Fractional sampling (FS) and Doppler diversity equalization in OFDM receivers can achieve two types of diversity (path diversity and frequency diversity) simultaneously on time-varying multipath channels. However FS with a higher sampling rate requires the large amount of complexity in demodulation. In this paper, a novel sampling point selection (SPS) scheme with MMSE equalization in FS-OFDM receivers is proposed. On fast time-varying multipath channels, the proposed scheme selects the appropriate samples from the fractionally sampled signals. Through the computer simulation, it is demonstrated that with the proposed scheme, both path diversity gain and Doppler diversity gain can increase as compared to a conventional non-SPS scheme.

In this paper, we investigate two receiver structures for spatially multiplexed transmission on MIMO frequency selective fading channels. Those receivers compensate the IAI (Inter-Antenna Interference) and ISI (Inter-Symbol Interference) in the time domain. We first propose the MIMO sequential equalizer in which the block of several receives symbols is processed symbol by symbol by MLD (Maximum Likelihood Detection). Next we investigate the MIMO MLSE (Maximum Likelihood Sequence Estimation) receiver in which the terminated block trellis is decoded by the Viterbi algorithm. The bit error rates of two time domain receivers are examined through computer simulations and we also compare their BER characteristics to those of the conventional MIMO SC-FDE.

Delay Tolerant Networks (DTNs) are a class of emerging networks that experience frequent and long-duration partitions. Delay is inevitable in DTNs, so ensuring the validity and reliability of the message transmission and making better use of buffer space are more important than concentrating on how to decrease the delay. In this paper, we present a novel routing protocol named Location and Direction Aware Priority Routing (LDPR) for DTNs, which utilizes the location and moving direction of nodes to deliver a message from source to destination. A node can get its location and moving direction information by receiving beacon packets periodically from anchor nodes and referring to received signal strength indicator (RSSI) for the beacon. LDPR contains two schemes named transmission scheme and drop scheme, which take advantage of the nodes' information of the location and moving direction to transmit the message and store the message into buffer space, respectively. Each message, in addition, is branded a certain priority according to the message's attributes (e.g. importance, validity, security and so on). The message priority decides the transmission order when delivering the message and the dropping sequence when the buffer is full. Simulation results show that the proposed LDPR protocol outperforms epidemic routing (EPI) protocol, prioritized epidemic routing (PREP) protocol, and DTN hierarchical routing (DHR) protocol in terms of packet delivery ratio, normalized routing overhead and average end-to-end delay. It is worth noting that LDPR doesn't need infinite buffer size to ensure the packet delivery ratio as in EPI. In particular, even though the buffer size is only 50, the packet delivery ratio of LDPR can still reach 93.9%, which can satisfy general communication demand. We expect LDPR to be of greater value than other existing solutions in highly disconnected and mobile networks.

In next-generation mobile communications, it is important to improve the throughput of the cell edge as well as that of the whole cell. Multi-link transmission from two adjacent BSs has been studied for improving the throughput at the cell edge in OFDM-based cellular systems, which are major candidates for next-generation mobile communication systems. In multi-link transmission, an MS at a cell edge receives signals from both adjacent BSs by orthogonally multiplexing those signals in the frequency domain. Therefore, the cell-edge MS can utilize the frequency and power resources of both adjacent BSs, which improves the cell-edge throughput. However, when the received timing difference between the signals from both BSs exceeds the maximum permissible value, adjacent-channel interference is caused by the collapse of the orthogonality. In this paper, to resolve this issue, we propose a novel timing-offset interference canceller. To clarify the performance of the proposed canceller, this paper evaluates its performance with respect to the residual interference power and the BER by computer simulation.

Threshold testing, which is an LSI testing method based on the acceptability of faults, is effective in yield enhancement of LSIs and selective hardening for LSI systems. In this paper, we propose test generation models for threshold test generation. Using the proposed models, we can efficiently identify acceptable faults and generate test patterns for unacceptable faults with a general test generation algorithm, i.e., without a test generation algorithm specialized for threshold testing. Experimental results show that our approach is, in practice, effective.

Estimating the ratio of two probability density functions (a.k.a. the importance) has recently gathered a great deal of attention since importance estimators can be used for solving various machine learning and data mining problems. In this paper, we propose a new importance estimation method using a mixture of probabilistic principal component analyzers. The proposed method is more flexible than existing approaches, and is expected to work well when the target importance function is correlated and rank-deficient. Through experiments, we illustrate the validity of the proposed approach.

In delay tolerant networks, energy efficient forwarding algorithms are significant to enhance the performance of message transmission probability. In this paper, we focus on the problem of optimal probabilistic epidemic forwarding with energy constraint. By introducing a continuous time model, we obtain the optimal static and dynamic policies for multi-messages forwarding. Extensive numerical results show that the optimal dynamic policy achieves higher transmission probability than the optimal static policy while the number of messages decreases the average transmission probability.

Although the probabilistic model checking tool called PRISM has been applied in many communication systems, such as wireless local area network, Bluetooth, and ZigBee, the technique is not used in a controller area network (CAN). In this paper, we use PRISM to model the mechanism of priority messages for CAN because the mechanism has allowed CAN to become the leader in serial communication for automobile and industry control. Through modeling CAN, it is easy to analyze the characteristic of CAN for further improving the security and efficiency of automobiles. The Markov chain model helps us to model the behaviour of priority messages.

This paper presents an approach to implementing simulation models for SAM fuzzy controllers without the use of external components. The approach represents a fuzzy controller as a composition of simple simulation models which involve only basic operations.

A high directivity microstrip coupler suppressing leak coupling with a cancellation circuit of a Wilkinson divider is presented. The presented coupler utilizes a cancellation circuit between a coupling port and an isolation port of the conventional microstrip coupler to enhance the isolation. The cancellation circuit consists of the Wilkinson divider, the multistage attenuator, and the phase offset line. The frequency to enhance the isolation is controlled by the attenuators. As the directivity is improved without the modification of the conventional coupler, the cancellation circuit can be applied to the fabricated conventional couplers. The measured directivity of the presented 1/18 λ coupler is improved from 4.8 dB to 43.0 dB at 2.6 GHz, compared with the conventional 1/4 λ coupler with -20 dB coupling. Simultaneously, the 27.4% relative bandwidth with the 20 dB directivity is achieved.

The BCH code is one of the well-known error correction codes and its decoding contains many operations in Galois field. These operations require many instruction steps or large memory area for look-up tables on ordinary processors. While dedicated hardware BCH decoders achieves higher decoding speed than software, the advantage of software decoding is its flexibility to decode BCH codes of variable parameters. In this paper, an auxiliary circuit to be embedded in a pipelined processor is proposed which accelerates software decoding of various BCH codes.

In this letter, we propose a novel approach to human activity recognition. We present a class of features that are robust to the tilt of the attached sensor module and a state transition model suitable for HMM-based activity recognition. In addition, postprocessing techniques are applied to stabilize the recognition results. The proposed approach shows significant improvements in recognition experiments over a variety of human activity DB.

This paper treats a band-broadening design technique of a dual-band branch-line coupler with matching networks composed of an impedance step and a short-circuited stub based on the equivalent admittance approach. By replacing each right-handed transmission line (RH-TL) with a composite right/left-handed transmission line (CRLH-TL), very flat couplings over a relative bandwidth of about 10% can be obtained at two arbitrary operating frequencies in comparison with previous CRLH-TLs branch-line couplers. Furthermore, by adding periodical open-circuited stubs into RH-TLs of the designed CRLH-TLs branch-line coupler with matching networks, the entire size of the coupler can be reduced to about 50%. Verification of these band-broadening and size-reduction design techniques can be also shown by an electromagnetic simulation and experiment.

This paper describes a black-box model of mixed analog-digital VLSI circuits for the prediction of microcontroller electromagnetic emissions without disclosure of manufacturer data. The model is based on small-signal simulations performed at the analog and digital building-block level, considering also layout and technology parameters, and modeling the parasitic substrate coupling paths and the interconnects. The developed model allows system designers to predict the impact of microcontroller operation on the system-level EMEs by carrying out low-time consuming simulations in the early design phases of their products thus minimizing unnecessary costs and scheduling delays. In this paper, the black-box model of an 8-bit microcontroller is described and it is employed to predict the conducted emission delivered through the input-output ports.

Micro-gap electrostatic discharge (ESD) events due to a human with charge voltages below 1000 V cause serious malfunctions in high-tech information devices. For clarifying such a mechanism, it is indispensable to grasp the spark process of such micro-gap ESDs. For this purpose, two types of spark-resistance laws proposed by Rompe-Weizel and Toepler have often been used, which were derived from the hypotheses that spark conductivity be proportional to the internal energies and charges injected into a spark channel, respectively. However, their validity has not well been verified. To examine which spark-resistance formula could be applied for micro-gap ESDs, with a 12-GHz digital oscilloscope, we previously measured the discharge currents through the hand-held metal piece from a charged human with respect to charged voltages of 200 V and 2000 V, and thereby derived the conductance of a spark gap to reveal that both of their hypotheses are roughly valid in the initial stage of sparks. In this study, to further verify the above spark hypotheses, we derived the discharge voltages in closed forms across a spark gap based on the above spark-resistance formulae, and investigated which spark-resistance formula could be applied for micro-gap ESDs in comparison of spark gaps estimated from the measured discharge currents. As a result, we found that Rompe-Weizel's formula could well explain spark properties for micro-gap ESDs than Toepler's one regardless of charge voltages and approach speeds.

This paper presents a fast method capable of accelerating the Smith-Waterman algorithm for biological database search on a cluster of graphics processing units (GPUs). Our method is implemented using compute unified device architecture (CUDA), which is available on the nVIDIA GPU. As compared with previous methods, our method has four major contributions. (1) The method efficiently uses on-chip shared memory to reduce the data amount being transferred between off-chip video memory and processing elements in the GPU. (2) It also reduces the number of data fetches by applying a data reuse technique to query and database sequences. (3) A pipelined method is also implemented to overlap GPU execution with database access. (4) Finally, a master/worker paradigm is employed to accelerate hundreds of database searches on a cluster system. In experiments, the peak performance on a GeForce GTX 280 card reaches 8.32 giga cell updates per second (GCUPS). We also find that our method reduces the amount of data fetches to 1/140, achieving approximately three times higher performance than a previous CUDA-based method. Our 32-node cluster version is approximately 28 times faster than a single GPU version. Furthermore, the effective performance reaches 75.6 giga instructions per second (GIPS) using 32 GeForce 8800 GTX cards.

One of the important technologies for the Future Internet is the delay-tolerant network, which enables data transfers even when mobile nodes are connected intermittently. Routing algorithms for a delay-tolerant network generally aim to increase the message delivery rate and decrease the number of forwarded messages in the situation of an intermittent connection. A fame-based strategy for delay-tolerant network routing is suggested in this work. The number of contacts of a node with other nodes, known as the fame degree in this work, is counted to rank the fame degree of the node. By utilizing the fame degree, the proposed routing algorithm determines the probability of forwarding the messages of a node to the contact node. Due to the characteristics of the proposed algorithm, it can be combined harmonically with the PROPHET routing algorithm. Through experiments on well-known benchmark datasets, the proposed algorithms shows better delivery rates with much lower number of forwarded messages and lower average hop counts of delivered messages compared to Epidemic, PROPHET and SimBet.

Control Area Network (CAN) development began in 1983 and continues today. The forecast for annual world production in 2008 is approximately 65-67 million vehicles with 10-15 CAN nodes per vehicle on average . Although the CAN network is successful in automobile and industry control because the network provides low cost, high reliability, and priority messages, a starvation problem exists in the network because the network is designed to use a fixed priority mechanism. This paper presents a priority inversion scheme, belonging to a dynamic priority mechanism to prevent the starvation problem. The proposed scheme uses one bit to separate all messages into two categories with/without inverted priority. An analysis model is also constructed in this paper. From the model, a message with inverted priority has a higher priority to be processed than messages without inverted priority so its mean waiting time is shorter than the others. Two cases with and without inversion are implemented in our experiments using a probabilistic model checking tool based on an automatic formal verification technique. Numerical results demonstrate that low-priority messages with priority inversion have better expression in the probability in a full queue state than others without inversion. However, our scheme is very simple and efficient and can be easily implemented at the chip level.

A direct-conversion receiver integrated with the CMOS subharmonic frequency tripler (SFT) for V-band applications is designed, fabricated and measured using 0.13-µm CMOS technology. The receiver consists of a low-noise amplifier, a down-conversion mixer, an output buffer, and an SFT. A fully differential SFT is introduced to relax the requirements on the design of the frequency synthesizer. Thus, the operational frequency of the frequency synthesizer in the proposed receiver is only 20 GHz. The fabricated receiver has a maximum conversion gain of 19.4 dB, a minimum single-side band noise figure of 10.2 dB, the input-referred 1-dB compression point of -20 dBm and the input third order inter-modulation intercept point of -8.3 dB. It draws only 15.8 mA from a 1.2-V power supply with a total chip area of 0.794 mm0.794 mm. As a result, it is feasible to apply the proposed receiver in low-power wireless transceiver in the V-band applications.

Designing ship controllers is a challenging problem because of nonlinear dynamics, uncertainty in parameters and external disturbances. Furthermore, the interaction between yaw and roll angles increase the complexity of this issue when autopilot and roll stabilizer are considered together. In this research, a MIMO sliding mode controller is designed to control yaw and roll angles simultaneously. The major contribution of the paper is designing an integrated controller based on a nonlinear model of ship as well as considering analytic bounds of uncertainties. Then, in order to reduce the chattering phenomenon and to improve the tracking ability of the system, the control scheme has been modified using an integral switching variable. Simulation results show the success of the proposed method to overcome nonlinearity and disturbances, as well as high performance in rough wave conditions. Also, comparison between the proposed controller and two SISO control schemes demonstrates advantages of the integrated control method.