Software Radio Research Articles

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.

M-CUBE

Millimeter-wave (mmWave) technologies represent a cornerstone for emerging wireless network infrastructure, and for RF sensing systems in security, health, and automotive domains. However, the lack of an experimental platform has been impeding research in this field. In this article, we propose to fill the gap with M3 (M-Cube), the first mmWave massive MIMO software radio. M3 features a fully reconfigurable array of phased arrays, with up to 8 RF chains and 256 antenna elements. Despite the orders of magnitude larger antenna arrays, its cost is orders of magnitude lower, even when compared with state-of-the-art single RF chain mmWave software radios. Case studies have demonstrated the usefulness of M3 design for research in mmWave massive MIMO communication and sensing.

Towards an IEEE 802.11 Compliant System for Outdoor Vehicular Visible Light Communications

As a complementary technology to existing Radio Frequency (RF)-based solutions such as Cellular V2X (C-V2X) and Dedicated Short Range Communication (DSRC), Vehicular VLC (V-VLC) is gaining more attention in the research community as well as in the industry. This paper introduces a complete IEEE 802.11 compliant V-VLC system. The system relies on Universal Software Radio Peripheral (USRP) software defined radios programmed using the GNU Radio framework, a typical car headlight plus a custom driver electronics for the high-power car LEDs (sender), and a photodiode (receiver). Building upon our earlier work, we, for the first time, experimentally explore the communication performance in outdoor scenarios, even in broad daylight, and show that rather simple optical modifications help to reduce the ambient noise to enable long distance visible light communication. Our system also supports Orthogonal Frequency-Division Multiplexing (OFDM) with a variety of Modulation and Coding Schemes (MCS) up to 64-QAM and is fully compliant with IEEE 802.11. We performed an extensive series of experiments to explore the performance of our system, even using higher order MCS in daylight. Our results demonstrated a high reliability for distances up to 75m with the presented system, regardless of the time of the day.

Low Complexity Non Maximally Coefficient Symmetry Multi Rate Filter Bank for Wideband Channelization

For extracting the individual channels from input signal of wideband, Software Radio Channelizer was often used on multi-standard wireless communication. Despite the effective channelizer design that decreases the complexity of computational, delay and power consumption is challenging. Thus, to promote the effectiveness of the channelizer, we have provided the Non-Maximally Coefficient Symmetry Multirate Filter Bank. For this, a sharp wideband channelizer is designed to be using the latest class of masking responses with Non-maximally Decimated Polyphase Filter. Moreover, coefficient symmetry is incorporated into the Non-Maximally Coefficient Symmetry Multirate Filter Bank to improve the hardware efficiency and functionality of the proposed schemes. To prove the complexity enhancement of the proposed system, the design is analyzed with communication standard with existing methods.

Adaptive Compressed Spectrum Sensing Using Neural Networks in Cognitive Radio Networks

In today's era of Internet of Things (IoT) applications, Cognitive Radio (CR) is recognized as the most promising technology to access the unused spectrum. Such CR networks can be easily built using Wide-band spectrum sensing. However, the processing of wide-band signals involves a high sampling rate. In such scenario, Compressed Spectrum Sensing (CSS) overcomes the challenges of real-time signal recovery and sampling. CSS uses Sparse signals which are widely used in many applications as they aid in processing large data. Beyond sparsity, all the real-world signals will have special structures (like Restricted Isometric property, Null space property). Moreover, it is very hard to determine the domain in which the signal is sparse. To find this we need a random measurement matrix which plays an important role in extracting the sparse coefficients of the signal. In this paper, a customized neural network is employed to identify the peculiar structures of sparse signals for efficient recovery in real time. The neural network learns and trains an adaptive measurement matrix from the sparse signals to reduce the sensing overhead. The transmitter and receiver systems are configured using Universal Software Radio Peripheral (USRP) boards with LabVIEW® and MATLAB® extensions for peer to peer communications. The implementation results depict the superior performance of neural network based recovery in assimilating the additional structures of real-time signals.

Implementation of Digital Communication System using Weil Sequence for Efficient Information Transmission

This paper deals with the implementation of a digital communication system using the software LabVIEW, wherein Weil sequences are used for encrypting the information signal and then BPSK (Binary phase shift keying) modulation technique is applied. A real time implementation is also developed using Universal Software Radio Peripheral (USRP 2930). The two Pseudo Random noise sequences namely Legendre and Weil sequences are discussed in this paper. These PN sequences find applications in satellite route frameworks, for example, Indian Regional Navigation Satellite System (IRNSS) and Global Positioning System (GPS). When the PRN sequences are utilized for transmission in GPS satellites, they assist in recognizing various satellites which operate at equivalent frequencies.

LPWAN in the TV White Spaces

Low-Power Wide-Area Network (LPWAN) is an enabling Internet-of-Things technology that supports long-range, low-power, and low-cost connectivity to numerous devices. To avoid the crowd in the limited ISM band (where most LPWANs operate) and cost of licensed band, the recently proposed Sensor Network over White Spaces (SNOW) is a promising LPWAN platform that operates over the TV white spaces. As it is a very recent technology and is still in its infancy, the current SNOW implementation uses the Universal Software Radio Peripheral devices as LPWAN nodes, which has high costs (≈$750 USD per device) and large form-factors, hindering its applicability in practical deployment. In this article, we implement SNOW using low-cost, low form-factor, low-power, and widely available commercial off-the-shelf (COTS) devices to enable its practical and large-scale deployment. Our choice of the COTS device (TI CC13x0: CC1310 or CC1350) consequently brings down the cost and form-factor of a SNOW node by 25× and 10×, respectively. Such implementation of SNOW on the CC13x0 devices, however, faces a number of challenges to enable link reliability and communication range. Our implementation addresses these challenges by handling peak-to-average power ratio problem, channel state information estimation, carrier frequency offset estimation, and near-far power problem. Our deployment in the city of Detroit, Michigan, demonstrates that CC13x0-based SNOW can achieve uplink and downlink throughputs of 11.2 and 4.8 kbps per node, respectively, over a distance of 1 km. Also, the overall throughput in the uplink increases linearly with the increase in the number of SNOW nodes.

Fiber-Wireless Testbed using Software Defined Radio for Protocol and Algorithm Testing

Fiber-Wireless (FiWi) network is able to provide abundant bandwidth capacity and mobility to the end-users. It also eliminates the needs of having complete tedious end-to-end fiber installation from the central office to the users which saves tremendous capital expenditure. However, FiWi is still progressing. Researchers worldwide are still developing experimental works for improvement on the network reliability, quality-of-services and security. Almost all recently proposed testbed designed for FiWi are using hardware that lacks in programmability feature, making it difficult to implement any protocols and algorithms. A testbed must be flexible, scalable and reprogrammable so that various experiments and testing can be implemented easily for testing purposes. In this paper, a reprogrammable FiWi testbed using software defined radio (SDR) is proposed. One of the most prominent SDR available in the market is Universal Software Radio Peripheral (USRP). It is chosen to be used in this paper as it is equipped with a user-friendly programming platform; LabVIEW. To test the testbed’s reprogrammability feature, two algorithms are implemented for proof-of-concept; collision avoidance and dynamic bandwidth allocation. The collision avoidance algorithm is implemented in the wireless side of the testbed using the concept of Carrier Sensing Multiple Access/Collision Avoidance. At the fiber domain, a dynamic bandwidth allocation-limited scheduling is incorporated in the testbed. The results show that algorithms implemented in the testbed are in-line with the expected results. It proves that the testbed can be used for future algorithm testing for research purposes.

Implementation of reconfigurable emergency wireless communication system through SDR relay

Software Defined Radio (SDR) replaces a traditional hardware radio with software radio, thus it allows more functions to be integrated into radio devices. The Multiband operation of SDR allows to redefine, reconfigure and realize any type of radio in a short time. Interoperability expands the standards, frequency bands, modulation, and helps to operate reliably even during disaster situations. The conventional communication system fails to communicate during natural calamities, hence there is a need for an alternative, to establish reliable communication links. But the hardware infrastructure issues hinder interoperability and act as a barrier for communication systems. During such situations, the signal is affected by a lot of channel impairments such as small scale and large scale fading due to Non-line of sight. Hence there is a need for a relay unit between transmitter and receiver. SDR or Reprogrammable Radio supports interoperability so that it can establish communication between any types of devices. Therefore in this paper the Emergency Wireless Communication System have been implemented using different type of SDR i.e. VUSDR, Hack RF One, and USRP N210 as an alternative solution for interoperability that provide reliable communication for emergency services.

A Comparative Experimental Study of MIMO A&F and D&F Relay Nodes Using a Software-Defined Radio Platform

The relaying technologies in co-operative systems are considered a core element in actual and future wireless communications, assisting the network by enhancing its reliability and improving its capability through exploiting co-operativity. In this paper, a co-operative system testbed based on Software Defined Radio (SDR) through Universal Software Radio Peripherals (USRPs) and the MatlabTM software is presented. The main novelty in this development of the platform is the implementation of 4G signal features, such as Physical Downlink Shared Channel (PDSCH) and Downlink Shared Channel (DL-SCH) for transport channel coding, which is one of the main contribution of the paper. The developed Multi-Input and Multi-Output (MIMO) SDR co-operative platform is capable of developing prototypes for the Relay Nodes. More specifically, the Amplify-&-Forward (A&F)—with or without Zero Forcing (ZF) and Minimum Mean Square Error (MMSE) Pre-Equalization—and Decode-&-Forward (D&F) protocols were implemented. Both Single-Input and Single-Output (SISO) and MIMO modes are supported by our testbed. The developed A&F and D&F MIMO co-operative systems in this paper utilize Orthogonal Space-Frequency Block Codes (OSFBCs) for the transmission of data symbols from the source to the destination. Our results show that relay nodes can substantially improve the Bit Error Rate (BER) and throughput in communications between the eNodeB (eNB) and User Equipment (UE). In particular, the maximum throughput achieved by conventional MIMO A&F is 9.3Mbps at SNR=16dB, which is 4Mbps higher than throughput of MIMO Non-Co-operative. It also shows the capacity improvement when considering the pre-equalization in the A&F schemes, compared to the conventional A&F Relay Node. For example, with MIMO A&F-MMSE pattern, a value of 11.8 Mbps is achieved for SNR=16dB, which is 84.8 % of the maximum system throughput (13.95 Mbps). On the other hand, the obtained results with D&F schemes far exceed those obtained with A&F strategies, achieving the maximum performance with the 2 × 2 MIMO D&F protocol from SNR=8dB. Furthermore, this work constitutes a first stage to the implementation of a 5G New-Radio Co-operative System platform.

Software Defined Radio Based Non-orthogonal Multiple Access (NOMA) Systems

This paper focuses primarily on the study of the implementation of Non-orthogonal multiple access (NOMA) systems on Software defined radio (SDR) platforms, since NOMA has been recognized as a key enabling technology for the fifth generation (5G) wireless networks. A comprehensive review of the original birth, the latest trends, and the future research directions of NOMA is given in this paper. Specifically, several Successive Interference Cancellation (SIC) receivers are provided with mathematical analysis, such as the Ideal SIC receiver, Symbol-level SIC receiver, Codeword-level SIC receiver and Log likelihood ratio (LLR) based receivers. Furthermore, the bit error rate of two users’ signals is analyzed by implementing the NOMA system with and without the SIC using GNU Radio software. In addition, the performance of orthogonal multiple access (OMA) and NOMA systems is compared in terms of rate pairs (throughput), spectral efficiency and energy efficiency. Finally, the results reveal that the NOMA system performs better than OMA systems and it will be highlighted that SDR is a flexible platform to implement and test future wireless technologies.

An Experimental Study on D2D Route Selection Mechanism in 5G Scenarios

This paper demonstrates a route selection mechanism on a testbed with heterogeneous device-to-device (D2D) wireless communication for a 5G network scenario. The source node receives information about the primary users’ (PUs’) (or licensed users’) activities and available routes from the macrocell base station (or a central controller) and makes a decision to select a multihop route to the destination node. The source node from small cells can either choose: (a) a route with direct communication with the macrocell base station to improve the route performance; or (b) a route with D2D communication among nodes in the small cells to offload traffic from the macrocell to improve spectrum efficiency. The selected D2D route has the least PUs’ activities. The route selection mechanism is investigated on our testbed that helps to improve the accuracy of network performance measurement. In traditional testbeds, each node (e.g., Universal Software Radio Peripheral (USRP) that serves as the front-end communication block) is connected to a single processing unit (e.g., a personal computer) via a switch using cables. In our testbed, each USRP node is connected to a separate processing unit, i.e., raspberry Pi3 B+ (or RP3), which offers three main advantages: (a) control messages and data packets are exchanged via the wireless medium; (b) separate processing units make decisions in a distributed and heterogeneous manner; and (c) the nodes are placed further apart from one another. Therefore, in the investigation of our route selection scheme, the response delay of control message exchange and the packet loss caused by the operating environment (e.g., ambient noise) are implied in our end-to-end delay and packet delivery ratio measurement. Our results show an increase of end-to-end delay and a decrease of packet delivery ratio due to the transmission of control messages and data packets in the wireless medium in the presence of the dynamic PUs’ activities. Furthermore, D2D communication can offload 25% to 75% traffic from macrocell base station to small cells.

Experimentations on the Transmit Power of a Universal Software Radio Peripheral Using GNU Radio Framework and a Handheld RF Explorer

The Universal Software Radio Peripheral (USRP) and GNU Radio framework have a wide range of applications and are actively in use for teaching, research and for practical deployment of various trending wireless technologies. In this work, we explore the relationships between the power outputs of a USRP B200 device and its operating frequencies and USRP Hardware Driver (UHD) gains. These relationships are not precisely specified on the device datasheet, thereby hindering prompt design and experimentation decisions among Software Defined and Cognitive Radio (SDCR) researchers. A general purpose handheld spectrum analyser was engaged for recording the power outputs from the USRP B200 device within an experimental testbed that was setup for this study. The B200 device was driven by a GNU radio flowgraph designed for both wired and wireless modes and running on a general purpose host computer in the testbed. The results indicate that the output power decreases while the centre frequency increases, whereas the output power increases as the UHD gain increases from 65 dB until the device reaches the saturation point at 89.9 dB. These results provide a handy toolkit for SDCR researchers and practitioners.

Unmanned Aerial Vehicle (UAV) GPS Jamming Test by using Software Defined Radio (SDR) platform

This paper discusses the existing jamming method from previous publication and how the method is modified to accomplished the GPS jamming of Unmanned Aerial Vehicle (UAV). This paper also presents the result from the field test of UAV GPS jamming by using Software Defined Radio (SDR) and GNU Radio software. The field test is carried out to study the performance of the jamming signal produced and the effect of elevation angle on the jamming range. The test subject used in this field test is DJI Phantom 4 Pro, a commercial consumer grade drone.

A Multipulse Radar Signal Recognition Approach via HRF-Net Deep Learning Models.

In the field of electronic countermeasure, the recognition of radar signals is extremely important. This paper uses GNU Radio and Universal Software Radio Peripherals to generate 10 classes of close-to-real multipulse radar signals, namely, Barker, Chaotic, EQFM, Frank, FSK, LFM, LOFM, OFDM, P1, and P2. In order to obtain the time-frequency image (TFI) of the multipulse radar signal, the signal is Choi–Williams distribution (CWD) transformed. Aiming at the features of the multipulse radar signal TFI, we designed a distinguishing feature fusion extraction module (DFFE) and proposed a new HRF-Net deep learning model based on this module. The model has relatively few parameters and calculations. The experiments were carried out at the signal-to-noise ratio (SNR) of −14 ∼ 4 dB. In the case of −6 dB, the recognition result of HRF-Net reached 99.583% and the recognition result of the network still reached 97.500% under −14 dB. Compared with other methods, HRF-Nets have relatively better generalization and robustness.

Specific Emitter Identification Based on Software-Defined Radio and Decision Fusion

Specific emitter identification (SEI) uses the unintentional modulation information carried by the emitter waveform, i.e., radio frequency fingerprints, to realize the matching identification of the received signal and its corresponding emitter. We propose an emitter identification scheme based on deep learning (DL). The received signal is subjected to time-varying filtered empirical mode decomposition (tvf-EMD). The obtained intrinsic mode functions (IMFs) are subjected to Hilbert transformation to obtain a 3D-Hilbert spectrum, using amplitude frequency aggregation characteristics obtained by projection to express the nonstationary information of the signal and calculate its bispectral diagonal slice as the second feature. A squeeze-and-excitation block (SEB) is introduced to a convolutional neural network (CNN) to focus on the effective area in the feature map, and support vector machine (SVM) is used to fuse the decision information of the two types of features. We collect four types of steady-state signals on a software-defined radio (SDR) sensor platform based on GNU Radio and universal software radio peripherals (USRP), and study the algorithm performance. The results show that our scheme has strong generalization, high recognition accuracy, and broad application prospects compared with other SEI methods.

Physical principles of work and basic features of Universal Software Radio Peripheral

The current stage in the development of info communication systems is characterized by an active search for a solution to the problem of signal processing in dynamically changing conditions. Growing requirements for bandwidth implemented in practice lead researchers to search for new solutions that can work under restrictions previously considered fundamental, such as a high level of intersymbol distortions [1]. There are many useful signal recognition techniques that use a statistical apparatus, an apparatus for predicting dynamic processes, and means combining the features of different principles. Ensuring the reception of signals transmitted over the meteor channel of a radio communication requires, in addition to modern analog-to-digital conversion devices, the ability to directly synthesize precision signals for heterodyning systems, correlation analysis and statistical processing of a signal-noise complex. Similar problems arise in more traditional applications, such as radar and radio navigation. The most preferred tools of the developer and designer in all cases are devices that implement the technology of software-defined radio (SDR). The article describes the physical principles of Universal Software Radio Peripheral operating using software-defined radio (SDR) technology. It shows the implementation of the technology of software-defined radio system according to the concept of USRP for various tasks, architecture and generalized structure.

A USRP-Based Testbed for Wideband Ranging and Positioning Signal Acquisition

For validation and demonstration of high accuracy ranging and positioning algorithms and systems, a wideband radio signal generation and acquisition testbed, tightly synchronized in time and frequency, is needed. The development of such a testbed requires solutions to several challenges. Tight time and frequency synchronization, derived from a centrally distributed time-frequency reference signal, needs to be maintained in the hardware of the transmitter and receiver nodes, and wideband signal acquisition requires sustainable data throughput between the receiver and host PC as well as data storage at GB level. This article presents a testbed for wideband radio signal acquisition, for validation and demonstration of high accuracy ranging and positioning. It consists of multiple Ettus X310 universal software radio peripherals (USRPs) and supports high accuracy (<; 100 ps) time-deterministic, sustainable signal transmission and acquisition, with a bandwidth up to 320 MHz (in dual channel mode) and frequencies up to 6 GHz. Generation and processing of wideband arbitrary signal waveforms is done offline. To realize these features, radio frequency on chip (RFNoC) compatible HDL units were developed for integration in the X310 SDR platform. Wideband transmission and signal acquisition at a lower duty cycle is applied to reduce the data offloading throughput to the host's personal computer (PC). Benchmarking of the platform was performed to demonstrate sustainable long duration dual channel acquisition. Indoor range measurements with the synchronous operation of the testbed show a decimeter-level accuracy.

A Conformance Testing Methodology and System for Cognitive Radios

The fifth generation (5G) of mobile networks has started its operation in some countries and is aimed at meeting demands beyond the current system capabilities such as the huge amount of connected devices from IoT applications (e.g., smart cities), explosive growth of high‐speed mobile data traffic (e.g., ultrahigh definition video streaming), and ultrareliable and low latency communication (e.g., autonomous vehicle). To attend to these needs, the electromagnetic spectrum must be made available, but the static spectrum allocation policy has caused a spectrum shortage and impaired the employment/expansion of the wireless systems. To overcome this issue, the dynamic spectrum access (DSA) has been promoted in 5G/6G networks, which is enabled by the cognitive radio (CR) technology. Although diverse mechanisms have been developed to tackle the challenges that emerge in different CR layers/functionalities, a standardized testing methodology and system for CR is still immature. Existing standards or methodologies and systems for CR only focus on the definition of network technologies (e.g., IEEE 802.22 and IEEE 802.11af), performance evaluation of CR algorithms/mechanisms, or definition of the device cognition level via performance results or psychometric approaches, not covering systems/methodologies to verify if the device meets the CR capabilities and regulatory policies, neglecting the conformance testing. In this respect, this paper proposes a flexible methodology and system for CR conformance testing under two perspectives, functionalities and limits. We instantiate it by using the Universal Software Radio Peripheral (USRP) software‐defined radio platform and present a proof‐of‐concept with a conformance metric. The results show the feasibility of our proposal.

Performance Analysis and Software-Defined Implementation of Real-Time MIMO FSO With Adaptive Switching in GNU Radio Platform

In this paper, we provide the first software-based implementation of multiple-input multiple-output (MIMO) free space optical (FSO) link with the adaptive switching based on the software defined radio developed by GNU Radio software system, which emulates the real-time capability of the proposed scheme. We propose a switching mechanism to independently configure each transmitter and receiver, based on the channel state information provided at the transmitter via a feedback link and evaluate the link performance under atmospheric conditions such as fog and turbulence. We also validate the advantages of mitigating both the turbulence and fog in the proposed multiple input multiple output FSO system by means of numerical simulations and the developed GNU Radio software platform. We demonstrate that the proposed system can effectively operate in heavy fog with bit error rates (BER) within the range of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−8</sup> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 10^{-7}$ </tex-math></inline-formula> over link spans of 100, 200 and 300 m. Additionally the system has been shown to mitigate moderate turbulence over a 100 m link span with BER of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 10^{-7}$ </tex-math></inline-formula> .