A low-PAPR low-pilot overhead Reference Signal for the DFT-spread OFDM Modulation

With the current deployment of high throughput satellite (HTS) providing several gigabits of capacity in multiple spot beams, satellite networks may ultimately play a significant role in the 5G landscape. This trend is supported by several initiatives starting with two study items at the 3GPP. Although not central at the time being, the question of defining a new waveform for satellite may come at the forefront in the near future. With power fluctuations similar to those of single carrier (SC) waveforms, the discrete Fourier transform-spread orthogonal frequency division multiplexing (DFT-s-OFDM) modulation appears as a relevant candidate for such a waveform. Despite its strong advantages, DFT-s-OFDM still lacks of reference signals (RS) combining low power fluctuations with low pilot overhead. In this paper, we propose a new pilot scheme where reference samples are introduced prior to DFT in front of information data. The overall symbol is generated after cancellation of the data contribution onto the pilot samples and the insertion of a cyclic prefix (CP) related to the pilot part. Doing so, the channel can be estimated from the first samples of the pilot symbol used as a known short OFDM symbol. Performance evaluations assess the relevance of the proposed scheme, especially for satellite contexts.