Techniques for compatibility between UEs that transmit SRS in only an existing SRS region and UEs that can transmit SRS using resources in an existing SRS region, an added SRS region, or both. Techniques for frequency domain subbband hopping using counters or subband hop shifts are disclosed. Techniques for compatibility for SRS transmissions that can use different scrambling sequence IDs, comb types, sequence/group hopping, and open loop power control are disclosed.