Using digital watermarking to enhance security in wireless medical image transmission

This is the published version of the article. Copyright 2010 Mary Ann Liebert Inc.During the last few years, wireless networks have been increasingly used both inside hospitals and in patients’ homes to transmit medical information. In general, wireless networks suffer from decreased security. However, digital watermarking can be used to secure medical information. In this study, we focused on combining wireless transmission and digital watermarking technologies to better secure the transmission of medical images within and outside the hospital. Methods: We utilized an integrated system comprising the wireless network and the digital watermarking module to conduct a series of tests. Results: The test results were evaluated by medical consultants. They concluded that the images suffered no visible quality degradation and maintained their diagnostic integrity. Discussion: The proposed integrated system presented reasonable stability, and its performance was comparable to that of a fixed network. This system can enhance security during the transmission of medical images through a wireless channel.The General Secretariat for Research and Technology of the Hellenic Ministry of Development and the British Council

Spread spectrum techniques for indoor wireless IR communications

Multipath dispersion and fluorescent light interference are two major problems in indoor wireless infrared communications systems. Multipath dispersion introduces intersymhol interference at data rates above 10 Mb/s, while fluorescent light induces severe narrowband interference to baseband modulation schemes commonly used such as OOK and PPM. This article reviews the research into the application of direct sequence spread spectrum techniques to ameliorate these key channel impairments without having to resort to complex signal processing techniques. The inherent properties of a spreading sequence are exploited in order to combat the ISI and narrowband interference. In addition, to reduce the impact of these impairments, the DSSS modulation schemes have strived to be bandwidth-efficient and simple to implement. Three main DSSS waveform techniques have been developed and investigated. These are sequence inverse keying, complementary sequence inverse keying, and M-ary biorthogonal keying (MBOK). The operations of the three systems are explained; their performances were evaluated through simulations and experiments for a number of system parameters, including spreading sequence type and length. By comparison with OOK, our results show that SIK, CSIK, and MBOK are effective against multipath dispersion and fluorescent light interference becausc the penalties incurred on the DSSS schemes are between 0-7 dB, while the penalty on OOK in the same environment is more than 17 dB. The DSSS solution for IR wireless transmission demonstrates that a transmission waveform can he designed to remove the key channel impairments in a wireless IR system

Radio Frequency Fingerprinting Techniques through Preamble Modification in IEEE 802.11b

Wireless local area networks are particularly vulnerable to cyber attacks due to their contested transmission medium. Access point spoofing, route poisoning, and cryptographic attacks are some of the many mature threats faced by wireless networks. Recent work investigates physical-layer features such as received signal strength or radio frequency fingerprinting to identify and localize malicious devices. This thesis demonstrates a novel and complementary approach to exploiting physical-layer differences among wireless devices that is more energy efficient and invariant with respect to the environment than traditional fingerprinting techniques. Specifically, this methodology exploits subtle design differences among different transceiver hardware types. A software defined radio captures packets with standard-length IEEE 802.11b preambles, manipulates the recorded preambles by shortening their length, then replays the altered packets toward the transceivers under test. Wireless transceivers vary in their ability to receive packets with preambles shorter than the standard. By analyzing differences in packet reception with respect to preamble length, this methodology distinguishes amongst eight transceiver types from three manufacturers. All tests to successfully enumerate the transceivers achieve accuracy rates greater than 99%, while transmitting less than 60 test packets. This research extends previous work illustrating RF fingerprinting techniques through IEEE 802.15.4 wireless protocols. The results demonstrate that preamble manipulation is effective for multi-factor device authentication, network intrusion detection, and remote transceiver type fingerprinting in IEEE 802.11b

Experimental Study of Multirate Margin in Software Defined Multirate Radio

Due to the recent development of spectrally-efficient modulation schemes, IEEE 802.11 Wifi and IEEE 802.16 WiMax radios support wireless communication at multiple bit rates. While high-rate transmission allows delivering more information in less time, the corresponding performance improvement is less than expected due to the PHY- and MAC-layer overheads, imposed by the 802.11/16 standards. This is particularly true in wireless ad hoc networks as there exist rate-distance and rate-hop count tradeoffs. The concept of multi-rate margin is proposed in this thesis, which exploits the difference in communication characteristics at different rates and serves as the fundamental ingredient for an opportunistic transmission protocol, targeted to meliorate the ad hoc mobile wireless network performance. In this thesis, the multi-rate margin is analyzed with theoretical derivation, perceived with simulation result using MATLAB and observed through real world testing using USRP and GNU Radio, which is a recent implementation of Software Defined Radi

MedLAN: Compact mobile computing system for wireless information access in emergency hospital wards

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.As the need for faster, safer and more efficient healthcare delivery increases, medical consultants seek new ways of implementing a high quality telemedical system, using innovative technology. Until today, teleconsultation (the most common application of Telemedicine) was performed by transferring the patient from the Accidents and Emergency ward, to a specially equipped room, or by moving large and heavy machinery to the place where the patient resided. Both these solutions were unpractical, uneconomical and potentially dangerous. At the same time wireless networks became increasingly useful in point-of-care areas such as hospitals, because of their ease of use, low cost of installation and increased flexibility. This thesis presents an integrated system called MedLAN dedicated for use inside the A&E hospital wards. Its purpose is to wirelessly support high-quality live video, audio, high-resolution still images and networks support from anywhere there is WLAN coverage. It is capable of transmitting all of the above to a consultant residing either inside or outside the hospital, or even to an external place, thorough the use of the Internet. To implement that, it makes use of the existing IEEE 802.11b wireless technology. Initially, this thesis demonstrates that for specific scenarios (such as when using WLANs), DICOM specifications should be adjusted to accommodate for the reduced WLAN bandwidth. Near lossless compression has been used to send still images through the WLANs and the results have been evaluated by a number of consultants to decide whether they retain their diagnostic value. The thesis further suggests improvements on the existing 802.11b protocol. In particular, as the typical hospital environment suffers from heavy RF reflections, it suggests that an alternative method of modulation (OFDM) can be embedded in the 802.11b hardware to reduce the multipath effect, increase the throughput and thus the video quality sent by the MedLAN system. Finally, realising that the trust between a patient and a doctor is fundamental this thesis proposes a series of simple actions aiming at securing the MedLAN system. Additionally, a concrete security system is suggested, that encapsulates the existing WEP security protocol, over IPSec

Role of Wireless technology in mobile augmented reality system (MARS)

Not availabl

Transmit simulation and receive optimizations for 802.11b networks

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 72-73).This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.The simulation presented in this paper provides an implementation of a full simulated transmit chain from packet encoding through base band modulation for the 802.11b wireless networking standard. This forward transmit chain is coupled with a physical channel simulation that can introduce a number of different channel effects to simulate interference caused in the real world. Packets which the transmit simulation produces can be sent to a receive simulation to test design parameters or can be modulated and sent to 802.11b hardware to test hardware implementation. Using former procedure, this paper also evaluates implementations of a Phase lock loop used to track Frequency Doppler and a Time Tracking Loop used to track Code Doppler under various Signal to Noise levels. The results from these simulations can be used to optimize various receive parameters and algorithms.by Pascal F. Rettig.M.Eng