Multi-hop information spreading methods for appropriate number of terminals in ERESS

There have been an enormous number of victims by a number of disasters such as fires, earthquakes, terrorisms and chemical explosion around the world. In these disasters, it is very important to detect the occurrence of them as soon as possible, and evacuate people quickly. To cope with these issues, the authors are developing ERESS (Emergency Rescue Evacuation Support System). ERESS is based on Mobile Ad-hoc NETworks (MANET) and aims to reduce the number of victims in panic-type disasters. This system consists of new mobile terminals (handset size) with advanced disaster recognition algorithm and acquires sensor information such as acceleration, direction difference and walking steps. Collected information about them is used for detecting the occurrence of a disaster. However, until now, there is no suitable information spreading method for ERESS to collect their information effectively. In this paper we propose three information spreading methods which are suitable for ERESS. The proposed methods are a TTL (Time To Live) control, a transmission power control, and an integrated method using separated sectors. We show the validity of the proposed methods by computer simulations.