This paper describes a communication/ranging pulse-based transceiver that enables physical-layer security against relay attack. A reconfigurable transceiver system with concatenation operation is designed by having PPM/PWM-based two-bit communication between the prover and the verifier, significantly reducing the processing latency of the prover. Multichannel transmission with enhanced spectral efficiency and link margin are realized with channel hopping and subband hopping methods. A prototype 6-8GHz UWB/VWB transceiver is implemented in 65nm CMOS. The transceiver achieves a processing latency of <; 3.5ns for the prover and an RMS ranging accuracy of 1.0cm for the verifier, consuming 8.3mW with -73dBm sensitivity at 5Mb/ s.