Method and apparatus for signal detection in radio frequency identification system

An apparatus for signal detection of a reader in a Radio Frequency IDentification (RFID) system, the apparatus comprising:

• a low-noise amplifier for low-noise amplifying a received signal of an antenna;
• a receiver unit for detecting a Continuous Wave (CW) signal and a tag signal in the low-noise amplified signal;
• a transmitter unit for frequency up-converting an input signal, and outputting the up-converted signal;
• a Phase Locked Loop (PLL) for generating a frequency signal according to a transmission signal band or a reception signal band, and transferring the generated frequency signal to the transmitter unit or a receiver unit;
• a receiver unit switch for connecting the receiver unit with the low-noise amplifier or a directional coupler;
• and
• a controller unit for controlling a frequency of the frequency signal generated by the PLL, turning off transmission power in a case of a Listen Before Talk (LBT) scheme, controlling the receiver unit switch to connect the receiver unit with the low-noise amplifier, and determining if a corresponding channel is an idle channel, by using a power value of the signal output from the transmitter unit,
• wherein the controller unit controls the PLL to frequency shift a signal of the corresponding channel by a prescribed frequency or converts a frequency response characteristic of a Direct Current (DC) remover provided in the receiver unit into a low-pass filter characteristic corresponding to a fundamental frequency of the corresponding channel, thereby enabling the receiver unit to detect a signal of the corresponding channel where the LBT scheme is to be performed.

A method for signal detection of a reader in a Radio Frequency IDentification (RFID) system, the method comprising:

• a setup step of turning off transmission power in a case of a Listen Before Talk (LBT) scheme, switching an antenna provided in the reader to a receiver unit provided in the reader, and setting a fundamental frequency corresponding to a channel where the LBT scheme is to be performed;
• a low-noise amplification step of low-noise amplifying a signal received by the antenna;
• a signal detection step of frequency down-converting a signal input into the receiver unit, removing a Direct Current (DC) component from the frequency down-converted signal in a predetermined manner, and then low-pass filtering the DC-removed signal;
• and
• a channel check step of determining if the channel is an idle channel, by using a power value of the low-pass filtered signal,
• wherein removing the DC component from the frequency down-converted signal in the predetermined manner comprises controlling a Phase Locked Loop (PLL) to frequency shift a signal of the corresponding channel by a prescribed frequency or converting a frequency response characteristic of a DC remover provided in the receiver unit into a low-pass filter characteristic corresponding to the fundamental frequency of the corresponding channel, thereby enabling the receiver unit to detect a signal of the corresponding channel where the LBT scheme is to be performed.

A method for signal detection of a reader in a Radio Frequency IDentification (RFID) system, the method comprising:

• a group setting step of setting a given number of neighboring channels among channels allocated to the RFID system as a channel group;
• a group filter setting step of changing frequency characteristics of a Direct Current (DC) remover and a low-pass filter, which are provided in a receiver unit included in the reader, in such a manner as to correspond to an overall frequency band of the channel group;
• a group filtering step of low-noise amplifying a signal of the channel group, down-converting the low-noise amplified signal to a low frequency band, removing a DC component from the down-converted signal, and low-pass filtering the DC-removed signal;
• a group power measurement step of measuring a power value of the low-pass filtered signal;
• and
• an idle group check step of determining if the channel group is an idle group including an idle channel, by using the measured power value.