Location cognition is a challenging task in cognitive wireless systems when there is no explicit ... more Location cognition is a challenging task in cognitive wireless systems when there is no explicit location information system available, such as Global Positioning System (GPS) or dense wireless beacons. This paper decribes a simple-but-effective method of real-time location cognition which can be used by wireless devices in WLAN systems without depending on any location service infrastructure. The method is based
We introduce a concept of noise robustness in dynamical systems with noise and argue that this co... more We introduce a concept of noise robustness in dynamical systems with noise and argue that this concept is essential to guarantee the reliability of physical random bit generators (RBGs). As an example of promising physical RBGs we consider a chaotic laser system and show that it has the property of noise robustness with respect to changes in the temporal correlation of the noise source. Moreover, employing a simple model of tangent space dynamics, we give a theoretical interpretation of the numerical results and in particular show that the Lyapunov exponent determines a theoretical boundary of a noise-robust region in parameter space. These theoretical results are expected to be significant not only for chaotic lasers, but also for a broad class of chaotic dynamical systems with correlated noise.
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009
Fast and reliable generation of non-deterministic random numbers is needed to improve the securit... more Fast and reliable generation of non-deterministic random numbers is needed to improve the security of existing information and communication systems, including transactions on the internet and distributed data storage systems. Realising practical quantum key distribution systems in the future will also require high-speed generation of random sequences to modulate transmission parameters. Random physical phenomena, such as quantum optical noise and
This paper proposes multipoint-to-multipoint (MPtoMP) real-time broadcast transmission using netw... more This paper proposes multipoint-to-multipoint (MPtoMP) real-time broadcast transmission using network coding for ad-hoc networks like video game networks. We aim to achieve highly reliable MPtoMP broadcasting using IEEE 802.11 media access control (MAC) that does not include a retransmission mechanism. When each node detects packets from the other nodes in a sequence, the correctly detected packets are network-encoded, and the encoded packet is broadcasted in the next sequence as a piggy-back for its native packet. To prevent increase of overhead in each packet due to piggy-back packet transmission, network coding vector for each node is exchanged between all nodes in the negotiation phase. Each user keeps using the same coding vector generated in the negotiation phase, and only coding information that represents which user signal is included in the network coding process is transmitted along with the piggy-back packet. Our simulation results show that the proposed method can provide higher reliability than other schemes using multi point relay (MPR) or redundant transmissions such as forward error correction (FEC). We also implement the proposed method in a wireless testbed, and show that the proposed method achieves high reliability in a real-world environment with a practical degree of complexity when installed on current wireless devices.
Location cognition is a challenging task in cognitive wireless systems when there is no explicit ... more Location cognition is a challenging task in cognitive wireless systems when there is no explicit location information system available, such as Global Positioning System (GPS) or dense wireless beacons. This paper decribes a simple-but-effective method of real-time location cognition which can be used by wireless devices in WLAN systems without depending on any location service infrastructure. The method is based
We introduce a concept of noise robustness in dynamical systems with noise and argue that this co... more We introduce a concept of noise robustness in dynamical systems with noise and argue that this concept is essential to guarantee the reliability of physical random bit generators (RBGs). As an example of promising physical RBGs we consider a chaotic laser system and show that it has the property of noise robustness with respect to changes in the temporal correlation of the noise source. Moreover, employing a simple model of tangent space dynamics, we give a theoretical interpretation of the numerical results and in particular show that the Lyapunov exponent determines a theoretical boundary of a noise-robust region in parameter space. These theoretical results are expected to be significant not only for chaotic lasers, but also for a broad class of chaotic dynamical systems with correlated noise.
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009
Fast and reliable generation of non-deterministic random numbers is needed to improve the securit... more Fast and reliable generation of non-deterministic random numbers is needed to improve the security of existing information and communication systems, including transactions on the internet and distributed data storage systems. Realising practical quantum key distribution systems in the future will also require high-speed generation of random sequences to modulate transmission parameters. Random physical phenomena, such as quantum optical noise and
This paper proposes multipoint-to-multipoint (MPtoMP) real-time broadcast transmission using netw... more This paper proposes multipoint-to-multipoint (MPtoMP) real-time broadcast transmission using network coding for ad-hoc networks like video game networks. We aim to achieve highly reliable MPtoMP broadcasting using IEEE 802.11 media access control (MAC) that does not include a retransmission mechanism. When each node detects packets from the other nodes in a sequence, the correctly detected packets are network-encoded, and the encoded packet is broadcasted in the next sequence as a piggy-back for its native packet. To prevent increase of overhead in each packet due to piggy-back packet transmission, network coding vector for each node is exchanged between all nodes in the negotiation phase. Each user keeps using the same coding vector generated in the negotiation phase, and only coding information that represents which user signal is included in the network coding process is transmitted along with the piggy-back packet. Our simulation results show that the proposed method can provide higher reliability than other schemes using multi point relay (MPR) or redundant transmissions such as forward error correction (FEC). We also implement the proposed method in a wireless testbed, and show that the proposed method achieves high reliability in a real-world environment with a practical degree of complexity when installed on current wireless devices.
Uploads
Papers by Peter Davis