Browsing by Subject "Joint energy and information transfer"
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Item Open Access Coding schemes for energy harvesting and multi-user communications(Bilkent University, 2017-12) Dabirnia, MehdiMany wireless communication and networking applications can bene t from energy harvesting and wireless energy transfer including wireless sensor networks, radio frequency identi cation systems and wireless body networks. Some of the advantages that energy harvesting provides for such applications include energy self-su ciency, ability to implement them in hard-to-reach places, reducing the required battery size or even removing the battery completely from the wireless units. In such systems the required energy for the system operation is obtained from a renewable energy source such as solar, thermal or kinetic energy or from a man-made source such as radio frequency (RF) signals, arti cial light, etc. While there has been decades of designs and developments of energy harvesting nodes from circuit and device engineering perspectives, only recent studies consider the speci c constraints of these systems from a communications point of view, and signi cant challenges and problems still remain unsolved, particularly, at the physical layer. With the motivation of addressing some of the above challenges, our main focus in this thesis is the design and analysis of capacity approaching coding schemes for several energy harvesting and multiuser scenarios; in particular, by exploiting nonlinear codes concatenated with low-density parity-check (LDPC) codes for these scenarios. First, novel code design approaches are studied for the joint energy and information transfer speci cally, employment of nonlinear trellis codes (NLTCs) in serial concatenation with outer LDPC codes is proposed, and an algorithm is developed to design the NLTCs prior to optimizing the outer LDPC code using the EXIT analysis. The designed codes are shown to improve upon the o -the-shelf point-to-point (P2P) codes and outperform the alternative of utilizing linear codes with time switching and the reference scheme of concatenating LDPC codes with nonlinear memoryless mappers (NLMMs). This coding approach is then examined for the energy harvesting channel (EHC) implementing two decoding approaches at the receiver side wherein the rst one ignores the memory in the battery state, while the second one incorporates this memory into the trellis. Compared with the P2P codes and the reference schemes, the newly designed codes consistently o er better performance. This code design approach is explored for the case of discrete memoryless interference channels (DMICs) implementing the Han-Kobayashi (HK) encoding and decoding strategy as well. A stability condition is derived for the concatenated coding scheme and it is utilized in the process of designing the outer LDPC code employing the EXIT analysis. It is demonstrated that the designed codes achieve rate pairs close to the optimal boundary of the HK subregion and outperform the single user codes with time sharing. Furthermore, code design principles are also investigated for the two-user Gaussian interference channel with fading employing trellis-based codes with short block lengths. Finally, the problem of designing explicit and implementable codes is studied for a two-user interference channel with energy harvesting transmitters, and a design framework is proposed employing similar techniques developed for the DMIC and EHC.Item Open Access Nonlinear code design for joint energy and information transfer(IEEE, 2015-06) Dabirnia, Mehdi; Duman, Tolga M.Harvesting energy from radio frequency signals along with transmitting data through them is appealing for different wireless communication scenarios such as RFID systems and implantable devices. In this paper, we propose a technique to design nonlinear codes for use in such systems taking into account both energy transmission and error rate requirements. Specifically, we propose using concatenation of a nonlinear trellis code with an outer low density parity check code. Via examples, we observe that our designed codes operate at SNRs 2.4dB away from information theoretic limits, and they outperform reference schemes of concatenating LDPC codes with nonlinear memoryless mappers and using classical linear block codes in a time switching mode. We note that it is possible to close the gap to the information theoretic limits further by more sophisticated receiver designs and more complex encoders. © 2015 IEEE.Item Open Access On code design for joint energy and information transfer(Institute of Electrical and Electronics Engineers Inc., 2016) Dabirnia M.; Duman, T. M.Harvesting energy from radio frequency signals along with transmitting data through them is appealing for different wireless communication scenarios, such as radio frequency identification (RFID) systems and implantable devices. In this paper, we propose a technique to design nonlinear codes for the use in such systems taking into account both energy transmission and error rate requirements. In particular, we propose using concatenation of a nonlinear trellis code (NLTC) with an outer low-density parity-check (LDPC) code. We design the NLTC based on maximization of its free distance. We give necessary and sufficient conditions for its catastrophicity; in order to avoid catastrophic codes, we connect each designed NLTC to a corresponding linear convolutional code allowing for the use of simpler conditions for verification. Furthermore, we use EXIT charts to design the outer LDPC code while fixing the inner NLTC. Via examples, we demonstrate that our designed codes operate at ∼ 0.8 dB away from the information theoretic limits, and they outperform both regular LDPC codes and optimized irregular LDPC codes for additive white Gaussian noise (AWGN) channels. In addition, we show that the proposed scheme outperforms the reference schemes of concatenating LDPC codes with nonlinear memoryless mappers and using classical linear block codes in a time switching mode. © 2016 IEEE.