SAR Range-Doppler algorithm (RDA) to generate images of finer resolution and higher quality. In addition, validating the proposed algorithm and evaluating its performance according to some evaluation indices such as peak sidelobe ratio (PSLR), integrated sidelobe ratio (ISLR), and the impulse response width (IRW). Also, this paper presents a comprehensive analysis and hardware implementation of the two SAR algorithms, based on software-defined radio (SDR) architecture where it is characterized by less complexity, low cost, and high flexibility due to the usage of both software data processing and software waveform generation. Two Universal Software Radio Peripheral (USRP-2932) and NI-LabVIEW® software development environment are the platforms used for the hardware validation process. The transmitted waveform is a linear frequency modulated (LFM) signal generated by the first USRP (transmitter) which will hit a target located at a certain distance. The second USRP is used as a receiver for target’s echo processing and detection. This processing stage contains two architectures, which are the matched filter pulse compression architecture and the stretch range focusing approach. Finally, the validation process of the hardware results is performed based on the pre-mentioned evaluation indices.

Open-access millimeter-wave software-defined radios in the PAWR COSMOS testbed: Design, deployment, and experimentation

While millimeter-wave (mmWave) wireless has recently gained tremendous attention with the transition to 5G, developing a broadly accessible experimental infrastructure will largely facilitate the research and allow the community to make significant progress in this area. In this paper, we present the design and implementation of various programmable and open-access mmWave software-defined radios (SDRs) that have been deployed in the PAWR COSMOS advanced wireless testbed, in both indoor and outdoor environments. These programmable mmWave radios are based on the IBM 28GHz 64-element dual-polarized phased array antenna module (PAAM) subsystem board and the Sivers IMA 60GHz WiGig transceiver. These front ends are integrated with USRP SDRs or Xilinx RFSoC boards, which provide baseband signal processing capabilities. Moreover, we present measurements of the TX/RX beamforming performance and example experiments (e.g., real-time channel sounding and RFNoC-based 802.11ad preamble detection), using the mmWave radios. Finally, we discuss ongoing enhancement and development efforts focusing on these radios.

Software-Defined Radio Implementation and Performance Evaluation of Frequency-Modulated Antipodal Chaos Shift Keying Communication System

This paper is devoted to software-defined radio (SDR) implementation of frequency modulated antipodal chaos shift keying (FM-ACSK) transceiver and presents results of prototype testing in real conditions. This novel and perspective class of spread-spectrum communication systems employs chaotic synchronization for the acquisition and tracking of the analog chaotic spreading code and does not need resource-demanding cross-correlation. The main motivation of the given work is to assess the performance of FM-ACSK in real conditions and demonstrate that chaotic synchronization can be considered an efficient spread-spectrum demodulation method. The work focuses on the real-time implementation aspects of the modulation-demodulation algorithms, forward error correction (FEC) and symbol timing synchronization approach in MATLAB Simulink. The performance of the presented prototype is assessed via extensive testing, which includes measurement of bit error ratio (BER) in single-user and multi-user scenarios, estimation of carrier frequency offset (CFO) impact and image transmission over-the-air between two independent sites and comparison with classical frequency hopping spread spectrum (FHSS). The paper shows that the presented class of the spread spectrum communication systems demonstrates good performance in low signal-to-noise ratio (SNR) conditions and in terms of BER significantly outperforms the classic spread-spectrum modulation schemes which employ correlation-based detection.

A Digital Self-Interference Cancellation Scheme for In-Band Full-Duplex-Applied 5G System and Its Software-Defined Radio Implementation

The development of mobile communication technology toward 6G is difficult because the required spectrum resources have already been allocated to existing systems. Therefore, new communication systems must have high spectral efficiency to effectively utilize the available resources. This article proposes a digital self-interference (SI) canceller that can be applied to full-duplex cellular systems based on the current 5G signal format (5G-FDC) to introduce in-band full-duplex systems beyond 5G. Specifically, we reorganize the 5G demodulation reference signal (DMRS) and define a novel DMRS configuration, in which the DMRSs for uplink and downlink communications do not interfere with each other. The proposed DMRS configuration effectively improves the accuracy of the SI channel estimation. Moreover, we propose a channel extrapolation scheme that suppresses the channel estimation degradation, which deteriorates the block error rate performance. Additionally, we propose a noise estimation method to improve the low-density parity check decoding performance of the desired signal in 5G-FDC systems. The effectiveness of the proposed method is demonstrated through computer simulations and experimentally by using our developed and implemented software-defined radio-based 5G-FDC prototype. Digital SI cancellation performances of 50 dB and 30.6 dB are observed in the simulation and experimental evaluations, respectively.

Experimental SDR implementation of cooperative spectrum sensing in cognitive radio networks

In this paper, a Software Defined Radio (SDR) implementation of Cooperative Spectrum Sensing (CSS) is investigated. More precisely, various local spectrum sensing algorithms have been implemented and validated on USRP B210 using the Qt framework. The realized test bed is based on a client-server architecture. In the client interface, different spectrum sensing techniques have been implemented and analyzed. The fusion center interface implements all hard decision combination schemes, namely OR, AND, and the MAJORITY rule. Finally, several realistic scenarios have been considered to validate our SDR implementation. Moreover, these implementations allowed us to assess the efficiency of different hard-decision combination schemes for cooperative detection in the context of cognitive radio. Besides, the performance improvement is analytically evaluated and corroborated by the experimental results. These results regarding real scenarios confirm that Goodness of Fit-based (GoF) sensing methods outperform conventional methods. Furthermore, theoretical and simulation results from CSS have been validated experimentally that OR-rule gives clearly better results than other hard decisions combinations schemes.

Software defined radio implementation of a secure waveform for real‐time data transmission using universal software radio peripheral

AbstractIn the present work, we propose a new approach to secure waveforms for data transmission in software defined radio (SDR) based communication systems. For more precision, SDR implementation and validation, using Universal software radio peripherals (USRPs) B210 platforms, of a chaos‐based cryptosystem is used for securing transmitted multimedia data such as text, image, and video. For this, new GNU‐radio companion (GRC) blocks are developed and integrated in the GRC software environment to use effectively our solution. In this context, we have integrated GRC block for the Lorenz chaotic generator which generates chaotic signals. These signals are then used to generate the encryption keys by inserting a dedicated GRC block. The latest and largest development GRC block concerns the proposed solution for the chaotic synchronization problem, which is a challenge when applying chaotic systems to secure data transmission. The implemented chaotic cryptosystem is based on one time pad cipher, knowing that it's the most suitable for chaos‐based cryptography. The obtained results of the security analysis of the proposed cryptosystem validate its robustness. In fact, the generated encryption keys deemed robust after passing through two statistical tests batteries namely, NIST and DIEHARD. In addition, a good result is obtained by a large security evaluation of the encrypted data through several metrics, which are compared to some previous works. Finally, we have experimentally validated a secure waveform between two USRPs platforms for different types of data information like text, image, and video. Furthermore, a graphical communication interface is designed to guarantee easy access and broad flexible applicability of the developed solution.

A multi-agent reinforcement learning-based collaborative jamming system: Algorithm design and software-defined radio implementation

In multi-agent confrontation scenarios, a jammer is constrained by the single limited performance and inefficiency of practical application. To cope with these issues, this paper aims to investigate the multi-agent jamming problem in a multi-user scenario, where the coordination between the jammers is considered. Firstly, a multi-agent Markov decision process (MDP) framework is used to model and analyze the multi-agent jamming problem. Secondly, a collaborative multi-agent jamming algorithm (CMJA) based on reinforcement learning is proposed. Finally, an actual intelligent jamming system is designed and built based on software-defined radio (SDR) platform for simulation and platform verification. The simulation and platform verification results show that the proposed CMJA algorithm outperforms the independent Q-learning method and provides a better jamming effect.

LoRa Signal Synchronization and Detection at Extremely Low Signal-to-Noise Ratios

In recent years, LoRa has been deployed in countless Internet of Things (IoT) applications across the globe. However, as LoRa is a proprietary technology, research into its physical-layer performance has been challenging. Implementing LoRa on software-defined radio (SDR) platforms yields valuable insight into the physical layer of the LoRa standard and paves the way for improvements in packet reception capabilities for LoRa receivers. This article presents an independently developed packet reception algorithm, which drastically improves the physical performance of LoRa communication links. The advanced signal presence detection, synchronization, and symbol detection strategies are shown to significantly increase packet reception ratios in extremely adverse noise conditions. Multiple algorithm variations are presented and compared in terms of bit error rate (BER) performance and computational cost. In comparison to a theoretical system with perfect channel state information, the simulated BER performance of the best performing algorithm only requires an increase of 1.6 dB in signal-to-noise ratio (SNR) to exhibit the same performance. Finally, SDR implementations of the algorithms exhibit average SNR performance gains up to 4.7 dB when compared to commercially available hardware.

Digital Doppler-Cancellation Servo for Ultrastable Optical Frequency Dissemination Over Fiber.

Progress made in optical references, including ultrastable Fabry-Perot cavities, optical frequency combs, and optical atomic clocks, has driven the need for ultrastable optical fiber networks. Telecom-wavelength ultrapure optical signal transport has been demonstrated on distances ranging from the laboratory scale to the continental scale. In this article, we present a Doppler-cancellation setup based on a digital phase-locked loop (PLL) for ultrastable optical signal dissemination over fiber. The optical phase stabilization setup is based on a usual heterodyne Michelson-interferometer setup, while the software-defined radio (SDR) implementation of the PLL is based on a compact commercial board embedding a field-programmable gate array and analog-to-digital and digital-to-analog converters. Using three different configurations, including an undersampling method, we demonstrate a 20-m-long fiber link with residual fractional frequency instability as low as 10-18 at 1000 s and optical phase noise of -70 dBc/Hz at 1 Hz with a telecom frequency carrier.

Implementation of a Noise-Shaped Signaling System through Software-Defined Radio

Along with the development of electromagnetic weapons, Electronic Warfare (EW) has been rising as the future form of war. Especially in the area of wireless communications, high security defense systems such as Low Probability of Detection (LPD), Low Probability of Interception (LPI), and Low Probability of Exploitation (LPE) communication algorithms are being studied to prevent military force loss. One LPD, LPI, and LPE communication algorithm, physical-layer security, has been discussed and studied. We propose a noise signaling system, a type of physical-layer security, which modifies conventionally modulated I/Q data into a noise-like shape. To suggest the possibility of realistic implementation, we use Software-Defined Radio (SDR). Since there are certain hardware limitations, we present the limitations, requirements, and preferences of practical implementation of the noise signaling system. The proposed system uses ring-shaped signaling, and we present a ring-shaped signaling system algorithm, SDR implementation methodology, and performance evaluations of the system using the metrics of Bit Error Rate (BER) and Probability of Modulation Identification (PMI), which we obtain by using a Convolutional Neural Network (CNN) algorithm. We conclude that the ring-shaped signaling system can perform high LPI/LPE communication functioning because an eavesdropper cannot obtain the correct modulation scheme information. However, the performance can vary with the configurations of the I/Q data-modifying factors.

Recent advancement in the design of mixers for software‐defined radios

The implementation of software-defined radio necessitates a versatile radio frequency (RF) front-end that can support multiple standards in different frequency bands. This article presents the state-of-the-art multiband and wideband mixers in the context of different receiver architectures suitable for software-defined radio (SDR). Wideband and multiband mixer designs reported in the literature are categorized on the basis of their circuit architecture. This study tabulates the results of mixer designs with an emphasis on noise figure (NF), conversion gain (CG), linearity, and image rejection ratio. The best parameters reported in the comparison are 68–84 dB of CG, 3.2 dB of NF, 2.5 mW of power consumption, 12.5 dBm of third-order input intercept point, and 0.015 mm2 of area at different frequencies. The study also discusses the design challenges and techniques to overcome those issues. The article concludes with the summary and prospective developments for SDR architectures.

Crosstalk in modern software defined radio for the implementation of frequency modulated continuous wave radar

This study investigates crosstalk and leakage in the Software Defined Radio implementation of Frequency Modulated Continuous Wave (FMCW) radar systems. Empirical measurements of leakage power were conducted during the implementation of FMCW radar using National Instruments Universal Software Radio Peripheral (USRP) boards. Mono-static and bi-static/distributed Transmitter-Receiver configurations are compared for low power micro-Doppler applications. The impact of crosstalk on the dynamic range of the target is also investigated. The impact of electric noise generated by a windy source on the receiving USRP is also investigated. Furthermore, a simple splitter based approach is proposed to overcome the challenge of synchronisation or recovery of transmitted waveform in distributed configurations.

EPR Everywhere.

This review is inspired by the contributions from the University of Denver group to low-field EPR, in honor of Professor Gareth Eaton’s 80th birthday. The goal is to capture the spirit of innovation behind the body of work, especially as it pertains to development of new EPR techniques. The spirit of the DU EPR laboratory is one that never sought to limit what an EPR experiment could be, or how it could be applied. The most well-known example of this is the development and recent commercialization of rapid-scan EPR. Both of the Eatons have made it a point to remain knowledgeable on the newest developments in electronics and instrument design. To that end, our review touches on the use of miniaturized electronics and applications of single-board spectrometers based on software-defined radio (SDR) implementations and single-chip voltage-controlled oscillator (VCO) arrays. We also highlight several non-traditional approaches to the EPR experiment such as an EPR spectrometer with a “wand” form factor for analysis of the OxyChip, the EPR-MOUSE which enables non-destructive in situ analysis of many non-conforming samples, and interferometric EPR and frequency swept EPR as alternatives to classical high Q resonant structures.

Analysis study and SDR implementation of GoF‐based spectrum sensing for cognitive radio

Cognitive radio (CR) technology is getting extensive attention to eliminate the problem of spectrum scarcity. This technology is based on Software Defined Radio (SDR) and some integrated intelligent functions such as spectrum sensing. This function is one of the crucial elements and its hardware implementation is important for the practical realization of the CR. This paper presents experimental results of the hardware implementation of the Goodness of Fit (GoF) based sensing for CR. Universal Software Radio Peripheral platform (USRP) is used for the experiments conducted. The choice of GoF based sensing for detecting spectrum holes is motivated by the advantage of requiring fewer samples to achieve the same sensing performance compared to Energy Detector (ED). Besides, the analytical expressions for the theoretical detection performance are derived. Computer simulations are carried out to evaluate the impact of fading channels on GoF based sensing. Numerical results confirm that the proposed GoF based sensing method outperform ED under fading channels. Furthermore, theoretical results of GoF based spectrum sensing are validated experimentally taking into account some parameters such as sample rate and sensing time. Finally, several scenarios of wideband GoF based sensing are considered to demonstrate the strengths of the considered method.

On The Quality Measurements of RF Signals Using GNU Radio for Software Defined Radio Implementations in Future RF Networks

This paper presents the evaluation of the signal quality based on the Error Vector Magnitude (EVM) online measurements for different radio access modulations implemented over the GNU radio platform for Software Defined Radio (SDR) developments. It is demonstrated that when a transmitted symbol is unknown by the receiver, the EVM can be calculated by measuring the closest distance between the received symbol and the ideal one of the analyzed digital constellation. The implementation of the EVM measurements through software development for multilevel digital modulations has enabled obtaining and assessing the Signal-to-Noise Ratio (SNR) and Bit Error Rate (BER) values. Results show that the SNR measurements accordingly depicts the expected behavior of the analyzed digital modulations and BER floor appears at high level modulation formats due to the way the EVM itself has been obtained.

Towards an SDR implementation of LoRa: Reverse-engineering, demodulation strategies and assessment over Rayleigh channel

LoRa is a popular low-rate, Low-Power Wide Area Network (LPWAN) technology providing long range wireless access over unlicensed sub-GHz frequency bands to the Internet of Things (IoT). It has been used in many applications ranging from smart building to smart agriculture. LoRa is a patented modulation. However preliminary reverse-engineering efforts documented parts of it. In this article, we detail the different stages of LoRa transceivers: channel (de)coding, (de)whitening, (de)interleaving and (de)modulation with reverse-engineering in mind. Closed-form expressions for each of these stages are given, and different demodulation and decoding strategies are presented. This allows for a complete modeling of LoRa, which enables Software Defined Radio (SDR) implementations, as well as performance assessment under various channel conditions. These simulations show that LoRa systems have good properties for time and/or frequency selective channels (especially for the latter), thanks to the robustness of its underlying Chirp-Spread Spectrum (CSS) modulation.

Latency-Aware Power Management in Software-Defined Radios

Cloud computing provides benefits in terms of equipment consolidation and power savings from higher utilization for virtualizable software. Cellular communication software faces challenges in cloud computing platforms. BSs create a specific load profile that differs from traditional cloud service loads. Cellular communication system implementations have real-time deadlines with fixed, periodic latency requirements. In this paper, we assess the suitability of an unmodified Ubuntu Linux OS running on a commodity server to operate latency-critical software using a 4G LTE BS software-defined radio implementation. Scaling of the CPU clock frequency is shown to be feasible without excessive impact on the platform’s ability to meet the 4 ms processing delay requirement imposed by the LTE standard. Measurements show the relationship between the processor’s operating frequency and the number of missed subframe processing deadlines to be nonlinear. The results obtained also indicate that a high computational capacity does not suffice to ensure satisfactory operation since fronthaul processing overhead can limit achievable performance. Use of offload-capable network interface cards is studied as a potential remedy.