As a promising solution to alleviating the energy bottleneck in wireless devices with limited battery capacity, simultaneous wire? less information and power transfer (SWIPT) techniques have been widely researched in cellular networks. To further improve the spectral and energy efficiency of wireless information and power transfer, the combination of SWIPT and new techniques in cellu? lar networks has drawn much attention recently. In this paper, we comprehensively survey the key techniques for SWIPT, the com? bination of SWIPT and new techniques in cellular networks, challenges and open issues. The key techniques for SWIPT including traditional power splitting, time switching, etc., and joint receiving and transmitting techniques such as eigenchannels and mixed signals are provided in detail. Furthermore, the applications of SWIPT to recent techniques such as SWIPT?assisted non?orthogo? nal multiple access, SWIPT?assisted device?to?device communication, and SWIPT?assisted full?duplex communication, are compre? hensively summarized in this paper. The potential open issues including the management of dynamic harvested energy, trading be? tween wireless power transfer and traffic offloading, and effects of the mode switching at energy harvesting devices, are outlined as well.