In this poster, we propose a new tool, i.e. a node placement adviser, which supports deployment workers of sensor networks. The adviser tool is realized in the form of mobile terminal software and acts as a proxy of an additional node, as well as communicating with those already placed. Based on the communication results, it indicates how favorable the current location is to a worker.

Personal health care is a promising application of a body area network (BAN). The BAN for health care application consists of a data collector and multiple wearable sensors that send data to the collector according to a sampling interval determined by the application. The data collector may be any hand-held or portable device such as a mobile phone, a PDA or a wristwatch. An individual user needs a BAN to detect, track or manage his/her health. Multiple BANs for such purpose are likely to appear in a nearby area, especially a place where population density is high. Since multiple BANs must share wireless medium in this scenario, a problem of packet collisions among BANs is unavoidable. To deal with such problem, this study proposes an adaptive scheme to allocate channel and time for coexisting BANs. The proposed scheme distinguishes inter-BAN and intra-BAN communications, and adaptively allocates channel and time according to the current number of BANs that exist in a nearby area. As a salient feature, the proposed scheme allocates time by attempting to satisfy the requirement of sampling interval determined by the application. The evaluation results demonstrate that our scheme achieves much higher packet delivery rate than the existing scheme.

The spread of DLNA (digital living network alliance) certified consumer electronics has already started and there are some proposals for communication systems involving two home networks linked via virtual private network (VPN), that aim to use consumer electronics from the Internet. However, those systems have some problems. For example, against the user's wishes, the ITN connection makes all the contents available for other users as well. The user cannot access content because DLNA devices refuse access from outside the home network. In this paper, we propose a new system that expands the interconnection area from a home network to a mobile phone and consumer electronics in other home networks. Furthermore, we evaluate the proposed system by constructing a test bed that includes consumer electronics obtainable at stores.

Most sensor nodes usually have the ability to vary their own wireless transmission power. Hence they have the potential to control the network topology, which is the pattern of links connecting pairs of nodes in a network. In this paper, we propose a connectivity ascertainment based distributed topology control algorithm. The algorithm draws out the potential from nodes for constructing an energy-efficient network topology. Each node performs the algorithm and makes local decisions about its transmission power; these local decisions minimize the total transmission power of the network, while maintaining network connectivity. Specifically, each node ascertains the existence of an actual path that is a substitute for a wireless link to an own edge node, which requires the maximum transmission power among its own neighbors. To contribute to path ascertaining, the other nodes use locally-collected information. If a node can ascertain the existence, it decides to remove the wireless link to the edge node by reducing the transmission power. The node targets a new edge node from among its own current neighbors and performs the same process until there are no substitute paths to the target. We show that these local decisions collectively guarantee global connectivity and minimize the total transmission power of the network. We also evaluated the performance of our algorithm on terms of network connectivity and transmission power reduction using simulation studies.