On the accuracy of RFID-based localization in a mobile wireless network testbed

The extensive recent research in protocols development for wireless networks must be complemented with simple yet efficient prototyping and evaluation mechanism. MiNT-2 is a miniaturized multi-hop wireless network testbed that addresses this challenge by combining the benefits of existing protocol evaluations strategies: simulations and custom built large scale wireless network testbeds. A key component of MiNT-2 is the ability of testbed nodes to move around in the testbed space, whether to reconfigure the network topology or to emulate node mobility patterns. Consequently, we need to devise accurate mechanisms for node localization - the ability of a node to be aware of its exact location in the testbed space. This paper presents the details of the current RFID-based node localization mechanism in MiNT-2. We describe the sources of inaccuracy encountered when using RFID tags due to the error margin associated with the reading range of tags. We then present the implementation and evaluation of two approaches which can be combined to improve the overall accuracy of the RFID-based localization system. Through our experimental evaluation, we show that the proposed approaches improve the accuracy of RFID-based localization mechanisms by up to 58.22% for dense deployment of RFID tags. Though described in the context of the MiNT-2 testbed, our localization techniques are also applicable in more general settings where accurate and inexpensive positioning of mobile nodes is important.