Synchronizing indoor radio nodes

A non-transitory computer-readable storage medium for use in conjunction with a radio node, the computer-readable storage medium configured to store program instructions, wherein, when executed by the radio node, the program instructions cause the radio node to perform operations comprising:

• arbitrating with other radio nodes in a set of radio nodes in a cellular-telephone network based on a selection technique to select a synchronization master in the set of radio nodes, wherein the set of radio nodes comprises the radio node,
• wherein the synchronization master specifies time, frequency, and phase synchronization for the set of radio nodes, and
• wherein the selection technique comprises:
• determining a type of communication environment of the set of radio nodes, wherein the determined type of radio environment specifies a predefined synchronization performance of the synchronization master,
• wherein, when the determined type of communication environment excludes overlap between the set of radio nodes and a macrocell in the cellular-telephone network, the synchronization master is a given radio node in the set of radio nodes that:
• detects signals from a global position system (GPS) within a time interval;
• when the signals from the GPS are not detected by the set of radio nodes within the time interval, has the predefined synchronization performance in a precision time protocol (PTP);
• and
• when the set of radio nodes do not have the predefined synchronization performance in the PTP, has a crystal oscillator with a largest stability in the set of radio nodes;
• and
• when the synchronization master is different from the radio node, synchronizing with the synchronization master.

A method for selecting a synchronization master, comprising:

• by a radio node:
• arbitrating with other radio nodes in a set of radio nodes in a cellular-telephone network based on a selection technique to select the synchronization master in the set of radio nodes, wherein the set of radio nodes comprises the radio node,
• wherein the synchronization master specifies time, frequency, and phase synchronization for the set of radio nodes, and
• wherein the selection technique comprises:
• determining a type of communication environment of the set of radio nodes, wherein the determined type of radio environment specifies a predefined synchronization performance of the synchronization master,
• wherein, when the determined type of communication environment excludes overlap between the set of radio nodes and a macrocell in the cellular-telephone network, the synchronization master is a given radio node in the set of radio nodes that:
• detects signals from a global position system (GPS) within a time interval;
• when the signals from the GPS are not detected by the set of radio nodes within the time interval, has the predefined synchronization performance in a precision time protocol (PTP);
• and
• when the set of radio nodes do not have the predefined synchronization performance in the PTP, has a crystal oscillator with a largest stability in the set of radio nodes;
• and
• when the synchronization master is different from the radio node, synchronizing with the synchronization master.