hi, lets consider S transmitted signal power, N noise power and I interference power:
SNR = S/N : SNR is signal to Noise ratio
SINR= S/(N+I) : SINR is signal to interference plus noise ratio
RS SNR: is reference signal signal to noise ratio,RS SNR should be higher than transmission power because RSs are important for :
1- making channel estimation and equalization and generating CQI (channel quality indicator) feedback
2- RS contains transmitted signals modulation and channel coding information so receiver can do demodulation and decoding operations.