Patent ID: 7312692

Claim:
A method for selecting by a base station at least one transponder out of a plurality of transponders, said method comprising the following steps a) to e) performed as a first selection procedure at a first selection level and steps f) and g) performed as a second selection procedure at a second selection level: a) controlling by said base station (BS) a first selection procedure, b) producing by each transponder (TR 1 , TR 2 , . . . ) a random transponder number, c) generating in said base station (BS) numbered time slots so that each time slot has a time slot number, d) transmitting by each transponder a marker to said base station during a time slot having a respective time slot number coinciding with said respective random transponder number, e) selecting that transponder which was the only transponder transmitting during said coinciding time slot, and performing said second selection procedure at said second selection level by f) checking whether more transponders than one have transmitted a respective marker in the same time slot to provide a respective collision signal, and g) performing under the control of said base station and in response to said collision signal a second selection procedure as any one of a stochastic, a deterministic, and a mixed stochastic-deterministic selection procedure, said method further comprising generating any random transponder number, including said random transponder number of step b), by means of at least one clocked, linear shift register, providing a clock signal for operating said at least one clocked, linear shift register, and feed back controlling a supply of said clock signal to said clocked, linear shift register in response to a power consumption of said at least one transponder so that said clock signal supply is deactivated during phases of an increased power input to said at least one transponder compared to an average power input to said at least one transponder.