Time and frequency tracking reference signals in new radio

Abstract

In NR, a slot structure of a UE may be dynamic due the number of symbols of PDCCH and whether the slot has UL data, among other considerations. Additionally, to support multi-TRP/multi-panel/multi-BWP operation, a UE may be configured with multiple TRSs, and when a UE needs to receive multiple TRSs in the same slot, efficient signaling of the TRSs is important because of the high overhead involved. During a transmission, a UE may need to do beam switching when there is a beam failure, but existing systems do not have mechanisms for the UE to synchronize time and frequency with a new beam. Further, when a UE switches to a new beam, the effect on scheduled TRS transmission for old beams is unclear. Fine frequency and time tracking may also be required during an initial access procedure. Existing NR systems do not address how a UE may perform time and frequency tracking during an initial access procedure. Additionally, URLLC data may need to be transmitted to a UE immediately in an NR system. Existing NR systems do not address sending a TRS to a UE with URLLC data. Embodiments described herein address these and other issues.

What is claimed: 
     
         1 . An apparatus comprising a processor, a memory, and communication circuitry connecting the apparatus to a network, the apparatus further comprising computer-executable instructions stored in the memory of the apparatus which, when executed by the processor of the apparatus, cause the apparatus to perform operations comprising, locating a tracking reference signal comprising resources in a burst, the burst comprising one or more symbols within first five symbols of one or more slots. 
     
     
         2 . The apparatus of  claim 1 , wherein some resources of the tracking reference signal are frequency multiplexed with a demodulation reference signal. 
     
     
         3 . The apparatus of  claim 1 , wherein some resources of the tracking reference signal are frequency multiplexed with resources of a control resource set. 
     
     
         4 . The apparatus of  claim 1 , wherein:
 a first symbol of the tracking reference burst is located within a symbol carrying a control resource set; and   a second symbol of the tracking reference burst is located within the symbol carrying the demodulation reference signal.   
     
     
         5 . The apparatus of  claim 1 , wherein one or more tracking reference bursts are located within a mini slot. 
     
     
         6 . The apparatus of  claim 1 , wherein the tracking reference burst in a first slot is repeated in a second slot. 
     
     
         7 . The apparatus of  claim 1 , wherein the instructions further cause the apparatus to receive a configuration of the tracking reference signal dynamically in a downlink control information in a physical downlink control channel. 
     
     
         8 . An apparatus comprising a processor, a memory, and communication circuitry connecting the apparatus to a network, the apparatus further comprising computer-executable instructions stored in the memory of the apparatus which, when executed by the processor of the apparatus, cause the apparatus to perform operations comprising:
 receive a first tracking reference burst in a first beam;   receive a second tracking reference burst in a second beam; and   perform time and frequency tracking using the first tracking burst signal for data of the first beam and second tracking reference burst for data on the second beam.   
     
     
         9 . The apparatus of  claim 8 , wherein the first and second tracking reference bursts are transmitted in the same slots. 
     
     
         10 . The apparatus of  claim 9 , wherein the first and second tracking reference signals are frequency division multiplexed or time division multiplexed. 
     
     
         11 . The apparatus of  claim 8 , wherein:
 the first and second beams are quasi co-located, and   the time and frequency tracking comprises joint estimation through the first and second tracking reference signals.   
     
     
         12 . An apparatus comprising a processor, a memory, and communication circuitry connecting the apparatus to a network, the apparatus further comprising computer-executable instructions stored in the memory of the apparatus which, when executed by the processor of the apparatus, cause the apparatus to perform operations comprising:
 locating a tracking reference signal, the tracking reference signal having some resources within a mini slot and some resources outside of the mini slot.   
     
     
         13 . The apparatus of  claim 12 , wherein some of the resources are within a physical downlink control channel. 
     
     
         14 . The apparatus of  claim 12 , wherein some of the resources are within a physical downlink shared channel for the apparatus. 
     
     
         15 . The apparatus of  claim 12 , a first set of resources of the tracking reference signal precedes the mini-slot, and the mini-slot contains a second set of resources of the tracking reference signal. 
     
     
         16 . The apparatus of  claim 15 , wherein the resources of the physical downlink control channel or physical downlink shared channel is rate-matched around the first set of resources of the tracking reference signal. 
     
     
         17 . The apparatus of  claim 12 , the mini-slot contains a first set of resources of the tracking reference signal, and a second set of resources of the tracking reference signal follows the mini-slot. 
     
     
         18 . The apparatus of  claim 17 , wherein the resources of the physical downlink control channel or physical downlink shared channel is rate-matched around the second set of resources of the tracking reference signal. 
     
     
         19 . The apparatus of  claim 12 , wherein the instructions further cause the apparatus to receive a configuration of the tracking reference signal dynamically in a downlink control information in a physical downlink control channel within the mini slot.