peter davis - Academia.edu (original) (raw)

Papers by peter davis

The IEEE Conference on Local Computer Networks 30th Anniversary (LCN'05)l, 2005

We propose two methods for improving the stability of communication in ad hoc wireless networks -... more We propose two methods for improving the stability of communication in ad hoc wireless networks - firstly, the selection of reliable neighbors for data relay based on monitoring signal strength variations and secondly, the synchronous update of routing tables. These methods were designed to overcome problems observed in recent large testbed experiments. We show the dramatic improvement in stability and reduction of packet error rate which was achieved when we introduced these methods to an implementation of the OLSR routing protocol. Specifically we evaluated performance in a 50-node ad hoc wireless network, and showed a reduction in the packet error rate from 12% to less than 1

Nonlinear Theory and Its Applications, IEICE, 2015

Physical random bit generators (RBGs) that generate unpredictable bits at high speed are now of i... more Physical random bit generators (RBGs) that generate unpredictable bits at high speed are now of increasing importance in information science and technology. since they are expected to generate unpredictable random bits with high speed. From the viewpoint of applications for security, it is a crucial issue to be able to give a guarantee of the unpredictability of random bits. In this paper, we review research on physical RBGs, particularly focusing our attention on the studies of the unpredictability of random bits generated by laser systems, which are promising entropy sources for physical RBGs. Finally, we report recent research results on noise-robustness, which could be crucial for reliability of physical RBG.

Fiber Optic Components and Optical Communication, 1996

A novel adaptive output selection scheme has been proposed for searching among a large number of ... more A novel adaptive output selection scheme has been proposed for searching among a large number of multistable oscillation modes in a chaotic optical ring. The modes correspond to digital bit sequences, and the optical ring is potentially useful for generating digital optical signals. The adaptation is based on the collision avoidance between peaks in the oscillation pattern and pulses from another signal source. The collision signal is optically fedback into the optical ring and drives the system into a weakly chaotic regime until a fit oscillation mode which results in no collision in the output is obtained through chaotic mode transitions. Experiments have been performed using 21-bit oscillation modes and the results show that fit oscillation modes can be autonomously chosen with the proposed method. In particular, it was shown that the method can be successful even if the periods and pulse widths of the colliding signals are not the same and shown how the condition for successful collision avoidance can be determined in terms of the power in the collision pulses. Potential applications of the proposal in optical communication networks are discussed.

IEICE Proceeding Series, 2014

24th International Conference on Distributed Computing Systems Workshops, 2004. Proceedings., 2004

We study latency fluctuation during UDP packet exchange in ad hoc wireless groups. We focus on wi... more We study latency fluctuation during UDP packet exchange in ad hoc wireless groups. We focus on wireless media access using carrier sensing multiple access with collision avoidance, specifically the 802.11 protocol. We show that there can be large intermittent fluctuations in transmission times when packet exchange is done using UDP unicast. We show how the conditions for the onset of large fluctuations can be estimated, and how these estimates can be used in the design of applications which require real-time data exchanges with low latency.

2009 IEEE Wireless Communications and Networking Conference, 2009

A multi-player video game via wireless connections using portable devices is one of the most popu... more A multi-player video game via wireless connections using portable devices is one of the most popular applications of ad-hoc networks. Broadcast transmissions can be used for many- to-many communications in multi-player games. However, reliable broadcast communications are hard to realize because of the lack of retransmissions in the medium access control (MAC) layer. In this paper, we propose a broadcast

Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2010

Physical Review A, 2011

It is shown that broadband chaos suitable for fast nondeterministic random-bit generation in smal... more It is shown that broadband chaos suitable for fast nondeterministic random-bit generation in small devices can be achieved in a semiconductor laser with a short external cavity. The design of the device is based on a theoretical model for nondeterministic random-bit generation by amplification of microscopic noise. Moreover, it is demonstrated that bit sequences passing common tests of statistical randomness at rates up to 2.08 Gbits/s can be generated using on-chip lasers with a monolithically integrated external cavity, amplifiers, and a photodetector.

Optics Letters, 1998

We propose a novel reflector, called a chaos mirror, designed by use of the principles of chaotic... more We propose a novel reflector, called a chaos mirror, designed by use of the principles of chaotic reflection. A feature of the reflector is that it converts a one-dimensional spread of incident rays into a two-dimensional spread of reflected rays. This can be useful for making free-space optical beam links by sweeping a transmission beam in only one dimension.

Optics Express, 2011

We report a novel chaos semiconductor laser chip in which a distributed feedback (DFB) laser, two... more We report a novel chaos semiconductor laser chip in which a distributed feedback (DFB) laser, two semiconductor optical amplifiers (SOAs) and a photodiode (PD) are monolithically integrated with a passive ring waveguide. The ring-type structure with the two separate SOAs achieves stronger delayed optical feedback compared to previous chaos laser chips which use linear waveguide and facet-reflection. The integrated PD allows efficient detection of the optical signal with low optical loss. A rich variety of dynamical behaviors and optical signals can be selectively generated via injection currents to the two separate SOAs. In particular, the strong optical feedback makes possible the generation of strong broadband optical chaos, with very flat spectrum of ±6.5 dB up to 10 GHz. The stability and quality of the chaotic mode is demonstrated using strict statistical tests of randomness applied to long binary sequences extracted by sampling the optical intensity signal.

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, 2006

Secret key agreement is a procedure for agreeing on a secret key by exchanging messages over a pu... more Secret key agreement is a procedure for agreeing on a secret key by exchanging messages over a public channel when a sender, a legitimate receiver and an eavesdropper have access to correlated sources. Maurer, IEEE Trans. Inf. Theory 1993 defined secret key capacity, which is the least upper bound of the key generation rate of the secret key agreement, and

IEICE Transactions on Communications, 2009

This paper proposes bidirectional packet aggregation and coding (BiPAC), a packet mixing techniqu... more This paper proposes bidirectional packet aggregation and coding (BiPAC), a packet mixing technique which jointly applies packet aggregation and network coding in order to increase the number of supportable VoIP sessions in wireless multi-hop networks. BiPAC applies network coding for aggregated VoIP packets by exploiting bidirectional nature of VoIP sessions, and largely reduces the required protocol overhead for transmitting short

IEEE Journal of Quantum Electronics, 1998

An adaptive optical sequence generation scheme has been described in a nonlinear optical ring whi... more An adaptive optical sequence generation scheme has been described in a nonlinear optical ring which exhibits chaotic dynamics. The adaptation is based on avoidance of collisions between the ring output and signals from another source. It is shown that collision-avoiding sequences can be autonomously selected via chaotic mode transitions induced by the feedback of collision signals. Experimental results demonstrate that the method can be successful for various collision signal patterns with different periods and pulsewidths. The mechanism of inducing chaos with collision signals is examined both experimentally and with numerical simulations and the results verify the effectiveness of the proposed adaptation method. A possible application of the proposed signal generation scheme in intelligent optical communication networks is mentioned.

Electronics and Communications in Japan, 2010

Chaos synchronization of two semiconductor lasers commonly driven by a chaotic semiconductor lase... more Chaos synchronization of two semiconductor lasers commonly driven by a chaotic semiconductor laser subject to optical feedback was observed. Strongly correlated chaos synchronization between the two response lasers was observed even when the correlation between the drive and response lasers was low. It is shown that the cross correlation between the two responses is larger than that between the drive and response lasers over a wide parameter region.