Tool release: gathering 802.11n traces with channel state information
22 Jan 2011-Vol. 41, Iss: 1, pp 53-53
TL;DR: The measurement setup comprises the customized versions of Intel's close-source firmware and open-source iwlwifi wireless driver, userspace tools to enable these measurements, access point functionality for controlling both ends of the link, and Matlab scripts for data analysis.
Abstract: We are pleased to announce the release of a tool that records detailed measurements of the wireless channel along with received 802.11 packet traces. It runs on a commodity 802.11n NIC, and records Channel State Information (CSI) based on the 802.11 standard. Unlike Receive Signal Strength Indicator (RSSI) values, which merely capture the total power received at the listener, the CSI contains information about the channel between sender and receiver at the level of individual data subcarriers, for each pair of transmit and receive antennas.Our toolkit uses the Intel WiFi Link 5300 wireless NIC with 3 antennas. It works on up-to-date Linux operating systems: in our testbed we use Ubuntu 10.04 LTS with the 2.6.36 kernel. The measurement setup comprises our customized versions of Intel's close-source firmware and open-source iwlwifi wireless driver, userspace tools to enable these measurements, access point functionality for controlling both ends of the link, and Matlab (or Octave) scripts for data analysis. We are releasing the binary of the modified firmware, and the source code to all the other components.
Citations
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01 Sep 2016
TL;DR: CWISE is presented, an accurate WiFi-Inertial SLAM system without the requirement for Access Points' positions, specialized infrastructure and fingerprinting, which relies only on a commercial wireless card with two antennas and an IMU.
Abstract: WiFi-based localization has received increasing attentions these years as WiFi devices are low-cost and universal. Recent years, tens of WiFi-based localization systems have been proposed which could achieve decimeter-level accuracy with the commercial wireless cards and with no specialized infrastructure. However, such systems require the positions of the Access Points or fingerprint map to be known in advance. In this paper, we present CWISE, an accurate WiFi-Inertial SLAM system without the requirement for Access Points' positions, specialized infrastructure and fingerprinting. CWISE relies only on a commercial wireless card with two antennas and an IMU. We test the CWISE system on a flying quadrotor and it shows that the system is able to work in real time and achieves the mean accuracy of 1.60m.
19 citations
Cites background or methods from "Tool release: gathering 802.11n tra..."
...11n CSI tool [19] to collect the CSI information for any successfully received packets with a specialized destination MAC address....
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...AoA based approaches: After CSI-tools using Intel 5300 [19] and Atheros ar9300 [20] wireless card being released, AoA estimation has become available with commercial wireless card and AoA based WiFi localization has become a popular research area for indoor localization....
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...It is well-known that the performance of wireless networks depends heavily on the physical layer details of the RF channel [19]....
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05 Nov 2018
TL;DR: CardioFi is proposed: a system that can accurately monitor vital signs through COTS WiFi hardware with omnidirectional antennas and it is shown that CardioFi estimates heart rate with 1.1 beats per minute (bpm) median error, which compares favorably with systems equipped with directional antennas.
Abstract: Heart rate is one of the most important vital signals for personal health tracking. A number of approaches were proposed to monitor heart rate, ranging from wearables to device-less systems. While WiFi has been shown to track heart rate accurately, existing solutions rely on directional antennas to improve the signal quality and ultimately the accuracy of heart rate estimation. Special hardware used in these approaches limits their applicability and truly device-less and ubiquitous heart rate monitoring is yet to be achieved.In this paper, we propose CardioFi: a system that can accurately monitor vital signs through COTS WiFi hardware with omnidirectional antennas. Our key challenge is the substantial radio frequency noise that affects WiFi transmissions in real-world environments. However, we observe that a few sub-carriers are typically less affected by multipath and the heart beating motion can be accurately detected in their frequency spectrum. We present a novel sub-carrier selection scheme that allows us to detect and amplify signal from these sub-carriers even in low signal-to-noise ratio scenarios. We show that CardioFi estimates heart rate with 1.1 beats per minute (bpm) median error, which compares favorably with systems equipped with directional antennas. Furthermore, we show that state-of-art heart rate estimation algorithms do not perform well in low SNR scenarios and CardioFi improves their 50- and 90-th percentile error by 40% and 176%, respectively.
19 citations
29 Mar 2019
TL;DR: This paper proposes an extended MUSIC algorithm to improve accuracy with limited localization information in OFDMA backscatter mechanism, and implements a prototype under the 802.11g framework in WARP.
Abstract: OFDMA Wi-Fi backscatter can significantly improve the communication efficiency and meanwhile maintain ultra-low power consumption; however, the ground-up reworking on the core mechanism of traditional Wi-Fi system revolutionizes the basis of many existing Wi-Fi based mechanisms. In this paper, we explore how localization can be realized based on OFDMA backscatter, where a batch localization mechanism utilizing concurrent communication in the OFDMA backscatter system is proposed. We present a series of mechanisms to deal with the fundamental change of assumptions brought by the new paradigm. First, we process signals at the receiver in a finer granularity for signal classification. Then we remove phase offsets in real time without interrupting the communication. Finally, we propose an extended MUSIC algorithm to improve accuracy with limited localization information in OFDMA backscatter mechanism. We implement a prototype under the 802.11g framework in WARP, based on which we conduct comprehensive experiments to evaluate our propose mechanism. Results show that our system can localize 48 tags simultaneously, while achieving average localization errors within 0.49m. The tag's power consumption is about 55-81.3μW.
18 citations
Cites methods from "Tool release: gathering 802.11n tra..."
...Applying existing Wi-Fi localization mechanisms to OFDMA Wi-Fi backscatter platform is confrontedwith the following challenges: First, existingWi-Fi localization techniques [19, 29] based on Intel 5300 tool kit [14] leverage channel state information (CSI) from the single transmitter; however, CSI observed by the receiver as shown in Fig....
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...Existing localization techniques [19–21, 29] localize the target based on CSI collected by Intel 5300 tool kit [14] which derives 30 CSI measurements for 64 subcarriers from each packet....
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...Since Intel 5300 tool kit derives packet-level CSI based on the preamble [13, 14] that exactly comes from the transmitter instead of tags, packet-level CSI cannot be utilized to localize tags....
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...With fine-grained CSI available [14], recent researches explore the method of device-free localization and even achieve a better performance than device-based localization [22, 23, 25, 26, 30]....
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TL;DR: In this article, an autonomous self-calibrating method was proposed to facilitate site survey for deploying CSI-based Wi-Fi localization systems, which achieved promising localization accuracy even without labor-intensive site survey.
Abstract: Channel state information (CSI) based Wi-Fi localization can achieve admirable decimeter-level accuracy; however, such systems require labor-intensive site survey to calibrate the AP position and the antenna array direction, which hinders practical large-scale deployment. In this article, we reveal an interesting finding that the calibration efforts for deploying the CSI localization system can be significantly reduced by simply replacing the ordinary linear antenna layout of the AP with the non-linear layout. In particular, we first present an autonomous self-calibrating method to significantly facilitate site survey for deploying CSI localization systems. Then we propose a systematical evaluation mechanism to show the fundamental reason why linear antenna layout usually leads to serious errors and why non-linear antenna layout is better off. Finally, we build a testbed with COTS devices and conduct comprehensive experiments. Results show that triangular antenna layout can achieve 80% angle of arrival (AoA) measurement error within 9° for any direction in contrast to 16° based on linear antenna layout. Moreover, we can realize promising localization accuracy as previous works even without labor-intensive site survey, where 80% localization error is within $0.60m$ .
18 citations
Dissertation•
07 Dec 2017TL;DR: It is shown that this mitigation, in its current state, is insufficient to prevent tracking, and presents two tools: an experimental Wi-Fi tracking system for testing and public awareness raising purpose, and a tool estimating the uniqueness of a device based on the content of its emitted signals even if the identifier is randomized.
Abstract: The recent spread of everyday-carried Wi-Fi-enabled devices (smartphones, tablets and wearable devices) comes with a privacy threat to their owner, and to society as a whole. These devices continuously emit signals which can be captured by a passive attacker using cheap hardware and basic knowledge. These signals contain a unique identifier, called the MAC address. To mitigate the threat, device vendors are currently deploying a countermeasure on new devices: MAC address randomization. Unfortunately, we show that this mitigation, in its current state, is insufficient to prevent tracking. To do so, we introduce several attacks, based on the content and the timing of emitted signals. In complement, we study implementations of MAC address randomization in some recent devices, and find a number of shortcomings limiting the efficiency of these implementations at preventing device tracking. At the same time, we perform two real-world studies. The first one considers the development of actors exploiting this issue to install Wi-Fi tracking systems. We list some real-world installations and discuss their various aspects, including regulation, privacy implications, consent and public acceptance. The second one deals with the spread of MAC address randomization in the devices population. Finally, we present two tools: an experimental Wi-Fi tracking system for testing and public awareness raising purpose, and a tool estimating the uniqueness of a device based on the content of its emitted signals even if the identifier is randomized.
18 citations
Additional excerpts
...makes it possible to access it using an o -the-shelf network card [84]....
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References
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30 Aug 2010
TL;DR: It is shown that, for the first time, wireless packet delivery can be accurately predicted for commodity 802.11 NICs from only the channel measurements that they provide, and the rate prediction is as good as the best rate adaptation algorithms for 802.
Abstract: RSSI is known to be a fickle indicator of whether a wireless link will work, for many reasons. This greatly complicates operation because it requires testing and adaptation to find the best rate, transmit power or other parameter that is tuned to boost performance. We show that, for the first time, wireless packet delivery can be accurately predicted for commodity 802.11 NICs from only the channel measurements that they provide. Our model uses 802.11n Channel State Information measurements as input to an OFDM receiver model we develop by using the concept of effective SNR. It is simple, easy to deploy, broadly useful, and accurate. It makes packet delivery predictions for 802.11a/g SISO rates and 802.11n MIMO rates, plus choices of transmit power and antennas. We report testbed experiments that show narrow transition regions (
697 citations
"Tool release: gathering 802.11n tra..." refers methods in this paper
...It works on up-to-date Linux operating systems: in our testbed we use Ubuntu 10.04 LTS with the 2.6.36 kernel....
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01 Oct 2001
TL;DR: The Internet is going mobile and wireless, perhaps quite soon, with a number of diverse technologies leading the charge, including, 3G cellular networks based on CDMA technology, a wide variety of what is deemed 2.5G cellular technologies (e.g., EDGE, GPRS and HDR), and IEEE 802.11 wireless local area networks (WLANs).
Abstract: At some point in the future, how far out we do not exactly know, wireless access to the Internet will outstrip all other forms of access bringing the freedom of mobility to the way we access the we...
615 citations
07 Jan 2010
TL;DR: This tutorial provides a brief introduction to multiple antenna techniques, and describes the two main classes of those techniques, spatial diversity and spatial multiplexing.
Abstract: The use of multiple antennas and MIMO techniques based on them is the key feature of 802.11n equipment that sets it apart from earlier 802.11a/g equipment. It is responsible for superior performance, reliability and range. In this tutorial, we provide a brief introduction to multiple antenna techniques. We describe the two main classes of those techniques, spatial diversity and spatial multiplexing. To ground our discussion, we explain how they work in 802.11n NICs in practice.
89 citations