Wireless Communication and Mobile Computing

The unparalleled scale and density of Disney’s physical venues give rise to wireless-research topics in relatively uncharted operating regimes, with cost structures that can amortize across tens to hundreds of millions of units. Our work focuses on the physics of radio and antennas—with applications both analog and digital—as well as the algorithms and protocols necessary for wireless networking. Our research agenda is inspired primarily by opportunities at Walt Disney Parks and Resorts, Disney Consumer Products and at ESPN.

Projects

(in alphabetical order)

60 GHz Real-Time Wireless Video Broadcasting
Wireless streaming of high-definition video is a promising application for 60 GHz links because multi-Gb/s data rates are possible. In particular we consider a sports stadium broadcasting system where video signals from multiple cameras are transmitted to a central location. Due to the high pathloss of 60 GHz radiation over the large distances encountered in this setting, the use of relays is required. This project designed a quality-aware coding and relaying algorithm for maximization of the overall video quality. We considered a scheme where the source can split its data stream into parallel streams that can be transmitted via different relays to the destination. Simulations show that the proposed scheme outperforms other schemes that do not take the peculiarities of millimeter-wave video links into account. Our results indicate that high quality transmission is possible for at least ten cameras over distances of 300 m. Furthermore, optimization of the video quality gives results that can significantly outperform schemes that only aim to maximize data rates.

Acoustic Data Transmission to Ad-hoc Mobile Phone Arrays
In show environments like cinemas, theaters, music concerts, entertainment theme parks, or at sport stadiums, offering a reliable communication channel from the show event (movie, concert) towards mobile phones located in the audience enables interesting new applications. For example, events in a movie can trigger additional and assisting information to appear on a phone's display. This is particularly attractive when there is no need for a wireless infrastructure. Avoiding the need for a dedicated wireless infrastructure, the movie (or show) can directly interact with phones in the audience, independently of the local resources. Wirelessly communicating data from a movie to mobile phones in a cinema can be realized by using the cinema audio system and multiple loudspeakers. The system introduced in this project addresses the problem of how to offer a larger throughput per mobile phone over the acoustic channel, with higher reliability. We let multiple phones observe independently the incoming audio signals from loudspeakers. The phones group together and connect with each other via radio communication, so that they can jointly process the received data messages. Phones at different locations often observe different audio channel error characteristics, which can be exploited during error handling (spatial diversity), once they are connected with each other.

Acoustic Data Transmission to Collaborating Smartphones – An Experimental Study
The acoustic capabilities (i.e. microphone) and the fast processors of modern smartphones allow for the transmission of data to groups of such devices through the audio channel. We discuss an acoustic data transmission system for broadcast communication to a multitude of smartphones without the need of a radio access point. Acoustic data transmission is particularly attractive in scenarios that involve sound systems (e.g., movie theaters or open-air film festivals). We discuss different techniques to hide data in sound tracks and how to form a microphone array from a collection of smartphones in the same location. Collaborating smartphones share (using their radio interfaces to form an ad hoc network) the received data streams to jointly correct errors. With a testbed of up to four smartphones, we demonstrate how the robustness and reliability of a downlink broadcast via an acoustic communication system can be improved by collaboration between spatially distributed devices. With field tests in different scenarios, we investigate the potential gain of the collaboration in a real environment.

Activity and Mobility Modeling of Theme Park Guests
Guest services offered in parks and resorts may rely on wireless communication in the future. Examples are location-based applications, mobile games, information guides, multimedia sharing, and mobile social networks. Rolling out a wireless infrastructure to support such services in parks may create challenges beyond deployment and maintenance. For example, access points and antennas may be too visible and might interfere with artistic intentions. However, a continuous connectivity provided by base stations and cellular infrastructure is not always needed. Instead, direct links between the wireless devices carried by guests might provide enough capacity. The adhoc mode of Wi-Fi, Bluetooth, or ZigBee enables wireless devices to communicate directly when within each other’s coverage range. Additional mesh networks might assist only where needed at key locations. Naturally, such adhoc communication will experience occasional disruptions as wireless links will appear and disappear with the guest mobility. The effect of the disruptions depends on the number and density of devices and the guest activity like walking speed or directions. Therefore, it is essential to evaluate the performance of future wireless communication with tools using realistic mobility and activity models.

Backscatter Sensing
This project seeks to design a wireless bend sensor using backscatter radio frequency (RF) tags (often referred to as radio frequency identification (RFID) tags) operating at 5.8GHz. While many conventional wireless sensors require an analog-to-digital converter and transmitting hardware, this sensor will not require such tag complexity because the transducer is an integral part of the RF tagís transmission circuit. The result is that the hardware complexity and power consumption are reduced to a point that, in principle, the sensor can be made passive -- i.e., requiring no internal power source. Such a sensor would be useful for applications where small, light-weight, and low-maintenance sensors are required.

Cellular Wi-Fi and TV White Space
Many wireless networks rely on the Wi-Fi standard IEEE 802.11. Advantages of 802.11 are simplicity, reliability, and the wide availability of low cost implementations. In this project, an extension to the existing 802.11 standard towards support of cellular networks is developed, which will facilitate 802.11 to be applicable for wide-area broadband access using the so-called TV white space spectrum, as well as paired downlink and uplink spectrum allocated to cellular networks. The extension consists of the introduction of frequency division multiplex to 802.11, which is a spectrum access scheme well established in cellular networks such as GSM, IS-95, UMTS, and LTE. By applying this scheme, the low-cost and robust Wi-Fi technology may serve as candidate not only for TV white space networks but also for cellular networks.

Geolocation with Mobile Devices
Allowing guests of entertainment parks or at cruise liners to localise themselves is an interesting technical challenge and important for new types of wireless services. Such geolocation is typically based on cellphone determining their locations with the help of GPS or cellular base stations. Drawbacks of GPS are high battery consumption and the need for a clear view of the sky, making it impractical at cruise liners, in indoor areas, tree-covered zones, or similar environments where obstacles shadow the GPS signals. Approaches using the cellular network are not reliable and precise enough. In this project, we look at various technologies to improve the reliability of the geolocation services. We develop a station identity management system that preserves base station location privacy. The objective is to allow only authorized parties to obtain the locations of guests. We further investigate ways to exploit Wi-Fi time-of-flight measurements for precise and reliable localization.

Internet of Toys
The emerging Internet of Things (IoT) will provide Internet connectivity to a broad variety of objects, such as industrial sensors, home appliances, and consumer electronics including toys. A new standardized IoT protocol software for wireless connectivity will enable toys to interoperate with other toys and smart objects around them. The IoT software will enable toys to be accessed, monitored, and acted on remotely. Our project CALIPSO (http://www.ict-calipso.eu) is partially funded by the research program of the European Commission. As part of this three-year project, Disney Research works together with several industry and academic partners to create an innovative solution for wireless IoT systems. The new CALIPSO communication protocol software enables toys to discover other objects, build mobile ad hoc networks, and communicate in a very energy-efficient way to maximize their battery lifetime. We envision several Disney-related scenarios in which the software will help creating innovative toy play patterns and experience designs.
Disney Research's main contribution to Calipso is the new Multi-Hop Power Saving Mode for IEEE 802.11 Wireless LAN. IoT devices often need to communicate with each other and with Internet gateways over multi-hop links. While most IoT scenarios assume that for this purpose devices use energy-efficient radios such as IEEE 802.15.4 Wireless Personal Area Networks, there are scenarios in which IEEE 802.11 Wireless LAN is preferred. We extend the IEEE 802.11 Power Saving Mode (PSM), which allows WLAN devices to enter a low-power doze state to save energy, with a traffic announcement scheme that facilitates multi-hop communication. The scheme propagates traffic announcements along multi-hop paths to ensure that all intermediate nodes remain awake to forward the pending data frames with minimum latency. Our testbed measurements demonstrate that the proposed Multi-Hop PSM (MH-PSM) improves end-to-end delay and doze time compared to the standard PSM; therefore, it optimises WLAN to meet the networking requirements of IoT devices. MH-PSM is software-implementable since it does not require changes to the hardware and lower layers of IEEE 802.11. We implemented MH-PSM as part of a WLAN driver for Contiki, which is an operating system for resource-constrained IoT devices.

LED-to-LED Visible Light Communication Networks
Visible Light Communication (VLC) with Light Emitting Diodes (LEDs) as transmitters and receivers enable low bitrate wireless adhoc networking. LED-to-LED VLC adhoc networks with VLC devices communicating with each other over free space optical links typically achieve a throughput of less than a megabit per second at distances of no more than a few meters. LED-to-LED VLC adhoc networks are useful for combining a smart illumination with low-cost networking. We present and evaluate a software-based VLC physical layer and a VLC medium access control layer that retain the simplicity of the LED-to-LED approach. The design satisfies the requirement that LEDs should always be perceived as on with constant brightness. In each VLC device, in addition to an LED, only a low-cost microcontroller is required for handling the software-based communication protocol. The results of our performance measurements confirm recent claims about the potential of LED-to-LED VLC adhoc networks as a useful technology for sensor networks, smart and connected consumer devices, and the Internet-of-Things.

Low-Latency Broadcasting of Live Video Using Wi-Fi
The project addresses the problem of near real-time delivery of high-quality live video streams to multiple users via Wi-Fi. The users may be equipped with off-shelf portable devices such as tablets. Multiple streams are transmitted from one or multiple Wi-Fi access points (e.g. Wi-Fi enabled cameras) simultaneously. Each user may chose to view one stream in full resolution or multiple streams in reduced resolution. The number of users may be such that unicasting the streams to each of them exceeds the available network capacity. Therefore, the streams must be delivered via broadcast transmissions. Broadcasts in Wi-Fi are not acknowledged by the receivers and, therefore, retransmissions are disabled, which significantly increases the packet loss rate (PLR). While various retransmission schemes for broadcasting can be envisioned (e.g. driven by the user with the highest PLR) they would increase the transmission latency. Therefore, solutions based on FEC are preferred since they introduce minimum latency. Lower PHY modes (e.g. up to 6 Mb/s) provide stronger FEC protection, but reduce the network capacity, especially when multiple transmitters are competing for the channel using CSMA/CA. The project aims to build a reliable, low-latency video broadcasting solution for Wi-Fi by combining resilient video/image coding, FEC, and collision-free scheduling of transmitters.

Lumitrack: Low Cost, High Precision, High Speed Tracking with Projected m-Sequences

Magnetoquasistatic Position and Orientation Tracking
The goal of this project is to determine the position and orientation of a light weight, low-frequency transmitter using quasistatic magnetic fields in environments where line-of-sight occlusions and multipath propagation reduce the accuracy of conventional optical and high-frequency wireless tracking systems. This technology could be used in many applications including athlete tracking, video game control, and handheld device localization.

MOSAIC-2B: Mobile Empowerment for the Socio-Economic Development in South Africa
MOSAIC2B is a European research project aiming to develop and test a new framework that uses cloud-based applications, innovative low-cost internet delivery mechanisms (delay tolerant networks and opportunistic communications) and affordable mobile technologies to support local entrepreneurs, especially in rural villages. Disney Research Zurich, together with a consortium of European and South African partners builds upon the use case of mobile digital cinemas to run real life experiments demonstrating and evaluating the technological and economic viability of according innovations. In essence MOSAIC2B delivers a combination of mobile digital cinemas for edutainment (educational content and entertainment), mobile consumer services as well as visual analytics and interactive tools to obtain real-time knowledge of on-going processes and to support decision making. The case of South African micro entrepreneurs delivering edutainment to rural consumers serves as a showcase for broad based economic activities at the bottom of the economic pyramid in the developing world. Adapted innovative services at affordable cost offer sustainable access to new markets on a global scale to the benefit of the under-serviced population.

Ranging for Backscatter RFID
This project seeks to measure the distance between a backscatter RF tag and the tag reader with millimeter-level accuracy while respecting the bandwidth limitations of the 5.8 GHz ISM frequency band. The project uses a composite dual-frequency, continuous-wave (DFCW) and continuous wave (CW) radar to determine the range between the tag and reader and a spatial averaging algorithm to reduce the bandwidth required.

RFID Shakables: Pairing Radio-Frequency Identification Tags with the Help of Gesture Recognition
A novel approach for pairing RFID-enabled devices is introduced and evaluated in this work. Two or more devices are moved simultaneously through the radio field in close proximity of one or more RFID readers. Gesture recognition is applied to identify the movements of the devices, to mark them as a pair. This application is of interest for social networks and game applications in which play patterns with RFID-enabled toys are used to establish virtual friendships. In wireless networking, it can be used for user-friendly association of devices. The approach introduced here works with off-the-shelf passive RFID tags, as it is software-based and does not require hardware or protocol modifications. Every RFID reader constantly seeks for tags, thus, as soon as one tag is in its vicinity, the reader reports the presence of the tag. Such binary information is used to recognize the movement of tags and to pair them, if the gesture patterns match each other. We show via experimental evaluation that this feature can be easily implemented. We determine the required gesture interval duration and characteristics for accurate gesture and matching detection.

Transmit Diversity for Backscatter RFID
The read range of passive, backscatter radio frequency (RF) tags is limited by the power delivered to the RF tag’s integrated circuit. This project seeks to increase the power delivered to passive backscatter RF tags using transmit diversity – a method that uses multiple antennas and channel knowledge to focus power at a specific location.

Visible Light Communication
Light Emitting Diodes (LEDs) are used in consumer electronics, toys, light bulbs, cars, and monitors. With LEDs, it is possible to control light brightness at a frequency much higher than conventional light bulbs: LEDs can be switched on and off at very high rates. As result, LED-based lighting can be used for wireless communication services by modulating the intensity of the emitted light. Further, LEDs can also be used as receivers just like photodiodes. We call this concept Visible Light Communication (VLC) with LED-to-LED networking. Significant research contributions have been achieved by Disney Research in the area of networked systems for VLC. VLC creates opportunities for low-cost, safe, and environmentally friendly wireless communication solutions. We focus on connected toys and light bulb networks. Our work targets a full system design that spans from hardware prototypes to communication protocols, and applications.

Wireless LAN in Paired Radio Spectrum with Downlink-Uplink Separation
Wireless Local Area Networks (WLANs) based on the IEEE~802.11 standard apply a simple contention-based radio access protocol. Downlink communication from access points to mobile stations shares the radio channel with uplink communication from mobile stations to the access points. This protocol is due to the contention-based design that targets the operation in unlicensed spectrum. In the future, because of the growing demand for wireless communication services, WLANs might not only operate in unlicensed but also in licensed spectrum. However, licensed spectrum favors the use of separate (paired) radio channels for downlink and uplink communication -- a setup that requires frequency-division-duplex communication. This paper describes and evaluates the feasibility of a WLAN system operating in paired spectrum with a proof of concept implementation. Our testbed employs off-the-shelf WLAN chips (two per device) and driver modifications that enable the system to operate with downlink-uplink separation while still maintaining the ability to function in unlicensed (single-channel) spectrum. We provide insights based on our testbed and evaluate the performance of our solution.