The medium-access control (MAC) protocols for wireless networks proposed or implemented to date based on collision-avoidance handshakes between the sender and receiver either require carrier sensing or the assignment of unique codes to nodes to ensure that intended receivers hear data packets without interference from hidden sources. We present and analyze a protocol that we call channel-hopping multiple access (CHMA) for multi-channel, ad-hoc networks which does not require carrier sensing or the assignment of unique codes to nodes to ensure collision-free reception of data at the intended receivers in the presence of hidden terminals. We compare CHMA against MACA-CT and show considerable improvement in the performance achieved. The correct avoidance of collisions in CHMA protocols is verified, and their throughput and delay characteristics is studied analytically. CHMA protocols are applicable to ad-hoc networks based on commercial off-the shelf spread spectrum radios operating in unlicensed frequency bands.