Do we have mobiles with 4 Tx antenna in 4G or 5G?
Do you mean for UL MIMO, right?
I never see UL 2 layer UE.
One plus 8T.
Iphone 12 mini
Do you mean like these models?
I was just asking, not aware if any…
I think SRS in Uplink are transmitted from RX antenna of UE in 5G. What do you think?
Otherwise how one should understand this explanation?
3GPP TS 38.306 version 15.5.0 Release 15
supportedSRS-TxPortSwitch indicates SRS Tx port switching pattern supported by the UE. The indicated UE antenna switching capability of ′xTyR′ corresponds to a UE, capable of SRS transmission on ′x′ antenna ports over total of ′y′ antennas, where ′y′ corresponds to all or subset of UE receive antennas, where 2T4R is two pairs of antennas;
I think it’s 1st SRS UE transmit at Tx1, 2nd SRS at Tx2.
For example this is how it looks for srs 1T4R:
So you see there are 4 antenna for transmitting SRS.
Even if parameter is 1T4R.
According to picture above it is not like you mentioned.
Also SRS transmission on RX antenna is important for SRS weighting of beamforming.
So it has to be from 4 RX antenna of the UE.
Have a look on sharetechnote explanation:
What do you think?
It all looks like SRS signals are transmitted by 4 RX antenna of the mobile.
1T4R I think: at the same time, UE can transmit with 1 antenna, receive with 4 antenna.
Yes, 1 transmission at a time. But from the 4 RX antenna not from the 2 TX antenna:
So SRS are transmitted from RX antenna based on the picture above it says very clear transmission at symbol l0 from antenna 0, transmission at symbol l1 from antenna 1, and so on, till antenna 4.
Why don’t you think UE can equip physical Ant elements with duplex properties like eNB say 4 phy antennas can be 4trx?
May be design constraints.
Because I am not aware of UEs having 4TX antenna.
And because SRS has to be transmiited from RX antennas for reciprocity in TDD for UL and DL, that’s why.
I think antenna has both TX and RX function.
Let me rephrase my question: have you seen UEs supporting 4x4 MIMO in UL for PUSCH data?
I think only 2x2 UL MIMO by now.
That means 2 TX antenna for PUSCH but for SRS there are 4 TX antenna.
I never saw any chipset that supports more than 2x2 UL MIMO.
Even if UE have 4 antennas for DL/UL.
Indeed but for SRS it needs 4 distinct TX antenna.
That are the same as RX antenna.
Value of parameter supportedSRS-TxPortSwitch which can be 1T2R or 1T4R or 2T4R or T=R.
That means most New UEs might have 4 TX RX antennas but since chipset dont have more than 2x2 UL MIMO capability it may not use it.
Wild guess antenna experts help here🤞
Is just for SRS.
Is different when you say about an UE it supports 2T4R.
Is this is concluded because DL MIMO is 4x4 but UL MIMO is 2x2?
Yes, but for SRS is different notation: value of parameter supportedSRS-TxPortSwitch which can be 1T2R or 1T4R or 2T4R or T=R.
We have single SRS TX as of now.
Dual SRS also there in new releases, but not available now.