Simultaneous information and power transfer over the wireless channelspotentially offers great convenience to mobile users. Yet practical receiverdesigns impose technical constraints on its hardware realization, as practicalcircuits for harvesting energy from radio signals are not yet able to decodethe carried information directly. To make theoretical progress, we propose ageneral receiver operation, namely, dynamic power splitting (DPS), which splitsthe received signal with adjustable power ratio for energy harvesting andinformation decoding, separately. Three special cases of DPS, namely, timeswitching (TS), static power splitting (SPS) and on-off power splitting (OPS)are investigated. The TS and SPS schemes can be treated as special cases ofOPS. Moreover, we propose two types of practical receiver architectures,namely, separated versus integrated information and energy receivers. Theintegrated receiver integrates the front-end components of the separatedreceiver, thus achieving a smaller form factor. The rate-energy tradeoff forthe two architectures are characterized by a so-called rate-energy (R-E)region. The optimal transmission strategy is derived to achieve differentrate-energy tradeoffs. With receiver circuit power consumption taken intoaccount, it is shown that the OPS scheme is optimal for both receivers. For theideal case when the receiver circuit does not consume power, the SPS scheme isoptimal for both receivers. In addition, we study the performance for the twotypes of receivers under a realistic system setup that employs practicalmodulation. Our results provide useful insights to the optimal practicalreceiver design for simultaneous wireless information and power transfer(SWIPT).
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