arXiv subjects

Adrish Banerjee

Publications and source records attributed to Adrish Banerjee.

At least 19 recordsLinked to original sources

arXiv2025

ISI-Aware Code Design: A Linear Approach Towards Reliable Molecular Communication

Intersymbol Interference (ISI) is a major bottleneck in Molecular Communication via Diffusion (MCvD), degrading system performance. This paper introduces two families of linear channel codes to mitigate ISI: Zero Pad Zero Start (ZPZS) and Zero Pad (ZP) codes, ensuring that each codeword avoids consecutive bit-1s. The ZPZS and ZP codes are then combined to form a binary ZP code, offering a higher code rate than linear ZP codes and allowing simple decoding via the Majority Location Rule (MLR). Additionally, a Leading One Zero Pad (LOZP) code is proposed, which relaxes zero-padding constraints by prioritizing the placement of bit-1s, achieving a higher rate than ZP. A closed-form expression is derived to compute expected ISI, showing it depends on the average bit-1 density in the codewords. ISI and Bit Error Rate (BER) performance are evaluated under two MCvD channel models: (i) without refresh, where past bits persist longer, and (ii) with refresh, where the channel is cleared after each reception. Results show that the LOZP code performs better in the refresh channel due to initial bit-1 placement, while ZP excels without refresh by reducing average bit-1 density. The asymptotic upper bound on code rate illustrates a trade-off between ISI and rate. Simulations demonstrate that ZP and LOZP codes improve BER by controlling bit-1 positions and density, providing better reliability in ISI-dominated regimes compared to conventional error-correcting codes.

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arXiv2025

HiKO: A Hierarchical Framework for Beyond-Second-Order KO Codes

This paper introduces HiKO (Hierarchical Kronecker Operation), a novel framework for training high-rate neural error-correcting codes that enables KO codes to outperform Reed-Muller codes beyond second order. To our knowledge, this is the first attempt to extend KO codes beyond second order. While conventional KO codes show promising results for low-rate regimes ($r < 2$), they degrade at higher rates -- a critical limitation for practical deployment. Our framework incorporates three key innovations: (1) a hierarchical training methodology that decomposes complex high-rate codes into simpler constituent codes for efficient knowledge transfer, (2) enhanced neural architectures with dropout regularization and learnable skip connections tailored for the Plotkin structure, and (3) a progressive unfreezing strategy that systematically transitions from pre-trained components to fully optimized integrated codes. Our experiments show that HiKO codes consistently outperform traditional Reed-Muller codes across various configurations, achieving notable performance improvements for third-order ($r = 3$) and fourth-order ($r = 4$) codes. Analysis reveals that HiKO codes successfully approximate Shannon-optimal Gaussian codebooks while preserving efficient decoding properties. This represents the first successful extension of KO codes beyond second order, opening new possibilities for neural code deployment in high-throughput communication systems.

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arXiv2025

DeepPolar+: Breaking the BER-BLER Trade-off with Self-Attention and SMART (SNR-MAtched Redundancy Technique) decoding

DeepPolar codes have recently emerged as a promising approach for channel coding, demonstrating superior bit error rate (BER) performance compared to conventional polar codes. Despite their excellent BER characteristics, these codes exhibit suboptimal block error rate (BLER) performance, creating a fundamental BER-BLER trade-off that severely limits their practical deployment in communication systems. This paper introduces DeepPolar+, an enhanced neural polar coding framework that systematically eliminates this BER-BLER trade-off by simultaneously improving BLER performance while maintaining the superior BER characteristics of DeepPolar codes. Our approach achieves this breakthrough through three key innovations: (1) an attention-enhanced decoder architecture that leverages multi-head self-attention mechanisms to capture complex dependencies between bit positions, (2) a structured loss function that jointly optimizes for both bit-level accuracy and block-level reliability, and (3) an adaptive SNR-Matched Redundancy Technique (SMART) for decoding DeepPolar+ code (DP+SMART decoder) that combines specialized models with CRC verification for robust performance across diverse channel conditions. For a (256,37) code configuration, DeepPolar+ demonstrates notable improvements in both BER and BLER performance compared to conventional successive cancellation decoding and DeepPolar, while achieving remarkably faster convergence through improved architecture and optimization strategies. The DeepPolar+SMART variant further amplifies these dual improvements, delivering significant gains in both error rate metrics over existing approaches. DeepPolar+ effectively bridges the gap between theoretical potential and practical implementation of neural polar codes, offering a viable path forward for next-generation error correction systems.

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arXiv2025

On Designing Novel ISI-Reducing Single Error Correcting Codes in an MCvD System

Intersymbol Interference (ISI) has a detrimental impact on any Molecular Communication via Diffusion (MCvD) system. Also, the receiver noise can severely degrade the MCvD channel performance. However, the channel codes proposed in the literature for the MCvD system have only addressed one of these two challenges independently. In this paper, we have designed single Error Correcting Codes in an MCvD system with channel memory and noise. We have also provided encoding and decoding algorithms for the proposed codes, which are simple to follow despite having a non-linear code construction. Finally, through simulation results, we show that the proposed single ECCs, for given code parameters, perform better than the existing codes in the literature in combating the effect of ISI in the channel and improving the average Bit Error Rate (BER) performance in a noisy channel.

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arXiv2023

Two-Dimensional Z-Complementary Array Quads with Low Column Sequence PMEPRs

In this paper, we first propose a new design strategy of 2D $Z$-complementary array quads (2D-ZCAQs) with feasible array sizes. A 2D-ZCAQ consists of four distinct unimodular arrays satisfying zero 2D auto-correlation sums for non-trivial 2D time-shifts within certain zone. Then, we obtain the upper bounds on the column sequence peak-to-mean envelope power ratio (PMEPR) of the constructed 2D-ZCAQs by using specific auto-correlation properties of some seed sequences. The constructed 2D-ZCAQs with bounded column sequence PMEPR can be used as a potential alternative to 2D Golay complementary array sets for practical applications

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arXiv2023

Root Cross Z-Complementary Pairs with Large ZCZ Width

In this paper, we present a new family of cross $Z$-complementary pairs (CZCPs) based on generalized Boolean functions and two roots of unity. Our key idea is to consider an arbitrary partition of the set $\{1,2,\cdots, n\}$ with two subsets corresponding to two given roots of unity for which two truncated sequences of new alphabet size determined by the two roots of unity are obtained. We show that these two truncated sequences form a new $q$-ary CZCP with flexible sequence length and large zero-correlation zone width. Furthermore, we derive an enumeration formula by considering the Stirling number of the second kind for the partitions and show that the number of constructed CZCPs increases significantly compared to the existing works.

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arXiv2023

Bounds on Size of Homopolymer Free Codes

For any given alphabet of size $q$, a Homopolymer Free code (HF code) refers to an $(n, M, d)_q$ code of length $n$, size $M$ and minimum Hamming distance $d$, where all the codewords are homopolymer free sequences. For any given alphabet, this work provides upper and lower bounds on the maximum size of any HF code using Sphere Packing bound and Gilbert-Varshamov bound. Further, upper and lower bounds on the maximum size of HF codes for various HF code families are calculated. Also, as a specific case, upper and lower bounds are obtained on the maximum size of homopolymer free DNA codes.

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arXiv2022

On DNA Codes Over the Non-Chain Ring $\mathbb{Z}_4+u\mathbb{Z}_4+u^2\mathbb{Z}_4$ with $u^3=1$

In this paper, we present a novel design strategy of DNA codes with length $3n$ over the non-chain ring $R=\mathbb{Z}_4+u\mathbb{Z}_4+u^2\mathbb{Z}_4$ with $64$ elements and $u^3=1$, where $n$ denotes the length of a code over $R$. We first study and analyze a distance conserving map defined over the ring $R$ into the length-$3$ DNA sequences. Then, we derive some conditions on the generator matrix of a linear code over $R$, which leads to a DNA code with reversible, reversible-complement, homopolymer $2$-run-length, and $\frac{w}{3n}$-GC-content constraints for integer $w$ ($0\leq w\leq 3n$). Finally, we propose a new construction of DNA codes using Reed-Muller type generator matrices. This allows us to obtain DNA codes with reversible, reversible-complement, homopolymer $2$-run-length, and $\frac{2}{3}$-GC-content constraints.

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arXiv2019

Modeling and Analysis of Heterogeneous Traffic Networks with Anarchists and Socialist Traffic

In this paper, we consider a heterogeneous traffic network with multiple users classes which differ considerably in their path selection objective. In particular, we consider two classes of users: ones who seek to minimize social cost (socialists) and the ones with typical greedy objective (anarchists) which leads to a heterogeneous game termed as HetGame. The paper proposes an analytical framework to derive optimal/equilibrium flow in such a heterogeneous game along with a method for the same. The paper considers multiple examples of different networks to derive the optimal traffic assignment. We introduce two metrics: price of $\alpha$ anarchy and price of good behavior to evaluate the impact of anarchists and implications of central directives. Finally, the proposed algorithm is implemented for a real traffic network to derive insights.

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arXiv2019

On Low Complexity RLL Code for Visible Light Communication

Run length limited (RLL) codes are used in visible light communication (VLC) to avoid flicker and to support different dimming ranges such that communication is not affected by the variation in light intensity. In this paper, we propose a low complexity split phase code as RLL code in serial concatenation with the convolutional code as a forward error correcting code (FEC) for VLC. The split phase code can be represented by a two-state trellis-like code which can provide an iterative gain in FEC-RLL serial concatenation. We also use the extrinsic information transfer (EXIT) chart to explain the iterative decoding behavior of the proposed serial concatenated scheme. Furthermore, we use puncturing and compensation symbols to support various dimming range in VLC.

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arXiv2019

Harvest-or-Transmit Policy for Cognitive Radio Networks: A Learning Theoretic Approach

We consider an underlay cognitive radio network where the secondary user (SU) harvests energy from the environment. We consider a slotted-mode of operation where each slot of SU is used for either energy harvesting or data transmission. Considering block fading with memory, we model the energy arrival and fading processes as a stationary Markov process of first order. We propose a harvest-or-transmit policy for the SU along with optimal transmit powers that maximize its expected throughput under three different settings. First, we consider a learning-theoretic approach where we do not assume any apriori knowledge about the underlying Markov processes. In this case, we obtain an online policy using Q-learning. Then, we assume that the full statistical knowledge of the governing Markov process is known apriori. Under this assumption, we obtain an optimal online policy using infinite horizon stochastic dynamic programming. Finally, we obtain an optimal offline policy using the generalized Benders decomposition algorithm. The offline policy assumes that for a given time deadline, the energy arrivals and channel states are known in advance at all the transmitters. Finally, we compare all policies and study the effects of various system parameters on the system performance.

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arXiv2018

Speaker Recognition using Deep Belief Networks

Short time spectral features such as mel frequency cepstral coefficients(MFCCs) have been previously deployed in state of the art speaker recognition systems, however lesser heed has been paid to short term spectral features that can be learned by generative learning models from speech signals. Higher dimensional encoders such as deep belief networks (DBNs) could improve performance in speaker recognition tasks by better modelling the statistical structure of sound waves. In this paper, we use short term spectral features learnt from the DBN augmented with MFCC features to perform the task of speaker recognition. Using our features, we achieved a recognition accuracy of 0.95 as compared to 0.90 when using standalone MFCC features on the ELSDSR dataset.

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arXiv2018

Optimal Harvest-or-Transmit Strategy for Energy Harvesting Underlay Cognitive Radio Network

An underlay cognitive radio network with energy harvesting is considered which operates in slotted fashion. The primary user (PU) transmits with a constant power in each slot, while the secondary user (SU) either harvests energy from primary's transmission or transmits its data. We propose an optimal offline harvest-or-transmit strategy where in each slot, SU takes a decision whether to harvest energy or transmit its data limiting interference at the primary receiver. We aim to maximize the achievable rate of SU under energy causality and interference constraints. The optimization problem is formulated as a mixed integer non-linear program and the optimal harvest-or-transmit policy is obtained using generalized Benders decomposition algorithm. Through simulations, we analyze the effects of various system parameters and interference constraint at the primary receiver on the optimal policy.

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arXiv2018

Optimal User Scheduling in Energy Harvesting Wireless Networks

We consider a wireless network where multiple energy harvesting transmitters communicate with the common receiver in a time sharing manner. In each slot, a transmitter can either harvest energy or send its data to the receiver. Given a time deadline, the goal is to maximize the sum-rate of transmitters under random energy arrivals with both perfect and imperfect channel state information (CSI) at the receiver. The original sumrate maximization (SRM) problem is a non-convex mixed integer non-linear program (MINLP). To obtain the optimal scheduling policy, we first reduce the original optimization problem to a convex MINLP and solve it using the generalized Benders decomposition algorithm. We observe that the SRM problem results in an unfair rate allocation among transmitters, i.e., the transmitter closer to the receiver achieves a higher rate than that by the transmitter farther from the receiver. Hence, to induce fairness among transmitters, we consider the minimumrate maximization (MRM) problem. For the bounded channel estimation error, we obtain a robust scheduling policy by solving the worst-case SRM and MRM problems. Finally, we compare the proposed policies with myopic policies studied in the literature and show that the former outperform the latter in terms of achievable rates.

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arXiv2018

On the Spatial Performance of Users in Indoor VLC Networks with Multiple Reflections

In this paper, we present a stochastic geometry based framework to analyze the performance of downlink indoor visible light communication (VLC) networks at a typical receiver while considering reflections from the walls. A typical receiver is a arbitrarily located user in the room and may not necessarily be at the center and hence sees an asymmetric transmitter location process and interference at itself. We first derive the signal-to-interference-plus-noise ratio (SINR) and rate coverage probability for a typical user. We then present a framework to model the impact of wall reflections and extend the analysis to study the performance of VLC network in the presence of wall reflections. We show that the impact of user's location and reflections is significant on the performance of the user.

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arXiv2017

Online Time Sharing Policy in Energy Harvesting Cognitive Radio Network with Channel Uncertainty

This paper considers an energy harvesting underlay cognitive radio network operating in a slotted fashion. The secondary transmitter scavenges energy from environmental sources in half duplex fashion and stores it in finite capacity rechargeable battery. It splits each slot into two phases: harvesting phase and transmission phase. We model the energy availability at the secondary user as first order stationary Markov process. We propose a robust online transmission policy by jointly optimizing the time sharing between the two phases and transmit power of secondary user, which maximizes its average throughput by a given time deadline.We show the comparison of our proposed policy with the offline and myopic policies.

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arXiv2017

On Secure Communication using RF Energy Harvesting Two-Way Untrusted Relay

We focus on a scenario where two wireless source nodes wish to exchange confidential information via an RF energy harvesting untrusted two-way relay. Despite its cooperation in forwarding the information, the relay is considered untrusted out of the concern that it might attempt to decode the confidential information that is being relayed. To discourage the eavesdropping intention of the relay, we use a friendly jammer. Under the total power constraint, to maximize the sum-secrecy rate, we allocate the power among the sources and the jammer optimally and calculate the optimal power splitting ratio to balance between the energy harvesting and the information processing at the relay. We further examine the effect of imperfect channel state information at both sources on the sum-secrecy rate. Numerical results highlight the role of the jammer in achieving the secure communication under channel estimation errors. We have shown that, as the channel estimation error on any of the channels increases, the power allocated to the jammer decreases to abate the interference caused to the confidential information reception due to the imperfect cancellation of jammer's signal.

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arXiv2017

Interference-Aided Energy Harvesting: Cognitive Relaying with Multiple Primary Transceivers

We consider a spectrum sharing scenario where a secondary transmitter (ST) communicates with its destination via a decode-and-forward secondary relay (SR) in the presence of interference from multiple primary transmitters. The SR harvests energy from received radio-frequency signals that include primary interference and uses it to forward the information to the secondary destination. The relay adopts a time switching policy that switches between energy harvesting and information decoding over the time. Under the primary outage constraints and the peak power constraints at both ST and SR, to determine the average secondary throughput, we derive exact analytical expressions for the secondary outage probability and the ergodic capacity, which characterize the delay-limited and the delay-tolerant transmissions, respectively. We also investigate the effects of the number of primary transceivers and the peak power constraints on the optimal energy harvesting time that maximizes the secondary throughput. By utilizing the primary interference as an energy source, the secondary network achieves a better throughput performance compared to the case where the primary interference is ignored for energy harvesting purpose. Finally, we consider a case where ST also harvests energy from primary transmissions and compare its throughput performance with that of the non-energy harvesting ST case.

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