Wireless network signal to interference plus noise ratio estimation for a random access channel

A wireless device, comprising:

• an antenna for receiving a wireless transmission;
• preamble detector circuitry configured to identify within the received wireless transmission a plurality of preambles transmitted via a random access channel of a wireless network, the preamble detector circuitry comprising:
• noise floor estimator circuitry configured to:
• estimate, for a given preamble root sequence identified by the preamble detector circuitry, a noise floor value as mean energy of received signal samples, excluding detected preamble samples within each cyclic prefix window on the given preamble root sequence, below a noise floor threshold assigned to the given preamble root sequence;
• compute the noise floor threshold as a product of:
• average energy of the received signal samples less total signal energy contained in each cyclic prefix window in which a preamble is detected using the given preamble root sequence;
• and
• a predetermined normalized relative noise floor threshold based on a target false preamble detection rate;
• determine total interference energy of all preambles detected using a preamble root sequence other than the given preamble root sequence;
• and
• adjust the noise floor value for the given preamble root sequence based on the total interference energy.

A method, comprising:

• receiving signals transmitted via a random access channel of a wireless network;
• detecting preambles in the received signals;
• estimating, for a given preamble root sequence identified by the detecting, a noise floor value as mean energy of received signal samples, excluding detected preamble samples within each cyclic prefix window on the given preamble root sequence, below a noise floor threshold assigned to the given preamble root sequence;
• computing the noise floor threshold as a product of:
• average energy of the received signal samples less total signal energy contained in each cyclic prefix window in which a preamble is detected using the given preamble root sequence;
• and
• a predetermined normalized relative noise floor threshold based on a target false preamble detection rate.

A method, comprising:

• receiving signals transmitted via a random access channel of a wireless network;
• detecting preambles in the received signals;
• estimating, for a given preamble root sequence identified by the detecting, a noise floor value as mean energy of received signal samples, excluding detected preamble samples within each cyclic prefix window on the given preamble root sequence, below a noise floor threshold assigned to the given preamble root sequence;
• computing the noise floor threshold as a product of:
• average energy of the received signal samples less total signal energy contained in each cyclic prefix window in which a preamble is detected using the given preamble root sequence;
• and
• a predetermined normalized relative noise floor threshold based on a target false preamble detection rate;
• determining total interference energy of all preambles detected using a preamble root sequence other than the given preamble root sequence;
• and
• adjusting the noise floor value for the given preamble root sequence based on the total interference energy.

Apparatus for implementing a wireless base station, comprising:

• an antenna for receiving a wireless transmission;
• preamble detector circuitry configured to identify within the received wireless transmission a plurality of preambles transmitted via a random access channel of a wireless network, the preamble detector circuitry comprising:
• noise floor estimator circuitry configured to:
• estimate, for a given preamble root sequence identified by the preamble detector circuitry, a noise floor value as mean energy of received signal samples, excluding detected preamble samples within each cyclic prefix window on the given preamble root sequence, below a noise floor threshold assigned to the given preamble root sequence;
• compute the noise floor threshold as a product of:
• average energy of the received signal samples less total signal energy contained in each cyclic prefix window in which a preamble is detected using the given preamble root sequence;
• and
• a predetermined normalized relative noise floor threshold based on a target false preamble detection rate;
• and
• adjust the noise floor value for the given preamble root sequence based on total interference energy of all preambles detected using a preamble root sequence other than the given preamble root sequence.