Methods and apparatus for controlling uplink reference signal transmissions in a wireless communication network
In an example arrangement, a base station ( 16 ) serving a wireless device ( 14 ) controls the activation time for transmission by the wireless device ( 14 ) of aperiodic or semipersistent Sounding Reference Signals (SRS), but accounts for an activation-time recommendation made by a location server ( 20 ) with which the serving base station ( 16 ) provides its timing information. The arrangement allows the location server ( 20 ), which has a view of the overall timeline, to recommend an activation time while still leaving the serving base station ( 16 ) in control of the activation time, which the serving base station ( 16 ) shares with the location server ( 20 ). In turn, the location server ( 20 ) uses the activation time to configure neighboring base stations ( 16 ), for example, for coordinated reception of the SRS, for positioning the device ( 14 ) via Uplink Observed Time Difference of Arrival (UTDOA) determinations. Activation of the SRS provides, for example, increased SRS density as compared to any ongoing periodic SRS transmissions performed by the wireless device ( 14 ).
1. A method by a location server configured for operation in association with a wireless communication network, the method comprising:
sending a message, to a base station serving a wireless device, as a request to the base station to trigger activation of an aperiodic or semipersistent Sounding Reference Signal (SRS) configuration by the wireless device, the message comprising an indication of the aperiodic or semipersistent SRS configuration and a timing recommendation,
wherein the timing recommendation is an activation-time recommendation for when the base station should activate the wireless device to start transmission of SRS according to the aperiodic or semipersistent SRS configuration.
2. A location server configured for operation in association with a wireless communication network, the location server comprising:
communication circuitry configured to communicatively couple the location server to one or more nodes of the wireless communication network; and
processing circuitry operatively associated with the communication circuitry and configured to:
send a message, to a base station serving a wireless device, as a request to the base station to trigger activation of an aperiodic or semipersistent Sounding Reference Signal (SRS) configuration by the wireless device, the message comprising an indication of the aperiodic or semipersistent SRS configuration and a timing recommendation,
wherein the timing recommendation is an activation-time recommendation for when the base station should activate the wireless device to start transmission of SRS according to the aperiodic or semipersistent SRS configuration.
3. A base station configured for operation in association with a wireless communication network, the base station comprising:
communication circuitry configured for communicatively coupling the first base station to one or more wireless devices and for communicatively coupling the first base station to a location server;
processing circuitry operatively associated with the communication circuitry and configured to:
receive from a location server a message requesting the base station to trigger activation of an aperiodic or semipersistent Sounding Reference Signal (SRS) configuration by a wireless device, wherein the message comprises an indication of the aperiodic or semipersistent SRS configuration and a timing recommendation, wherein the timing recommendation is an activation-time recommendation for when the base station should activate the wireless device to start transmitting SRS according to the aperiodic or semipersistent SRS configuration; and
trigger the wireless device to activate the aperiodic or semipersistent SRS configuration.
4. The base station according to claim 3 , wherein the processing circuitry is configured to trigger the wireless device to activate the aperiodic or semipersistent SRS configuration by sending an indication of the aperiodic or semipersistent SRS configuration to the wireless device.
5. The base station according to claim 3 , wherein the processing circuitry is configured to trigger the wireless device to activate the aperiodic or semipersistent SRS configuration by transmitting a Downlink Control Information (DCI) trigger or a Medium Access Control Element (MAC CE) to the wireless device.
6. The base station according to claim 3 , wherein the processing circuitry is configured to trigger the wireless device to activate the aperiodic or semipersistent SRS configuration according to the activation-time recommendation.
7. A method by a base station configured for operation in association with a wireless communication network, the method comprising:
receiving a message, from a location server, requesting the base station to trigger activation of an aperiodic or semipersistent Sounding Reference Signal (SRS) configuration by a wireless device, wherein the message comprises an indication of the aperiodic or semipersistent SRS configuration and a timing recommendation, wherein the timing recommendation is an activation-time recommendation for when the base station should activate the wireless device to start transmitting SRS according to the aperiodic or semipersistent SRS configuration; and
triggering the wireless device to activate the aperiodic or semipersistent SRS configuration.
8. The method according to claim 7 , wherein triggering the wireless device to activate the aperiodic or semipersistent SRS configuration comprises sending an indication of the aperiodic or semipersistent SRS configuration to the wireless device.
9. The method according to claim 7 , wherein triggering the wireless device to activate the aperiodic or semipersistent SRS configuration comprises transmitting a Downlink Control Information (DCI) trigger or a Medium Access Control Element (MAC CE) to the wireless device.
10. The method according to claim 7 , wherein triggering the wireless device to activate the aperiodic or semipersistent SRS configuration comprises triggering the wireless device to activate the aperiodic or semipersistent SRS configuration according to the activation-time recommendation.