Showing papers in "IEICE Transactions on Communications in 2011"
TL;DR: The length dependence of the crosstalk in multi-core fibers has been investigated by introducing random fluctuation along longitudinal direction and the power coupling coefficients in the coupled-power theory in heterogeneous multi- core fiber with seven cores were estimated.
Abstract: The length dependence of the crosstalk in multi-core fibers has been investigated by introducing random fluctuation along longitudinal direction. The power coupling coefficients in the coupled-power theory in heterogeneous multi-core fiber with seven cores were estimated based on consideration of the power coupling coefficients of the homogeneous multi-core fiber. The crosstalk can be quantitatively evaluated by employing coupled-power theory instead of coupled-mode theory.
122 citations
TL;DR: This survey summarizes the state-of-the-art research on network coding, mainly focusing on its applications to computer networking, and provides a taxonomy of network coding research, i.e., the network coding design problem and network coding applications.
Abstract: SUMMARY This survey summarizes the state-of-the-art research on network coding, mainly focusing on its applications to computer networking. Network coding generalizes traditional store-and-forward routing techniques by allowing intermediate nodes in networks to encode several received packets into a single coded packet before forwarding. Network coding was proposed in 2000, and since then, it has been studied extensively in the field of computer networking. In this survey, we first summarize linear network coding and provide a taxonomy of network coding research, i.e., the network coding design problem and network coding applications. Moreover, the latter is subdivided into throughput/capacity enhancement, robustness enhancement, network tomography, and security. We then discuss the fundamental characteristics of network coding and diverse applications of network coding in details, following the above taxonomy.
75 citations
TL;DR: By numerical analysis, it is shown that the proposed distributed mobility schemes can give better performance than the existing centralized scheme in terms of the binding update and packet delivery costs, and that SD-PMIP provides the best performance among the proposed distribution schemes.
Abstract: In future mobile networks, the ever-increasing loads imposed by mobile Internet traffic will force the network architecture to be changed from hierarchical to flat structure. Most of the existing mobility protocols are based on a centralized mobility anchor, which will process all control and data traffic. In the flat network architecture, however, the centralized mobility scheme has some limitations, such as unwanted traffic flowing into the core network, service degradation by a single point of failure, and increased operational costs, etc. This paper proposes mobility schemes for distributed mobility control in the flat network architecture. Based on the Proxy Mobile IPv6 (PMIP), which is a well-known mobility protocol, we propose the three mobility schemes: Signal-driven PMIP (S-PMIP), Data-driven Distributed PMIP (DD-PMIP), and Signal-driven Distributed PMIP (SD-PMIP). By numerical analysis, we show that the proposed distributed mobility schemes can give better performance than the existing centralized scheme in terms of the binding update and packet delivery costs, and that SD-PMIP provides the best performance among the proposed distributed schemes.
44 citations
TL;DR: Key features of the first prototype of the BMI system for clinical application, which includes many new technologies such as two 64-channel integrated analog amplifier chips, a Bluetooth wireless data transfer circuit, a wirelessly rechargeable battery, 3 dimensional tissue-fitting high density electrodes, a titanium head casing, and a fluorine polymer body casing are described.
Abstract: The brain-machine interface (BMI) is a new method for man-machine interface, which enables us to control machines and to communicate with others, without input devices but directly using brain signals. Previously, we successfully developed a real time control system for operating a robot arm using brain-machine interfaces based on the brain surface electrodes, with the purpose of restoring motor and communication functions in severely disabled people such as amyotrophic lateral sclerosis patients. A fully-implantable wireless system is indispensable for the clinical application of invasive BMI in order to reduce the risk of infection. This system includes many new technologies such as two 64-channel integrated analog amplifier chips, a Bluetooth wireless data transfer circuit, a wirelessly rechargeable battery, 3 dimensional tissue-fitting high density electrodes, a titanium head casing, and a fluorine polymer body casing. This paper describes key features of the first prototype of the BMI system for clinical application.
42 citations
TL;DR: A method to construct bit-interleaved coded modulation with iterative demapping and decoding (BICM-ID) is developed that approaches the Shannon limit very closely at high spectrum efficiency.
Abstract: A method to construct bit-interleaved coded modulation with iterative demapping and decoding (BICM-ID) is developed that approaches the Shannon limit very closely at high spectrum efficiency, where amplitude-phase shift keying (APSK) constellations are designed and chosen. For 1/2-rate 64APSK, the Es/N0 threshold derived through extrinsic information transfer (EXIT) charts is less than 0.55dB away from the Shannon limit of the continuous-input additive white Gaussian noise (AWGN) channel, and exceeds the theoretical limit constrained by standard 64QAM-input.
34 citations
TL;DR: Using such an RF power imager, the power distributions of even impulsive RF signals and/or noises can be captured and visualized in situ and in real-time, while the electromagnetic environment is almost undisturbed by the EBG absorber.
Abstract: A thin electromagnetic band-gap (EBG) absorber is employed to capture the 2-d image of radio-frequency (RF) power distribution. The EBG absorber consists of an array of mushroom unit cells formed on a thin dielectric substrate with a metal backplane, and lumped resistors interconnecting the surface patches of the mushrooms. Around the resonance frequency at which the EBG structure acts as a high-impedance surface, the RF power incident on the surface is absorbed by the lumped resistors which are matched with the incident wave impedance. By detecting directly the amounts of power consumed by the individual resistors, an “RF power imager” can be constructed which captures the 2-d distribution of the RF power illuminating the EBG surface, where polarization discrimination is possible. The resonance (i.e., absorption) frequency is made tunable by adding varactor diodes in parallel with the lumped resistors. The EBG absorber tunable in the frequency range of 700 MHz–2.7 GHz is designed and fabricated, and its performance is evaluated by an equivalent-circuit analysis, simulation and measurement. It is shown that the small resistance of the varactors have a considerable effect on the absorption performance. RF power distributions radiated from a dipole antenna are successfully measured by a matrix of sensitive power detectors installed on the backside of the absorber. Using such an RF power imager, the power distributions of even impulsive RF signals and/or noises can be captured and visualized in situ and in real-time, while the electromagnetic environment is almost undisturbed by the EBG absorber. key words: EBG, absorber, RF power distribution, measurement, imaging
33 citations
TL;DR: A self-scheduling multi-channel cognitive MAC protocol that allows multiple secondary users to transmit data though the sensed idle channels by two cooperative channel sensing algorithms, i.e., fixed channel sensing and adaptive channel sensing, and by slotted contention mechanism to exchange channel request information for self- scheduling.
Abstract: As the demand for spectrum for future wireless communication services increases, cognitive radio technology has been developed for dynamic and opportunistic spectrum access, which enables the secondary users to use the underutilized licensed spectrum of the primary users. In particular, the recent studies on the MAC protocol for dynamic and opportunistic access have focused on sensing and using the vacant spectrum efficiently. Under the ad-hoc network environment, how the secondary users use the unused channels by the primary users affects the efficient utilization of channels and a cognitive radio system is required to follow the rapid and frequent changes in channel status. In this paper, we propose a self-scheduling multi-channel cognitive MAC (SMC-MAC) protocol, which allows multiple secondary users to transmit data though the sensed idle channels by two cooperative channel sensing algorithms, i.e., fixed channel sensing (FCS) and adaptive channel sensing (ACS), and by slotted contention mechanism to exchange channel request information for self-scheduling. The performance of the proposed SMC-MAC protocol is investigated via analysis and simulations. According to the results, the proposed SMC-MAC protocol is effective in allowing multiple secondary users to transmit data frames effectively on multi-channels and adaptively in response to the primary users' traffic dynamics.
31 citations
TL;DR: The motivations, concept, architecture, system configuration, and preliminary performance results of NerveNet, a conceptual regional wireless access platform in which multiple service providers provide their own services with shared use of the network and sensors, enabling a range of context-aware services.
Abstract: Wireless access networks of the future could provide a variety of context-aware services with the use of sensor information in order to solve regional social problems and improve the quality of residents' lives as a part of the regional infrastructure. NerveNet is a conceptual regional wireless access platform in which multiple service providers provide their own services with shared use of the network and sensors, enabling a range of context-aware services. The platform acts like a human nervous system. Densely located, interconnected access points with databases and data processing units will provide mobility to terminals without a location server and enable secure sensor data transport on a highly reliable, managed mesh network. This paper introduces the motivations, concept, architecture, system configuration, and preliminary performance results of NerveNet.
26 citations
TL;DR: The paper shows that the special impacting filter satisfies the above assumption, therefore, in the frame of binary detection theory, the excellent performance of high-efficiency EBPSK system can be explained and the correction of the theoretical BER formula can be validated.
Abstract: The extended binary phase shift keying (EBPSK) transmission system with ultra narrow bandwidth has excellent BER performance, which raises many doubts with the researchers. Therefore, on the premise of the existence of a special filter that can transform the modulated phase information into amplitude information, the theoretical BER formula of EBPSK system in Additive White Gaussian Noise (AWGN) channel has been deduced. This paper gives the theoretical values of the parameters in the above BER formula and discusses the effects of parameters on BER firstly. Then the paper shows that the special impacting filter satisfies the above assumption, therefore, in the frame of binary detection theory, the excellent performance of high-efficiency EBPSK system can be explained and the correction of the theoretical BER formula can be validated.
25 citations
TL;DR: Computer simulations verify the proposed signaling could outperform the S1 signaling and achieve similar robustness as the S2 signaling of the DVB-T2 standard.
Abstract: In this letter, a novel physical layer signaling transmission scheme is proposed, where the signaling information is conveyed by a pair of training sequences located in the odd and even subcarriers of an orthogonal frequency division multiplexing (OFDM) training symbol. At the receiver side, only a single correlator is required to detect the signaling information. Computer simulations verify the proposed signaling could outperform the S1 signaling and achieve similar robustness as the S2 signaling of the DVB-T2 standard.
24 citations
TL;DR: An effective algorithm, based on the filtered backprojection (FBP) approach, for the imaging of vegetation, with significant speed-ups are obtained by a parallel versions of the NUFFT algorithm, purposely designed to be run on Graphic Processing Units (GPUs) by using the CUDA language.
Abstract: We develop an effective algorithm, based on the filtered backprojection (FBP) approach, for the imaging of vegetation. Under the FBP scheme, the reconstruction amounts at a non-trivial Fourier inversion, since the data are Fourier samples arranged on a non-Cartesian grid. The computational issue is efficiently tackled by Non-Uniform Fast Fourier Transforms (NUFFTs), whose complexity grows asymptotically as that of a standard FFT. Furthermore, significant speed-ups, as compared to fast CPU implementations, are obtained by a parallel versions of the NUFFT algorithm, purposely designed to be run on Graphic Processing Units (GPUs) by using the CUDA language. The performance of the parallel algorithm has been assessed in comparison to a CPU-multicore accelerated, Matlab implementation of the same routine, to other CPU-multicore accelerated implementations based on standard FFT and employing linear, cubic, spline and sinc interpolations and to a different, parallel algorithm exploiting a parallel linear interpolation stage. The proposed approach has resulted the most computationally convenient. Furthermore, an indoor, polarimetric experimental setup is developed, capable to isolate and introduce, one at a time, different non-idealities of a real acquisition, as the sources (wind, rain) of temporal decorrelation. Experimental far-field polarimetric measurements on a thuja plicata (western redcedar) tree point out the performance of the set up algorithm, its robustness against data truncation and temporal decorrelation as well as the possibility of discriminating scatterers with different features within the investigated scene.
TL;DR: This paper presents an overview of radio interface technologies for cooperative transmission in 3GPP LTE-Advanced, i.e., coordinated multi-point (CoMP) transmission, enhanced inter-cell interference coordination (eICIC) for heterogeneous deployments, and relay transmission techniques.
Abstract: This paper presents an overview of radio interface technologies for cooperative transmission in 3GPP LTE-Advanced, i.e., coordinated multi-point (CoMP) transmission, enhanced inter-cell interference coordination (eICIC) for heterogeneous deployments, and relay transmission techniques. This paper covers not only the technical components in the 3GPP specifications that have already been released, but also those that were discussed in the Study Item phase of LTE-Advanced, and those that are currently being discussed in 3GPP for potential specification in future LTE releases.
TL;DR: Six human movement simulation by a commercial software (Poser7) and FDTD simulations for body area network propagation with one transmitter and six receivers demonstrate a polarization diversity effectiveness for dynamic wearable body Area network propagation.
Abstract: In this paper, we performed six human movement simulation by a commercial software (Poser7). We performed FDTD simulations for body area network propagation with one transmitter and six receivers. Received amplitudes were calculated for every time frame of 1/30s interval. We also demonstrated a polarization diversity effectiveness for dynamic wearable body area network propagation.
TL;DR: It is found that the corrugation transforms the current of parallel line mode to theCurrent of traveling wave radiation mode and the effective aperture is enlarged which yields high gain characteristics.
Abstract: Antipodal Fermi antenna (APFA) that uses an antipodal feeding section is proposed and its fundamental characteristics are presented. It is shown that the cross polarization level is decreased by 5-10dB by the presence of the corrugation. It is also found that high gain, low VSWR and low side lobes and low back lobes are obtained. The mechanism of operation principles is discussed by using FDTD analysis. It is found that the corrugation transforms the current of parallel line mode to the current of traveling wave radiation mode and the effective aperture is enlarged which yields high gain characteristics.
TL;DR: For the easy design of very small normal-mode helical antennas, an equation that helps determine the self-resonant structures of these antennas is developed and the expression for the capacitance of an NMHA is established.
Abstract: For the easy design of very small normal-mode helical antennas (NMHAs), an equation that helps determine the self-resonant structures of these antennas is developed. For this purpose, the expression for the capacitance of an NMHA is established. The accuracy of this design equation is confirmed by comparing the results obtained using the equation with the simulation results.
TL;DR: This paper describes an ultra-high capacity WDM transmission experiment, in which high speed polarization-division multiplexed (PDM) 16-ary quadrature amplitude modulation (16-QAM), generated by an optical synthesis technique, in combination with coherent detection based on digital signal processing with pilotless algorithms, realize the high spectral efficiency (SE) of 6.4b/s/Hz.
Abstract: This paper describes ultra-high capacity wavelength-division multiplexed (WDM) transmission technologies for 100-Tbit/s-class optical transport networks (OTNs). First, we review recent advances in ultra-high capacity transmission technologies focusing on spectrally-efficient multi-level modulation techniques and ultra-wideband optical amplification techniques. Next, we describe an ultra-high capacity WDM transmission experiment, in which high speed polarization-division multiplexed (PDM) 16-ary quadrature amplitude modulation (16-QAM), generated by an optical synthesis technique, in combination with coherent detection based on digital signal processing with pilotless algorithms, realize the high spectral efficiency (SE) of 6.4b/s/Hz. Furthermore, ultra-wideband hybrid optical amplification utilizing distributed Raman amplification (DRA) and C- and extended L-band erbium-doped fiber amplifiers (EDFAs) is shown to realize 10.8-THz total signal bandwidth. By using these techniques, 69.1-Tbit/s transmission is demonstrated over 240-km of pure silica-core fibers (PSCFs). Furthermore, we describe PDM 64-QAM transmission over 160km of PSCFs with the SE of 9.0b/s/Hz.
TL;DR: Various types of planar folded dipole antenna with a feed line with broadband characteristics are introduced and analyzed theoretically and experimentally and their characteristics are analyzed.
Abstract: Various planar folded dipole antennas with feed lines are introduced and analyzed. With the added feed line, the planar folded dipole antenna has two resonance modes. Moreover, adjusting the spacing and width of the feed line improves the broadband characteristics of the antenna. The attached feed line has not only an impedance transforming characteristic but also a bandwidth transforming characteristic. The bandwidth transforming characteristic means that the feed line can broaden the bandwidth of folded dipole antenna. A way to reduce the antenna area is also studied, and the characteristics of the resulting compact antenna are analyzed.
TL;DR: In this paper, the authors proposed a full-duplex relay based on zero-forcing beamforming (ZFBF) for a multiuser MIMO system, where the ZFBF is employed at the base station to suppress both the self-interference of the relay and the multi-user interference at the same time.
Abstract: In this paper, we propose a full-duplex relay (FDR) based on a zero-forcing beamforming (ZFBF) for a multiuser MIMO system The ZFBF is employed at the base station to suppress both the self-interference of the relay and the multiuser interference at the same time Numerical results show that the proposed FDR can enhance the sum rate performance as compared to the half-duplex relay (HDR), if sufficient isolation between the transmit and receive antennas is ensured at the relay
TL;DR: This work proposes a novel localization scheme based on DV-Hop to improve positioning accuracy with least error hop sizes of anchors and averageHop sizes of unknowns and shows that the proposed algorithm outperforms the DV- Hop algorithm in location estimations.
Abstract: DV-Hop algorithm produces errors in location estimations due to inaccurate hop size. We propose a novel localization scheme based on DV-Hop to improve positioning accuracy with least error hop sizes of anchors and average hop sizes of unknowns. The least error hop size of an anchor minimizes its location error, but it may be far small or large. To cope with this inconsistent hop size, each unknown node calculates its average hop size with hop sizes from anchors. Simulation results show that the proposed algorithm outperforms the DV-Hop algorithm in location estimations.
TL;DR: A new spectrum sensing framework that combines a blind source separation technique with conventional spectrum sensing techniques is introduced that allows the cognitive transmitter to continue to transmit during spectrum sensing, if it was in operation in the previous frame.
Abstract: Cognitive radio (CR) is a key solution for the problem of inefficient usage of spectral resources. Spectrum sensing in each CR aims at detecting whether a preassigned spectrum band is occupied by a primary user or not. Conventional techniques do not allow the CR to communicate with its own base station during the spectrum sensing process. So, only a part of the frame can be used for cognitive data transmission. In this paper, we introduce a new spectrum sensing framework that combines a blind source separation technique with conventional spectrum sensing techniques. In this way, the cognitive transmitter can continue to transmit during spectrum sensing, if it was in operation in the previous frame. Moreover, the accuracy is improved since the decision made by the spectrum unit in each frame depends on the decision made in the previous frame. We use Markov chain tools to model the behavior of our spectrum sensing proposal and to derive the parameters that characterize its performance. Numerical results are provided to confirm the superiority of the proposed technique compared to conventional spectrum sensing techniques.
TL;DR: This paper developed a new safety support system for children on school routes by using a mobile ad hoc network constructed from mobile phones with the Bluetooth function and evaluated the performance of grouping and the effectiveness of the approach.
Abstract: One of the most important duties of government is to maintain safety. In 2007, the Ministry of Internal Affairs and Communications of Japan tested 16 different models of a safety support system for children on school routes. One of the models was constructed and tested at a school in an area of the city of Hiroshima from September to December of 2007. A consortium was established by the city of Hiroshima; Hiroshima City University; Chugoku Electric Power Co., Inc.; and KDDI Corporation to conduct this project. For the model project, we developed a new safety support system for children on school routes by using a mobile ad hoc network constructed from mobile phones with the Bluetooth function. About 500 students and 50 volunteers used this system for four months. The support system provided good performance and accuracy in maintaining the safety of students on the way to school [7]. The basic idea of the safety support system is the grouping of children and volunteers using a mobile ad hoc network. In this paper, we present an outline of this system and evaluate the performance of grouping and the effectiveness of our approach.
TL;DR: Transoceanic WDM transmission of a pre-filtered polarization division multiplexed return-to-zero quaternary phased shift keying modulation format with multi-symbol detection is demonstrated, achieving 419% SE which is higher than the SE limit of the original memory-less PDM-RZ-QPSK format.
Abstract: We review our recent work on ultra-long-haul wavelength division multiplexed (WDM) transmission with high spectral efficiency (SE) employing tight pre-filtering and multi-symbol detection. We start the discussion with a theoretical evaluation of the SE limit of pre-filtered modulation in optical fiber communication systems. We show that pre-filtering induced symbol correlation generates a modulation with memory and thus, a higher SE limit than that of the original memory-less modulation. We also investigate the merits of utilizing the pre-filtering induced symbol correlation with multi-symbol detection to achieve high SE transmission. We demonstrate transoceanic WDM transmission of a pre-filtered polarization division multiplexed return-to-zero quaternary phased shift keying (PDM-RZ-QPSK) modulation format with multi-symbol detection, achieving 419% SE which is higher than the SE limit of the original memory-less PDM-RZ-QPSK format.
TL;DR: Experimental results show that the proposed scheme outperforms the recently developed DVC algorithms.
Abstract: We propose an efficient selective block encoding scheme with motion information feedback in distributed video coding (DVC). The proposed scheme estimates the spatial and temporal matching costs for each block in the side information (SI) and for the blocks with high matching costs, the motion information is provided to the encoder side to selectively encode the motion-compensated frame difference signal. Experimental results show that the proposed scheme outperforms the recently developed DVC algorithms.
TL;DR: In this article, the authors describe the optical transmission technologies that have been developed for SHV inter-equipment connects and links between outdoor sites and broadcasting stations, and present a detailed analysis of these technologies.
Abstract: ‘Super Hi-Vision’ (SHV) is promising as a future form of television. It is an ultra-high definition TV system that has 16 times the number of pixels of HDTV and employs a 22.2 multichannel sound system. It offers superior presence and gives the impression of reality. The information bitrates of the current prototypes range from 24 to 72Gbit/s, and a fiber optic transmission system is needed to transfer even just one channel. This paper describes the optical transmission technologies that have been developed for SHV inter-equipment connects and links between outdoor sites and broadcasting stations.
TL;DR: This letter derives another exact bit error rate (BER) for decode-and-forward (DF) relay systems over Rayleigh fading channels and extends the developed analytical method to adaptive-DF (ADF) schemes and the exact BER expressions are derived.
Abstract: In this letter, we derive another exact bit error rate (BER) for decode-and-forward (DF) relay systems over Rayleigh fading channels. At first, our focus is on fixed-DF (FDF) relay schemes in which the probability density function (PDF) is derived based on error-events at relay nodes. Some insight into how erroneous detection and transmission at relay nodes affect both the combined signal-to-noise ratio (SNR) and the averaged BER is obtained, and cooperative diversity is observed from the closed-form BER expression. In addition, the developed analytical method is extended to adaptive-DF (ADF) schemes and the exact BER expressions are derived. Simulation results are finally presented to validate the analysis.
TL;DR: This letter proposes a Partially Observable Markov Decision Process (POMDP) based Distributed Adaptive Opportunistic Spectrum Access (DA-OSA) Strategy for Cognitive Ad Hoc Networks (CAHNs) that uses the theories of sequential decision and optimal stopping to determine the optimal sensing channel set.
Abstract: In this letter, we propose a Partially Observable Markov Decision Process (POMDP) based Distributed Adaptive Opportunistic Spectrum Access (DA-OSA) Strategy for Cognitive Ad Hoc Networks (CAHNs). In each slot, the source and destination choose a set of channels to sense and then decide the transmission channels based on the sensing results. In order to maximize the throughput for each link, we use the theories of sequential decision and optimal stopping to determine the optimal sensing channel set. Moreover, we also establish the myopic policy and exploit the monotonicity of the reward function that we use, which can be used to reduce the complexity of the sequential decision.
TL;DR: A flexible emergency handling scheme for WBAN MAC protocols that can be applied to superframe-structured MAC protocols such as IEEE 802.15.4 and its extended versions is proposed.
Abstract: Wireless body area networks (WBANs) provide medical and/or consumer electronics (CE) services within the vicinity of a human body. In a WBAN environment, immediate and reliable data transmissions during an emergency situation should be supported for medical services. In this letter, we propose a flexible emergency handling scheme for WBAN MAC protocols. The proposed scheme can be applied to superframe-structured MAC protocols such as IEEE 802.15.4 and its extended versions. In addition, our scheme can be incorporated into the current working draft for IEEE 802.15.6 standards. Extensive simulations were performed and the low latency of emergent traffics was validated.
TL;DR: Simulation results show that the proposed RAMC protocol consistently achieves very high percentage of non-safety usage, while maintaining high safety message delivery ratios in various traffic density conditions.
Abstract: Dedicated Short Range Communication (DSRC) employs one control channel for safety-oriented applications and six service channels for non-safety commercial applications. However, most existing multi-channel schemes require all neighboring vehicles periodically (e.g. every 100 milliseconds) tune to the control channel for a full update of safety-oriented data before they can switch to the service channels for non-safety services. The safety exchange interval increases with the increase of traffic density. Consequently, under high traffic densities, the service channels are often completely idle while the control channel is congested. We propose a RSU Assisted Multi-channel Coordination MAC (RAMC) protocol that fully utilizes all channels to provide simultaneous safety and non-safety communications. Within the radio range of a roadside unit (RSU), vehicles are free to tune to any service channel. The RSU monitors all the safety messages being transmitted in both the control and service channels. Periodically, the RSU broadcasts a consolidated traffic view report to all neighboring vehicles in all channels. Therefore, a vehicle can operate in a service channel as long as it needs to achieve high throughput for non-safety applications, while maintaining adequate and timely safety awareness. Our simulation results show that the proposed RAMC protocol consistently achieves very high percentage of non-safety usage, while maintaining high safety message delivery ratios in various traffic density conditions.
TL;DR: A real-time traffic data collection policy based on the so-called “3R” philosophy, a unique vehicle classification method, and a reasonable traffic state quantification model are proposed to improve not only the effectiveness but also the scalability of the traffic state estimation model.
Abstract: SUMMARY This paper proposes a novel approach to traffic state estimation using mobile phones. In this work, a real-time traffic data collection policy based on the so-called “3R” philosophy, a unique vehicle classification method, and a reasonable traffic state quantification model are proposed. The “3R” philosophy, in which the Right data are collected by the Right mobile devices at the Right time, helps to improve not only the effectiveness but also the scalability of the traffic state estimation model. The vehicle classification method using the simple data collected by mobile phones makes the traffic state estimation more accurate. The traffic state quantification model integrates both the mean speed capacity and the density of a traffic flow to improve the comprehensibility of the traffic condition. The experimental results reveal the effectiveness as well as the robustness of the proposed solutions.
TL;DR: This paper proposes an extremely energy efficient layer-3 network architecture for the future Internet that combines the Service Cloud with the Cloud Router and application servers, with the Optical Aggregation Network realized by optical circuit switches, wavelength-converters, and wavelength-multiplexers/demultiplexers.
Abstract: The Internet is an extremely convenient network and has become one of the key infrastructures for daily life. However, it suffers from three serious problems; its structure does not suit traffic centralization, its power consumption is rapidly increasing, and its round-trip time (RTT) and delay jitter are large. This paper proposes an extremely energy efficient layer-3 network architecture for the future Internet. It combines the Service Cloud with the Cloud Router and application servers, with the Optical Aggregation Network realized by optical circuit switches, wavelength-converters, and wavelength-multiplexers/demultiplexers. User IP packets are aggregated and transferred through the Optical Aggregation Network to Cloud transparently. The proposed network scheme realizes a network structure well suited to traffic centralization, reduces the power consumption to 1/20-1/30 compared to the existing Internet, reduces the RTT and delay jitter due to its simplicity, and offers easy migration from the existing Internet.