Abstract For an indoor ultra-wideband (UWB) communication system, the line-of-sight (LOS) between the transmitter and receiver may be frequently blocked by moving people. Blocking of LOS may significantly affect the quality of service of on-going UWB communications. Based on the Angular Power Spectrum Density and the human blocking models, we build a packet-level UWB channel model considering the shadowing processes based on a Finite-state Markov Chain. The model is simple enough to be incorporated into existing network simulators like NS-2 and it can be used to facilitate protocol design and quality of service analysis for UWB based wireless personal area networks. Keywords channel model · UWB · angular power spectrum density