Browsing by Subject "Nonlinear trellis codes"

Now showing 1 - 4 of 4

Open Access
Code design for binary energy harvesting channel
(IEEE, 2017) Dabirnia, Mehdi; Duman, Tolga M.
We consider a binary energy harvesting communication system with a finite battery transmitter over a noisy channel, and design explicit and implementable codes based on concatenation of a nonlinear trellis code (NLTC) with an outer low density parity check (LDPC) code. We propose two different decoding methods where the simplified one ignores the memory in the battery state while the more sophisticated one utilizes the memory. Numerical results demonstrate that the designed codes outperform other reference schemes. The results also show the superiority of the improved decoding approach over the naive solution.
Open Access
Code design for discrete memoryless interference channels
(Institute of Electrical and Electronics Engineers, 2018) Dabirnia, Mehdi; Tanc, A. K.; Sharifi S.; Duman, Tolga M.
We study the design of explicit and implementable codes for the two-user discrete memoryless interference channels (DMICs). We consider Han-Kobayashi (HK) type encoding where both public and private messages are used and propose coding techniques utilizing a serial concatenation of a nonlinear trellis code (NLTC) with an outer low-density parity-check (LDPC) code. Since exact analytical treatment of the BCJR decoder for the inner trellis-based code appears infeasible, we analytically investigate the iterative decoding process in the asymptotic regime where the probability of decoding error tends to zero. Based on this approximate analysis, we derive a stability condition for this type of a concatenated coding scheme for the first time in the literature. Furthermore, we use an extrinsic information transfer analysis to design the outer LDPC code while fixing the inner NLTC, and utilize the derived stability condition to accelerate the design process and to avoid code ensembles that potentially produce high error floors. Via numerical examples, we demonstrate that our designed codes achieve rate pairs close the optimal boundary of the HK subregion, which cannot be obtained without the use of nonlinear codes. Also, we verify that the estimated thresholds of the designed codes via finite block length simulations and show that our designs significantly outperform the point-to-point optimal codes, hence demonstrating the need for designs specifically tailored for DMICs.
Open Access
Coding for two-user energy harvesting interference channel
(IEEE, 2020) Dabirnia, Mehdi; Duman, Tolga M.
A two-user interference channel with energy harvesting transmitters, each equipped with a finite battery, is considered. Achievable rate regions (ARRs) considering independent and identically distributed Shannon strategies at both users and ignoring the memory in the battery state are obtained for both single-user decoding and joint decoding at the receivers. Explicit and implementable codes based on concatenation of a nonlinear trellis code (NLTC) with an outer low-density parity-check code are designed, and it is demonstrated that rate pairs close to the boundary of ARR can be obtained with this approach. Furthermore, an improved alternative decoding scheme which exploits the memory in the battery state is developed, and it is shown to be highly superior to the simple decoding approach via numerical examples. Superiority of the newly developed practical channel coding solutions over the previously known alternative approaches are illustrated via extensive set of examples as well.
Open Access
Coding schemes for energy harvesting and multi-user communications
(2017-12) Dabirnia, Mehdi
Many 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.