On the Design of Multi-Hop Tag-to-Tag Routing Protocol for Large-Scale Networks of Passive Tags

Recently, tag-to-tag (T2T) backscattering technique in a passive RFID system has received broad attention due to its superiority for large-scale network applications. If used to implement a Network of Tags, use of T2T communication allows inherent communication parallelism, thus supporting orders of magnitude larger capacity than centralized RFID reader-based systems. To unleash the potential of T2T communication, turbo backscattering operation enables the implementation of a multi-hop network of tags, which supports larger network coverage of a Network of Tags. However, due to asymmetric communication links and interferences among tags' transmissions in such a T2T backscattering based network, the routing protocol design has become one of the main technical challenges, especially for large-scale networks. Furthermore, the computation time of T2T routing protocols increases exponentially with the number of tags, greatly limiting the practicability of such large-scale backscattering networks. In this paper, we present the design of a Network of Tags model to address these challenges, and we propose novel routing protocols for three distinct types of tags with different hardware capabilities. To address the issue of computational processing time of the routing protocol for large-scale T2T networks, we propose a new scheme with linear time complexity. We evaluate and compare the performance of the proposed protocols, as well as investigate the impact of network parameters on the performance.