This letter newly proposes a new multi-user detection scheme for multiple users using co-channel heterogeneous radio signals in ubiquitous antenna system. The ubiquitous antenna system is composed of multiple radio base stations (RBSs), the central control station (CCS) which performs the multi-user detection, and radio-on-fiber (RoF) link which connects the RBSs to the CCS. Computer simulation results show that the multi-user detector exploiting the minimum mean square error (MMSE)-based combiner and the serial interference canceller (SIC) in combination can achieve the coexistence of coded orthogonal frequency division multiplexing (COFDM) and direct sequence spread spectrum (DSSS) signals.