Norihiko Katayama

Channel models for wireless body area networks

Wireless patient monitoring using wearable sensors is a promising application. This paper provides stochastic channel models for wireless body area network (WBAN) on the human body. Parameters of the channel models are extracted from measured channel transfer functions (CTFs) in a hospital room. Measured frequency bands are selected so as to include permissible bands for WBAN; ultra wideband (UWB), the industry, science and medical (ISM) bands, and wireless medical telemetry system (WMTS) bands. As channel models, both a path loss model and a power delay profile (PDP) model are considered. But, even though path loss models are derived for the all frequency bands, PDP model is only for the UWB band due to the highly frequency selectiveness of UWB channels. The parameters extracted from the measurement results are summarized for each channel model.Wireless patient monitoring using wearable sensors is a promising application. This paper provides stochastic channel models for wireless body area network (WBAN) on the human body. Parameters of the channel models are extracted from measured channel transfer functions (CTFs) in a hospital room. Measured frequency bands are selected so as to include permissible bands for WBAN; ultra wideband (UWB), the industry, science and medical (ISM) bands, and wireless medical telemetry system (WMTS) bands. As channel models, both a path loss model and a power delay profile (PDP) model are considered. But, even though path loss models are derived for the all frequency bands, PDP model is only for the UWB band due to the highly frequency selectiveness of UWB channels. The parameters extracted from the measurement results are summarized for each channel model.

Channel model on various frequency bands for wearable Body Area Network

Body Area Network (BAN) is considered as a promising technology in supporting medical and healthcare services by combining with various biological sensors. In this paper, we look at wearable BAN, which provides communication links among sensors on body surface. In order to design a BAN that manages biologic information with high efficiency and high reliability, the propagation characteristics of BAN must be thoroughly investigated. As a preliminary effort, we measured the propagation characteristics of BAN at frequency bands of 400 MHz, 600 MHz, 900 MHz, and 2400 MHz respectively. Channel models for wearable BAN based on the measurement results were derived. Our results show that the channel models can be described by using a path loss model for all investigated frequency bands.

An experimental system enabling WBAN data delivery via satellite communication links

We describe an experimental system that combines a wireless body area network (WBAN) with satellite communication links to enable remote medical treatment and healthcare services. One main advantage of WBAN is that it enables automatic biosignal collection in real time which is essential in medical treatment and healthcare vigilance. The WBAN is implemented using ultra-wideband technology. Multi-hop mechanism is adopted to guarantee reliable connection. In case of less of medical resources such as in emergency, in rural or isolated areas, the system can send the corresponding biosignal to a remote hospital in real time to help patient management by introducing satellite communication links. In this paper, the whole experimental system is illustrated. Some basic experiments are carried out. It is confirmed that the multi-hop mechanism of WBAN works well and the relative delay of WBAN data delivery via satellite links is dependent on the satellite link capacity.

High-Speed Satellite Network Experiments using 622/1244 Mbps Modems

The National Institute of Information and Communications Technology (NICT) has developed a 622/1244 Mbps high-speed satellite communications network using the Wideband Internet Engineering Test and Demonstration Satellite (WINDS). A 622/1244 Mbps dual-rate burst modems were also developed. The high-speed dual rate burst modem is designed for the user data rates of 622 Mbps and 1244 Mbps with a single carrier of QPSK modulation. 622/1244 Mbps transmission test using the WINDS was conducted. The results showed that the Eb/No ratio required to achieve a BER at 10 -10 with FEC was less than 10 dB and 13 dB for 622 Mbps and 1244 Mbps respectively. They also showed that operation as a TDMA satellite communications system for using a 622/1244 Mbps burst modem and a three-dimensional 4KHDTV transmission experiment was successfully performed by this system.

An application of novel communications protocol to high throughput satellites

For network communications using modern high throughput satellite (HTS) on geostationary orbits, network throughput of transmission control protocol (TCP), one of the most popular protocols, is limited due to the packet loss on the satellite link. The packet loss is mainly caused by the attenuation of signals in severe weather conditions like heavy rain. It is high time to develop novel network communication techniques on the transport layer in TCP/IP designed for the systems and applications in broadband communications. In this paper, we introduce a high-speed data transfer protocol, named high-performance and flexible protocol (HpFP), to achieve high throughput for the HTS even with packet loss. The HpFP, in comparison with TCP-Hybla and UDP-based data transfer (UDT) protocols, is evaluated on a laboratory experiment simulating a geostationary orbit satellite link of 10 Gbps. It is clarified that the HpFP outperforms both the TCP-Hybla and the UDT showing high throughputs (close to 10 Gbps) when the packet loss ratio (PLR) is 1%, and remains more than 1 Gbps under even 10% PLR condition. Moreover, in case of no packet loss, the HpFP exhibits a quick start-up time (6 sec) at the initial phase to achieve 10 Gbps, while the TCP-Hybla and the UDT take 9 sec and 16 sec to their maximum throughputs, respectively.

A high-speed data transfer protocol for geostationary orbit satellites

In communication systems using geostationary orbit satellites, throughput of transmission control protocol (TCP) is limited due to the impact of latency on network and packet loss caused by signal attenuation in severe weather conditions like heavy rain. It is high time to develop network techniques and applications in broadband communications over the gigabit satellite and the high throughput satellite (HTS). In this paper, we introduce a high-speed data transfer protocol, named high-performance and flexible protocol (HpFP), to achieve high throughput over a geostationary satellite link even in severe weather conditions. The HpFP is firstly evaluated on a laboratory experiment simulating a geostationary orbit satellite link. It is clarified that the HpFP shows high throughputs even when the packet loss ratio (PLR) is 0.01%. We next carry out a field experiment using the Wideband InterNetworking engineering test and Demonstration Satellite (WINDS). The performance of the HpFP over single, dual, and multiple connections are evaluated. The result shows that the aggregate throughput of dual connections of HpFP almost reaches to the maximum bandwidth, and the time to the maximum bandwidth is within 3 sec which is over 20 times faster than that by the TCP. For multiple connections, the HpFP shares the bandwidth equally among all 50 connections.

The Tele-Operation Experiment of the Hybrid Remotely Operated Vehicle Using Satellite Link

Communication via satellite is the only method for communicating between the ocean and land. However, present commercial satellites cannot provide sufficient bandwidth to transmit the requisite volume of data. The National Institute of Information and Communications Technology (NICT) and the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) conducted broadband satellite communication experiments with the Wideband Inter-Networking engineering test and Demonstration Satellite (WINDS). Using WINDS, the tele-operation of a hybrid remotely operated vehicle (HROV), Otohime, was also carried out successfully.Copyright

High-Speed Transmission for Ka-Band Aeronautical Satellite Communications Using WINDS

Satellite communications are vital in the event of disaster, and fulfill supplementary communications needs, especially in aeronautical applications. The National Institute of Information and Communications Technology (NICT) conducts research on Ka-band satellite communications using the Wideband InterNetworking engineering test and Demonstration Satellite (WINDS). NICT has also developed an aeronautical earth station, which we flight tested in WINDS’s Chubu beam. We measured the propagation characteristics of multi-beam antenna mounted on WINDS to measure the variation of Doppler shift for Ka-band airplane-satellite communication. We also measured the tracking performance of the earth station antenna. In practical tests, NICT’s aeronautical earth station demonstrated uplink speeds up to 38 Mbps.

An implementation of multichannel multi-interface MANET for fire engines and experiments with WINDS satellite mobile earth station

We propose a novel communication system for an emergency fire response team, which provides Internet service on the way to and in the disaster area. The system is composed of a multi-interface mobile ad-hoc network (MANET) router, a Global Positioning System (GPS) receiver, and two Wi-Fi interfaces with directional antennas, which can be easily attached to the roof of a vehicle. The front-side Wi-Fi interface of the vehicle is operated in the infrastructure mode, and the rear-side interface is operated in the access point mode. Different channels are assigned to each AP interface of the vehicles. Infrastructure-mode Wi-Fi interfaces automatically scan and connect to an appropriate AP interface and create MANET links. Some experiments using this wireless system with the WINDS satellite mobile earth station and nine fire engines were conducted in Ebetsu, Hokkaido. We measured the TCP throughput and confirmed that a throughput of more than 10 Mbps was able to be obtained by most of the node pairs. In addition, high-vision video streaming was able to be successfully transmitted to the streaming server on the Internet through MANET and satellite communication links while they were platooning.

Development Status of Small-Sized Ka-band Mobile Terminal for Maritime Broadband Communications

Most recent development status of small-sized Ka-band mobile communications terminal is presented. The terminal is designed to operate at a minimum target speed of 5 Mbps to/from a Ka-band geostationary satellite, and will eventually be used for the purpose of research activity to explore marine resources within the Exclusive Economic Zone (EEZ) of Japan. The terminal is placed on Autonomous Surface Vehicle (ASV). Because the ASV is “unmanned” and is primarily controlled from a remote ground control station, several mechanisms are embedded into the design for safe and successful operations of the Ka-band terminal. Those key mechanisms are introduced in this paper as they make fault diagnosis easier and increase overall system reliability in case of primary communication channel failure.