Contention-based discovery and secure ranging techniques for congested environments

A method for secure ranging comprising performing, by a mobile device:

• receiving an assignment message from a first access device of a plurality of access devices, the assignment message identifying a first assigned response-slot of a plurality of response-slots of a response phase of a future ranging session;
• receiving, a polling message from the first access device, the polling message including access device identification information;
• determining a reception time of the polling message for the first access device;
• selecting the first assigned response-slot based on criteria associated with the polling message to direct a first response message to the first access device;
• transmitting first response message during the first assigned response-slot, the first response message including a mobile device identifier and timing information corresponding to the reception time of the polling message from the first access device;
• receiving an access message from the first access device;
• and
• responsive to the access message and at a location relative to an entryway of the first access device, providing an access credential to the first access device of the plurality of access devices.

A computing device for communicating with an access device, the computing device comprising:

• one or more memories;
• and
• one or more processors in communication with the one or more memories and configured to execute instructions stored in the one or more memories to performing operations comprising:
• receiving a plurality of polling messages, each polling message including an identifier of a respective access device of a plurality of access devices that transmit the polling message, wherein each polling message of the plurality of polling messages is transmitted during a polling phase;
• selecting a portion of a timeslot of a plurality of timeslots in a response phase of a communication session, wherein the selecting is based on criteria associated with the plurality of polling messages;
• transmitting a response message to a particular access device of the plurality of access devices during the portion of the timeslot of the response phase;
• receiving, from the particular access device and during a third phase, an assignment message including an assigned timeslot for the response phase of a future session;
• performing secure ranging the particular access device during the future session using the assigned timeslot;
• and
• providing an access credential to the particular access device responsive to a location determined using the secure ranging, where the location is a position relative to an entryway of the particular access device.

A computing device for secure ranging, the computing device comprising:

• one or more memories;
• and
• one or more processors in communication with the one or more memories and configured to execute instructions stored in the one or more memories to performing operations comprising:
• receiving an assignment message from a first access device of a plurality of access devices, the assignment message identifying a first assigned response-slot of a plurality of response-slots of a response phase of a future ranging session;
• receiving, a polling message from the first access device, the polling message including access device identification information;
• determining a reception time of the polling message for the first access device;
• selecting the first assigned response-slot based on criteria associated with the polling message to direct a first response message to the first access device;
• transmitting the first response message during the first assigned response-slot, the first response message including a mobile device identifier and timing information corresponding the reception time of the polling message from the first access device;
• receiving, from a first access device of the plurality of access devices, an access message from the first access device;
• and
• responsive to the access message and at a location relative to an entryway of the first access device, providing an access credential to the first access device of the plurality of access devices.