Time multiplexing communication with secondary cells

1. A method implemented by a network node of a cellular communication network, serving a plurality of user devices, the method comprising:

determining a downlink (DL) buffer status for each of a plurality of secondary cells (SCells);

determining a transmission routine for each of the plurality of SCells, using radio channels in an unlicensed spectrum, each transmission routine having an associated transmission period, based on the respective downlink (DL) buffer status; and

time multiplexing transmission from the plurality of SCells to the plurality of user devices by executing the transmission routines during their respective transmission periods.

2. The method of claim 1 , wherein a communication cycle includes a sequence of the transmission routines for the plurality of SCells.

3. The method of claim 2 , further comprising executing additional communication cycles based on the downlink buffer status.

4. The method of claim 3 , wherein the associated transmission period for an SCell may change in a subsequent communication cycle.

5. The method of claim 2 , wherein, within a communication cycle, all SCell reception routines are performed after all transmission routines.

6. The method of claim 1 , wherein each transmission periods ranges from zero to a maximum value, MAX_TX.

7. The method of claim 1 , further comprising:

determining a reception routine for each one of the plurality of SCells, each reception routine having an associated reception period; and

time multiplexing reception of data from the plurality of user devices to the plurality of SCells by executing the reception routines for their respective reception periods.

8. The method of claim 7 , wherein each one of the reception periods are above a minimum value, MIN_RX.

9. The method of claim 7 , wherein the reception routine of a given SCell is performed after the transmission routine for the given SCell.

10. The method of claim 1 , further comprising:

selecting a radio channel for use by based on channel quality measurements obtained from the plurality of user devices;

activating the SCell during the associated transmission period of a communication cycle; and

deactivating the SCell during a remainder time of the communication cycle.

11. The method of claim 10 , wherein the radio channel is used for communication between the SCell and at least one user device selected from the plurality of user devices based on channel quality measurements.

12. A network node within a cellular communication network, the network node comprising:

a user interface circuit, for communicating with at least one user device; and

a processing circuit, the processing circuit configured to:

determine a downlink (DL) buffer status for each of a plurality of secondary cells (SCells);

determine a transmission routine for each of the plurality of SCells, using radio channels in an unlicensed spectrum, each transmission routine having an associated transmission period, based on the respective downlink (DL) buffer status; and

time multiplex transmission from the plurality of SCells to a plurality of the at least one user device by executing the transmission routines for their respective transmission periods.

13. The network node of claim 12 , wherein a communication cycle includes a sequence of the transmission routines for the plurality of SCells.

14. The network node of claim 13 , wherein the processing circuit is further configured to execute additional communication cycles based on the downlink buffer status.

15. The network node of claim 14 , wherein the associated transmission period for an SCell can change in a subsequent communication cycle.

16. The network node of claim 13 , wherein, within a communication cycle, all SCell reception routines are performed after all transmission routines.

17. The network node of claim 12 , wherein each transmission periods ranges from zero to a maximum value, MAX_TX.

18. The network node of claim 12 , wherein the processing circuit is further configured to:

determine a reception routine for each one of the plurality of SCells, each reception routine having an associated reception period; and

time multiplex reception of data from the plurality of user devices to the plurality of SCells by executing the reception routines for their respective reception periods.

19. The network node of claim 18 , wherein each one of the reception periods are above a minimum value, MIN_RX.

20. The network node of claim 18 , wherein the reception routine of a given SCell is performed after the transmission routine for the given SCell.

21. The network node of claim 12 , wherein the processing circuit is further configured to:

select a radio channel for use by based on channel quality measurements obtained from the plurality of user devices;

activate the SCell during the associated transmission period of a communication cycle; and

deactivate the SCell during a remainder time of the communication cycle.

22. The network node of claim 21 , wherein the radio channel is used for communication between the SCell and at least one user device selected from the plurality of user devices based on channel quality measurements.

23. An apparatus, configured to:

determine a downlink (DL) buffer status for each of a plurality of secondary cells (SCells);

determine a transmission routine for each of the plurality of SCells, using radio channels in an unlicensed spectrum, each transmission routine having an associated transmission period, based on the respective downlink (DL) buffer status; and

time multiplex transmission from the plurality of SCells to a plurality of user devices by executing the transmission routines for their respective transmission periods.

24. A non-transitory computer-readable storage medium containing a computer program comprising executable instructions that, when executed by a processing circuit in a network node causes the network node to perform a method comprising:

determining a downlink (DL) buffer status for each of a plurality of secondary cells (SCells);

determining a transmission routine for each of the plurality of SCells, using radio channels in an unlicensed spectrum, each transmission routine having an associated transmission period, based on the respective downlink (DL) buffer status; and

time multiplexing transmission from the plurality of SCells to the plurality of user devices by executing the transmission routines during their respective transmission periods.