Reduction of false alarms in PDCCH detections

A system comprising:

• a sniffing device configured for receiving PDCCH transmissions from a wireless base station in a network operating according to the Long Term Evolution (“LTE”) standard;
• and
• a controller coupled to the sniffing device, the controller being configured to:
• monitor transmissions on the Physical Downlink Control CHannel (“PDCCH”) of the wireless base station;
• maintain a list of active Radio Network Temporary Identifiers (“RNTI's”) assigned by the wireless base station to user equipment;
• extract PDCCH detections from the monitored transmissions;
• apply at least one false alarm reduction strategy to eliminate invalid PDCCH detections from the extracted PDCCH detections, said false alarm reduction strategy including determining an RNTI that is valid for an extracted PDCCH detection, and determining if the valid RNTI is included in the list of active RNTI's;
• and
• determine scheduling information of the wireless base station from the extracted PDCCH detections;
• wherein the false alarm reduction strategy further includes comparing PDCCH detections with each other, and determining that a PDCCH detection is invalid if it is inconsistent with other PDCCH detections;
• and
• wherein a PDCCH detection is determined to be invalid if it includes an apparent parameter change that is unlikely to be valid, the apparent parameter change being at least one of an apparent change of a modulation scheme that is unlikely to be valid;
• an apparent change of a coding scheme that is unlikely to be valid;
• and an apparent change in DCI format that is unlikely to be valid.

A non-transitory computer readable medium storing a computer program, executable by a machine, for operating a sniffing device configured for receiving PDCCH transmissions from a wireless base station in a network operating according to the Long Term Evolution (“LTE”) standard, the computer program comprising executable instructions for:

• monitoring transmissions on the Physical Downlink Control CHannel (“PDCCH”) of the wireless base station;
• maintaining a list of active Radio Network Temporary Identifiers (“RNTI's”) assigned by the wireless base station to user equipment;
• extracting PDCCH detections from the monitored transmissions;
• applying at least one false alarm reduction strategy to eliminate invalid PDCCH detections from the extracted PDCCH detections, said false alarm reduction strategy including determining an RNTI that is valid for an extracted PDCCH detection, and
• determining if the valid RNTI is included in the list of active RNTI's;
• and
• determining scheduling information of the wireless base station from the extracted PDCCH detections;
• wherein the false alarm reduction strategy further includes comparing PDCCH detections with each other, and determining that a PDCCH detection is invalid if it is inconsistent with other PDCCH detections;
• and
• wherein a PDCCH detection is determined to be invalid if it includes an apparent parameter change that is unlikely to be valid, the apparent parameter change being at least one of an apparent change of a modulation scheme that is unlikely to be valid;
• an apparent change of a coding scheme that is unlikely to be valid;
• and an apparent change in DCI format that is unlikely to be valid.