Abstract: To analyze the performance of a code-orthogonalized transmitted-reference ultra-wideband (COTR-UWB) cooperative system, a cooperation model of COTR-UWB is proposed. Gaussian Q-function is invoked to derive the noncooperative symbol error rate (SER). Based on the three-node model, which uses amplify-and-forward relaying and maximal-ratio-combining as a cooperation strategy, Gaussian approximation is adopted to deduce a general expression of cooperative SER. Numerical analyses illustrate the theoretical results. Simulation results show that the cooperative communication system gains multiorder diversity. The effects of time-bandwidth, impulses, and instantaneous received SNR on the SER performance are also discussed.