AVSR: Asynchronous virtual slot-based ranging for user-oriented location services

In general, the asynchronous ranging is preferred over synchronous ranging since it does not require global synchronization and an expensive and precise oscillator. However, conventional asynchronous ranging requires two or more messages per ranging session for a reference node. This requirement might increase the network traffic considerably. For this reason, conventional ranging schemes are not suitable for user-oriented location service. In this paper, we propose (AVSR) asynchronous virtual slot-based ranging utilizing broadcast ranging request. The utilized virtual slot is accomplished in a fully distributed manner among reference nodes. The evaluation result demonstrates that in spite of very low traffic intensity, AVSR is more robust against ranging error than conventional ranging schemes: TWR and SDS-TWR.