Toshihisa Nabetani

A Simple and Efficient Selective Repeat Scheme for High Throughput WLAN, IEEE802.11n

The standardization of IEEE802.11n aims to achieve 100 Mbps at MAC-SAP (medium access control - service access point). The frame aggregation scheme in which MAC (medium access control) frames are aggregated into one PHY (physical) frame is proposed as the main MAC technique of IEEE802.11n, because it decreases MAC overhead. The block ack mechanism of IEEE802.11e is applied as a selective repeat method of the frame aggregation. In this paper, we propose the extended block ack mechanism as a selective repeat mechanism to be adapted to the frame aggregation scheme. We present the performance evaluation to compare the throughput of the extended block ack mechanism and the legacy block ack of IEEE802.11e and show that the average improvement is expected to be around 10% and the maximum improvement is about 39% compared with the conventional method.

Performance of simple and Smart PHY/MAC mechanisms for Body Area Networks

Measuring the living condition and health status of users using small sensing devices and collecting the data of each user over wireless networks is expected to be a new trend in healthcare. Body Area Network (BAN) is an emerging area of personal data communications that will facilitate the capture of data and its collection. Although the IEEE 802.15.6 standard for wireless body area networks was created for this purpose, it is very complex and is unsuitable for ultra low power sensors. A new BAN specification, under the Technical Committee (TC) on SmartBAN, is now being considered in the European Telecommunications Standards Institute (ETSI) targeting ultra low power devices. Some of the technical requirements of the new Smart BAN system includes ultra-low power consumption, coexistence with other wireless systems, a timely access mechanism and optimum control of quality of service (QoS) for emergency signals. A simple and energy efficient MAC/PHY system has been proposed by the authors as part of the ETSI TC Smart BAN specifications. In this paper, we introduce and evaluate our proposed Smart BAN system which is based on two channels, a control channel and a data channel. The control channel is used for announcements from which both nodes and neighboring hubs are able to gather information for use in co-existence algorithms as well as for initial connection setup. Our proposed system uses simple time division multiple access (TDMA) in the data channel so that the power consumption of nodes is kept low. A shared access mechanism has also been proposed to reduce the latency of emergency signals. We evaluate the access delay and power consumption of our system in this paper, and show that the proposed shared access mechanism reduces the latency of emergency signals.