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Optimal Error Correcting Code For Ternary Quantum Systems

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arXiv 2019年

作者： Majumdar, Ritajit Sur-Kolay, Susmita Advanced Computing & Microelectronics Unit Indian Statistical Institute India

Multi-valued quantum systems can store more information than binary ones for a given number of quantum states. For reliable operation of multi-valued quantum systems, error correction is mandated. In this paper, we propose a 5-qutrit quantum error correcting code and provide its stabilizer formulation. Since 5 qutrits are necessary to correct a single error, our proposed code is optimal in the number of qutrits. We prove that the error model considered in this paper spans the entire (3 × 3) operator space. Therefore, our proposed code can correct any single error on the codeword. This code outperforms the previous 9-qutrit code in (i) the number of qutrits required for encoding, (ii) our code can correct any arbitrary (3 × 3) error, (ii) our code can readily correct bit errors in a single step as opposed to the two-step correction used previously, and (iii) phase error correction does not require correcting individual subspaces. Copyright © 2019, The Authors. All rights reserved.

关键词： Many valued logics

Minimal degenerate CSS quantum code with low cost circuit

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arXiv 2019年

作者： Majumdar, Ritajit Sur-Kolay, Susmita Advanced Computing and Microelectronics Unit Indian Statistical Institute Kolkata India

Error correction is of utmost necessity for large-scale quantum computing. Quantum error correcting codes can be degenerate, if more than one type of error can map the input state to the same error state. In this paper, we propose a 6-qubit degenerate CSS code. We show that our proposed code can correct a single bit flip error, but arbitrarily many phase flip errors occurring on the codeword. Furthermore, it follows from a bound on CSS codes that the proposed code is the minimal binary CSS code which can encode a single qubit of information. We also perform a comparative study of the gate count required for a fault tolerant decomposition of the error correction circuit for the proposed code, with that for the existing 9-qubit, 7-qubit and 5-qubit binary QEC codes. Our results show, on an average over the different technologies a savings of 98.14% in the gate count for the proposed code over that for the 5-qubit code. Significant improvement of around 50% in gate count is also obtained when compared to those for the 9-qubit and 7-qubit codes. Copyright © 2019, The Authors. All rights reserved.

关键词： Error correction

A Randomized Algorithm for Joint Power and Channel Allocation in 5G D2D Communication

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A Randomized Algorithm for Joint Power and Channel Allocatio...

IEEE International Symposium on Network computing and Applications

作者： Subhankar Ghosal Sasthi C. Ghosh Advanced Computing and Microelectronics Unit Indian Statistical Institute Kolkata India

We formulate the joint power and channel allocation problem (JPCAP) for device to device (D2D) communication as a cost minimization problem, where cost is defined as a linear combination of the number of channels used and total power requirement. We first show that JPCAP is NP-hard and then propose a greedy channel and power allocation (GCPA) algorithm to assign channels and powers to the links. We design GCPA in such a fashion that there exists an order of the links for which it produces optimum solution. Finally using GCPA we develop a randomized algorithm (RA) that increase the optimum hitting probability by an exponential factor of total number of links. Through simulation, we evaluate the performance of RA and show that RA outperforms an existing approach.

关键词： Device-to-device communication Interference Resource management Receivers Transmitters Channel allocation Signal to noise ratio

$Q$-learning Based Network Selection Mechanism for CRNs with Secrecy Provisioning

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$Q$-learning Based Network Selection Mechanism for CRNs with...

IEEE International Symposium on Network computing and Applications

作者： Shankar K. Ghosh Sasthi C. Ghosh Advanced Computing & Microelectronics Unit Indian Statistical Institute Kolkata India

In near future, the spectrum resources shared by primary networks to spectrum pools are likely to use unlicensed band because of its increasing popularity. Due to the open access nature, in unlicensed band communication, eavesdroppers are capable of overhearing the traffic channels. This may lead to significant throughput degradation. Existing network selection mechanisms for cognitive radio networks (CRNs) do not consider this security threat adequately. In this work, we first propose a Q-learning based throughput estimation mechanism considering the possibility of throughput degradation caused by eavesdroppers. Then, based on estimated throughput values, we formulate the network selection problem in orthogonal frequency division multiple access (OFDMA) based CRNs as an integer linear program (ILP). Next, based on the ILP formulation, we propose a greedy algorithm for network selections in OFDMA based CRNs. Finally, performance of our proposed network selection mechanism has been compared with existing approaches through system level simulations.

关键词： Nickel Throughput Interference Security Base stations Degradation Resource management

Network-Assisted D2D Relay Selection Under the Presence of Dynamic Obstacles

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Network-Assisted D2D Relay Selection Under the Presence of D...

Conference on Local Computer Networks (LCN)

作者： Durgesh Singh Sasthi C. Ghosh Advanced Computing & Microelectronics Unit Indian Statistical Institute Kolkata India

Millimeter wave (mmWave) channels in device to device (D2D) communication are susceptible to blockages in spite of using directional beams from multi-input multi-output (MIMO) antennas to compensate for high propagation loss. This motivates one to look for the presence of obstacles while forming D2D links among user equipments (UEs) which are in motion. In D2D communication, moving UEs also act as relays to forward data from one UE to another which introduces the problem of relay selection. The problem becomes more challenging when the obstacles are also in motion (dynamic obstacles) along with the moving UEs. First we have developed a probabilistic model for relay selection which considers both moving UEs and dynamic obstacles. Then we have analyzed the probability of dynamic obstacles blocking a link in 3D Euclidean space by exploiting the information from MIMO radar connected to the base station. Finally, using this information, we have developed unique strategies based on simple geometry to find the best relay which maximizes the expected data rate. Through simulations we have shown that our proposed strategy gives a significant improvement in packet loss due to mobility of nodes and dynamic obstacles in a mmWave channel over the traditional approaches which do not consider dynamic obstacle's presence.

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Network-assisted D2D relay selection under the presence of dynamic obstacles

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arXiv 2019年

作者： Singh, Durgesh Ghosh, Sasthi C. Advanced Computing & Microelectronics Unit Indian Statistical Institute Kolkata700108 India

—Millimeter wave (mmWave) channels in device to device (D2D) communication are susceptible to blockages in spite of using directional beams from multi-input multi-output (MIMO) antennas to compensate for high propagation loss. This motivates one to look for the presence of obstacles while forming D2D links among user equipments (UEs) which are in motion. In D2D communication, moving UEs also act as relays to forward data from one UE to another which introduces the problem of relay selection. The problem becomes more challenging when the obstacles are also in motion (dynamic obstacles) along with the moving UEs. First we have developed a probabilistic model for relay selection which considers both moving UEs and dynamic obstacles. Then we have analyzed the probability of dynamic obstacles blocking a link in 3D Euclidean space by exploiting the information from MIMO radar connected to the base station. Finally, using this information, we have developed unique strategies based on simple geometry to find the best relay which maximizes the expected data rate. Through simulations we have shown that our proposed strategy gives a significant improvement in packet loss due to mobility of nodes and dynamic obstacles in a mmWave channel over traditional approaches which do not consider dynamic obstacle’s presence. Copyright © 2019, The Authors. All rights reserved.

关键词： 5G mobile communication systems

Web Service Selection with Correlations: A Feature-Based Abstraction Refinement Approach

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Web Service Selection with Correlations: A Feature-Based Abs...

IEEE International Conference on Service-Oriented computing and Applications (SOCA)

作者： Kaustabha Ray Ansuman Banerjee Swarup K. Mohalik Advanced Computing and Microelectronics Unit Indian Statistical Institute Ericsson Research Bangalore India

In this paper, we address the web service selection problem for linear workflows. Given a linear workflow specifying a set of ordered tasks and a set of candidate services providing different features for each task, the selection problem deals with the objective of selecting the most eligible service for each task, given the ordering specified. A number of approaches to solving the selection problem have been proposed in literature. With web services growing at an incredible pace, service selection at the Internet scale has resurfaced as a problem of recent research interest. In this work, we present our approach to the selection problem using an abstraction refinement technique to address the scalability limitations of contemporary approaches. Experiments on web service benchmarks show that our approach can add substantial performance benefits in terms of space when compared to an approach without our optimization.

关键词： Task analysis Web services Correlation Scalability Proposals Silicon compounds

Distributed relay selection in presence of dynamic obstacles in millimeter wave D2D communication

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arXiv 2019年

作者： Singh, Durgesh Chattopadhyay, Arpan Ghosh, Sasthi C. Advanced Computing and Microelectronics Unit Indian Statistical Institute Kolkata700108 India Department of Electrical Engineering Indian Institute of Technology Delhi

Millimeter wave (mmWave) device to device (D2D) communication is highly susceptible to obstacles due to severe penetration losses and requires almost a line of sight (LOS) communication path. D2D channel condition is local to devices/user equipments (UEs) and hence is not directly visible to the base station (BS). Thus quality of the D2D channel needs to be propagated to BS by UEs which may incur some delay. Hence the solution provided by BS to UEs using this gathered channel information might become less useful to establish communication due to moving obstacles. These types of obstacles might not be known in advance and hence may cause unpredictable fluctuations to the D2D channel quality. Hence we seek to learn the D2D channels using the finite horizon partially observable Markov decision process (POMDP) framework to model the uncertainty in such kind of network environments with dynamic obstacles. The objective is to minimize delay when channel quality deteriorates, by making UEs choose locally the best possible decision between i) to continue on the current relay link on which communication is taking place or ii) to switch to another good relay by exploring other possible UEs in its locality. We derive an optimal threshold policy which tells the UE to take appropriate decision locally. Later, we give a simplified and easy to implement stationary threshold policy which counts the number of successive acknowledgement failures, based on which UE make appropriate decision locally. Through extensive simulation, we demonstrate that our approach outperforms recent algorithms. Copyright © 2019, The Authors. All rights reserved.

关键词： Millimeter waves

Surface Code Design for Asymmetric Error Channels

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arXiv 2021年

作者： Azad, Utkarsh Lipińska, Aleksandra Mahato, Shilpa Sachdeva, Rijul Bhoumik, Debasmita Majumdar, Ritajit Center for Computational Natural Sciences and Bioinformatics International Institute of Information Technology Hyderabad India Center for Quantum Science and Technology International Institute of Information Technology Hyderabad India Xanadu TorontoONM5G 2C8 Canada Faculty of Mathematics and Computer Science Jagiellonian University Kraków Poland Department of Physics Indian Institute of Technology Dhanbad India Jülich Supercomputing Center Forschungszentrum Jülich Germany RWTH Aachen University Germany Advanced Computing & Microelectronics Unit Indian Statistical Institute Kolkata India

Surface codes are quantum error correcting codes typically defined on 2D array of qubits. In this paper, a [dx,dz] surface code design is being introduced, where dx(dz) represents the distance of the code for bit (phase) error correction, motivated by the fact that the severity of bit flip and phase flip errors in the physical quantum system is asymmetric. We present pseudo-threshold and threshold values for the proposed surface code design for asymmetric error channels in the presence of various degrees of asymmetry of Pauli Xˆ, Ŷ, and Ẑ errors in a depolarization channel. We demonstrate that compared to symmetric surface codes, our asymmetric surface codes can provide almost double the pseudo-threshold rates while requiring less than half the number of physical qubits in the presence of increasing asymmetry in the error channel. Our results show that for low degree of asymmetry, it is advantageous to increase dx along with dz. However, as the asymmetry of the channel increases, higher pseudo-threshold is obtained with increasing dz when dx is kept constant at a low value. Additionally, we also show that the advantage in the pseudo-threshold rates begins to saturate for any possible degree of asymmetry in the error channel as the surface code asymmetry is continued to increase. © 2021, CC BY-NC-ND.

关键词： Error correction