Abstract— This paper introduces two new tree-based anticollision schemes using multiple feedback symbols for uplink tag random access of emerging radio frequency identification (RFID) networks. To this end a uplink(UL) time slot requires an extra time portion called voting field in addition to the packet payload to obtain a slot based estimate for the number of contending tags. As a function of the voting field length we examine MAC efficiency improvements in terms of UL throughput, and compare it with the conventional binary tree based RFID MAC in ISO 18000-6 Type B standard.