Kensaku Asahi

A study on energy-efficient protocol based on the CSMA/CA in ad-hoc networks

This paper discusses a scheme for reducing the power consumption in the CSMA/CA ad hoc networks. We propose a simple CSMA/CA-based MAC protocol with the sleep mode which is applied during the period with and without the communication traffic, and describe the procedure of the proposed protocol. The performance is evaluated through computer simulations together with taking account of optimization for the value of k in the adaptive beacon mode. The simulated results show that remarkable reductions in the power consumption can be achieved with the proposed MAC protocol for the CSMA/CA ad hoc networks of the star type. Moreover, we introduce adaptive beacon mode to CSMA/CA scheme that control the beacon interval in accordance with the amount of traffic. Proposed scheme provide low power consumption in CSMA/CA and verify the effectiveness of the proposed scheme through simulation.

Proposal for a seamless connection method for remotely located Bluetooth devices

In view of the recent development of short-range wireless communication technologies, popularization of home automation is being anticipated. Hereafter, it is expected that the desire of manipulating short-range wireless communication devices located at home from the outdoors will increase. However, there exists a constraint of the reachable range of communication for such devices, and it is not possible to directly manipulate them from a remote location from home. In this paper, we propose a method to get connection with a remotely located Bluetooth device, by forwarding command and other messages exchanged between the hardware and software of Bluetooth device via the Internet. Based on this method, it is possible for a user to have seamless connection, by using ordinary Bluetooth applications, without the necessity of being conscious of the location of Bluetooth devices.

Proposal for an ad-hoc routing protocol considering traffic conditions and evaluation of UDP using a redundant route

We propose a new ad-hoc routing protocol named “PD-OLSR”(Protocol Dependent-OLSR) which makes the best of UDP and TCP, based on separate routing tables for UDP and TCP. It also enables the route selection to avoid network congestion, considering traffic conditions of nodes. In this paper, we show summary of PD-OLSR and performance evaluation. As a result of simulation, we confirmed that there are cases where we can get better performance with an increased number of hops by taking a redundant route, rather than taking the shortest one.

Development and evaluation of a scheme for detecting multiple approaching vehicles through acoustic sensing

We propose a robust scheme for detecting vehicles approaching from several directions to prevent crossing collisions. The scheme consists of three sequential operations. The first operation computes cross-power spectrum phase (CSP) coefficients of sound signals from a microphone array; the second operation classifies the information obtained by the CSP coefficients into multiple ranges of directions so as to separate multiple approaching vehicles. The last one detects approaching vehicles through a threshold operation of the clustered information. In order to evaluate the performance of the scheme, we constructed a large-scale database based on the acoustic and related information concerned with approaching vehicles. Using the database, we show that the scheme is robust for detecting not only a single but also multiple approaching vehicles.

Secure in-vehicle systems against Trojan attacks

Recently, driving support technologies, such as inter-vehicle and road-to-vehicle communication technologies, have been practically used. However, a problem has been pointed out that when a vehicle is connected with an external network, the safety of the vehicle is threatened. As a result, the security of vehicle control systems, which greatly affects vehicle safety, has become more important than ever. Ensuring the security of in-vehicle systems becomes an important priority, similar to ensuring conventional safety. The present study proposes a controller area network (CAN) communications method that uses a lightweight cipher to realize secure in-vehicle systems. The present study also constructs an evaluation system using a field-programmable gate array (FPGA) board and a radio-controlled car. This is used to verify the proposed method.

Electromagnetic analysis attack for a lightweight block cipher TWINE

The threat of electromagnetic analysis attacks against cryptographic circuits has been highlighted. Electromagnetic analysis attacks maliciously analyze confidential information using electromagnetic waves generated during the operation of a cryptographic circuit. At present, many studies have reported on electromagnetic analysis attacks against AES. However, few studies have investigated electromagnetic analysis attacks against lightweight ciphers. To secure the safety of a device to which a lightweight cipher is applied, measures against electromagnetic analysis attacks must be developed. To examine the measures taken to prevent electromagnetic analysis attacks, it is important to first evaluate and verify the vulnerability of a lightweight cipher against those types of attacks. This study propose a new electromagnetic analysis attack for a lightweight block cipher TWINE which is one of the most popular lightweight block ciphers.

Secure in-vehicle Systems using Authentication

Recently, driving support technologies have been practically used. However, a problem has been pointed out that when a vehicle is connected with an external network, the safety of the vehicle is threatened. Ensuring the security of in-vehicle systems becomes an important priority. The present study proposes a CAN communications method that uses a lightweight block cipher to realize secure in-vehicle systems. Experiments using both FPGA and a radiocontrolled car verify the proposed method.

Proposal for a wireless sensor network visualization system using location estimation technology

In recent years, popularization of wireless sensor networks in various fields including smart houses and environment monitoring systems at factories has been expected. However, it is difficult to grasp the structure and connectivity of dynamically changing networks, because sensor networks are connected by radio waves with each other. For that reason, it will be useful if the location of sensor devices and the structure of wireless sensor networks can be confirmed by visual observation at the time of maintenance or troubleshooting. In this paper, we propose a visualization system for wireless sensor networks using a tablet and location estimation technology. In our proposed system, we make it possible to observe the wireless sensor networks by eyes, by displaying the virtual object representing sensor device link information and sensing data, on the screen of the tablet whose location is estimated. We confirmed that the virtual object is superimposedly displayed in the sensor device on the camera screen, by implementing to iPad a prototype of the algorithm to estimate the locational relationship between the tablet and sensor devices.

Multiple Rounds Aware Power Analysis Attack for a Lightweight Cipher SIMECK

Information obtained through sensors and accumulated in wearable computers can be used as big data. To ensure the safety of this information, the security of wearable computers has become more important than ever before. However, the AES that has been widely used cannot be applied to wearable computers due to the size of the embedment area in those devices. Therefore, lightweight ciphers that can be embedded using small areas have begun to be studied. When a cryptographic circuit is used, it is extremely important to examine the measures taken to safeguard against power analysis attack. However, no study has reported on the attack against SIMECK which can be embedded in the smallest-scale circuit among lightweight ciphers. The present study proposes a method for performing power analysis attacks against SIMECK. To our knowledge, this is the first power analysis attack on SIMECK. Experiments using FPGA proved the validity of the proposed method.

Study on intelligibility improvement method based on subband waveform processing focusing on dynamic feature of speech

This paper describes intelligibility improvement method for speech signal based on subband waveform processing. Our approach is based on the observation that clear speech has higher delta-cepstrum value in transient parts between phonemes, and emphasizes delta-cepstrum of input speech by a filter in the cepstral domain which amplifies a particular modulation frequency. However, since this approach generates synthetic sound by using an analysis/synthesis system, quality of the generated sound is sometimes degraded. To prevent this degradation, a subband waveform-based method is introduced. This method divides an input signal into several subband signals by a quadrature mirror filter (QMF) which approximately enables perfect reconstruction of input signal from the subband signals, converts an amplification gain sequence in the cepstral domain into that in the subband-waveform domain, and then multiplies the converted amplification gain sequence to the subband signal on a sample-by-sample basis. Synthetic so...