Joint channel mitigation and side information estimation for GFDM systems in indoor environments

Generalized frequency division multiplexing (GFDM) is the foremost contender for physical layer of 5G communication. The flexible nature of GFDM allows multiple symbols in time domain to superimpose, thereby creating high peak to average power ratio (PAPR). The idea of selective mapping (SLM) is to use a sequence of phase rotation vectors for generating alternatives using original GFDM signal. Among them, signal with lowest PAPR is selected for transmission. This procedure requires mandatory side information (SI) estimation or transmission which in turn decreases data reliability or efficiency. To address these issues, authors present a modified approach of pilot-assisted GFDM SLM system without need of SI transmission and to enable joint PAPR reduction and data recovery. In the proposed approach, we utilize a common modulating phase to modulate all subcarriers in a subsymbol assuming that each subsymbol consists of at least two pilots. This creates an inherent SI cancellation mechanism using the pilots which are employed for channel estimation. For practical validation of proposed concepts, we used software-defined radio (SDR) experimental setup employing universal software radio peripheral USRP) 2953R as hardware and Labview as software. Experimental results show a significant reduction in out-of-band spectral leakage without disturbing the estimated channel response.