Efficient SRS resource indication methods
A method of identifying reference signal resources to be used in a transmission by a wireless device is disclosed. The method comprises a wireless device receiving signaling configuring the wireless device with a plurality of reference signal resource groups, each group comprising a plurality of reference signal resources. The wireless device subsequently receives an indication, in a control channel, of a selection of reference signal resources to be used. Each of the plurality of reference signal resources to be used is selected from a different one of the plurality of reference signal resource groups such that reference signal resources belonging to the same reference signal resource group are not selected for simultaneous use. A reference signal is then transmitted to a network node in the network using the indicated selection of reference signal resources.
1. A method in a wireless device, operable in a cellular wireless communication network, of identifying reference signal resources to be used in a transmission by the wireless device, the method comprising:
receiving signaling configuring the wireless device with a plurality of reference signal resource groups, each group comprising a plurality of reference signal resources;
receiving an indication, in a control channel, of a selection of reference signal resources to be used, wherein each of the plurality of reference signal resources to be used is selected from a different one of the plurality of reference signal resource groups such that reference signal resources belonging to the same reference signal resource group are not selected for simultaneous use; and
transmitting a reference signal to a network node in the network using the indicated selection of reference signal resources,
wherein the indication of the plurality of reference signal resources to be used includes a bit field, the length of the bit field depending on a maximum number of MIMO layers that the wireless device is capable of transmitting and a number of reference signal resources in a corresponding one of the reference signal resource groups.
2. The method of claim 1 , wherein the reference signal resources are sounding reference signal (SRS) resources.
3. The method of claim 1 , wherein the transmitted reference signal is an SRS.
4. The method of claim 1 , wherein the length of the bit field is sufficient to indicate S combinations of SRS resources, wherein:
S
=
∑
L
=
1
L
max
(
N
L
)
,
and
where L max is a maximum number of MIMO layers that the wireless device is capable of transmitting and N is the number of resources in the first reference signal resource group.
5. The method of claim 1 , wherein the reference signal is transmitted for beam management usage.
6. The method of claim 1 , wherein the wireless device includes multiple antenna panels, each one of the plurality of reference signal resource groups corresponding to a different one of the antenna panels.
7. The method of claim 1 , wherein receiving signaling configuring the wireless device with a plurality of reference signal resource groups includes receiving a radio resource control message that defines a control channel trigger associated with the plurality of reference signal resource groups; and
wherein receiving an indication, in a control channel, of a selection of reference signal resources to be used includes receiving a trigger associated with the plurality of reference signal resource groups and a resource indicator that indicates reference signal resources selected from among reference signal resources within the triggered plurality of reference signal resource groups.
8. A wireless device for facilitating communications in a cellular wireless communication network by obtaining an indication of reference signal resources to be used, the wireless device comprising:
a memory containing computer readable instructions; and
processing circuitry configured to execute the computer readable instructions, whereby the wireless device is operable to:
receive signaling that configures the wireless device with a plurality of reference signal resource groups, each group comprising a plurality of reference signal resources;
receive an indication, in a control channel, of a selection of reference signal resources to be used, wherein each of the plurality of reference signal resources to be used is selected from a different one of the plurality of reference signal resource groups such that reference signal resources belonging to the same reference signal resource group are not selected for simultaneous use; and
transmit a reference signal to a network node in the network using the indicated selection of reference signal resources,
wherein the indication of the plurality of reference signal resources to be used includes a bit field, the length of the bit field depending on a maximum number of MIMO layers that the wireless device is capable of transmitting and a number of reference signal resources in a corresponding one of the reference signal resource groups.
9. The wireless device of claim 8 , wherein the reference signal resources are sounding reference signal (SRS) resources.
10. The wireless device of claim 8 , wherein the length of the bit field is sufficient to indicate S combinations of SRS resources, wherein:
S
=
∑
L
=
1
L
max
(
N
L
)
,
and
where L max is a maximum number of MIMO layers that the wireless device is capable of transmitting and N is the number of resources in the first reference signal resource group.
11. The wireless device of claim 8 , wherein the reference signal is transmitted for beam management usage.
12. The wireless device of claim 8 , wherein the wireless device includes multiple antenna panels, each one of the plurality of reference signal resource groups corresponding to a different one of the antenna panels.
13. A method in a network node, of configuring and indicating use of reference signal transmission settings in a wireless device operable in a cellular wireless communication network, the method comprising:
transmitting signaling configuring the wireless device with a plurality of reference signal resource groups, each group comprising a plurality of reference signal resources; and
transmitting an indication, in a control channel, of a selection of reference signal resources to be used, wherein the network node selects each of the plurality of reference signal resources to be used from a different one of the plurality of reference signal resource groups such that reference signal resources belonging to the same reference signal resource group are not selected for simultaneous use; and
receiving a reference signal from the wireless device using the indicated selection of reference signal resources,
wherein the indication of the plurality of reference signal resources to be used includes a bit field, the length of the bit field depending on a maximum number of MIMO layers that the wireless device is capable of transmitting and a number of reference signal resources in a corresponding one of the reference signal resource groups.
14. The method of claim 13 , wherein the reference signal resources are sounding reference signal (SRS) resources.
15. The method of claim 13 , wherein the length of the bit field is sufficient to indicate combinations of SRS resources, wherein:
S
=
∑
L
=
1
L
ma
x
(
N
L
)
,
and
where L max is a maximum number of MIMO layers that the wireless device is capable of transmitting and N is the number of resources in the first reference signal resource group.
16. The method of claim 13 , wherein the received reference signal is used for beam management.
17. The method of claim 13 , wherein the wireless device includes multiple antenna panels, each one of the plurality of reference signal resource groups corresponding to a different one of the antenna panels.
18. The method of claim 13 , wherein transmitting signaling configuring the wireless device with a plurality of reference signal resource groups includes transmitting a radio resource control message that defines a control channel trigger associated with the plurality of reference signal resource groups; and
wherein transmitting an indication, in a control channel, of a selection of reference signal resources to be used includes transmitting a trigger associated with the plurality of reference signal resource groups and a resource indicator that indicates reference signal resources selected from among reference signal resources within the triggered plurality of reference signal resource groups.