eNB sends a 10 bit signaling parameter srs-ConfigIndex in SIB2, RRC Connection Setup & RRC Connection Reconfiguration. UE can transmit SRS every two subframes at the most and every 32 frame (320 subframe) at the least. srs-ConfigIndex indicates the periodicity of SRS transmission which can be (2,5,10,20,40,80,160,320 ms).
SRS is transmitted at the last symbol of UL slot with full system band area.
