1. A method for estimating a population of Radio Frequency Identification (RFID) sensors in an area based upon responses during an interrogation frame processed by a processing system in a transceiver system receiving the responses comprising: receiving responses from RFID sensors during a plurality of time slots of the interrogation frame; determining a contention resolution of each of the plurality of time slots; determining an address in a lookup table stored in memory based upon the contention resolutions of the time slots; reading a probability of a state in a state machine representing the contention resolutions of the plurality of time slots in the interrogation frame from the address in the lookup table wherein the lookup table stores the probability of each state in the state machine at a particular address of the lookup table; and determining an estimate of the population of the RFID sensors in the area based upon the reading of the probability of the state in the state machine and maximum a posteriori probability estimation.