LTE Concept and Applications

Well, we had discussed about uplink channel state information  Difference between SRS and DMRS by reference signals (SRS and DMRS). Now to achieve 1Gbps or more downlink speed in LTE with effective resource utilization of full bandwidth available,   CQI PMI RI and many more parameter play very important role. So what are CQI, PMI and RI in LTE? CQI (Channel Quality Indicator) , reported by UE to eNB. UE indicates modulation scheme and coding scheme to eNB , if used I would be able to demodulate and decode the transmitted downlink   data with maximum block error rate 10%. To predict the downlink channel condition, CQI feedback by the UE is an input. CQI reporting can be based on PMI and RI. Higher the CQI value (from 0 to 15) reported by UE, higher the modulation scheme (from QPSK to 64QAM ) and higher the coding rate will be used by eNB to achieve higher efficiency.  PMI (Precoding Matrix Indicator) , UE indicates to eNB , which precoding ma...

There are two types of reference signals used in LTE uplink, to estimate uplink channel quality. Which allow eNB to take smart decisions for resource allocation for uplink transmission, link adaptation and to decode transmitted data from UE . So to take first smart decision by eNB Sounding Reference Signal  (SRS) is being used. SRS is being transmitted by UE on the last symbol of subframe (in which subframe will come to know later). This SRS report the channel quality of over all bandwidth and using this information eNB assign the resource (to UE for uplink transmission )has better channel quality comparing to  other bandwidth  region. So is SRS optional in LTE? Yes. SRS is configurable and infact we do not need SRS at all in case eNB assign all resource block or full bandwidth or have no choice. Now on the basis of configuration and node wise there are two types of SRS (refer 36.211), cell specific (Common SRS) and UE specific (Dedicated SRS).  eNB...