Beam Management, Beam Switching and Beam Refinement in 5G NR

This is what you are looking for when there is a TCI change: MAC DL TB Report

Very clear here for your case :+1:.

@marcengo, could you please share snap of B9B9?
I don’t have it…

Just observation… No reference yet.

Thanks @marcengo! :wink:

One final Question, which @RFSpecialist asked earlier:
When we have SSB RSRP and CSI-RSRP in same MAC CSF info as Record 0 and record1, how can we know (If at all UE don’t know) the beam switching will be for CSI-BEAM or SS Beam?

Sample CSF message here:

Chipset timestamp: 2020-03-20 19:37:27.447903, CFN : 87
Dual Mode Index : 0
SIM Index : 255
Version : 65537
Major.Minor Version : 1.1
  log_fields_change
  log_fields_change_bmask : 0x0000
sub_id : 0
num_records : 3
Records
  Record[0]
    report_ul_time
      slot : 14
      numerology : 120kHz
      frame : 713
    carrier_id : 0
    report_id : 2
    report_type : APERIODIC
    num_bits_part1 : 35
    num_bits_part2 : 0
    is_rsrp : RSRP
    num_bits_part2 : 0
    debug_only : Result_from_WP
    report_quanlity : RSRP , SSB_INDEX
    resource1 : 8
    resource2 : 7
    resource3 : 5
    resource4 : 4
    resource_type : SSB
    num_resource_bits : 4
    pad : 0
    rsrp1 : 53
    rsrp2 : 47
    rsrp3 : 47
    rsrp4 : 46
    valid_rsrp : 4
  Record[1]
    report_ul_time
      slot : 14
      numerology : 120kHz
      frame : 713
    carrier_id : 0
    report_id : 0
    report_type : APERIODIC
    num_bits_part1 : 10
    num_bits_part2 : 0
    is_rsrp : RSRP
    num_bits_part2 : 8
    debug_only : Result_from_WP
    report_quanlity : CRI , RSRP
    resource1 : 5
    resource2 : 0
    resource3 : 0
    resource4 : 0
    resource_type : CSI_RS
    num_resource_bits : 3
    pad : 0
    rsrp1 : 55
    rsrp2 : 0
    rsrp3 : 0
    rsrp4 : 0
    valid_rsrp : 1
  Record[2]
    report_ul_time
      slot : 14
      numerology : 120kHz
      frame : 713
    carrier_id : 0
    report_id : 1
    report_type : APERIODIC
    num_bits_part1 : 10
    num_bits_part2 : 0
    is_rsrp : RSRP
    num_bits_part2 : 8
    debug_only : Result_from_WP
    report_quanlity : CRI , RSRP
    resource1 : 5
    resource2 : 0
    resource3 : 0
    resource4 : 0
    resource_type : CSI_RS
    num_resource_bits : 3
    pad : 0
    rsrp1 : 63
    rsrp2 : 0
    rsrp3 : 0
    rsrp4 : 0
    valid_rsrp : 1

Each of these records have a different report_id, so, different purposes.
Once you track it to the RRC message which did set-up the events, you will have an idea of what it is aimed for.

Like this part from bullets.
For CSI reporting, you can have NZP CSI RS for channel measurements (my take, this is where you will do refinement, I didn’t get to this part on my studies yet), NZP CSI RS for interfere measurements and CSI IM also for interference measurements.

It’s correct, channel measurement is main point here.
Without refined beam.

Seems the issue is with my tools before.
Thanks gent for the discussion…
Finally I found it now :slight_smile:

EQ1
NR 5G MAC DL TB Report

Time : 13:06:39.953
Length : 48
Log Code (Hex) : 0xB886
HW Timestamp : (36359385.00 ms) 10:05:59.385
Version : 65539
Log Fields Change
  Sleep : 0
  Beam Change : 0
  Signal Change : 0
  DL Dynamic Cfg Change : 0
  DL Config : 0
  UL Config : 0
  ML1 State Change : 0
Log Fields Change BMask : 0x0000
Num Records : 1
Records : 
  [0 ] : 
    System Time
      Slot : 9
      Numerology : 1
      Frame : 26
    Number of Active Carriers : 1
    Per Slot PDSCH logging : 
      [0 ] : 
        Carrier Id : 0
        MCE Bitmask : 
          TCI_STATE_IND_UE_PDCCH_MCE
        TCI State PDCCH
          number of cc : 1
          cc info : 
            [0 ] : 
              Serving Cell Id : 1
              Coreset Id : 1
              TCI State Id : 2
              CC Id : 0

If you see cri-RSRP on the reportQuantity, then…
image

I’d say, from a purely UE perspective, it will be hard to say it 100% what is the goal, you will likely to require some vendor info as well.
Or guess based on what happens after the report, beam change, mobility, etc…

Layer 3 rsrp based on CSI channel measurement.
Layer 1 rsrp based on CSI-RS beams.

Question:

  1. UE is in idle mode
  2. Initial access using ss beam done
  3. UE went to connected mode got a CSI-RS beam for data transmission

Will SS-beam be released after point3?
Or
Will UE report ss rsrp and csi rsrp during this connected mode also?

Yes, UE will report RSRP in connected mode as well.
For SSrsrp at L3 for cell change.
For SSrsrp at L1 for intra cell beam mobility.

Beamforming and Beam Management concepts plays a major role in 5G NR.

  • In idle mode beamforming is assisted by PSS, SSS, PBCH (SS Block) and DMRS.

  • In connected mode , CSI -RS is utlized to assist beamforming in the downlink and SRS in the uplink.

For the beam management in 5G NR we have four step process to know.

  1. Beam Sweeping
  2. Beam Measurement
  3. Beam Determination
  4. Beam Reporting

Additionally we can add Beam Recovery and Beam Switiching as well as a part of beam Management.