A substantial criterion with the use of wireless communication is the missing location information of the mobile participants. The RSSI (Received Signal Strength Indicator)-based localization technique is an easy and well known method to predict the position of an unknown node in indoor environments whereas additional measures are required for a sufficient accuracy. The distance-pending path loss is affected by strong variations, especially appearing as frequency specific signal dropouts. A diversity concept with redundant data transmission in different frequency bands can reduce the dropout probability. Not only the availability of the communication and the positioning, but also the accuracy of the localization can be increased by the diversity concept. Another improvement can be reached by a sensor fusion of the RSSI-based position data with an Inertial Navigation System. First experimental results with miniaturized transceiver prototypes show that a good performance for precision and availability can also be reached with low infrastructural costs.