Showing papers by "Hiroshi Harada published in 2015"

Some Initial Results and Observations from a Series of Trials within the Ofcom TV White Spaces Pilot

Abstract: TV White Spaces (TVWS) technology allows wireless devices to opportunistically use locally-available TV channels enabled by a geolocation database. The UK regulator Ofcom has initiated a pilot of TVWS technology in the UK. This paper concerns a large- scale series of trials under that pilot. The purposes are to test aspects of white space technology, including the white space device and geolocation database interactions, the validity of the channel availability/powers calculations by the database and associated interference effects on primary services, and the performances of the white space devices, among others. An additional key purpose is to perform research investigations such as on aggregation of TVWS resources with conventional resources and also aggregation solely within TVWS, secondary coexistence issues and means to mitigate such issues, and primary coexistence issues under challenging deployment geometries, among others. This paper provides an update on the trials, giving an overview of their objectives and characteristics, some aspects that have been covered, and some early results and observations.

IEEE 802.11af Indoor Experiment in UK Ofcom TVWS Trial Pilot Program

Abstract: This paper performs the world's first IEEE 802.11af based Wireless Local Area Networks (WLAN) operating in TV White Space (TVWS) indoor experiment in the Ofcom TVWS pilot program of the UK. The prototype system consists of TVWS Database (WSDB), Registered Location Secure Server (RLSS), and two prototype hardware for an Access Point (AP) and a Station (STA). The developed WSDB qualified by Ofcom TVWS pilot program of the UK. The prototype hardware meets to the transmission spectrum regulation of the European Telecommunication Standards Institute (ETSI). By using the developed system, a trial indoor experiment performed in the building of the King's College London (KCL), Denmark Hill Campus in London, UK. The prototype system and the experiment results show an effectiveness of the IEEE 802.11af and indicate the way to the practical application.

System evaluation of a practical IEEE 802.15.4/4e/4g multi-physical and multi-hop smart utility network

Abstract: This study evaluates the performance of a practical IEEE 802.15.4/4e/4g low-rate (LR) wireless personal area network (WPAN) with multiple physical (PHY) layers and multi-hop capabilities for smart utility networks, machine-to-machine networks and other advanced sensor networks. The proposal includes realistic design considerations addressing demands of practical applications, country-specific regulatory requirements and technical specification in international standards. A cross-layer open system interconnection model from the application, transport, network, medium access control, down to the multiple PHY layers is constructed based on the specification in IEEE 802.15.4 LR-WPAN and other layer-specific standards. Employing the cross-layer model, extensive computer simulations were conducted to investigate the performance of the LR-WPAN system in this application domain. As a result, the authors have successfully verified the simulated achievable average throughput in both PHY layer designs, multi-rate and multi-regional frequency shift keying (MR-FSK) and multi-rate and multi-regional orthogonal frequency division multiplexing (MR-OFDM) with the theoretical throughput by calculation. Secondly, in a multi-PHY environment with the presence of 30 interferer devices, throughput degradation of the victim system is observed within 30%. Furthermore, when interferer devices transmit frames with interval beyond 1 s, the degradation to the victim system becomes negligible. Thirdly, MR-FSK PHY has a simpler design with higher energy-efficiency, whereas MR-OFDM PHY is more complicated with more resilience to interference. They have found an interference tolerance capability difference of 15 dB between the MR-FSK and MR-OFDM systems. Fourthly, comparing with their single-hop counterparts, multi-hop systems have lower average throughput in MR-FSK by 25% and MR-OFDM by 10%. Finally, comparing with networks with periodical beacon transmissions, asynchronous networks have more inferior average throughput of 20% in MR-FSK and 3% in MR-OFDM, with the advantage of longer battery lifespan.

Path Loss and Throughput Estimation Models for an IEEE 802.11af Prototype

Abstract: An IEEE 802.11af indoor trial experiment has been conducted in the Ofcom pilot program of the United Kingdom. This paper describes an indoor propagation characterization and throughput estimation method using prototype devices based on the IEEE 802.11af standard. Since the IEEE 802.11af is recent technology for TV white space (TVWS) spectrum sharing, indoor propagation measurements at TVWS band for WLAN usage are very seldom in the previous researches. Path loss model parameters has been extracted for each line-of-sight (LoS) and non-LoS (NLoS) situation on the same floor. Also a fluctuation of measured path loss is analyzed using the log-normal and the extreme value distributions. A developed path loss model is useful for the location design of access points and the interference risk estimation for IEEE 802.11af devices. As another modeling, a throughput estimation model has been developed using the exponential distribution derived from the cumulative probability distribution (CDF) of measured throughputs. By combination of the developed path loss model and the throughput estimation model, throughput can be estimated as a function in each LoS and NLoS situation.

Greater reliability in disrupted metropolitan area networks: use cases, standards, and practices

Abstract: Unlike most general wireless users enjoying broadband access to the Internet and so on, a number of mission-critical applications such as PPDR are using narrowband systems that are only capable of transmitting voice and low-rate data. Broadband wireless networks with greater reliability are increasingly demanded by these applications including the emerging Smart Grid. With this vision, the IEEE 802.16 Working Group completed two standard amendments recently, IEEE Std 802.16n-2013 and IEEE Std 802.16.1a-2013. 802.16 network reliability is significantly increased by technical developments dealing with failures of network infrastructure stations, radio path and backhaul connectivity, and so on. This article serves to analyze the envisaged typical use cases of greater reliable broadband wireless networks, outline the main technical developments of the two standards, and introduce a recently developed practical system for PPDR applications in Japan.

The IEEE Dynamic Spectrum Access Networks Standards Committee (DySPAN‐SC) and IEEE 1900 Working Groups

Abstract: The IEEE Dynamic Spectrum Access (DSA) Networks Standards Committee (DySPAN‐SC) and associated IEEE 1900 working groups are concerned with the standardization of aspects of DySPAN and related technologies such as DSA, Cognitive Radio, and TV white space (TVWS), among others. This chapter overviews IEEE DySPAN‐SC and the IEEE 1900 standards working groups, as well as the underlying standards that have been or are being developed in those working groups. A particular aim is to provide detailed commentary on the scopes and purposes of the IEEE 1900 standards, as well as some of the underlying technical solutions that are assumed therein.

Wireless communication method

Abstract: A radio communication method capable of eliminating a blocking effect caused by a collision of many pieces of data is provided. The radio communication method relaying data from a lower terminal to an upper terminal, includes: a step of determining the number of lower terminals connectable to the upper terminal; a step of connecting the lower terminal and the upper terminal based on the determined connectable number; a step of transmitting a first data from the lower terminal to the upper terminal connected to each other; a step of causing the upper terminal to receive the first data transmitted from the lower terminal; and a step of combining the first data received by the upper terminal and a second data to be transmitted from the upper terminal and creating combined data; and a step causing the upper terminal transmitting the combined data to a further upper terminal.