Lets discuss - LTE Reference Signals, DMRS, sounding etc.
Reference signals in UPLINK
LTE Uplink reference signals are preliminarily known as Demodulation Reference Signals (DMRS) or Sounding Reference Signals.
In PUSCH channel, DMRS appears in the fourth resource element of every sub-carrier of a resource block transmitted.
In a PUCCH, the demodulation reference signal can appear in any resource elements 1, 2, 3, 4, or 5 depending on which of four PUCCH formats is employed.
It is also possible that sounding reference signals are also present in separate resource blocks.