Ultra wide band (UWB) technology is nowadays emerging as a strong candidate for indoor wireless applications, thanks to its low power consumption and high data rates. On the other hand, the use of multiple antennas in transmission and/or reception aims to achieve spatial diversity. It offers significant increases in data throughput without additional bandwidth or transmitted power. In wireless sensor networks (WSNs) the use of several transmitting or receiving elements is highly limited due to size constraints and complexity. In this scenario the idea of cooperative diversity appears as an alternative to the deployment of several antennas in the nodes. In this paper, we analyze and compare several cooperative diversity schemes for WSN using IR-UWB techniques in terms of error probability for different scenarios with multipath fading.