An RTLS for active RFID tracking, based on WSNs is presented in thesis. It is composed by two communication protocols. The first is a feedback based Topology Control Protocol that uses adaptive transmission power and adaptive throughput control mechanisms to create and maintain an operating WSN, while the second is a presence detection protocol that can track RFID tags by monitoring disseminated detection information via software agents. We apply our protocols in real indoors wireless sensor testbeds with multiple experimental scenarios to showcase scalability and trade-offs between network properties and configurable protocol parameters. By analysis of the real world experimental output, we present results that depict a more realistic view of topology control and presence detection problems in terms of load balancing, connectivity, reliability, fault tolerance and network traffic minimization. Finally, we also conduct some very focused simulations to assess the scalability of our protocols in very large networks.