CSI enhancements for URLLC
Systems and methods for Channel State Information (CSI) enhancements are provided. In some embodiments, a method performed by a wireless device for reporting channel conditions includes one or more of: receiving a Channel State Information-Interference Measurement (CSI-IM) pattern; and reporting channel conditions based on the CSI-IM pattern. In some embodiments, the CSI-IM pattern spans multiple Orthogonal Frequency-Division Multiplexing (OFDM) symbols on a single subcarrier in a slot. In this way, these CSI-IM patterns might allow better interference measurement by capturing interference in all OFDM symbols in a slot and thus more accurate interference estimation and CSI feedback. The enhanced aperiodic CSI might allow interference variations over time to be measured and reported so that proper margins can be applied by the base station in downlink scheduling to ensure reliable data delivery while maintaining high spectrum efficiency.
1 . A method performed by a wireless device for reporting channel conditions, the method comprising:
receiving a Channel State Information-Interference Measurement, CSI-IM, pattern, wherein the CSI-IM pattern comprises indication of CSI-IM resources occupying multiple symbols in a slot while not fully spanning the slot;
receiving an activation message indicating the CSI-IM pattern; and
reporting the channel conditions based on the CSI-IM pattern;
wherein the CSI-IM pattern:
(a) spans every other Orthogonal Frequency-Division Multiplexing, OFDM, symbols in a slot;
(b) comprises Resource Elements, REs, in the single subcarrier and every K th OFDM symbol in the slot in each Physical Resource Block, PRB, of configured Channel State Information—Reference Signal, CSI-RS, bandwidth, where K indicates symbol density of CSI-IM REs; and/or
(c) comprises the REs in the single subcarrier and multiple consecutive OFDM symbols in the slot in each PRB of the configured CSI-RS bandwidth.
2 . The method of claim 1 wherein the CSI-IM pattern comprises one or more of the group consisting of:
a configurable starting symbol;
a configurable starting symbol and duration in symbols;
a configurable starting symbol and a fixed duration;
a configurable starting symbol and symbol density;
a configurable starting symbol and symbol density, and a fixed number of CSI-IM RES;
different CSI-IM patterns in different PRBs; and
CSI-IM repetition in multiple slots.
3 . The method of claim 2 wherein the symbol density comprises the CSI-IM pattern in every K>1 symbol in the slot.
4 . The method of claim 1 wherein receiving the CSI-IM pattern further comprises receiving rules for handling collisions when the CSI-IM pattern overlaps with other signals or channels.
5 . The method of claim 4 further comprising:
assuming that CSI-IM REs overlapping with other reference signals or physical channels are not available for interference measurement.
6 . The method of claim 1 wherein receiving the CSI-IM pattern further comprises receiving an indication of a Zero Power, ZP, CSI-RS resource having exactly the same REs as the CSI-IM, wherein the ZP CSI-RS is introduced for Physical Downlink Shared Channel, PDSCH, rate matching.
7 . The method of claim 1 wherein the CSI-IM pattern is repeated in multiple slots for measuring and reporting Channel Quality Indication, CQI, variation due to interference variation.
8 . The method of claim 7 wherein the CQI variation comprises one or more of the group consisting of: a mean; a standard deviation; a variance; a minimum; and a percentile value of CQIs.
9 . The method of claim 1 wherein the CSI is an aperiodic CSI.
10 . A method performed by a base station for receiving channel conditions, the method comprising:
transmitting, to a wireless device, a Channel State Information-Interference Measurement, CSI-IM, pattern, wherein the CSI-IM pattern comprises indication of CSI-IM resources occupying multiple symbols in a slot while not fully spanning the slot;
sending an activation message indicating the CSI-IM pattern; and
receiving, from the wireless device, a channel conditions report based on the CSI-IM pattern;
wherein the CSI-IM pattern:
(a) spans every other Orthogonal Frequency-Division Multiplexing, OFDM, symbols in a slot;
(b) comprises Resource Elements, REs, in the single subcarrier and every K th OFDM symbol in the slot in each Physical Resource Block, PRB, of configured Channel State Information-Reference Signal, CSI-RS, bandwidth, where K indicates symbol density of CSI-IM REs; and/or
(c) comprises the REs in the single subcarrier and multiple consecutive OFDM symbols in the slot in each PRB of the configured CSI-RS bandwidth.
11 . The method of claim 10 wherein the CSI-IM pattern comprises one or more of the group consisting of:
a configurable starting symbol;
a configurable starting symbol and duration in symbols;
a configurable starting symbol and a fixed duration;
a configurable starting symbol and symbol density;
a configurable starting symbol and symbol density, and a fixed number of CSI-IM RES;
different CSI-IM patterns in different PRBs; and
CSI-IM repetition in multiple slots.
12 . The method of claim 11 wherein the symbol density comprises the CSI-IM pattern in every K>1 symbol in the slot.
13 . A wireless device for reporting channel conditions, the wireless device comprising:
one or more processors; and
memory storing instructions executable by the one or more processors, whereby the wireless device is operable to perform the steps of:
receiving a Channel State Information-Interference Measurement, CSI-IM, pattern, wherein the CSI-IM pattern comprises indication of CSI-IM resources occupying multiple symbols in a slot while not fully spanning the slot;
receiving an activation message indicating the CSI-IM pattern; and
reporting the channel conditions based on the CSI-IM pattern;
wherein the CSI-IM pattern:
(a) spans every other Orthogonal Frequency-Division Multiplexing, OFDM, symbols in a slot;
(b) comprises Resource Elements, REs, in the single subcarrier and every Kt OFDM symbol in the slot in each Physical Resource Block, PRB, of configured Channel State Information-Reference Signal, CSI-RS, bandwidth, where K indicates symbol density of CSI-IM REs; and/or
(c) comprises the REs in the single subcarrier and multiple consecutive OFDM symbols in the slot in each PRB of the configured CSI-RS bandwidth.
14 . A base station for receiving channel conditions, the base station comprising:
one or more processors; and
memory comprising instructions to cause the base station to perform the steps of:
transmitting, to a wireless device, a Channel State Information-Interference Measurement, CSI-IM, pattern, wherein the CSI-IM pattern comprises indication of CSI-IM resources occupying multiple symbols in a slot while not fully spanning the slot;
send an activation message indicating the CSI-IM pattern; and
receive, from the wireless device, a channel conditions report based on the CSI-IM pattern;
wherein the CSI-IM pattern:
(a) spans every other Orthogonal Frequency-Division Multiplexing, OFDM, symbols in a slot;
(b) comprises Resource Elements, REs, in the single subcarrier and every K th OFDM symbol in the slot in each Physical Resource Block, PRB, of configured Channel State Information-Reference Signal, CSI-RS, bandwidth, where K indicates symbol density of CSI-IM REs; and/or
(c) comprises the REs in the single subcarrier and multiple consecutive OFDM symbols in the slot in each PRB of the configured CSI-RS bandwidth.