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Yang S.-N.,Information and Communications Research Laboratories | Yang S.-N.,National Chiao Tung University | Wang H.-W.,National Chiao Tung University | Gan C.-H.,Information and Communications Research Laboratories | Lin Y.-B.,National Chiao Tung University
International Journal of Information Management | Year: 2013

With today's electric charging technology, charging time of an electric vehicle (EV) is much longer than that for a gasoline vehicle, and therefore the queueing effect at an EV charging station (CS) may be serious. That is, when an EV arrives at an overloaded CS, it is likely that the EV will wait for a long time before it is charged. This paper investigates the waiting problem for EV charging. We propose a Mobile CS (MCS) management system to dynamically distribute charging pole support that reduces the waiting times of EVs incurred in a fixed CS. A Mobile Charging Information Management System (MC-IMS) is presented to describe the execution flow of the MCS service. Simulation experiments are conducted to investigate the waiting time performance for the proposed mechanism. Our study indicates that the MCS-based MC-IMS provides effective EV charging with short waiting times. © 2012 Elsevier Ltd. All rights reserved.

Chow C.W.,National Chiao Tung University | Yeh C.H.,Information and Communications Research Laboratories | Lo S.M.G.,Chinese University of Hong Kong | Li C.,Chinese University of Hong Kong | Tsang H.K.,Chinese University of Hong Kong
Optics Express | Year: 2011

The integration of passive optical network (PON) and radio-over-fiber (ROF) networks could provide broadband services for both fixed and mobile users in a single and low-cost platform. Combining the long-reach (LR)-PON (>100 km) and the LR-ROF can further reduce the cost by simplifying the network architecture, sharing the same optical components and extending the coverage of ROF network. However, the transmission and distribution of ROF signal in LR network is very challenging due to the chromatic dispersion generated periodic power fading and code time-shifting effects in the optical fiber. In this work, we propose and experimentally demonstrate a LR-ROF signal distribution using single-sideband (SSB)-ROF signal generated by a silicon ring-modulator. The silicon modulator is compact and has low power consumption. Besides, one unique feature of the silicon ring-modulator is that it only modulates the signal wavelength at the resonant null. This makes it very suitable for the generation of the SSB-ROF signal. Numerical comparison of the SSB-ROF with the double-sideband (DSB)-ROF and optical carrier suppress (OCS)-ROF signals; as well as the fabrication of the silicon ring-modulator will be discussed. ©2011 Optical Society of America.

Yang S.-N.,Information and Communications Research Laboratories | Yang S.-N.,National Chiao Tung University | Cheng W.-S.,National Chiao Tung University | Hsu Y.-C.,Information and Communications Research Laboratories | And 2 more authors.
Mathematical and Computer Modelling | Year: 2013

Today, charging stations (CSs) for electric vehicles (EVs) are much less popular than gas stations. Therefore, searching and selecting CSs is an important issue for the drivers of EVs. This paper investigates the EV charging problem. We propose two types of CS-selection algorithms. The first type only utilizes local information of an EV. The second type utilizes the global information obtained through interactions between the EVs and a Global CS-selection (GCS) server through the mobile telecommunications network. Our study indicates that by using the global information (specifically the workload status of each CS), the EVs can be effectively charged with short waiting times at the CSs. © 2011 Elsevier Ltd.

Liu J.-C.,Yuanpei University | Chuang K.-Y.,Information and Communications Research Laboratories | Wen Y.-L.,Information and Communications Research Laboratories
Proceedings - 2012 6th International Conference on Genetic and Evolutionary Computing, ICGEC 2012 | Year: 2012

With the widely used of wellness selfmanagement devices, more and more services provide people upto- date wellness information such as blood pressure, SpO2, rate of heartbeat, etc. How to gather these data more efficiently is an important issue. Moreover, these data may be combined with the information of geographic location. The data gathering system need to deal with GIS-based information. We had proposed an innovated sensor observation service with web-based and GISbased architecture, which is named WSN Application Service Platform (WASP) [25]. Then, we proposed a flexible SWE-based Data Observation and Event Notification Framework on Social Networks for smart home applications [26] based on WASP. All sensors and devices provide their location information to data center and form a community. In this paper, we continue the frameworks that have proposed in [25] and [26]. We design an efficient platform to gather the wellness data from devices through wireless networks automatically. We also proposed an scheme can saving more power and bandwidth. Moreover, these wellness information can be shown immediately on social networks in specified groups. The proposed data gathering system is helpful and efficient for home medical treatment. © 2012 IEEE.

Wong K.-L.,National Sun Yat - sen University | Lu J.-Y.,National Sun Yat - sen University | Chen L.-Y.,National Sun Yat - sen University | Li W.-Y.,Information and Communications Research Laboratories | And 2 more authors.
Asia-Pacific Microwave Conference Proceedings, APMC | Year: 2016

A 16-antenna array disposed in the smartphone for the LTE MIMO operation in the 3.5-GHz band (3400 ∼ 3600 MHz) is presented. The array is fabricated by disposing four quad- Antenna linear (QAL) arrays along two long side edges of the system circuit board of the smartphone. The QAL array has a planar structure occupying a small area of 3 mm X 50 mm. Two QAL arrays spaced 20 mm are disposed along each side edge. Acceptable antenna performances and ECC (envelope correlation coefficient) values are obtained for the antennas in the array. The calculated ergodic channel capacities of the 16-antenna array in a 16 X 16 MIMO system reach about 66 ∼ 72 bps/Hz with a 20-dB signal-to-noise ratio. The obtained results of the 16-antenna array are presented. © IEEE.

Hsu C.-Y.,Information and Communications Research Laboratories | Chen R.-J.,Information and Communications Research Laboratories | Tseng F.-S.,National Sun Yat - sen University
IEEE Vehicular Technology Conference | Year: 2013

A bit-adaptive precoding matrix index (PMI) feedback mechanism is proposed in Long Term Evolution-Advanced (LTE-A). In Coordinated Multipoint Transmission (CoMP) scenarios, the number of feedback PMI bits for all channel state information (CSI) processes at the same time may be larger than that the current LTE-A system can support. However, in some environments like slow-fading channels, the number of feedback PMI bits is thus reduced at the cost of limited performance loss without changing the codebook in LTE-A. To carry out this concept, we build up a candidate set for each PMI in the codebook of LTE-A. Based on the previous selected PMI, the current selected PMI belongs to the candidate set of the previous selected PMI. The candidate set is defined as a subset of precoder indices in the codebook of LTE-A. Since the number of elements in the candidate set is smaller than that of all precoders in the codebook, the number of feedback PMI bits can be reduced. Simulations show that the feedback PMI overhead can be reduced at the cost of limited performance loss. When the mobility speed is 20 km/h, the SNR loss is about 0.25 dB for block error rate is 10 -2and the overhead reduction ratio is 25%. Copyright © 2013 by the Institute of Electrical and Electronic Engineers, Inc.

Weng Y.-T.,National Cheng Kung University | Weng Y.-T.,Far East University of Taiwan | Shieh C.-K.,National Cheng Kung University | Huang T.-C.,Lunghwa University of Science and Technology | Miao Y.-B.,Information and Communications Research Laboratories
Proceedings of the International Conference on Parallel and Distributed Systems - ICPADS | Year: 2011

Digital multimedia broadcasting services require resiliency against signal fading due to signal encounters with bad weather, terrain obstructions, such as tree, building, etc. There are several solutions that use peer-to-peer network to repair packet losses. But they have some shortcomings such as long lookup latency, control message overhead, flash crowd problem and low chunk availability. In this paper we propose a novel solution that considers load distribution in structured peer-to-peer networks and repairing packet losses in short lookup latency. Our proposed solution doesn't need to modify the codec technology for multimedia stream. Our proposed solution can achieve load evenly distributed, high chunk availability, short lookup latency and low control message overhead by using peer-to-peer network to repair packet losses in digital multimedia broadcasting systems. © 2011 IEEE.

Lin W.-Y.,University Road | Li M.-W.,University Road | Lan K.-C.,University Road | Hsu C.-H.,Information and Communications Research Laboratories
Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST | Year: 2012

802.11p, also known as WAVE, is a standard protocol intended for future traffic systems in order to support safety and commercial non-safety applications for vehicular communication. 802.11p is modified from 802.11a, and both are based on OFDM. The main difference between 802.11a and 802.11p is that the latter is proposed to use 10 MHz frequency bandwidth (half of bandwidth of 802.11a) in order to make the signal more robust against fading and increase the tolerance for multipath propagation effects of signals in a vehicular environment. In this paper, we investigate the performance difference between 802.11a and 802.11p for Vehicle-to-Infrastructure communication through real-world experiments. We measure contact duration and losses of 802.11p and 802.11a in both LOS and NLOS environments. In addition, we investigate their throughput with different modulations over various distances between OBU and RSU to evaluate the feasibility of using rate adaptation for non-safety V-to-I applications.

Chen K.-C.,National Taiwan University | Lin S.-Y.,Information and Communications Research Laboratories | Wu A.-Y.,National Taiwan University
2013 International Symposium on VLSI Design, Automation, and Test, VLSI-DAT 2013 | Year: 2013

The three-dimensional Network-on-Chip (3D NoC) has been proposed to solve the complex on-chip communication issues. However, the thermal problems become more exacerbated because of the larger power density and the heterogeneous thermal conductance in different silicon layer of 3D NoC. To regulate the system temperature, the Dynamic Thermal Management (DTM) techniques will be triggered when the device is thermal-emergent. However, these kinds of reactive DTM schemes result in significant system performance degradation. In this paper, we propose a proactive DTM with vertical throttling (PDTM-VT) scheme, which is controlled by the distributed Thermal Management Unit (TMU) of each NoC node. Based on the expected temperature resulted from the proposed thermal prediction model, the TMU can early control the temperature of the thermal-emergent device. The experimental results show that the proposed thermal prediction model has less than 0.25% prediction error against actual temperature measurement within 50ms. Besides, the PDTM-VT can reduce 11.84%∼23.18% thermal-emergent nodes and improve 0.47%∼47.90% network throughput. © 2013 IEEE.

Chen C.-M.,Harbin Institute of Technology | Lin Y.-H.,Carnegie Mellon University | Chen Y.-H.,Information and Communications Research Laboratories | Sun H.-M.,National Tsing Hua University
Journal of Information Hiding and Multimedia Signal Processing | Year: 2013

Aggregation schemes for reducing transmission cost have been proposed for wireless sensor networks for a long time. Aggregated results can be easily altered by adversaries since sensors are prone to being captured in a harsh environment. Hence, several secure data aggregation schemes have been proposed to solve this problem. Many schemes ensure data integrity during aggregation procedures, but most of them are post-active since integrity can only be confirmed after the data reaches the base station. Another limitation is that the network topology is assumed to be fixed. However, this assumption violates the characteristic of sensor networks. In this paper, we present a secure data aggregation scheme called SASHIMI. SASHIMI utilizes successively hierarchical inspecting of message integrity during aggregation. If attacks arise during aggregation, attacks can be detected within two levels of the hierarchal tree structure. In other words, penalty and overhead caused by attacks can be reduced. In average, SASHIMI incurs only O(n) communication cost where n is the number of nodes. In the case of attacks, SASHIMI performs better than existing schemes. Moreover, SASHIMI supports dynamic network topology. Finally, a comprehensive analysis demonstrates that SASHIMI is more secure and efficient than other schemes. © 2013 ISSN 2073-4212.

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