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Cross-Layer Device Fingerprinting System and Methods

Networks of connectivity-enabled devices, known as internet of things or IoT, involve interrelated devices that connect and exchange data with other IoT devices and the cloud. As the number of IoT devices and their applications continue to significantly increase, managing and administering edge and access networks have become increasingly more challenging. Currently, there are approximately 31 billion ‘‘things’’ connected to the internet, with a projected rise to 75 billion devices by 2025. Because of IoT interconnectivity and ubiquitous device use, assessing the risks, designing/specifying what’s reasonable, and implementing controls can be overwhelming to conventional frameworks. Any approach to better IoT network security, for example by improved detection and denial or restriction of access by unauthorized devices, must consider its impact on performance such as speed, power use, interoperability, and scalability. The IoT network’s physical and MAC layers are not impenetrable and have many known threats, especially identity-based attacks such as MAC spoofing events. Common network infrastructure uses WPA2 or IEEE 802.11i to help protect users and their devices and connected infrastructure. However, the risk of MAC spoofing remains, as bad actors leverage public tools on 802.11 commodity hardware, or intercept sensitive data packets at scale, to access users physical layer data, and can lead to wider tampering and manipulation of hardware-level parameters.

(2023-116) Users are Closer than they Appear: Protecting User Location from WiFi Aps

Researchers from UC San Diego have developed MIRAGE, an algorithm that the user can employ on their devices (e.g., smartphone) to maintain their location privacy if desired without compromising their Wi-Fi’s quality of service.The innovation would be additional software on the user's WiFI device, enabling which would make the listening WiFI AP infrastructure unable to detect the user's location unless and until the user is willing to provide it. All of this happens without any compromise to the data rate of the WiFi-user communication.

(SD2023-333) A System for Decoding Error-Correcting Codes

This invention is a new system of algorithms for decoding linear block codes. Given the received message block, the decoding algorithm is designed to recover the truly transmitted symbols.Engineers from UC San Diego have invented a decoding system that can be shown to achieve near-optimal decoding performance for general linear codes of dimension less than or equal to 128. In particular, for Reed–Muller codes, this new algorithm is the first to be shown with simulation evidence to achieve the optimal block error rate for communications over binary symmetric channels. This invention employs multiple Monte Carlo Markov chain subdecoders in parallel, which is a novel idea compared to the existing art. 

(SD2022-181) R-Fiducial: Reliable and Scalable Radar Fiducials for Smart mmwave Sensing

Millimeter wave sensing has recently attracted a lot of attention given its environmental robust nature. In situations where visual sensors like cameras fail to perform, mmwave radars can be used to achieve reliable performance. However, because of the poor scattering performance and lack of texture in millimeter waves, radars can not be used in several situations that require precise identification of objects.  A video demonstration of R-fiducial could be found at 

(SD2022-190) Virtualized User-proportionate MIMO

Frequency-division multiple access (FDMA) is a channel access method used in some multiple-access protocols. FDMA allows multiple users to send data through a single communication channel, such as a coaxial cable or microwave beam, by dividing the bandwidth of the channel into separate non-overlapping frequency sub-channels and allocating each sub-channel to a separate user. FDMA is highly power‐efficient and can work with single antenna base stations. This is because FDMA separates users in spectrum and then samples the net increased bandwidth.Digital beamforming is highly spectrum efficient, however needs multiple antenna base stations. This is because to resolve the multiple users interfering we need to sample the signals from multiple antennas to cancel out the interferences, which requires a dedicated downconversion chain per antenna. The requirement of multiple downconversion chains makes the solution power hungry, and thus has limited adoption.


Antennas are transducers that convert electronic signals into electromagnetic (EM) waves and vice-versa. An antenna can be electrically excited by a transmission line, an aperture coupling, or wirelessly by another source of electromagnetic wave. One type of antenna is a patch antenna formed by mounting a first sheet of metal over a second sheet of metal serving as a ground plane. Patch antennas have a low profile and are thus suitable for mounting on a surface. However, patch antennas may be less efficient and exhibit higher than desirable return loss. A dielectric resonator antenna (DRA), which that includes a dielectric resonator disposed on top of another substrate in which the dielectric resonator is housed, may exhibit significantly lower losses than traditional metallic patch antennas. Nevertheless, conventional dielectric resonator antennas have limited beam steering capabilities. In particular, conventional dielectric resonator antennas exhibit a low quality factor (Q factor) at millimeter wave (mm-wave) frequencies. 

(SD2022-327) Design and Evaluation of a Miniaturized Force Sensor Based on Wave Backscattering

Wireless researchers at UC San Diego have invented a wireless force sensor comprising a deformable passive force sensor that induces a change in an interrogation RF signal present on a conductive connection to produce a changed reflective signal and an ID circuit that responds with an ID and the changed reflective signal.

(SD2023-064) A programmable antenna arrays for 5G/6G networks: Flexible Directional Frequency Multiplexing for Multi-user Millimeter-wave Networks using Delay Phased Array

Modern mmWave systems cannot scale to a large number of users because of the inflexibility in performing directional frequency multiplexing. All the frequency components in the mmWave signal are beamformed to one direction via pencil beams and cannot be streamed to other user directions. Engineers from UC San Diego present mmFlexible, a flexible mmWave system that enables flexible directional frequency multiplexing, allowing different frequency components to radiate in multiple arbitrary directions with the same pencil beam.

Dynamically Tuning IEEE 802.11 Contention Window Using Machine Learning

The exchange of information among nodes in a communications network is based upon the transmission of discrete packets of data from a transmitter to a receiver over a carrier according to one or more of many well-known, new or still developing protocols. In this context, a protocol consists of a set of rules defining how the nodes interact with each other based on information sent over the communication links. Often, multiple nodes will transmit a packet at the same time and a collision occurs. During a collision, the packets are disrupted and become unintelligible to the other devices listening to the carrier activity. In addition to packet loss, network performance is greatly impacted. The delay introduced by the need to retransmit the packets cascades throughout the network to the other devices waiting to transmit over the carrier. Therefore, packet collision has a multiplicative effect that is detrimental to communications networks. As a result, multiple international protocols have been developed to address packet collision, including collision detection and avoidance. Within the context of wired Ethernet networks, the issue of packet collision has been largely addressed by network protocols that try to detect a packet collision and then wait until the carrier is clear to retransmit. Emphasis is placed in collision detection, i.e., a transmitting node can determine whether a collision has occurred by sensing the carrier. At the same time, the nature of wireless networks prevents wireless nodes from being able to detect a collision. This is the case, in part, because in wireless networks the nodes can send and receive but cannot sense packets traversing the carrier after the transmission has started. Another problem arises when two transmitting nodes are out of range of each other, but the receiving node is within range of both. In this case, a transmitting node cannot sense another transmitting node that is out of communications range. IEEE 802.11 protocols are the basis for wireless network products using the Wi-Fi brand and are the world's most widely used wireless computer networking standards. With IEEE 802.11 packet collision features come deficiencies, like fairness. 802.11’s approach to certain parameters after each successful transmission may cause the node who succeeds in transmitting to dominate the channel for an arbitrarily long period of time. As a result, other nodes may suffer from severe short-term unfairness. Also, the current state of the network (e.g., load) is something that also should be factored. In general, there is a need for techniques to recognize network patterns and determine certain parameters that are responsive to those network patterns.

(SD2022-254) Enabling WiFi Sensing for Robot Localization and Navigation

Researchers from UC San Diego have developed a technology that integrates WiFi as a sensor to simultaneously locate the robot and Map the WiFi access point (APs) in the environment.The invention allows for any WiFi receiver and transmitter to be repurposed to be used for localization purposes for a robot. The invention makes use of both WiFi access points deployed in the environment and one deployed on the robot to get accurate location of the robot in large spaces. Simultaneous localization and mapping (SLAM) is the computational problem of constructing or updating a map of an unknown environment while simultaneously keeping track of an agent's location within it.

Inertial Odometry System and Methods

Although GPS can be used for localization outdoors, indoor environments (office buildings, shopping malls, transit hubs) can be particularly challenging for many of the general population, and especially for blind walkers. GPS-denied environments have received considerable attention in recent years as our population’s digital expectations grow. To address GPS-denied environments, various services have been explored, including technology based on Bluetooth low energy (BLE), Wi-Fi, and camera. Drawbacks with these approaches are common, including calibration (fingerprinting) overhead using Wi-Fi, beacon infrastructure costs using BLE, and unoccluded visibility requirements in camera-based systems. While localization and wayfinding using inertial sensing overcomes these challenges, large errors with accumulated drift are known. Moreover, the decoupling of the orientation of the phone from the direction of walking, as well as accurately detecting walker’s velocity and detecting steps and measuring stride lengths, have also been challenges for traditional pedestrian dead reckoning (PDR) systems. Relatedly, blind walkers (especially those who do not use a dog guide) often tend to veer when attempting to walk in a straight line, and this unwanted veering may generate false turn detections with such inertial methods.

Collision Avoidance in Multi-hop Wireless Networks

In most wireless ad-hoc multi-hop networks, a node competes for access to the same wireless communication channel, often resulting in collisions (interference) and ineffective carrier sensing. These issues have been targeted through the medium access control (MAC) interconnection layer by a variety of channel access schemes, towards improving how the nodes share the wireless channel and achieve a high quality of service. For example, there are contention-based MAC schemes, like Carrier-Sense Multiple Access (CSMA) and Additive Links On-Line Hawaii Area (ALOHA), and contention-free MAC schemes, like time division multiplexing access (TDMA). However, the former is a poor performer in hidden- and exposed-terminal environments, and the latter, where the node system is time-synchronized and the time frame is divided and multiple time-slots are allocated to the nodes, has limited data rates (bandwidth) and undesirable latency. Over the years, there have been many other MAC schemes that address interference and conflict, as well as improving criteria like throughput, fairness, latency, energy, and overhead. These modern protocols implement more sophisticated distributed transmission queues consisting of a sequence of transmission turns that grows and shrinks on demand. However, challenges remain in these more recent MAC protocols, such as long delays for allowing nodes to join the network, and/or the use of transmission frames with complex structures to allocate time slot portions to signaling packets for elections.

Systems For Pulse-Mode Interrogation Of Wireless Backscatter Communication Nodes

Measurement of electrical activity in nervous tissue has many applications in medicine, but the implantation of a large number of sensors is traditionally very risky and costly. Devices must be large due to their necessary complexity and power requirements, driving up the risk further and discouraging adoption. To address these problems, researchers at UC Berkeley have developed devices and methods to allow small, very simple and power-efficient sensors to transmit information by backscatter feedback. That is, a much more complex and powerful external interrogator sends an electromagnetic or ultrasound signal, which is modulated by the sensor nodes and reflected back to the interrogator. Machine learning algorithms are then able to map the reflected signals to nervous activity. The asymmetric nature of this process allows most of the complexity to be offloaded to the external interrogator, which is not subject to the same constraints as implanted devices. This allows for larger networks of nodes which can generate higher resolution data at lower risks and costs than existing devices.

Flippo The Robo-Shoe-Fly: A Foot Dwelling Social Wearable Companion

Social interactions in school and office settings traditionally involve few coordinated physical interactions, and most group engagement centers on sharing electronic screens. Wearable robot companions are a promising new direction for encouraging coordinated physical movement and social interaction in group settings. A UC Santa Cruz researcher has developed a wearable social companion that encourages users to interact via physical movement.

A Novel Iot Protocol Architecture; Efficiency Through Data And Functionality Sharing Across Layers

The Internet’s TCP/IP protocol architecture is a layered system design. As such, the functions performed by the TCP/IP protocol suite are implemented at different protocol layers, where each layer provides a specific set of services to the layer above through a well-defined interface. Using this interface, data being received or sent is passed up or down the stack on its way through the network.However, layered design approaches can increase overhead, as each layer incurs additional communication (e.g., additional header field) and processing costs. Furthermore, limiting the flow between layers to data plane information restricts the sharing of control information across layers and may lead to functions being duplicated at different layers. 

Noise Reduction In High Frequency Amplifiers Using Transmission Lines To Provide Feedback

Low noise amplifiers are ubiquitous in wireless data network receivers and radios. Themaximum transmission distance is limited by the receiver noise which is mostly determined by the noise figure of the first amplifier stage, the LNA. Reduction of LNA noise is thus always desirable in that it can increase transmission range or reduce power consumption resulting in higher performance or reduced system cost. This approach lowers the noise of the LNA relative to the other available methods.

Carrier Sense Multiple Access With Collision Avoidance And Pilots (CSMA/CAP)

In most wireless ad-hoc multi-hop networks, a node competes for access to shared wireless medium, often resulting in collisions (interference). A node is commonly equipped with a transceiver that possesses mounted half-duplex omnidirectional antenna. Transmission degradation can occur when terminals are hidden from each other by physical structure, such as buildings. Moreover, since half-duplex nodes cannot receive while transmitting, not all packets sent by different terminals are detected by one another. In fact, no channel-access protocol based on the traditional handshake over a single channel can guarantee collision-free transmissions. Problems can arise in multi-hop wireless networks when hidden terminals, exposed transmitters, or exposed receivers are present.

(SD2021-331) SyncScatter: Enabling WiFi like synchronization & range for WiFi backscatter communication

WiFi backscattering can enable direct connectivity of IoT devices with commodity WiFi hardware at low power. However, most existing work in this area has overlooked the importance of synchronization and, as a result, accepted either limited range between the transmitter and the IoT device, reduced throughput via bit repetition, or both.

(SD2021-267) Improving the Range of WiFi Backscatter Via a Passive Retro-Reflective Single-Side-Band-Modulating MIMO Array

Wi-Fi is the most ubiquitous wireless networking technology for loT in homes, offices, and businesses. Since the power of Wi-Fi transceivers (10s-to-100s of mW) can be prohibitively high for emerging classes of loT devices (which desire <100μW), recent work has suggested piggybacking baseband signals from the loT device directly on top of incident Wi-Fi signals generated by access points (APs) via Wi-Fi-compatible backscatter modulation, where as low as 28μW of active power has been demonstrated. However, the major limitation of this approach is range.

(SD2019-199) ULoc: Robust, Scalable and cm-Accurate UWB Tag Localization

Researchers from UC San Diego have developed ULoc, a scalable, low-power, and cm-accurate UWB localization and tracking system in the form of a VR headset tracking, that provides real-time accurate 3D indoor localization.

(SD2020-249) Adaptive Bias Circuits For CMOS Millimeter-Wave Power Amplifiers: state-of-the-art back-off efficiency for silicon Ka-band Doherty PAs using single inputs and without digital predistortion

Power amplifier performance for emerging 5G mm-wave systems poses significant challenges for output power, efficiency and linearity. Efficiency in backoff is a key concern, given the peak-to-average power ratio of order 6-9dB for 5G signals. As a result, considerable attention has been given to composite amplifiers featuring backoff efficiency enhancement, particularly Doherty amplifiers. Adaptive bias circuits have been previously developed for use with power amplifiers at low microwave frequencies (for example, 1-2GHz as applied in 2G, 3G and 4G cellular networks).  Direct application of these techniques is not straightforward at higher frequencies, such as 28GHz as used for 5G wireless communications, because the transistors have less gain at the high frequencies. 

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