Method and Apparatus for Enhanced Uplink Reference Signal in Listen-Before-Talk Systems

A wireless device configured for operation in a wireless communication network and comprising:

• a communication interface configured for transmitting signals to the wireless communication network and receiving signals from the wireless communication network;
• and
• a processing circuit operatively associated with the communication interface and configured to:
• perform a listen-before-talk (LBT) operation to assess whether a communication channel is clear to use for an uplink transmission by the wireless device;
• begin transmitting an enhanced Reference Signal (RS), responsive to determining that the communication channel is clear, to thereby capture the communication channel;
• and
• transition from transmission of the enhanced RS to transmission of uplink data at a defined time after capturing the communication channel,
• wherein the processing circuit is configured to transmit the enhanced RS according to configuration information that is at least in part signaled from the wireless communication network, and
• wherein the configuration information defines or controls any one or more of the following items:
• a frequency comb pattern or repetition factor to be used for mapping the enhanced RS to corresponding Resource Elements (REs) defined in association with the communication channel;
• a bandwidth parameter to define or limit the bandwidth of the enhanced RS;
• a cyclic shift parameter to define the cyclic shift used by the wireless device for transmission of the enhanced RS;
• an orthogonal cover code (OCC) to be applied by the wireless device to the enhanced RS, at least for cases when the enhanced RS is transmitted in multiple symbol periods within a given subframe;
• an enablement parameter, the value of which enables or disables use of the enhanced RS by the wireless device;
• and
• a mode parameter, the value of which indicates that the enhanced RS is to be used only for uplink RS transmission after the LBT operation, while a legacy Sounding Reference Signal (SRS) is to be used in a last symbol of each configured subframe, for the remainder of the uplink transmission, or that the enhanced RS is to be used for both uplink RS transmission after the LBT operation and also in the remainder of the uplink transmission.

A method of operation by a wireless device configured for operation in a wireless communication network, said method comprising:

• performing a listen-before-talk (LBT) operation to assess whether a communication channel is clear to use for an uplink data transmission by the wireless device;
• beginning transmission of an enhanced Reference Signal (RS), responsive to determining that the communication channel is clear, to thereby capture the communication channel;
• and
• transitioning from transmission of the enhanced RS to transmission of uplink data at a defined time after capturing the communication channel,
• wherein the method includes transmitting the enhanced RS according to configuration information that is at least in part signaled from the wireless communication network, and
• wherein the configuration information defines or controls any one or more of the following items:
• a frequency comb pattern or repetition factor to be used for mapping the enhanced RS to corresponding Resource Elements (REs) defined in association with the communication channel;
• a bandwidth parameter to define or limit the bandwidth of the enhanced RS;
• a cyclic shift parameter to define the cyclic shift used by the wireless device for transmission of the enhanced RS;
• an orthogonal cover code (OCC) to be applied by the wireless device to the enhanced RS, at least for cases when the enhanced RS is transmitted in multiple symbol periods within a given subframe;
• an enablement parameter, the value of which enables or disables use of the enhanced RS by the wireless device;
• and
• a mode parameter, the value of which indicates that the enhanced RS is to be used only for uplink RS transmission after the LBT operation, while a legacy Sounding Reference Signal ( ) is to be used in a last symbol of each configured subframe, for the remainder of the uplink transmission, or that the enhanced RS is to be used for both uplink RS transmission after the LBT operation and also in the remainder of the uplink transmission.

A network node configured for operation in a wireless communication network and comprising:

• a communication interface configured for sending signaling to one or more wireless devices operating in the wireless communication network and receiving signaling from such wireless communication devices;
• and
• a processing circuit operatively associated with the communication interface and configured to:
• determine device-specific configuration settings for one or more of the wireless devices,
• wherein the device-specific configuration settings control, for a corresponding one of the wireless devices, at least one of the following:
• whether the wireless device uses an enhanced Reference Signal (RS) for capturing communication channels, wherein said capturing is a part of listen-before-talk (LBT) operations performed by the wireless device;
• and
• one or more configuration settings controlling corresponding transmission parameters of any enhanced RS transmissions by the wireless device;
• and
• sending the corresponding device-specific configuration settings individually to the one or more wireless devices.

A method of operation by a network node that is configured for operation in a wireless communication network, said method comprising:

• determining device-specific configuration settings for one or more of the wireless devices, wherein the device-specific configuration settings control, for a corresponding one of the wireless devices, at least one of the following:
• whether the wireless device uses an enhanced Reference Signal (RS) for capturing communication channels, wherein said capturing is a part of listen-before-talk (LBT) operations performed by the wireless device;
• and
• one or more configuration settings controlling corresponding transmission parameters of any enhanced RS transmissions by the wireless device;
• and
• sending the corresponding device-specific configuration settings individually to the one or more wireless devices.