A reduced PAPR PR-NMDFB based DUC architecture for transmit downlink of combined 3GPP LTE and UMTS signals

This paper describes a step forward in the utilization of non-maximally decimated filter banks (NMDFBs) with perfect reconstruction (PR) property in modern software defined radios. In particular, here we apply the tone reservation (TR) technique for reducing the peak to average power ratio (PAPR) to a PR analysis-synthesis chain which has been designed for a combined Third Generation Partnership Protocol (3GPP), Long Term Evolution (LTE) and Universal Mobile Telecommunications System (UMTS) digital up converter (DUC). The DUC architecture was proposed in an early paper and the efficacy of the design has been tested in an industrial environment and verified for being prototyped on real chips. Similar to orthogonal frequency division multiplexing (OFDM) systems, the proposed architecture is affected by the PAPR issue. Here we borrow the TR reservation technique which was developed in the OFDM scenario and we apply it to the proposed architecture. Of course, given the difference between OFDM and NMDFB systems, different design constraints have to be taken into account. Preliminary simulation results show good performance in reducing the crest factor (CF) which, along with the limited workload required by the proposed architecture, encourage us to implement this solution in the next generation of communication chips.