Abstract
In this paper, an efficient Active Constellation Extension (ACE) based on Extension Projection Onto the Convex Sets (EPOCS-ACE) scheme is proposed for reducing Peak-to-Average Power Ratio (PAPR) of Orthogonal Frequency Division Multiplexing (OFDM) signals especially with a large number of sub-carriers and high-order constellation. Utilizing the specially designed iterative procedure, considerable PAPR reduction gains not only can be obtained with just one iteration but also can be adjusted dynamically to adapt the different designed requirements for OFDM systems. Moreover, both the novel peaks-clipping strategy and specific extension rules are designed to ensure BER performance while reducing PAPR. The theoretical analysis in terms of the selection criterion for compensation factors, optimization for correction factor, reachable bound of CCDF and computation complexity is derived. Simulation results show that, compared to existing ACE methods, EPOCS-ACE is able to obtain better overall performance in the aspect of PAPR, BER, and complexity for broadband OFDM systems.
Highlights
Orthogonal Frequency Division Multiplexing (OFDM) is widely adopted in modern wireless communications because of its high spectral efficiency and transmission reliability
Being a multi-carrier modulation technique, OFDM system suffers from a critical drawback: The time-domain OFDM signal which is superimposed by several orthogonal waveforms has a variable envelope resulting in a high Peak-to-Average Power Ratio (PAPR) [1], [2]
If the linear range of High Power Amplifier (HPA) or the accuracy of Digital-to-Analog converter (DAC) is not sufficient, the high PAPR may lead to the inter-modulation among sub-carriers and undesired Out-of-Band Interference (OBI) of OFDM signals [4]
Summary
Orthogonal Frequency Division Multiplexing (OFDM) is widely adopted in modern wireless communications because of its high spectral efficiency and transmission reliability. As a consequence, designing a specialized ACE scheme which can obtain a considerable PAPR gain with fast convergence speed can significantly reduce the computation complexity, and improve its applicability for the broadband and high-rate OFDM systems. Compared with the traditional ACEs, EPOCS-ACE is able to obtain the faster convergence speed with only one iteration required to approach the given PAPR level, and the better overall performance could be acquired for the broadband OFDM signals employing with high-order QAM. To tackle the trade-off problem between PAPR reduction and BER performance, the self-adaption clipping strategy is used and it can dynamically adjust the clipping threshold for OFDM signals with different PAPRs. What’s more, extension rules for the high-order constellation points, such as 256-QAM and 1024-QAM, are designed specially to ensure the in-band distortion does not deteriorate seriously while reducing PAPR.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
