Support of network based positioning by sounding reference signal
A method of network-based positioning using sounding reference signal (SRS) is proposed. An eNodeB configures a number of parameters of a periodic SRS transmission for a user equipment (UE). The eNodeB then transmits SRS configuration data for SRS measurements performed by a location measurement unit (LMU). The SRS configuration data includes cell-specific SRS bandwidth configuration and UE-specific SRS bandwidth configuration. The SRS configuration data may further include a number of antenna ports for SRS transmission, SRS frequency hopping bandwidth configuration, information on whether SRS sequence-group hopping is enabled, and Δ SS when SRS sequence hopping is enabled. Upon receiving the SRS configuration data, the LMU is able to perform timing measurements over the received SRS signals from the UE. In one embodiment, the LMU detects SRS dropping to avoid performance degradation of the network-based positioning.
1. A method comprising:
configuring a number of parameters of a periodic sounding reference signal (SRS) for a user equipment (UE) by a base station, wherein the periodic SRS is used for network-based positioning;
scheduling periodic SRS transmissions in specific uplink subframes based on predefined rules to reduce SRS dropping; and
transmitting SRS configuration data to a location measurement unit (LMU), wherein the SRS configuration data is selected from the number of parameters of the periodic SRS by the base station to be used for SRS measurements for the network-based positioning for the UE, wherein the SRS configuration data includes cell-specific SRS bandwidth configuration and UE-specific SRS bandwidth configuration, wherein the SRS configuration data further includes a total number of SRS transmissions for the positioning and a bitmap, and wherein each bit indicates whether a corresponding SRS transmission is dropped by the UE.
2. The method of claim 1 , wherein the SRS configuration data includes a number of antenna ports for SRS transmission, wherein the number of antenna ports is set to one when the base station starts the positioning, and wherein the base station re-configures the number of antenna ports when the base station stops the positioning.
3. The method of claim 1 , wherein the SRS configuration data further includes SRS frequency hopping bandwidth configuration.
4. The method of claim 1 , wherein the SRS configuration data further includes cell-specific information on whether SRS sequence-group hopping is enabled.
5. The method of claim 1 , wherein the SRS configuration data further includes a delta sequence shift Δ SS when SRS sequence hopping is enabled.
6. A method comprising:
receiving sounding reference signal (SRS) configuration data transmitted from a base station, wherein the SRS configuration data is used for SRS measurements by a location measurement unit (LMU) for network-based positioning, wherein the SRS configuration data includes cell-specific SRS bandwidth configuration and UE-specific SRS bandwidth configuration, and wherein the SRS configuration data further includes a total number of SRS transmissions for the positioning and a bitmap, wherein each bit indicates whether a corresponding SRS transmission is dropped by the UE;
receiving a sounding reference signal transmitted from a user equipment, wherein the sounding reference signal has an SRS sequence, and wherein the SRS transmission is scheduled in specific uplink subframes for reducing SRS dropping based on predefined rules; and
performing timing measurements for the received signal using the SRS configuration data.
7. The method of claim 6 , wherein the SRS configuration data includes a number of antenna ports for SRS transmission, and wherein the number of antenna ports is set to one for the positioning.
8. The method of claim 6 , wherein the SRS configuration data further includes SRS frequency hopping bandwidth configuration.
9. The method of claim 6 , wherein the SRS configuration data further includes cell-specific information on whether SRS sequence-group hopping is enabled.
10. The method of claim 6 , wherein the SRS configuration data further includes a delta sequence shift Δ SS when SRS sequence hopping is enabled.
11. A location measurement unit (LMU), comprising:
a radio frequency module that receives sounding reference signal (SRS) configuration data transmitted from a base station, wherein the SRS configuration data is used for SRS measurements for network-based positioning, wherein the set of SRS configuration data includes cell-specific SRS bandwidth configuration and UE-specific SRS bandwidth configuration, wherein the SRS configuration data further includes a total number of SRS transmissions for the positioning and a bitmap, wherein each bit indicates whether a corresponding SRS transmission is dropped by the UE, wherein the RF module also receives a sounding reference signal transmitted from a user equipment, and wherein the SRS transmission is scheduled in specific uplink subframes for reducing SRS dropping based on predefined rules; and
an SRS measurement module that performs timing measurements for the received signal using the SRS configuration data.
12. The LMU of claim 11 , wherein the SRS configuration data includes a number of antenna ports for SRS transmission, and wherein the number of antenna ports is set to one for the positioning.
13. The LMU of claim 11 , wherein the SRS configuration data further includes SRS frequency hopping bandwidth configuration.
14. The LMU of claim 11 , wherein the SRS configuration data further includes cell-specific information on whether SRS sequence-group hopping is enabled.
15. The LMU of claim 11 , wherein the SRS configuration data further includes a delta sequence shift Δ SS when SRS sequence hopping is enabled.