Mobility enhancement with channel state information reference signals (CSI-RS)
Certain aspects may help enhance mobility of a UE, for example, utilizing downlink and/or uplink reference signals to assist in locating and/or handing over a UE in a cell with multiple transmit reception points (TRPs).
1. A method for wireless communications by a user equipment (UE), comprising:
measuring one or more cell specific channel state information reference signals (CSI-RSs) including a cell identifier (ID), after exiting a reduced power state;
transmitting an uplink reference signal to a first transmit receive point (TRP) in the cell;
receiving signaling from the network, based on the uplink reference signal, of an indication of a second TRP for handover of the UE, wherein the signaling of the indication of the second TRP for handover comprises using a physical downlink control channel (PDCCH) scrambled by both an ID of the UE and the cell ID; and
monitoring for another PDCCH from the second TRP.
2. The method of claim 1 , wherein monitoring for the other PDCCH from the second TRP comprises at least one of:
monitoring for a paging indication in the other PDCCH, scrambled or otherwise identified using the ID of the UE and an ID of the second TRP, while the UE is in an idle mode; or
monitoring a schedule specific to the UE in the other PDCCH while the UE is in a connected mode.
3. The method of claim 1 , further comprising performing at least one of radio link monitoring (RLM), frequency tracking loop or time tracking loop updating, or open loop power control based on the cell specific CSI-RSs.
4. The method of claim 1 , further comprising receiving a physical downlink shared channel (PDSCH) having an ID of the second TRP as payload.
5. The method of claim 1 , wherein the signaling of the indication of the second TRP is transmitted from multiple TRPs as a single frequency network (SFN) transmission.
6. The method of claim 1 , further comprising:
deciding to transmit the uplink reference signal when a measured signal quality of the TRP specific CSI-RS is below a threshold value.
7. The method of claim 1 , further comprising accessing the cell using a random access channel (RACH) configuration using information received in a TRP-specific synchronization signal from the first TRP.
8. A method for wireless communications by a first transmit receive point (TRP) in a cell of a network, comprising:
transmitting one or more cell specific channel state information reference signals (CSI-RSs) including an identifier (ID) of the cell, discoverable by a user equipment (UE) upon exiting a reduced power state;
receiving an uplink reference signal from the UE; and
transmitting, to the UE, signaling of an indication of a second TRP for handover of the UE based on the uplink reference signal, wherein the signaling of the indication of the second TRP for handover comprises using a physical downlink control channel (PDCCH) scrambled by both an ID of the UE and the ID of the cell.
9. The method of claim 8 , further comprising receiving a physical downlink shared channel (PDSCH) having an ID of the second TRP as payload.
10. The method of claim 8 , wherein the signaling of the indication of the second TRP is transmitted from multiple TRPs as a single frequency network (SFN) transmission.
11. The method of claim 8 , further comprising:
transmitting a TRP-specific synchronization signal including an ID of the first TRP to the UE; and
receiving a random access channel (RACH) transmission from the UE based on a RACH configuration associated with the first TRP.