This article “LTE SINR vs 5G SINR” discusses a common question that “what is the difference between 5G SINR and LTE SINR and why do we have so many different types of SINRs in 5G.” For instance, in 5G, we have SS SINR, CSI-RS SINR and then there is PDSCH SINR while in LTE, we just have a single SINR that is usually used for all purposes. So, in this session, I have explained why do we need multiple SINRs in 5G and what is the functionality of each of these SINRs. I hope you will all like it 🙂
LTE SINR vs 5G SINR: Why Do We Have Different Types Of SINRs In 5G?
In LTE, the Cell Reference Signals are used for both coverage and link estimation. For different cells, the RS move in frequency domain based on PCI. Therefore, the interference between them is reduced.
RS SINR = RSRP / RS_Interference
5G SS SINR
For 5G, UE measures coverage based on SSS in SSB. So, SS_RSRP and SS_SINR are important values. However, on different cells, the location of SSS is same so all the SSS will interfere with each other and thus SS SINR would be low.
SS SINR = SS RSRP / SS_Interference
Note : SS SINR is used for N310/311 as well
5G CSI-RS SINR
Since SS_RSRP and SS_SINR is something related to coverage and mobility, 5G needs another SINR for link estimation. This one can be calculated based on mobile implementation. One way to calculate it is based on CSI-RS/CSI-IM as stated in 3GPP.
CSI-RS SINR = CSI RSRP / CSI Interference
Convert CSI-RS SINR to CQI and send to gNB
Note: CSI-RS SINR > SS-SINR as CSI-RS are lean in structure and can move with PCI
5G PDSCH SINR
Another aspect of 5G SINR is based on PDSCH SINR. Many mobiles use a combination of both CSI resources along with PDSCH resources to estimate SINR and then convert it to CQI.
Thus, PDSCH SINR is usually the best SINR as it does not have any interference other than load based interference.
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