Hi Everyone.
Iave a question regarding beam switching antenna.
As per definition single beam switching antenna can have multiple beams like traffic/CSI, control beam. So if any operator is planning to use this, they select few beams out of all these pattern which is called beam set.
Can someone advice what logic generally taken into consideration to choose such beam set?
Not sure I got your question.
You are asking why UE reports only 4 beams and gnodeB decides to use only one of it?
Or are you asking how beam switching is happening?
So gnodeB transmits periodically CSI-RS beams (for example peridically every 20 msec gNodeb transmits 64 CSI-RS beams in different angular directions in mmwave for example).
UE measures and reports the best 4 beams with their RSRP out of 64 beams (let’s say beam7, beam 32, beam 11 and beam 13 with their RSRP. let’s say beam 7 is the strongest RSRP) and then gNodeB will transmit the PDSCH in the same direction of the best reported beam let’s say beam 7.
Idea is that AAU cannot ensure a high gain with a large beamwidth. Higher is the gain, narrower is the beamwidth.
For example at a gain of 27 dBi that is typically for an AAU the beam will be like 7 degrees beamwidth so this narrow beam has to be pointed in several directions to cover the whole footprint of the sector/cell.
Hi @RFSpecialist.
Currently I’m working on Asset radio Aircom planning tool.
In which for 5G-NR planning, we use beam switching antenna.
That antenna can have multiple beam pattern upto 256 having unique beam index number.
In those patterns there might be multiple control beam patterns depending on horizontal or vertical beam switching.
Similarly multiple traffic/CSI beam patterns are given.
But operator generally don’t use all the beam pattern for simulation purpose.
They have given flexibility to make a beam set out of all these pattern in which they have to have at least one control beam(wide angle beam) and remaining traffic beams corresponding to one frequency.
So I want to know what kind of logic can be applied to chose such beam set?
There’s no wide angle beam except SSB beams.
Everything is beamformed in 5G.
But altough specs mention 64 beams in mmwave not all vendors implemented 64 beams.
I can’t help you with your question, maybe somebody else can.
Even SSB beams are not wide angle.
No problem @RFSpecialist.
Later I will share some pattern mask to make my question more approachable.
Ok.
For example there are 4 beams for PDCCH that could cover the cell for one vendor.
So for every type of traffic there is a different beam pattern:PDCCH, PDSCH, CSI, SSB, etc.
There are separate beam for PDCCH you mean. As per my understanding we have:
- ssb beams and same will transmit pdcch DCI format.
- basic beam set like 3-2-3 define positions of beams then left and right edge angle defined beam coverage.
Not sure for 256 patterns may be its atoll antenna pattern.
Anyone having idea for parameter need to be configured so LTE and NR can be synchronized.
So what is the logic to choose anntena beams set?
I mean UE just sent back 4 beams and not using all beams?
There is 64 beams why not using thdem all?
And SSBs are used as wide angle beam?
UE select best beam as per SSB RSRP threshold configured from network.
But UE send back 4 beams with their RSRP, no?
And then gNB will choose the best of four beams.
In Uplink I think same beam use with concept of beam correspondence.
Beams cover area under one sector.
It’s not possible for 1 UE to utilize all beams.
What do you mean? Currently all vendors not using all supported 64 beams pattern. They use some of it.
Not all 64 beams implemented.
So why?
Please understand 64 beams for analog beamforming i.e. mmWave using beam sweeping it’s upto vendor implementation and depend on RU capability as per AE (Antenna Elements).