Two major 5G services are known as enhanced-mobile- broadband (eMBB) and ultra-reliable low-latency communication (URLLC). In downlink eMBB and URLLC multiplexed systems, some eMBB data resources have to be preempted for the transmission of URLLC data. One main issue for eMBB receiver is to detect the resource blocks being preempted. A common approach for the problem is the use of indicators. However, this will result in significant overheads. In this paper, we propose an indicator-free method to solve the problem. The proposed method uses a precoding scheme adding correlation to URLLC data, and a simple detection method can then be applied at the receiver to distinguish eMBB or URLLC data, blindly. Theoretical URLLC data detection and eMBB symbol error rates are also derived such that the optimum system parameters can be determined. Finally, simulations show that the proposed method can yield satisfactory results.