Spectral mask filling for PAPR reduction in large bandwidth mmWave systems

Future communication systems such as 5G will explore mmWave frequencies where large bandwidth is available to support the exponentially increasing mobile broadband data traffic. However, mmWave systems come with the limitation that PA efficiency is significantly lower at mmWave frequencies due to reduced transistor gains and lossy interconnects. This low PA efficiency combined with the need to support high data rates with high order modulation and OFDM make PAPR considerations very important for mmWave systems. We propose a new method to reduce PAPR in mmWave systems called spectral mask filling. This method utilizes any available spectrum between the guard tones at the edge of the band and the spectral mask to generate a PAPR reduction signal. While the method is general, it is especially suitable for large bandwidth systems, where the spectrum mask is less stringent. For an example 60 GHz system, this technique can provide 2–2.5 dB PAPR gains over clipping based solutions with the addition of < 2% extra energy in the guard tones. We also develop two architectures: a feed-forward and a reduced complexity architecture that can support real-time, low-latency implementations. The spectral mask filling technique has no impact on EVM or spectral efficiency and does not require any side information transmission. It is applicable to both OFDM and single-carrier systems.