Operation of cellular communication networks on unlicensed frequency bands

An apparatus comprising:

• at least one processing core,
• at least one non-transitory memory including computer program code, the at least one non-transitory memory and the computer program code being configured to, with the at least one processing core, cause the apparatus at least to perform:
• obtaining, from a cellular base station, a first opportunity for a first data transmission on an unlicensed frequency band, wherein the first opportunity is within a first period reserved for first transmission opportunities on a frequency channel;
• determining an ending time of the first period reserved for first transmission opportunities and/or an ending time of a maximum period of time based on a received signalling, wherein the received signalling comprises a group or cell common control signalling;
• upon detecting that the frequency channel is occupied at a beginning of the first opportunity, determining a second opportunistic resource for the first data transmission or a second transmission, wherein the second opportunistic resource is a second opportunity for the first data transmission outside of the first period reserved for first transmission opportunities and within or outside of the maximum period of time;
• and
• receiving or transmitting using the second opportunistic resource.

A system comprising:

• an apparatus;
• at least one processing core,
• at least one non-transitory memory including computer program code, the at least one non-transitory memory and the computer program code being configured to, with the at least one processing core, cause the apparatus at least to perform:
• obtaining, from a cellular base station, a first opportunity for a first data transmission on an unlicensed frequency band, wherein the first opportunity is within a first period reserved for first transmission opportunities on a frequency channel;
• determining an ending time of the first period reserved for first transmission opportunities and/or an ending time of a maximum period of time based on a received signalling, wherein the received signalling comprises a group or cell common control signalling;
• upon detecting that the frequency channel is occupied at a beginning of the first opportunity, determining a second opportunistic resource for the first data transmission or a second transmission, wherein the second opportunistic resource is a second opportunity for the first data transmission outside of the first period reserved for first transmission opportunities and within or outside of the maximum period of time;
• and
• receiving or transmitting using the second opportunistic resource.