Channel access procedures in a wireless network
A base station performs channel access procedures for transmission on the plurality of LAA cells comprising a first cell group and a second cell group. The channel access procedures comprising a first channel access procedure of a first cell of the first cell group. The first channel access procedure is dependent on a second channel access procedure of a second cell of the first cell group and is independent of a third channel access procedure of a third cell of the second cell group.
1. A method comprising:
receiving, by a base station, one or more messages indicating support for a plurality of unlicensed frequency bands;
encoding, by the base station, a plurality of transport blocks (TBs) for transmission on a plurality of licensed assisted access (LAA) cells operating in the plurality of unlicensed frequency bands;
performing, by the base station, listen before talk (LBT) procedures for transmission on the plurality of LAA cells, the LBT procedures comprising a first LBT procedure of a first LAA cell, a second LBT procedure of a second LAA cell, and a third LBT procedure of a third LAA cell, the first LBT procedure being:
dependent on the second LBT procedure of the second LAA cell in a same unlicensed frequency band as the first LAA cell; and
independent of the third LBT procedure of the third LAA cell in a different unlicensed frequency band than the first LAA cell; and
transmitting, on one or more cells of the plurality of LAA cells when the LBT procedures indicate a clear channel on the one or more cells.
2. The method of claim 1 , wherein a first group of LAA cells, in an unlicensed frequency band that includes the first LAA cell and the second LAA cell, employs a first multi-carrier access procedure type and a second group of LAA cells, in an unlicensed frequency band that includes the third LAA cell, employs a second multi-carrier access procedure type.
3. The method of claim 1 , wherein at least one of the LBT procedures is a multi-carrier access procedure type A or a multi-carrier access procedure type B.
4. The method of claim 1 , further comprising transmitting one or more radio resource control (RRC) messages comprising configuration parameters of the plurality of LAA cells.
5. The method of claim 1 , wherein a first group of LAA cells, in an unlicensed frequency band that includes the first LAA cell and the second LAA cell, and a second group of LAA cells, in the unlicensed frequency band that includes the third LAA cell, are pre-configured in the base station.
6. The method of claim 1 , wherein:
a first cell group comprises first LAA cells of an unlicensed frequency band that includes the first LAA cell and the second LAA cell; and
a second cell group comprises second LAA cells of an unlicensed frequency band that includes the third LAA cell.
7. The method of claim 6 , wherein one or more first channel access parameters of the first cell group are configured differently from second channel access parameters of the second cell group.
8. The method of claim 6 , wherein:
LBT procedures on the first LAA cells employ a first threshold; and
LBT procedures on the second LAA cells employ a second threshold different from the first threshold.
9. The method of claim 6 , wherein the LBT procedures comprise:
selecting the second LAA cell uniformly randomly from the first cell group;
performing the second LBT procedure on the second LAA cell employing a long monitoring period;
performing the first LBT procedure on the first LAA cell employing a short monitoring period;
transmitting on the second LAA cell based on the second LBT procedure indicating a clear channel; and
transmitting on the first LAA cell based on the first LBT procedure and the second LBT procedure indicating a clear channel.
10. A base station comprising:
one or more processors; and
memory storing instructions that, when executed by the one or more processors, cause the base station to:
receive one or more messages indicating support for a plurality of unlicensed frequency bands;
encode a plurality of transport blocks (TBs) for transmission on a plurality of licensed assisted access (LAA) cells operating in the plurality of unlicensed frequency bands;
perform listen before talk (LBT) procedures for transmission on the plurality of LAA cells, the LBT procedures comprising a first LBT procedure of a first LAA cell, a second LBT procedure of a second LAA cell, and a third LBT procedure of a third LAA cell, the first LBT procedure being:
dependent on the second LBT procedure of the second LAA cell in a same unlicensed frequency band as the first LAA cell; and
independent of the third LBT procedure of the third LAA cell in a different unlicensed frequency band than the first LAA cell; and
transmit on one or more cells of the plurality of LAA cells when the LBT procedures indicate a clear channel on the one or more cells.
11. The base station of claim 10 , wherein a first group of LAA cells, in an unlicensed frequency band that includes the first LAA cell and the second LAA cell, employs a first multi-carrier access procedure type and a second group of LAA cells, in an unlicensed frequency band that includes the third LAA cell, employs a second multi-carrier access procedure type.
12. The base station of claim 10 , wherein at least one of the LBT procedures is a multi-carrier access procedure type A or a multi-carrier access procedure type B.
13. The base station of claim 10 , wherein the instructions, when executed, further cause the base station to transmit one or more radio resource control (RRC) messages comprising configuration parameters of the plurality of cells.
14. The base station of claim 10 , wherein a first group of LAA cells, in an unlicensed frequency band that includes the first LAA cell and the second LAA cell, and a second group of LAA cells, in an unlicensed frequency band that includes the third LAA cell, are pre-configured in the base station.
15. The base station of claim 10 , wherein:
a first cell group comprises first LAA cells of an unlicensed frequency band that includes the first LAA cell and the second LAA cell; and
a second cell group comprises second LAA cells of an unlicensed frequency band that includes the third LAA cell.
16. The base station of claim 15 , wherein one or more first channel access parameters of the first cell group are configured differently from second channel access parameters of the second cell group.
17. The base station of claim 15 , wherein:
LBT procedures on the first LAA cells employ a first threshold; and
LBT procedures on the second LAA cells employ a second threshold different from the first threshold.
18. The base station of claim 15 , wherein the instructions for the channel access procedures further cause the base station to:
select the second LAA cell uniformly randomly from the first cell group;
perform the second LBT procedure on the second LAA cell employing a long monitoring period;
perform the first LBT procedure on the first LAA cell employing a short monitoring period;
transmit on the second LAA cell based on the second LBT procedure indicating a clear channel; and
transmit on the first LAA cell based on the first LBT procedure and the second LBT procedure indicating a clear channel.