Impulse radio ultra wideband (IRI-UWB) communication is becoming an important technology for future wire less Personal Area Networks (WPANs). A critical challenge in IR-UWB system design is multi-user interference (MUI). A RAKE receiver is proposed to mitigate the MUI that occurs in some ad-hoc networks like WPAN for IR-UWB system where concurrent transmission are allowed without power control. The proposed RAKE receiver is shown to contribute to a mitigation of multiple access interference (MAI) especially at medium input bit energy –to-noise ratio (Eb/No) values and small number of RAKE taps (fingers). This receiver is based on chip decision after maximum ratio combining and then the final decision based on the number of pulses per symbols. In such scenarios, the conventional RAKE receiver is completely fails to get the expected BER, and does not always perform well. On the other hand, the proposed RAKE receiver has similar complexity as the conventional RAKE. The binary phase shift keying (BFSK) modulation scheme is used in this paper. The performance of the proposed RAKE is evaluated with the Non Line of sight (NLOS)indoor channel model proposed by the IEEE 802.15.3a (COM3) for WPAN with distances (4-10) m.