In this contribution, we study the performance analysis of the Multiband Orthogonal Frequency Division Multiplexing Ultra Wide Band (MBOFDM UWB) high data rate system. The major problem of the MBOFDM UWB high data rate system is the cohabitation of more than three piconets sharing the same group of subbands over the same channel. As an alternative way to enhance the spectral efficiency of MBOFDM UWB system, the Channel Division Multiple Access (ChDMA) could be employed to explore the high diversity of UWB channels. The idea behind the ChDMA is to assimilate the channel impulse response (CIR) related to each user as a CDMA code signature. This approach increases the performance of the system by guarantying simultaneous access. Simulations are run over UWB indoor channel model and it is shown that MBOFDM UWB ChDMA outperforms MBOFDM UWB in respect of the metric of capacity. The simulations are performed through Minimum Mean Square Error receivers (MMSE) and the performance is evaluated based on the tradeoff between spectral efficiency (bit/s/Hz) and the ratio of number of users and "code" length. Numerical results show the advantage of ChDMA approach to enhance spectral efficiency of MBOFDM UWB high data rate system based on the accommodation of simultaneous operating piconets (SOPs).