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Performance Assessment of IEEE 802.11p with an Open Source SDR-based Prototype
Abstract
We present a complete simulation and experimentation framework for IEEE 802.11p. The core of the framework is an SDR-based OFDM transceiver that we validated extensively by means of simulations, interoperability tests, and, ultimately, by conducting a field test. Being SDR-based, the transceiver offers important benefits: It provides access to all data down to and including the physical layer, allowing for a better understanding of the system. Based on open and programmable hardware and software, the transceiver is completely transparent and all implementation details can be studied and, if needed, modified. Finally, it enables a seamless switch between simulations and experiments and, thus, helps to bridge the gap between theory and practice. Comparing the transceiver's performance with independent results from simulations and experiments, we underline its potential to be used as a tool for further studies of IEEE 802.11p networks both in field operational tests as well as simulation based development of novel physical layer solutions. To make the framework accessible to fellow researchers and to allow reproduction of the results, we released it under an Open Source license.
... Among various existing work of open-source implementations of IEEE 802.11 standards, the work in this paper is primarily motivated by a widely-used open-source project, WIME [8], which provides a GNU Radio based package for SDR platforms. However, the open-source package in the WIME project only supports single data stream transmission defined in IEEE 802.11a/g/p. ...
... Based on the format in Fig. 2, the auto correlation is expected to reach the maximum value starting from the beginning of GI2 and drops from the end of GI2 so that the center of the plateau shall correspond to the middle point of GI2. While the work in [8] use the cross-correlation method for a SISO packet, we have preferred the auto-correlation method for the MIMO packet. ...
... A. SISO 1) Simulation Studies: We first compare the performance of GR-WiFi on Legacy transmissions with WIME [8]. To compute the PDR result on each SNR value, 1000 UDP packets with a random 500-byte payload for each packet are generated and white Gaussian noise with the amplitude corresponding to the given SNR is added to the signal. ...
Since its first release, WiFi has been highly successful in providing wireless local area networks. The ever-evolving IEEE 802.11 standards continue to add new features to keep up with the trend of increasing numbers of mobile devices and the growth of Internet of Things (IoT) applications. Unfortunately, the lack of open-source IEEE 802.11 testbeds in the community limits the development and performance evaluation of those new features. Motivated by an existing popular open-source software-defined radio (SDR) package for single-user single-stream transmission based on the IEEE 802.11/a/g/p standard, in this paper we present GR-WiFi, an open-source package for single-user and multi-user multi-input multi-output (MIMO) transmissions based on 802.11n and 802.11ac standards. The distinct features of GR-WiFi include the support of parallel data streams to single or multiple users, and the compatible preamble processing to allow the co-existence of conventional, high-throughput (HT) and very-high-throughput (VHT) traffics. The performance of GR-WiFi is evaluated through both extensive simulation and real-world experiments.
... In this study, we present a public dataset for WiFibased human activity recognition. Moreover, for CSI data collection, we propose a platform that consists of USRP hardware and an open-source WiFi transceiver software package gr-foo designed in [8]. Instead of popular WiFi NIC cards, the use of USRP B200 Mini devices provides better signal quality and flexibility in radio frequency selection. ...
... and gr-foo. These WiFi packages are initially proposed for wireless communications research in [8]. Because of its efficiency and stability, we choose this software for WiFi signal generation and CSI signal extraction. ...
... For the hardware setting, we use laptops with Ubuntu 20.04 OS, USRP B200mini-i devices, and VERT-2450 antennas. The software GNU Radio provides an environment for running the WiFi package named gr-ieee802-11 [8], which is responsible for base-band signal processing. These WiFi packages are initially proposed for wireless communications research in [8]. ...
Recently, human activity recognition based on wireless signals has become an active and promising research direction. Researchers have shown that machine learning (ML) models can accurately classify some activities of a person standing between the WiFi transmitter and receiver. However, the availability of public datasets is limited due to labor-intensive dataset collection. Moreover, an efficient signal segmentation algorithm is required for application in practical scenarios. This paper presented a signal enhancement framework for WiFi-based human activity recognition using ML-based signal segmentation. Specifically, we proposed a stable channel state information (CSI) collection platform based on stable USRP devices. Using this platform, we released a public dataset (WiAR-UIT) for various human activities to control smart home devices. To enhance the prediction accuracy as well as the converging ability of ML models, we proposed two algorithms for automatic signal segmentation. The first algorithm uses conventional signal processing procedures (SIGPRO-SEGM). The second algorithm is dataset-independent and based on a CNN model (ML-SEGM). Applying these segmentation algorithms to our dataset, the best performance of 99.2% accuracy is obtained. Moreover, the accuracy is improved by 35% for some ML models including K-nearest neighbors, support vector machine, decision tree, random forest, and multi-layer perceptron. Finally, we have deployed a real-time client–server application using the above segmentation algorithms to emphasize the potential and practicality of the proposed research direction.
... While the assumption in Equation (1) [16]. Each OFDM burst, as depicted in Figure 2, contains training sequences known to the transmitter and receiver. ...
... The estimated CFO values in Equation (2) are used as RFF features, which comprise the first stage of the detection scheme in Figure 2. This was realized with an SDR testbed that consisted of a GNURadio software implementation of OFDM-based transceiver (complying with IEEE 802.11a/g/p recommendations [16]), Figure 3, and USRP B210 hardware from Ettus research, as well as HackRF hardware. GNURadio enables one to develop and deploy real-world radio systems. ...
The authentication of wireless devices through physical layer attributes has attracted a fair amount of attention recently. Recent work in this area has examined various features extracted from the wireless signal to either identify a uniqueness in the channel between the transmitter–receiver pair or more robustly identify certain transmitter behaviors unique to certain devices originating from imperfect hardware manufacturing processes. In particular, the carrier frequency offset (CFO), induced due to the local oscillator mismatch between the transmitter and receiver pair, has exhibited good detection capabilities in stationary and low-mobility transmission scenarios. It is still unclear, however, how the CFO detection capability would hold up in more dynamic time-varying channels where there is a higher mobility. This paper experimentally demonstrates the identification accuracy of CFO for wireless devices in time-varying channels. To this end, a software-defined radio (SDR) testbed is deployed to collect CFO values in real environments, where real transmission and reception are conducted in a vehicular setup. The collected CFO values are used to train machine-learning (ML) classifiers to be used for device identification. While CFO exhibits good detection performance (97% accuracy) for low-mobility scenarios, it is found that higher mobility (35 miles/h) degrades (72% accuracy) the effectiveness of CFO in distinguishing between legitimate and non-legitimate transmitters. This is due to the impact of the time-varying channel on the quality of the exchanged pilot signals used for CFO detection at the receivers.
... Thus, we avoid extending frame size or transmitting additional frames. To evaluate our work under a realistic setup, we first extend the gr-ieee802-11 [16] GNURadio library to support IEEE 802.11ac (40 MHz bandwidth), then implement eP-Mod, and finally experimentally evaluate our proposed scheme using a commercial AP and a USRP receiver. To complement our experiments, we also formally model and analyze our proposed technique to ensure its correctness. ...
... Open-source full-stack implementations of Wi-Fi such as Openwifi [14] do not support the 802.11ac protocol or preamble modification, and their FPGA implementation of the preamble is not supported in easily accessible boards either. Therefore, we extend gr-ieee802-11 GNU-Radio library [16] to study the feasibility of our proposed method in a real setup, we use a testbed consisting of an Ettus USRP B210, connected to an Intel Core i5 host running Ubuntu 19.10 via virtual machine within the range of a real AP (Aruba)-see Figure 7. ...
... To demonstrate the communication capability with the same waveform, we also implement a communication receiver flowgraph that performs frame detection, synchronization, estimation, equalization, and demodulation stages. We develop our MIMO OFDM receiver based on a SISO OFDM (i.e., 802.11p) receiver implementation presented in [11]. ...
... MIMO OFDM Equalizer: Unlike other receiver blocks that are adopted from [11], we implement our MIMO OFDM equalizer block that performs MIMO channel estimation, data stream equalization, and SNR estimation. When an NDP frame is received, this block performs MIMO channel estimation and stores estimated channel matrix in a file. ...
Large-scale deployment of connected vehicles with cooperative sensing and maneuvering technologies increases the demand for vehicle-to-everything communication (V2X) band in 5.9 GHz. Besides the V2X spectrum, the under-utilized millimeter-wave (mmWave) bands at 24 and 77 GHz can be leveraged to supplement V2X communication and support high data rates for emerging broadband applications. For this purpose, joint radar-communication (JRC) systems have been proposed in the literature to perform both functions using the same waveform and hardware. In this work, we present a software-defined multiple-input and multiple-output (MIMO) JRC with orthogonal frequency division multiplexing (OFDM) for the 24 GHz mmWave band. We implement a real-time operating full-duplex JRC platform using commercially available software-defined radios and custom-built mmWave front-ends. With fully digital MIMO architecture, we demonstrate simultaneous data transmission and high-resolution radar imaging capabilities of MIMO OFDM JRC in the mmWave band.
... Our new simulations incorporate various channel models and a realistic Wi-Fi environment, enhancing beyond the scope of our preliminary work. Furthermore, to do the over-the-air experiments with commercial AP-USRP testbed, in this paper, we extend the gr-ieee802-11 [15] library to support 802.11ax, advancing from our preliminary work on 802.11ac [13], and preamble modification. We have also verified that the current draft of IEEE 802.11be (the upcoming standard-Wi-Fi 7), does not amend any CE components [16]. ...
Wireless local area networks remain vulnerable to attacks initiated during the connection establishment (CE) phase. Current Wi-Fi security protocols fail to fully mitigate attacks like man-in-the-middle, preamble spoofing, and relaying. To fortify the CE phase, in this paper we design a backward-compatible scheme using a digital signature interwoven into the preambles at the physical (PHY) layer with time constraints to effectively counter those attacks. This approach slices a MAC-layer signature and embeds the slices within CE frame preambles without extending frame size, allowing one or multiple stations to concurrently verify their respective APs' transmissions. The concurrent CEs are supported by enabling the stations to analyze the consistent patterns of PHY-layer headers and identify whether the received frames are the anticipated ones from the expected APs, achieving 100% accuracy without needing to examine their MAC-layer headers. Additionally, we design and implement a fast relay attack to challenge our proposed defense and determine its effectiveness. We extend existing open-source tools to support IEEE 802.11ax to evaluate the effectiveness and practicality of our proposed scheme in a testbed consisting of USRPs, commercial APs, and Wi-Fi devices, and we show that our relay attack detection achieves 96-100% true positive rates. Finally, end-to-end formal security analyses confirm the security and correctness of the proposed solution.
... We focus on nodes 1 → 4 as depicted in Fig. 1a, which share a bandwidth of 10 MHz. Nodes 1 → 2 are deployed through the srsRAN protocol stack [79], while nodes 3 → 4 are deployed with the Wi-Fi Stack, which is based on the open-source GNU Radio implementation of the IEEE 802.11a/g/p standard [96]. Cellular node 1 and Wi-Fi node 3 are BSs, while nodes 2 and 4 serve as the respective cellular and Wi-Fi UEs. ...
Reconfigurable Intelligent Surfaces (RISs) are a promising technique for enhancing the performance of Next Generation (NextG) wireless communication systems in terms of both spectral and energy efficiency, as well as resource utilization. However, current RIS research has primarily focused on theoretical modeling and Physical (PHY) layer considerations only. Full protocol stack emulation and accurate modeling of the propagation characteristics of the wireless channel are necessary for studying the benefits introduced by RIS technology across various spectrum bands and use-cases. In this paper, we propose, for the first time: (i) accurate PHY layer RIS-enabled channel modeling through Geometry-Based Stochastic Models (GBSMs), leveraging the QUAsi Deterministic RadIo channel GenerAtor (QuaDRiGa) open-source statistical ray-tracer; (ii) optimized resource allocation with RISs by comprehensively studying energy efficiency and power control on different portions of the spectrum through a single-leader multiple-followers Stackelberg game theoretical approach; (iii) full-stack emulation and performance evaluation of RIS-assisted channels with SCOPE/srsRAN for Enhanced Mobile Broadband (eMBB) and Ultra Reliable and Low Latency Communications (URLLC) applications in the worlds largest emulator of wireless systems with hardware-in-the-loop, namely Colosseum. Our findings indicate (i) the significant power savings in terms of energy efficiency achieved with RIS-assisted topologies, especially in the millimeter wave (mmWave) band; and (ii) the benefits introduced for Sub-6 GHz band User Equipments (UEs), where the deployment of a relatively small RIS (e.g., in the order of 100 RIS elements) can result in decreased levels of latency for URLLC services in resource-constrained environments.
... As shown in Fig. 2, a preprocessing step is set up in both the training and inference stages. Specifically, for the received signal, a standard synchronization algorithm as in [32] is firstly employed to precisely find the start point of the packet. Then, the preamble part is extracted, followed by the frequency offset compensation [33] which aims to prevent it from affecting the RFF extraction. ...
Radio frequency fingerprint identification (RFFI) is a promising device authentication approach by exploiting the unique hardware impairments as device identifiers. Because the hardware features are extracted from the received waveform, they are twisted with the channel propagation effect. Hence, channel elimination is critical for a robust RFFI system. In this paper, we designed a channel-robust RFFI scheme for IEEE 802.11 devices based on spectral regrowth and proposed a carrier frequency offset (CFO)-assisted collaborative identification mechanism. In particular, the spectral regrowth was utilized as a channel-resilient RFF representation which is rooted in the power amplifier nonlinearity. While CFO is time-varying and cannot be used alone as a reliable feature, we used CFO as an auxiliary feature to adjust the deep learning-based inference. Finally, a collaborative identification was adopted to leverage the diversity in a multi-antenna receiver. Extensive experimental evaluations were performed in practical environments using 10 IEEE 802.11 devices and a universal software radio peripheral (USRP) X310 receiver with 4 antennas. The results demonstrated the effectiveness of the proposed method against diverse channel conditions and CFO drift, where an average classification accuracy of 92.76% was achieved against channel variations and a 5-month time span, significantly outperforming existing methods.
... It is shown that the proposed radar platform can detect a drone flying at the distance of about 50 m with the speed of 12 km/h. Finally, the study in [3] provided an open-source SDR-based framework for IEEE802.11p. This prototype can be used for further studies of IEEE 802.11p novel physical layer solutions. ...
... The main GNURadio module is Wifi Physical Hierarchy, and it will both receive data from MAC and receive from other transmitting station/access point. Figure 5. 16 from [40], and we modified its frequency, encoding and sample rate to match 802.11ah standard. ...
Improving access and quality of public health services in Indonesia is still a big challenge. Geographic obstacles, shortage, and maldistribution of specialist/doctors especially in rural areas are some of the challenges to be answered. In 2016, the city council of Makassar Indonesia has developed a telemedicine system called "home care" to overcome those challenges. They created mobile healthcare vehicle called "Dottoro ta" that gives healthcare services 24 hours/day to the community. This vehicle is equipped with ElectroCardioGraphy (ECG), UltraSonoGraphy (USG) and other standard medical equipment. When patients call this service, a team consisting of doctors, nurses and drivers will move to the patient's location and gives a proper treatment. Meanwhile, the development of Internet of Things (IoT) technologies offers a broad opportunity to improve these services. Changing this equipment with IoT devices will offer a lot of advantages. IoT is the recent technological term, which is a collection of devices or sensors that have connectivity to the internet. Here, the Internet does not have to be a global connection; indeed, a Local Area Network (LAN) is also possible as long as it supports TCP/IP protocols. Most IoT devices use wireless connections to ensure mobility and portability. However, wireless devices have some fundamental issues such as energy consumption, noise and interference of wireless communication. IoT has many variations for implementation including healthcare sectors. Today, sensor nodes have changed into small, unobtrusive and powerful devices, which can be easily accommodated into wearable devices such as smart watches, bracelets, gloves or buttons. Thus, it gives more convenient way to collect the health condition data of patients using wearable sensors and then send, analyzed and stored the data in the cloud. For example, by using heart rate sensors, the conditions of the patients such as heart attacks, anxiety and stress can be continuously monitored. Another potential of using IoT on health sectors is telemedicine field, enabling doctors/nurses to perform retrieval of data in real-time and immediately perform diagnostics on the spot, without preoccupied with the installation of conventional medical devices. This will speed up diagnosis and give a positive impact on the health of the patient. Indeed, deploying IoT system in the health sector has several advantages over conventional wired systems such as ease of use, reducing the risk of infection, reducing the risk of failure, reducing user discomfort, increasing mobility, improving the efficiency of hospital care, and lower installation costs. However, providing the robust transmission in the wireless communication is a challenge in the healthcare domain, because continuous updated health data is very important for the treatment of the patients. In this research activity, we propose a new cross layer protocol to overcome this problem. The proposal takes advantages of beacon power measurements in the node’s PHY layer to determine whether there is interference from the human body or not. This information is used by the MAC layer to decide the transmission of packets. Our results show that there are significant improvements of the PER while maintaining the throughput relatively the same as the conventional protocol. We analytically show the effect of body pathloss on 802.11ah network and its effects in terms of power consumption for the healthcare sensors. We compare the standard pathloss of 802.11ah with body pathloss. We see that body pathloss increase PER and decrease throughput because the body absorbs the electromagnetic signal. We also propose a novel cross-layer algorithm to counter the effect of body pathloss. The idea is to defer the data transmission if there is a high probability of body pathloss by detecting the received power of beacon.
... The program makes use of several add-ons for GNU Radio. The WiFi blocks and general flowchart for the transceiver and receiver are adapted from [35]. This allows for sending and receiving messages in the 802.11 ...
Blind intersections have high accident rates due to the poor visibility of oncoming traffic, high traffic speeds, and lack of infrastructure (e.g., stoplights). These intersections are more commonplace in rural areas, where traffic infrastructure is less developed. The Internet of Vehicles (IoV) aims to address such safety concerns through a network of connected and autonomous vehicles (CAVs) that intercommunicate. This paper proposes a Road-Side Unit-based Virtual Intersection Management (RSU-VIM) over 802.11p system consisting of a Field-Programmable Gate Array (FPGA) lightweight RSU that is solar power-based and tailored to rural areas. The RSU utilizes the proposed RSU-VIM algorithm adapted from existing virtual traffic light methodologies to communicate with vehicles over IEEE 802.11p and facilitate intersection traffic, minimizing visibility issues. The implementation of the proposed system has a simulated cloud delay of 0.0841 s and an overall system delay of 0.4067 s with 98.611% reliability.
... By doing so, most of the physical layer functionalities can be implemented through the modifiable software platform. This allows reducing the hardware cost by adding new wireless features without the requirement of new components, which is highly desirable by service providers and product developers through end users [8]. Furthermore, software-defined radio (SDR) enables easy implementation of a range of RF and optical systems by adopting a common platform architecture and by using offthe-shelf components such as the wireless open-access research platform boards, and universal software radio peripherals (USRPs). ...
... SISO/MIMO and 802.11a/g fullduplex [180]. Bloessl et al. [181] present both simulation and experimentation framework of IEEE 802.11 p based SDR Orthogonal Frequency Division Multiplexing (OFDM) with extensive validation test for interoperability, field trial, and important benefits obtained through SDR-based transceiver. The transceiver's transparency open and programmable hardware and software, implement and provide detail access to all data below, including the physical layer for better understanding of the system. ...
The realization of open-source-defined wireless networks in the telecommunication domain is accomplished through the fifth-generation network (5G). In contrast to its predecessors (3G and 4G), the 5G network can support a wide variety of heterogeneous use cases with challenging requirements from both the Internet and the Internet of Things (IoT). The future sixth-generation (6G) network will not only extend 5G capabilities but also innovate new functionalities to address emerging academic and engineering challenges. The research community has identified these challenges could be overcome by open-source-defined wireless networks, which is based on open-source software and hardware. In this survey, we present an overview of different aspects of open-source-defined wireless networks, comprising motivation, frameworks, key technologies, and implementation. We start by introducing the motivation and explore several frameworks with classification into three different categories: black-box, grey-box, and white-box. We review research efforts related to open-source-defined Core Network (CN), Radio Access Network (RAN), Multi-access Edge Computing (MEC), the capabilities of security threats, open-source hardware, and various implementations, including testbeds. The last but most important in this survey, lessons learned, future research direction, open research issues, pitfalls, and limitations of existing surveys on open-source wireless networks are included to motivate and encourage future research.
... This is the case of IEEE 802.11p for vehicular communications. In [47], the authors have evaluated a SDR of [48]. They compared the performances of SDR to the off-the-shelf boards (Cohda boards) [49] without proposing an approach to improve the obtained results. ...
... In order to implement this, we use an SDR controlled in GNURadio [5] running the 802.11 stack published in [6]. Fig. 1 shows the measurement setup in this work, with Fig. 1a illustrating the signal flow. ...
This paper describes the measurement setup for the proliferation of the vehicular communication systems in operating cars. The setup builds on a communication sniffer which detects cooperative awareness messages broadcast from ETSI ITS-G5 systems, decodes them and records the public information in these messages. The experimental characterization of the setup in an outdoor scenario is presented in order to verify the sniffer's performance with respect to transmit power and communication range. The setup is deployed for measurements on a busy road with slow moving traffic in the center of the city of Linz, Austria. The number of active users as well as their transmit power, duration of the transmission and packet length have been recorded.
... To showcase how Colosseum can facilitate these operations, we instantiate a Wi-Fi network through an open-source GNU Radio-based implementation of the IEEE 802.11a/g/p standard [37]. We deploy 50 Wi-Fi transceivers in a Colosseum urban scenario and measure the Signal to Interference plus Noise Ratio (SINR) in the case nodes do not move (Fig. 8, top), and in the case they move with an average speed of 3 m/s (Fig. 8, bottom). ...
Colosseum is an open-access and publicly-available large-scale wireless testbed for experimental research via virtualized and softwarized waveforms and protocol stacks on a fully programmable, "white-box" platform. Through 256 state-of-the-art Software-defined Radios and a Massive Channel Emulator core, Colosseum can model virtually any scenario, enabling the design, development and testing of solutions at scale in a variety of deployments and channel conditions. These Colosseum radio-frequency scenarios are reproduced through high-fidelity FPGA-based emulation with finite-impulse response filters. Filters model the taps of desired wireless channels and apply them to the signals generated by the radio nodes, faithfully mimicking the conditions of real-world wireless environments. In this paper we describe the architecture of Colosseum and its experimentation and emulation capabilities. We then demonstrate the effectiveness of Colosseum for experimental research at scale through exemplary use cases including prevailing wireless technologies (e.g., cellular and Wi-Fi) in spectrum sharing and unmanned aerial vehicle scenarios. A roadmap for Colosseum future updates concludes the paper.
... It is compliant with LTE Release 9 and supports up to 20 MHz bandwidth channels as well as transmission modes from 1 to 4, all using the FDD configuration. The IEEE 802.11p transceiver is implemented through a GNU Radio flowgraph, released by the WiME project [47], and it is interoperable with commercial IEEE 802.11p devices. We mention here that, because of processing delay limitations, the IEEE 802.11p transceiver lacks important features of the standard such as ACKs and CSMA/CA mechanisms. ...
New-generation wireless networks are designed to support a wide range of services with diverse key performance indicators (KPIs) requirements. A fundamental component of such networks, and a pivotal factor to the fulfillment of the target KPIs, is the virtual radio access network (vRAN), which allows high flexibility on the control of the radio link. However, to fully exploit the potentiality of vRANs, an efficient mapping of the rapidly varying context to radio control decisions is not only essential, but also challenging owing to the interdependence of user traffic demand, channel conditions, and resource allocation. Here, we propose CAREM, a reinforcement learning framework for dynamic radio resource allocation in heterogeneous vRANs, which selects the best available link and transmission parameters for packet transfer, so as to meet the KPI requirements. To show its effectiveness, we develop a testbed for proof-of-concept. Experimental results demonstrate that CAREM enables an efficient radio resource allocation under different settings and traffic demand. Also, compared to the closest existing scheme based on neural network and the standard LTE, CAREM exhibits an improvement of one order of magnitude in packet loss and latency, while it provides a 65% latency improvement relatively to the contextual bandit approach.
... For the baseband transmitter/receiver implementation, we modified the GNU Radio-based Open Source stack for IEEE 802.11a/g/p developed by Bloessl et al. [23]. The core of this framework is a modular OFDM transceiver that is fully interoperable with commercially available systems and has been thoroughly evaluated in [24]. The main motivation for building upon this implementation is to test and evaluate the performance of our V-VLC system with commercially available prototypes, as soon as these become available. ...
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.
The relentless demand for data in our society has driven the continuous evolution of wireless technologies to enhance network capacity. While current deployments of 5G have made strides in this direction using massive multiple-input–multiple-output (MIMO) and millimeter-wave (mmWave) bands, all existing wireless systems operate in a half-duplex (HD) mode. Full-duplex (FD) wireless communication, on the other hand, enables simultaneous transmission and reception (STAR) of signals at the same frequency, offering advantages such as enhanced spectrum efficiency, improved data rates, and reduced latency. This article presents a comprehensive review of FD wireless systems, with a focus on hardware design, implementation, cross-layered considerations, and applications. The major bottleneck in achieving FD communication is the presence of self-interference (SI) signals from the transmitter (TX) to the receiver, and achieving SI cancellation (SIC) with real-time adaption is critical for FD deployment. The review starts by establishing a system-level understanding of FD wireless systems, followed by a review of the architectures of antenna interfaces and integrated RF and baseband (BB) SI cancellers, which show promise in enabling low-cost, small-form-factor, portable FD systems. We then discuss digitalcancellation techniques, including digital signal processing (DSP)-and learning-based algorithms. The challenges presented by FD phased-array and MIMO systems are discussed, followed by system-level aspects, including optimization algorithms, opportunities in the higher layers of the networking protocol stack, and testbed integration. Finally, the relevance of FD systems in applications such as next-generation (xG) wireless, mmWave repeaters, radars, and noncommunication domains is highlighted. Overall, this comprehensive review provides valuable insights into the design, implementation, and applications of FD wireless systems while opening up new directions for future research.
In this paper, a scalable and real-time decision-based carrier tracking for software defined radio (SDR) for M-ary QAM modulation has been proposed and tested in real-time using the universal software radio peripheral (USRP)-2922. The proposed system provides real-time decision-based carrier tracking for improved efficiency and performance. The real-time transfer of data has been done using the USRP-2922 hardware using the M-ary QAM modulation scheme for data transmission. The novelty of the proposed system is that one can transfer random data (binary bits), text or an image which can be encoded using the desired forward error correction codes (FEC) namely the convolution coding/Viterbi soft decision decoding and the turbo coding/decoding. The proposed novel SDR transceiver system with real-time decision-based carrier tracking shows an improved performance for different parameters such as the bit error rate (BER) and signal to noise ratio (Eb/No).
Radio frequency fingerprint (RFF) identification is an emerging device authentication technique that exploits the hardware imperfections resulting from the manufacturing process. Due to the varying impact of the wireless channel during RFF training and test stages, it is challenging to design channel-independent RFF techniques. This paper designs a channel robust RFF identification scheme by leveraging the different spectrum of adjacent signal symbols, named the difference of the logarithm of the spectrum (DoLoS), which does not rely on a single RFF feature or requires additional manipulation of the devices under test. Specifically, DoLoS exploits the fact that two different symbols in a packet exhibit different RFF features but have a similar channel response during the channel coherence time. We implemented the DoLoS with the IEEE 802.11 orthogonal frequency division multiplexing (OFDM) system as a case study. We carried out extensive experiments using 7 Wi-Fi devices of the same model in different wireless channel environments, including 12 data collection positions in two completely different environments. Compared with conventional RFF identification schemes that do not eliminate channel effects, our scheme is robust to channel variations and the highest identification accuracy is 99.02% in the single-environment evaluation and 97.05% in the cross-environment evaluation.
Train-to-train (T2T) communication is proposed as an auxiliary safety-guaranteed measure for railway communications. Vehicular communication standards have been supporting railway use cases and T2T communications. It is essential to consider the propagation characteristics of railway environments with dedicated T2T channel models for simulation and testing of vehicular communication standards. In this paper, we propose six tapped delay line (TDL) channel models for T2T communications in Hilly Terrain and Railway Station. The measurement based proposed channel models consider different T2T distances and relative speeds of up to 50 km/h with trains moving in an approaching maneuver. Also, a study about the Doppler-delay behavior in the considered scenarios is presented using the scattering function. The proposed TDL channel models as well as the measured propagation characteristics are used in a 802.11bd simulation framework. Both simulation results, which are based on the TDL channel models or on the measurements, are compared to each other. The results show a very good match between the TDL channel models and the measurement data and indicate a good accuracy of the theoretical derivations and the simulation method.
The plethora of Internet of Things (IoT) protocols and the upcoming availability of new spectrum bands for wirelessly connected devices have made software-defined radio (SDR) technology increasingly useful to interact with radio-based communication. While SDR-based tools have grown in popularity in recent years due to their flexibility and adaptability towards new protocols, SDR software interfaces remain highly complex and technical, and inherently require specialized skillsets in digital signal processing (DSP) to operate. To address this problem, we present Snout, an SDR middleware platform that encapsulates and abstracts much of the current complexity in SDR toolchains. This allows SDR developers to create wireless networking applications usable by a wide range of users. For instance, network security professionals can monitor the IoT landscape across multiple protocols without needing to interact with the underlying software-defined DSP. Snout implements interfaces with common network analysis tools to allow for integration with traditional network security solutions, facilitating use cases such as traffic analysis or rogue device detection. Its software architecture enables scalability in terms of protocols and processing by modularizing the signal processing pipeline. To demonstrate Snout’s capabilities, we show how it can encapsulate GNU Radio flowgraphs, facilitate simultaneous multi-protocol scanning, and convert existing SDR-based protocol implementations into fully contained applications. We further demonstrate how Snout can handle GNU Radio flowgraphs with other signal processing software simultaneously. Through extensive experiments, we demonstrate that Snout incurs limited CPU performance overhead below 4% and a memory footprint below 100MB, and handles large amounts of events with sub-millisecond latency.
Printed Antennas discusses the latest advances such as the Internet of Things for antenna applications, device-to-device communication, satellite communication, and wearable textile antenna in the field of communication. It further presents methods and techniques used for the enhancement of the performance parameters of the microstrip antenna and covers the design of conformal and miniaturized antenna structures for various applications. It will serve as an ideal reference text for senior undergraduates, graduate students, and researchers in fields including electrical engineering, electronics and communications engineering, and computer engineering.
This paper investigates the performance of three lightweight authenticated ciphers namely ACE, SPIX and WAGE in the WiFi and CoAP handshaking authentication protocols. We implement the WiFi and CoAP handshake protocols and the IEEE802.11a physical layer communication protocol in software defined radio (SDR) and embed these two handshaking protocols into the IEEE802.11a OFDM communication protocol to measure the performance of three ciphers. We present the construction of KDF and MIC used in the handshaking authentication protocols and provide optimized implementations of ACE, SPIX and WAGE including KDF and MIC on three different (low-power) microcontrollers. The performance results of these three ciphers when adopted in WiFi and CoAP protocols are presented. Our experimental results show that the cryptographic functionalities are the bottleneck in the handshaking and data protection protocols.KeywordsInternet of Things (IoT)Security and privacyLightweight cryptographyMicrocontroller implementationAuthentication protocolIEEE 802.11a OFDM transmissionSoftware defined radio
The need for wireless communication is growing at an unprecedented pace, making the wireless spectrum at a premium. To use the spectrum more efficiently, a promising solution was proposed to enable two concurrent users to transmit their signals in the same frequency at the same time, and then decode the superimposed signal. In current systems, the superimposed signal is decoded by successive interference cancellation (SIC) that requires strict power control upon each individual user. However, this requirement is infeasible for many IoT devices that are heterogeneous and often low cost. For other superimposed signal decoding technologies that require no power control, a reliable performance can be only achieved by introducing repetitive information in each transmission, which, in turn, reduces the spectrum efficiency. In this article, we introduce Chitchat, a new solution to decode the superimposed signal from two concurrent transmitters without any power control nor repetitive transmissions. Chitchat presents a rotation-code-based idea to provide both the diversity gain and the coding gain, so that it can achieve high reliability while preserving the spectrum efficiency. We implement Chitchat on a software-defined radio platform, and evaluate its performance in various scenarios.
New-generation wireless networks are designed to support a wide range of services with diverse key performance indicators (KPIs) requirements. A fundamental component of such networks, and a pivotal factor to the fulfillment of the target KPIs, is the virtual radio access network (vRAN), which allows high flexibility on the control of the radio link. However, to fully exploit the potentiality of vRANs, an efficient mapping of the rapidly varying context to radio control decisions is not only essential, but also challenging owing to the interdependence of user traffic demand, channel conditions, and resource allocation. Here, we propose CAREM, a reinforcement learning framework for dynamic radio resource allocation in heterogeneous vRANs, which selects the best available link and transmission parameters for packet transfer, so as to meet the KPI requirements. To show its effectiveness, we develop a testbed for proof-of-concept. Experimental results demonstrate that CAREM enables an efficient radio resource allocation under different settings and traffic demand. Also, compared to the closest existing scheme based on neural network and the standard LTE, CAREM exhibits an improvement of one order of magnitude in packet loss and latency, while it provides a 65% latency improvement relatively to the contextual bandit approach.
This paper presents and analyzes a test campaigns outcomes to assess the application-level performance of IEEE 802.11p at high speeds of up to 250 km/h. The main focus is on safety-related applications, but we also discuss performance figures resulting from additional tests performed to address other purposes that might use lower transmission powers. In particular, we investigate the impact that speed, transmission power, distance, and different degrees of congestion may have on application-level metrics such as TCP Goodput, UDP Goodput, RTT, Jitter, and Datagram/Packet Loss in real-world scenarios, and aim to find out which guarantees can be obtained in those environments with generic off-the-shelf equipment. Overall, the results indicate that IEEE 802.11p can satisfy safety-related requirements even as vehicles move with high velocity in heavily congested networks. For other kinds of applications, the performance might be compromised, especially under congestion, but figures attest that these networks may also serve additional purposes unanticipated when the standard was introduced.
Current wireless network simulators provide very detailed and deterministic models of the network protocol layers, whereas rather simple and stochastic models, based on the signal-to-noise ratio, are used for the simulation of the physical layer. Although this approach can be sufficient to study the behavior of different upper layer protocol variations, it prevents an easy alteration of the physical layer because a stochastic abstraction of the physical layer must be provided in advance. In particular, the simulation of distributed systems with physical layers that are designed to have several senders transmitting signals at the same time intentionally, is hardly possible with current approaches. A further problem of stochastic physical layer simulations is the fact that the radio channel's influence must also be carried out stochastically, which limits the advantage of accurate ray-optical channel models. We present a novel approach for the accurate simulation of the physical layer by utilizing existing software-defined radio implementations to create signals, to calculate interference and to decode signals. This technique enables us to simulate wireless networks holistically and, furthermore, we can fully exploit the possibilities of available ray-optical channel models.
Connected Vehicles is a currently hot topic, which can be said to have emerged under the inspiration of the Internet of Things. Motivated by a myriad of traffic safety, decongestion, and respectively, driver comfort applications, the subject is gaining more and more popularity among both researchers and industry. Our interests in the topic are focused on both the communication links and the precise localization of the vehicles. These topics are catalyzed by applications such as high precision collaborative vehicular positioning and autonomous driving. The robustness of the radio links in this context is hence at the backbone of vehicular ad-hoc networks, and respectively, of initial cooperative positioning estimates. The subsequent communication protocol is based on the IEEE 802.11p standard of the WAVE (Wireless Access in Vehicular Environments) technology. As part of the post-transmission channel modeling, we introduce in this paper a new channel estimator structure based on a low complexity adaption of Kohonen's Self-Organizing Map complemented by a filtered decision feedback layer. Furthermore, we study the key factors that would lead to a further performance optimization of our estimator while also comparing it to the state of the art solutions existing already in the literature.
We review commercially available software- defined radio platforms and classify them with respect to their ability to enable rapid prototyping of next-generation wireless systems. In particular, we first discuss the research challenges imposed by the latest software-defined radio enabling technologies including both analog and digital processing hardware. Then we present the state-of-the-art commercial software-defined radio platforms, describe their software and hardware capabilities, and classify them based on their ability to enable rapid prototyping and advance experimental research in wireless networking. Finally, we present three experimental testbed scenarios (wireless terrestrial, aerial, and underwater) and argue that the development of a system design abstraction could significantly improve the efficiency of the prototyping and testbed implementation process.
The flexible interface between the medium access layer and the custom physical layer of the Rice University Wireless Open-Access Research Platform (WARP) provides a high performance research tool for clean-slate cross layer designs. As we target a community platform, we have implemented various basic PHY and MAC technologies over WARP. Moreover, we are implementing cross-layer schemes such as rate adaptation and crosslayer MIMO MAC protocols. In this demo, we demonstrate the flexibility of the interaction between the the WARP PHY and MAC layers by showing the capability to instantaneously change the modulation scheme, disabling/enabling MAC features such as carrier sensing or RTS/CTS 4-way handshake, and different multi-rate schemes.
We present a solution for enabling standard compliant channel access for a fully software-based Software Defined Radio (SDR) architecture. With the availability of a GNU Radio implementation of an Orthogonal Frequency Division Multiplexing (OFDM) transceiver, there is substantial demand for standard compliant channel access. It has been shown that implementation of CSMA on a host PC is infeasible due to system-inherent delays. The common approach is to fully implement the protocol stack on the FPGA, which makes further updates or modifications to the protocols a complex and time consuming task. We take another approach and investigate the feasibility of a fully software-based solution and show that standard compliant broadcast transmissions are possible with marginal modifications of the FPGA. We envision the use of our system for example in the vehicular networking domain, where broadcast is the main communication paradigm. We show that our SDR solution exactly complies with the IEEE 802.11 Distributed Coordination Function (DCF) as well as Enhanced Distributed Channel Access (EDCA) timings. We were even able to identify shortcomings of commercial systems and prototypes.
Vehicular wireless channels are highly time-varying and the pilot pattern in
the 802.11p orthogonal frequency-division multiplexing frame has been shown to
be ill suited for long data packets. The high frame error rate in off-the-shelf
chipsets with noniterative receiver configurations is mostly due to the use of
outdated channel estimates for equalization. This paper deals with improving
the channel estimation in 802.11p systems using a cross layered approach, where
known data bits are inserted in the higher layers and a modified receiver makes
use of these bits as training data for improved channel estimation. We also
describe a noniterative receiver configuration for utilizing the additional
training bits and show through simulations that frame error rates close to the
case with perfect channel knowledge can be achieved.
The Cooperative Awareness Basic Service and Decentralized Environmental Notification Basic Service have been standardized by the European Telecommunications Standards Institute (ETSI) to support vehicular safety and traffic efficiency applications needing continuous status information about surrounding vehicles and asynchronous notification of events, respectively. These standard specifications detail not only the packet formats for both the Cooperative Awareness Message (CAM) and Decentralized Environmental Notification Message (DENM), but also the general message dissemination rules. These basic services, also known as facilities, have been developed as part of a set of standards in which both ISO and ETSI describe the Reference Communication Architecture for future Intelligent Transportation Systems (ITS). By using a communications stack that instantiates this reference architecture, this paper puts in practice the usage of both facilities in a real vehicular scenario. This research work details implementation decisions and evaluates the performance of CAM and DENM facilities through a experimental testbed deployed in a semi-urban environment that uses IEEE 802.11p (ETSI G5-compliant), which is a WiFi-like communication technology conceived for vehicular communications. On the one hand, this validation considers the development of two ITS applications using CAM and DENM functionalities for tracking vehicles and disseminating traffic incidences. In this case, CAM and DENM have demonstrated to be able to offer all the necessary functionality for the study case. On the other hand, both facilities have been also validated in a extensive testing campaign in order to analyze the influence in CAM and DENM performance of aspects such as vehicle speed, signal quality or message dissemination rules. In these tests, the line of sight, equipment installation point and hardware capabilities, have been found as key variables in the network performance, while the vehicle speed has implied a slight impact.
In September 2013, leading experts in Inter-Vehicle Communication (IVC) from all over the world met at the renowned Dagstuhl castle for a seminar discussing the question "Inter-Vehicular Communication – Quo Vadis?" The objective was to identify the current state of the art and, more importantly, the open challenges in R&D from both a scientific and an industry point of view. After more than a decade of research on vehicular networks, the experts very seriously asked the question whether additional research in this field is necessary and if so, which will be the most intriguing and innovative research directions. It turned out that the overall perspective changed in the last few years, mainly as a result of the ongoing Field Operational Tests (FOTs) in the U.S. and in Europe. In this article, we report the key outcomes and results from the discussions pointing to new research directions and new challenges that need to be met for a second generation of vehicular networking applications and protocols. In particular, we present the reports and findings from the four working groups on scientific foundations of vehicular networking, Field Operational Tests, IVC applications, and heterogeneous vehicular networks.
Over the past few years a range of new Media Access Control (MAC) protocols have been proposed for wire- less networks. This research has been driven by the observation that a single one-size-fits-all MAC protocol cannot meet the needs of diverse wireless deployments and applications. Unfortunately, most MAC functional- ity has traditionally been implemented on the wireless card for performance reasons, thus, limiting the opportu- nities for MAC customization. Software-defined radios (SDRs) promise unprecedented flexibility, but their ar- chitecture has proven to be a challenge for MAC proto- cols. In this paper, we identify a minimum set of core MAC functions that must be implemented close to the radio in a high-latency SDR architecture to enable high per- formance and efficient MAC implementations. These functions include: precise scheduling in time, carrier sense, backoff, dependent packets, packet recognition, fine-grained radio control, and access to physical layer information. While we focus on an architecture where the bus latency exceeds common MAC interaction times (tens to hundreds of microseconds), other SDR architec- tures with lower latencies can also benefit from imple- menting a subset of these functions closer to the radio. We also define an API applicable to all SDR architectures that allows the host to control these functions, providing the necessary flexibility to implement a diverse range of MAC protocols. We show the effectiveness of our split- functionality approach through an implementation on the GNU Radio and USRP platforms. Our evaluation based on microbenchmarks and end-to-end network measure- ments, shows that our design can simultaneously achieve high flexibility and high performance.
A thorough understanding of the communications channel between vehicles is essential for realistic modeling of Vehicular Ad Hoc Networks (VANETs) and the development of related technology and applications. The impact of vehicles as obstacles on vehicle-to-vehicle (V2V) communication has been largely neglected in VANET research, especially in simulations. Useful models accounting for vehicles as obstacles must satisfy a number of requirements, most notably accurate positioning, realistic mobility patterns, realistic propagation characteristics, and manageable complexity. We present a model that satisfies all of these requirements. Vehicles are modeled as physical obstacles affecting the V2V communication. The proposed model accounts for vehicles as three-dimensional obstacles and takes into account their impact on the LOS obstruction, received signal power, and the packet reception rate. We utilize two real world highway datasets collected via stereoscopic aerial photography to test our proposed model, and we confirm the importance of modeling the effects of obstructing vehicles through experimental measurements. Our results show considerable obstruction of LOS due to vehicles. By obstructing the LOS, vehicles induce significant attenuation and packet loss. The algorithm behind the proposed model allows for computationally efficient implementation in VANET simulators. It is also shown that by modeling the vehicles as obstacles, significant realism can be added to existing simulators with clear implications on the design of upper layer protocols.
This paper presents Sora, a fully programmable soft- ware radio platform on commodity PC architectures. Sora combines the performance and fidelity of hardware SDR platforms with the programmability and flexibil- ity of general-purpose processor (GPP) SDR platforms. Sora uses both hardware and software techniques to ad- dress the challenges of using PC architectures for high- speed SDR. The Sora hardware components consist of a radio front-end for reception and transmission, and a radio control board for high-throughput, low-latency data transfer between radio and host memories. Sora makes extensive use of features of contemporary proces- sor architectures to accelerate wireless protocol process- ing and satisfy protocol timing requirements, including using dedicated CPU cores, large low-latency caches to store lookup tables, and SIMD processor extensions for highly efficient physical layer processing on GPPs. Us- ing the Sora platform, we have developed a demonstra- tion radio system called SoftWiFi. SoftWiFi seamlessly interoperates with commercial 802.11a/b/g NICs, and achieves equivalent performance as commercial NICs at each modulation.
The flexible interface between the medium access layer and the custom physical layer of the Rice University Wireless Open-Access Research Platform (WARP) provides a high performance research tool for clean-slate cross layer designs. As we target a community platform, we have implemented various basic PHY and MAC technologies over WARP. Moreover, we are implementing cross-layer schemes such as rate adaptation and crosslayer MIMO MAC protocols. In this demo, we demonstrate the flexibility of the interaction between the the WARP PHY and MAC layers by showing the capability to instantaneously change the modulation scheme, disabling/enabling MAC features such as carrier sensing or RTS/CTS 4-way handshake, and different multi-rate schemes.
We present an approach for using signal traces from Field Operational Tests (FOTs) for later evaluations and comparative studies of receive algorithms for the IEEE 802.11p PHY. In particular, we use Software Defined Radios (SDRs) to record the raw signal, i.e., complex baseband samples, from IEEE 802.11p transmissions during an experiment on the road. These samples are later used with our GNU Radio-based IEEE 802.11p implementation for studying different receive algorithms -- allowing for optimal comparability and repeatability. We exemplarily evaluate four typical algorithms ranging from simple ones currently used in commodity WLAN chips to more sophisticated ones proposed specifically for vehicular applications. We can show that fast fading scenarios lead to a significant packet error rate when using the standard algorithms. For better comparability, we make both our GNU Radio implementation as well as the collected traces publicly available.
Software Defined Radio (SDR) is an approach where signal processing components of a radio transceiver are moved from the dedicated hardware to a combination of software and general purpose processors. This change offers many advantages, mainly for experimentation and prototyping as it allows to modify low-level functions without any change in hardware, but may also permit to contribute to solve future Internet challenges such as the ever necessary equipment upgrades caused by the rapidly growing demands of users. Recently, an implementation of a SDR IEEE 802.11 transceiver has been presented. Although this tool shows a clever realization, it presents some performance issues, bounding the obtained data rates. In this work we propose a set of software improvements to accelerate the implementation with the aim of improving achieved the data transfer rates. The experimental evaluation conducted reveals, depending on the Modulation and Coding Scheme (MCS) used, that our proposal obtains improvement factors between 2× and 10×.
The current advances in the Intelligent Transportation Systems (ITS) reveal new solutions which are in need of validation in real-world deployments. The practicality, implementability, latency and robustness of such methods are key insights into their wide acceptance, and finally, absorption by standardization organizations. This paper discusses an approach to rapidly prototype newly proposed Wireless Access in Vehicular Environments (WAVE) algorithms based on the open source community and the emergence of Software Defined Radio (SDR). Concretely, this work details the practical deployment of a new adaptive channel estimation method in the context of IEEE 802.11p based vehicular communications. The development steps are illustrated and some challenges involved by real-world deployment (e.g. the phase tracking problem) are treated. Consequently, practical methods to solve the observed impairments are derived and implemented for real-time operation and validation.
Many theories and empirical research show the critical role of social relationships in shaping human behavior. Mobile and persuasive technologies present increased opportunities for affecting people's behavior. We propose the relational intervention model, which provokes a paired helper when the user performs a target behavior. In this demo, we present BeUpright, a posture-correction mobile application based on the relational intervention model.
GNU Radio is an ecosystem for software radio development. It is composed of both the free and open source software and a community of professionals, experts, scientists, hobbyists, and enthusiasts that works on projects from research, prototyping, new models of communications and services, and science experiments. GNU Radio has a thriving community of members and contributors that is constantly pushing the project forward. Such a diverse and thriving user community has helped build GNU Radio into a large project with many tools and capabilities. In this chapter, we explore some of the areas where people are developing increasingly powerful signal systems and exploring new territory. To help understand how we can do so many things in this project, we review the overall architecture of the GNU Radio project as a framework for building software radio solutions. We explain the design principles and methods for moving and processing data within GNU Radio flowgraphs and blocks, and we provide a bit of an exploration into the performance concepts and tradeoffs that the project deals with. Finally, we go over a scenario of using GNU Radio in a dynamic spectrum access scenario to show off some of the powerful tools and concepts within this field of interest.
Vehicular networks provide the basis for a wide range of both safety and non-safety applications. One of the key challenges for wide acceptance is to which degree the drivers' privacy can be protected. The main technical privacy protection mechanism is the use of changing identifiers (from MAC to application layer), so called pseudonyms. The effectiveness of this approach, however, is clearly reduced if specific characteristics of the physical layer (e.g., in the transmitted signal) reveal the link between two messages with different pseudonyms. In this paper, we present such a fingerprinting technique: the scrambler attack. In contrast to other physical layer fingerprinting methods, it does not rely on potentially fragile features of the channel or the hardware, but exploits the transmitted scrambler state that each receiver has to derive in order to decode a packet, making this attack extremely robust. We show how the scrambler attack bypasses the privacy protection mechanism of state-of-the-art approaches and quantify the degradation of drivers' location privacy with an extensive simulation study. Based on our results, we identify additional technological requirements in order to enable privacy protection mechanisms on a large scale.
Inter-vehicle communication promises to prevent accidents by enabling applications such as cross-traffic assistance. This application requires information from vehicles in Non-Line-of-Sight (NLOS) areas due to building at intersection corners. The periodic Cooperative Awareness Messages (CAM) are foreseen to be sent via 5.9 GHz IEEE 802.11p. While it is known that existing micro-cell models might not apply well, validated propagation models for vehicular 5.9 GHz NLOS conditions are still missing. In this paper, we develop a 5.9 GHz NLOS path-loss and fading model based on real-world measurements at a representative selection of intersections in the city of Munich. We show that a) the measurement data can very well be fitted to an analytical model, b) the model incorporates specific geometric aspects in closed-form as well as normally distributed fading in NLOS, and c) the model is of low complexity, thus, could be used in large-scale packet-level simulations. A comparison to existing micro-cell models shows that our model significantly differs.
The exploration is built upon Delphi’s, Nissan’s, Cohda Wireless’ and Savari’s experiences in Asia, Europe and U.S.A. It describes and derives lessons from all four companies’ contributions in projects such as SMARTWAY in Japan, Drive C2X and in Europe, as well as the Connected Vehicle Safety Pilot in the U.S.A. All the above programs were implemented by means of the Dedicated Short Range Communication (DSRC) technology in the SHF spectrum based on the IEEE 802.11p/Wireless Access in Vehicular Environments (WAVE) standard. The study is supplemented with insights regarding complementary technologies such DSRC in the lower UHF frequency band (i.e. 700 MHz) as well as a V2X implementation through the 4G LTE (Long Term Evolution) cellular telecommunication technology. This paper addresses issues regarding the physical layer (PHY) of the DSRC system. The combination of the delay profile caused by multipath propagation along with the motion-based Doppler spread leads to time and frequency dispersion. This limits the number of bytes acceptable for reliable communication or requires a solution at the receiver end. The analysis of the Doppler spread shows that DSRC implemented at 700 MHz is more immune from data packet length issues as opposed to 5 GHz DSRC. On the other hand, 700 MHz DSRC exhibits a much longer delay spread. Thus, guard time interval specified in ASTM E2213-03 cannot be applied as is to 700 MHz DSRC. This paper refers to the German project CoCarX and the Japanese SKY for pedestrian for studying the feasibility a V2X system built on the 4G/LTE technology and its infrastructure. It provides on a vision for an accelerated V2X deployment based on a heterogeneous system. Last, we recommend the ITS stakeholders to carry out extensive research and validation works on DSRC capacity for ensuring a large scale deployment.
Software Defined Radios (SDRs) have become a fundamental building block for research on wireless networks. Yet, using this platform for experiments in the field is hindered by many practical difficulties, an important one being the need for Automatic Gain Control (AGC). We demonstrate a way of implementing an AGC algorithm directly in the FPGA where we are able to meet tough timing constraints. This allows using SDRs not just for lab experiments but also for measurement campaigns or deployments in the field. With extending our GNU Radio-based Open Source stack for IEEE802.11a/g/p WLAN with AGC, we provide an SDR platform that can be integrated into existing WiFi networks just as well as into future vehicular networks.
In the domain of Inter-Vehicle Communication (IVC), even though first field operational tests are already going on, performance evaluation is still dominated by simulation experiments. Yet, they require a very specific methodology as well as adapted tools and models not straightforwardly found in other domains. In this chapter, we first describe the required methodology in terms of scalability and applicability to select the right models and their interactions. In particular, we classify each class of models as in increasing level of granularity, and discuss in details the trade-off between scalability and applicability typical to IVC simulations. We then introduce some of the most widely used and openly available simulation frameworks applicable to the domain of IVC, and emphasize their capabilities related to the required methodology. In particular, we present the IVC simulation toolkits Veins, iTETRIS, and VSimRTI, three prominent simulation platforms openly available for IVC simulations. To provide guidelines for efficient and scalable simulations of IVC applications, we discuss the appropriate selection of models and their level of granularity as function of the IVC application requirements, and provide an overview of their corresponding support in each of toolkit.
With this essential guide to vehicular networking, you will learn about everything from conceptual approaches and state-of-the-art protocols, to system designs and their evaluation. Covering both in- and inter-vehicle communication, this comprehensive work outlines the foundations of vehicular networking as well as demonstrating its commercial applications, from improved vehicle performance, to entertainment, and traffic information systems. All of this is supported by in-depth case studies and detailed information on proposed protocols and solutions for access technologies and information dissemination, as well as topics on rulemaking, regulations, and standardization. Importantly, for a field which is attracting increasing commercial interest, you will learn about the future trends of this technology, its problems, and solutions to overcome them. Whether you are a student, a communications professional or a researcher, this is an invaluable resource.
In the last few years, software defined radio has become a widespread tool for research and development in the wireless arena. One of the drivers of this success is GnuRadio, an open source collection of signal processing routines, together with the inception of commercially available software radio front-ends to complete the signal chain. A number of wireless protocols have been developed on top of Gnu- Radio, including the ubiquitous 802.11 standard. In this article, we focus on the use and performance evaluation of the 802.11 BBN software-based transmitter and receiver implementation, highlighting its capabilities and limitations. In order to achieve this, we analyze the BER and packet error rate measurements on a reference scenario.
We present the first steps towards an Open Source simulation and experimentation framework for IEEE 802.11p networks. The framework is implemented based on GNURadio, a real-time signal processing framework for use in Software Defined Radio (SDR) systems. The core of the framework is a modular Orthogonal Frequency Division Multiplexing (OFDM) transceiver, which has been thoroughly evaluated: First, we show that its computational demands are so low that it can be run on low-end desktop PCs or laptops and thus, the transceiver is also feasible to use in field operational tests. Secondly, we present simulation results to highlight the transceiver's capability to study and debug PHY and MAC variants in a reproducible manner. We show that the simulations match very well to a widely accepted error model for IEEE 802.11p networks. Finally, we discuss results from an extensive set of measurements that compare our SDR-based transceiver with commercial grade IEEE 802.11p cards. We made the framework available as Open Source to make the system accessible for other researchers and to allow reproduction of the results. This might also pave the way for future proofing cars by means of fully reconfigurable radios.
Experimental research on wireless communication protocols frequently requires full access to all protocol layers, down to and including the physical layer. Software Defined Radio (SDR) hardware platforms, together with real-time signal processing frameworks, offer a basis to implement transceivers that can allow such experimentation and sophisticated measurements. We present a complete Orthogonal Frequency Division Multiplexing (OFDM) receiver implemented in GNU Radio and fitted for operation with an Ettus USRP N210. To the best of our knowledge, this is the first prototype of a GNU Radio based OFDM receiver for this technology. Our receiver comprises all layers up to parsing the MAC header and extracting the payload of IEEE 802.11a/g/p networks. It supports both WiFi with a bandwidth of 20 MHz and IEEE 802.11p DSRC with a bandwidth of 10 MHz. We validated and verified our implementation by means of interoperability tests, and present representative performance measurements. By making the code available as Open Source we provide an easy-to-access system that can be readily used for experimenting with novel signal processing algorithms.
Due to differences in the operating system and the effects of sample rate on the computational load of a software radio, we have historically had a difficult time understanding the performance boundaries of software radio applications. This problem further leads to difficulties in debugging, optimization, and profiling analysis of both software radio frameworks and applications.
This paper introduces a new tool developed for GNU Radio that starts to solve these problems. Called Performance Counters, GNU Radio now has an inbuilt ability to measure its performance for offline optimization as well as real-time behavioral analysis and adaptation. The Performance Counters are designed such that a GNU Radio application can directly sample them or access them through the use of ControlPort, another new tool that enables remote interaction with GNU Radio. We show in this paper some of the tools we have developed around ControlPort and the Performance Counters that will help us better understand GNU Radio's performance and capabilities as well as lead to better on-line adaptation of radios.
The 802.11p/WAVE standard relies on the presence of onboard units (OBUs) and roadside units (RSUs) for communications in vehicular networks. In this paper, we study the benefits of deploying RSUs to improve communications in highway scenarios. We develop an analytical model to analyze communication delay in a highway scenario with bidirectional traffic, considering both connected and disconnected RSUs, and validate our model via simulations and experimental measurements with 802.11p equipment. Contrary to conventional wisdom, our results show that significant benefits of RSUs in terms of connectivity and message dissemination can only be achieved when the deployed RSUs are interconnected. Conversely, deploying a large number of disconnected RSUs will lead to little or no benefit in message dissemination delay.
The IEEE 802.11 working group proposed a standard for the physical and medium access control layers of vehicular networks called 802.11p. In this paper we report experimental results obtained from communication between vehicles using 802.11p in a real scenario. The main motivation is the lack of studies in the literature with performance data obtained from off-the-shelf 801.11p devices. Our study characterizes the typical conditions of an 802.11p point-to-point communication. Such a study serves as a reference for more refined simulation models or to motivate enhancements in the PHY/MAC layers. Field tests were carried out varying the vehicle's speed between 20 and 60 km/h and the packet length between 150 and 1460 bytes, in order to characterize the range, throughput, latency, jitter and packet delivery rates of 802.11p links. It was observed that communication with vehicles in motion is unstable sometimes. However, it was possible to transfer data at distances over 300 m, with data rates sometimes exceeding 8 Mbit/s.
In this paper, we present the concepts and methods developed for the autonomous vehicle known as AnnieWAY, which is our winning entry to the 2011 Grand Cooperative Driving Challenge. We describe algorithms for sensor fusion, vehicle-to-vehicle communication, and cooperative control. Furthermore, we analyze the performance of the proposed methods and compare them with those of competing teams. We close with our results from the competition and lessons learned.
We discuss the applicability of simplified Two-Ray Ground path loss models to simulation-based performance evaluation studies of Inter-Vehicle Communication (IVC) protocols. We contrast this with the applicability of a more exact Two-Ray Interference model. A key result is that, in most cases, the commonly used simplified Two-Ray Ground models add no additional value compared to the most simple Free-space model – in particular in highway and suburban environments. We further argue that replacing a simplified with a fully featured Two-Ray Interference model can not only substantially improve the accuracy of simulation results but also allow capturing one notable artifact that becomes immediately visible in field tests, namely strong signal attenuation at short and medium ranges. We implemented the Two-ray Interference model within the Veins simulation framework and validated it using analytical predictions and field measurements. We show the impact of the more accurate Two-Ray Interference model, which only comes with negligible additional computational cost for simulation experiments.
A reliable robust wireless network of connected vehicles is desired to enable a number of future telematics and infotainment applications in the vehicular domain. To achieve this objective, vehicle-to-vehicle (V2V) communication is standardized by the IEEE 802.11p Dedicated Short Range Communications (DSRC) standard. Providing reliable communication performance in a highly dynamic time-varying V2V channel is a challenging task. To tackle this challenge, we propose a dynamic equalization scheme, on top of the existing DSRC technology, that significantly improves the packet error rate (PER) of data transmissions without changing the DSRC standard. We also show a hardware implementation of this scheme based on a field-programmable gate array (FPGA) to demonstrate its implementation feasibility. Furthermore, we extend our improved equalization scheme to various data rate options available in the DSRC standard, showing that the proposed scheme is sufficiently generic to support different types of V2V communication. Finally, we report the results of investigating the dependence of wireless communication performance (in terms of PER and throughput) on various design parameters such as packet length, payload size, and data rate.
Vehicle-to-vehicle and vehicle-to-roadside communications is required for numerous applications that aim at improving traffic safety and efficiency. In this setting, however, gauging system performance through field trials can be very expensive especially when the number of studied vehicles is high. Therefore, many existing studies have been conducted using either network or physical layer simulators; both approaches are problematic. Network simulators typically abstract physical layer details (coding, modulation, radio channels, receiver algorithms, etc.) while physical layer ones do not consider overall network characteristics (topology, network traffic types, and so on). In particular, network simulators view a transmitted frame as an indivisible unit, which leads to several limitations. First, the impact of the vehicular radio channel is typically not reflected in its appropriate context. Further, interference due to frame collisions is not modeled accurately (if at all) and, finally, the benefits of advanced signal processing techniques, such as interference cancellation, are difficult to assess. To overcome these shortcomings we have integrated a detailed physical layer simulator into the popular NS-3 network simulator. This approach aims to bridge the gap between the physical and network layer perspectives, allow for more accurate channel and physical layer models, and enable studies on cross-layer optimization. In this paper, we exemplify our approach by integrating an IEEE 802.11a and p physical layer simulator with NS-3. Further, we validate the augmented NS-3 simulator against an actual IEEE 802.11 wireless testbed and illustrate the additional value of this integration.
To make transportation safer, more efficient, and less harmful to the environment, traffic telematics services are currently being intensely investigated and developed. Such services require dependable wireless vehicle-to-infrastructure and vehicle-to-vehicle communications providing robust connectivity at moderate data rates. The development of such dependable vehicular communication systems and standards requires accurate models of the propagation channel in all relevant environments and scenarios. Key characteristics of vehicular channels are shadowing by other vehicles, high Doppler shifts, and inherent nonstationarity. All have major impact on the data packet transmission reliability and latency. This paper provides an overview of the existing vehicular channel measurements in a variety of important environments, and the observed channel characteristics (such as delay spreads and Doppler spreads) therein. We briefly discuss the available vehicular channel models and their respective merits and deficiencies. Finally, we discuss the implications for wireless system design with a strong focus on IEEE 802.11p. On the road towards a dependable vehicular network, room for improvements in coverage, reliability, scalability, and delay are highlighted, calling for evolutionary improvements in the IEEE 802.11p standard. Multiple antennas at the onboard units and roadside units are recommended to exploit spatial diversity for increased diversity and reliability. Evolutionary improvements in the physical (PHY) and medium access control (MAC) layers are required to yield dependable systems. Extensive references are provided.
The Car2Car communication will use a reserved frequency band at 5.9 GHz. One of the key requirements for a Car2Car antenna is that the gain is concentrated in the horizontal plane, which is a problem due to the limited ground plane of a car roof. The influence of roof curvature, roof racks and panorama glass roofs were investigated to quantify them. To the authors knowledge such measurements have not been published yet. Three different antennas were simulated and measured on round ground planes and real car roofs in different configurations. The configuration with a panorama glass roof showed an unexpected high loss of gain in the direction of the glass roof in the range of 15 to 20 dB which result in a drastically reduced communication range to the front direction. This phenomenon is still under investigation.
As a modification to IEEE 802.11a, the current DSRC standard copes adequately with many of the impairments found in the vehicular wireless channel. However, measurements have shown that these mobile channels exhibit substantially shorter coherence times than those encountered in the indoor environments expected by 802.11a. We propose a modification to the coherent OFDM structure of DSRC, known as time-domain differential OFDM, that preserves the benefits of OFDM while adding robustness to short coherence times. Simulations verify the efficacy of this method over various Doppler spreads and packet lengths.
OFDM PHY has been selected as North American DSRC standard (IEEE 802.11p). In this paper, we present a robust inner receiver suitable for DSRC communications, whose core is composed by a synchronizer, a one-tap frequency domain equalizer (FDE) and a pilot-based phase estimator. The equalizer uses least-mean-square (LMS) algorithm to track not only the variation of the DSRC channel in 5.9GHz band but also the residual frequency/phase errors that are not yet being corrected by the synchronizer device. In order to keep the LMS equalizer working well, we utilize a pilot-based phase estimator to help estimate the variation and the errors. The simulation results indicate that our proposed inner receiver works fairly well for two DSRC channel models.
In the IEEE 802.11a wireless local area network (WLAN) orthogonal frequency division multiplexing (OFDM) systems, signal detection is to detect the arrival of the OFDM packets. Due to the burst transmission characteristics, a simple and robust signal detection algorithm is required for practical hardware implementation. We designed and compared three signal detection algorithms, which were performed based on the short training sequences transmitted in front of each OFDM packet, for IEEE 802.11a systems. A series of Monte-Carlo simulations were conducted to evaluate the performance of these three signal detection algorithms.
The IEEE 802.11 OFDM physical layer was designed primarily for indoor local area networks. Commercially available 802.11 radios suffer greatly reduced performance, even failing completely, when deployed outdoors, where long delay spreads cause self-interference, and vehicular mobility causes fast variations in the radio channel parameters. This article describes an advanced OFDM receiver that overcomes these problems. It works by combining all useful received energy, accounting for inter-symbol interference, and accurately tracking radio channel variations. Complexity and performance advantages arc gained by splitting the processing between the time and frequency domains. Computer simulations show that even for outdoor urban environments at speeds greater than 140 mph, this receiver delivers performance comparable to a non-mobile, indoor system.
A rapid synchronization method is presented for an orthogonal
frequency-division multiplexing (OFDM) system using either a continuous
transmission or a burst operation over a frequency-selective channel.
The presence of a signal can be detected upon the receipt of just one
training sequence of two symbols. The start of the frame and the
beginning of the symbol can be found, and carrier frequency offsets of
many subchannels spacings can be corrected. The algorithms operate near
the Cramer-Rao lower bound for the variance of the frequency offset
estimate, and the inherent averaging over many subcarriers allows
acquisition at very low signal-to-noise ratios (SNRs)
Inspecting GNU radio applications with ControlPort and performance counters
- T W Rondeau
- T Shea
- N Goergen
The scrambler attack: A robust physical layer attack on location privacy in vehicular networks
- B Bloessl
- C Sommer
- F Dressler
- D Eckhoff
SIMD programming in GNU Radio: Maintainable und user-friendly algorithm optimization with VOLK
- T W Rondeau
- N Mccarthy
- T Shea
Validation of OFDM error rate model in ns-3
- pei
Impact of vehicles as obstacles in vehicular networks
- M Boban
- T Vinhosa
- J Barros
- M Ferreira
- O K Tonguz
SIMD programming in GNU Radio: Maintainable und user-friendly algorithm optimization with VOLK
- rondeau