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.
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TL;DR: Although infrastructure mobility has been discussed in the context of Google Balloons, ad hoc networks, and delay tolerant networks, it is believed that the possibility of moving personal devices in homes and offices is relatively unexplored, and could open doors to new kinds of innovation.
Abstract: This paper explores the possibility of injecting mobility into wireless network infrastructure. We envision WiFi APs on wheels that move to optimize user performance. Movements need not be all around the floor, neither do they have to operate on batteries. As a first step, WiFi APs at home could remain tethered to power and Ethernet outlets while moving in small areas (perhaps under the couch). If such systems prove successful, perhaps future buildings could offer explicit support for network infrastructure mobility. This paper begins with a higher level discussion of robotic wireless networks—the opportunities and the hurdles—and then pivots by developing a smaller slice of the vision through a system called iMob . With iMob , a WiFi AP is mounted on a Roomba robot and made to periodically move within a $2x2$ sqft region. The core questions pertain to finding the best location to move to, such that the SNRs from its clients are strong, and the interferences from other APs are weak. Our measurements show that the richness of wireless multipath offers significant opportunities—even within a $2x2$ sqft region, locations exist that are $1.7x$ better than the average location in terms of throughput. When multiple APs in a neighborhood coordinate, the gains can be even higher. In sum, although infrastructure mobility has been discussed in the context of Google Balloons, ad hoc networks, and delay tolerant networks, we believe that the possibility of moving our personal devices in homes and offices is relatively unexplored, and could open doors to new kinds of innovation.
11 citations
Cites background from "Tool release: gathering 802.11n tra..."
...Clients record the per-packet channel state information (CSI) for offline analysis [16], [17]....
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TL;DR: An accurate corruption estimation approach, AccuEst, which utilizes per-byte SINR (Signal-to-Interference-and-Noise Ratio) to detect corruption, which is implemented in a coding-based transmission protocol and results show that the packet delivery ratio is improved.
Abstract: Cross-Technology Interference affects the operation of low-power ZigBee networks, especially under severe WiFi interference. Accurate corruption estimation is very important to improve the resilience of ZigBee transmissions. However, there are many limitations in existing approaches such as low accuracy, high overhead, and requirement of hardware modification. In this paper, we propose an accurate corruption estimation approach, AccuEst, which utilizes per-byte SINR (Signal-to-Interference-and-Noise Ratio) to detect corruption. We combine the use of pilot symbols with per-byte SINR to improve corruption detection accuracy, especially in highly noisy environments (i.e., noise and interference are at the same level). We extract pilot symbols by leveraging protocol signatures. In addition, we design an adaptive pilot instrumentation scheme to strike a good balance between accuracy and overhead. We implement AccuEst on the TinyOS 2.1.1/TelosB platform and evaluate its performance through extensive experiments. Results show that AccuEst improves corruption detection accuracy by 79.4 percent on average compared with state-of-the-art approach (i.e., CARE) in highly noisy environments. In addition, AccuEst reduces pilot overhead by 83.7 percent on average compared to the traditional pilot-based approach. We implement AccuEst in a coding-based transmission protocol, and results show that with AccuEst, the packet delivery ratio is improved by 22.1 percent on average.
11 citations
Additional excerpts
..., 5,300NIC[42]), our approach can be easily applied....
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01 Aug 2019
TL;DR: In order to support optimized Received Signal Strength monitoring, a low-cost sensor platform based on Blue-tooth Low Energy is introduced and the characteristics of this platform are described in detail and a device-free indoor localization application is presented.
Abstract: In order to support optimized Received Signal Strength monitoring, a low-cost sensor platform based on Blue-tooth Low Energy is introduced. Using this platform RSS measurements of individual radio channels can be performed within a highly configurable mesh network with sampling rates of up to 5 kHz and an accuracy of 0.2 dB. Measured RSS can be either shared between all devices in the network in real-time or they may be stored inside each device during the time of measurement and get distributed afterwards. We analyse and describe the characteristics of the suggested platform in detail and present, as an example, a device-free indoor localization application.
11 citations
10 Nov 2019
TL;DR: This dataset contains data of nine different participants over three different days, with an two participants repeating the activities over an additional three days.
Abstract: In our current society, unobtrusive sensing has become an important tool to monitor the physical world, as it is easy to use and privacy-aware. Remote sensing is a new and heavily researched technology based on the analysis of radio signals. A particular field research in this area is the analysis of channel state information with the raw signal, as this contains the most information. While most research focuses on analysis of individuals or clustered data, little to no research has gone into the analysis of channel state information of multiple people over multiple days for different and comparable activities. This dataset contains data of nine different participants over three different days, with an two participants repeating the activities over an additional three days. The dataset is available at the 4TU.ResearchData under the CC BY-NC-SA license [4].
11 citations
Cites background or methods from "Tool release: gathering 802.11n tra..."
...Each trace also contains more information regarding noise and antennas [3]....
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...There are different connectivity options using the Linux CSI Tool [3]....
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TL;DR: Using existing commodity Wi-Fi devices to design and implement a long-term device-free human daily vitality system, WiMonitor, which can continuously capture the target’s vitality information in a multi-room home environment without compromising the privacy of the target.
Abstract: For a large population of elderly who live alone, a continuous long-term daily monitoring system is critical and imminently needed to enhance the quality of their lives. Continuous monitoring of vitality information (i.e., which area the elder is staying in, the motion state and activity intensity of an elder) is essential for elderly care. In this paper, we use existing commodity Wi-Fi devices to design and implement a long-term device-free human daily vitality system, WiMonitor. Our system can continuously capture the target’s vitality information in a multi-room home environment without compromising the privacy of the target. In a continuous 22-day experiment, WiMonitor successfully captures the human vitality information accurately. We believe our system can provide valuable long-term monitoring data for both researchers and health care personnel.
11 citations
Cites methods from "Tool release: gathering 802.11n tra..."
...Halperin, D.; Hu, W.; Sheth, A.; Wetherall, D. Tool release: Gathering 802.11 n traces with channel state information....
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...Fortunately, through Intel 5300 CSI Tools [43], we can get RS I and the gain ffi i t f agc in every rec ived CSI packet....
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...Through Intel 5300 CSI Tools, the denominator can be calculated as: N−1 ∑ n=0 |y(n)|2 = 10 RSSI−44−agc 10 , (15) The numerator of Equation (14) represents the signal power after AGC in the frequency domain, and can be calculated as [42]: N−1 ∑ k=0 ∣∣Yg(k)∣∣2 = N−1∑ k=0 ∣∣Hg(k)·LTF(k)∣∣2 = N−1∑ k=0 ∣∣Hg(k)∣∣2, (16) where LTF is the Long Training Field, which is used to estimate the CSI [42]....
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...The CSI tool developed by Halperin [43] is installed on each miniPC to collect the CSI samples of each received packet....
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...Through Intel 5300 CSI Tools, the denominator can be calculated as: ( ) 441 2 10 0 =10 RSSI agcN n y n − −− = , (15) i r . i l r cessi i t e i-Fi receiver block diagra ....
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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