A novel application-specific communications scheme for RF-based indoor wireless localization networks is proposed. In such a system wireless <i>badges,</i> attached to people or objects, report positions to wireless <i>router </i>units. Badges have very limited communication, energy, and processing capabilities. Routers are responsible for propagating collected badge information hop-by-hop toward one <i>central unit </i>of the system and are significantly less constrained by battery than the badges. Each unit can radiate a special sequence of bits at selected frequencies, so that any router in the wireless neighborhood can sense, store, aggregate and forward Received Signal Strength Indicator (RSSI) information. Once the central unit receives RSSI from routers, it calculates the overall relative position of each unit in the system. This new scheme has been developed based on the Chipcon CC1010 Evaluation Module with limited communication capabilities. The implemented protocol rules allow scalability of numerous system parameters. The feasibility of the proposed protocol is simulated on a typical floor: 2-dimensional topology where routers are deployed in a grid fashion. Results show that assuming normal operation and a maximum of thousand badges the system can periodically report about every five seconds. Different scenarios are compared, and the proposed scheme is demonstrated to meet strict reliability requirements while providing energy-efficient badges and an acceptable level of latency.
The proposed research focuses on the communication in an RF-based indoor wireless localization system. In such a system, wireless badges attached to people or devices report positions to wireless gateway units. Badges have very limited communication, energy, as well as processing capabilities. However, gateways are significantly less constrained by battery than the badges. Wireless gateway units route collected badge information hop-by-hop towards one central unit of the system. We assume that each gateway unit has one transceiver antenna and is able to determine its own relative position in the system. The goal of this research is to develop an application-specific scheme for information routing and topology control among gateway units with maximum reliability, flexibility, adaptability and acceptable latency. We implemented two protocols (a robust one and a traffic-aware one), however, we shall show that for large networks, the use of multiple routing algorithms is beneficial. We assume that the topology control is fully centralized and the central unit is responsible for network management. We simulated the feasibility of the proposed novel two-protocol routing scheme and compared this scheme to a well-known dynamic source routing scheme. We demonstrated noticeable improvements in terms of robustness, traffic-awareness, and throughput. We also showed that the use of multiple protocols in our application-specific wireless indoor localization system will enhance the overall system performance.