Sabita Maharjan

Dr. Sabita Maharjan

Associate Professor, Department of Informatics, University of Oslo, Problemveien 7, 0315 Oslo, Norway

Research Focus & Metrics

Academic Career Length

17Years (2010-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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18 September 2019 in IEEE Transactions on Industrial Informatics
Verified
Journal Article
Closed access
YLYunlong Lu
Yunlong Lu
XHXiaohong Huang
Xiaohong Huang
YDYueyue Dai
Yueyue Dai
SMSabita Maharjan
Sabita Maharjan
YZYan Zhang
Yan Zhang
The rapid increase in the volume of data generated from connected devices in Industrial Internet of Things (IIoT) paradigm, opens up new possibilities for enhancing the quality of service for the emerging applications through data sharing. However, security and privacy concerns (e.g, data leakage) are major obstacles for data providers to share their data in wireless networks. The leakage of private data can lead to serious issues beyond financial loss for the providers. In this article, we first propose a blockchain empowered secure data sharing architecture for distributed multiple parties. Then, we transfer the data sharing problem into a machine learning problem by incorporating privacy-preserved federated learning. The privacy of data is well maintained by sharing the data model instead of revealing the actual data. Finally, we integrate federated learning in the consensus process of permissioned blockchain thus the computing work for consensus can also be used for federated training. Numerical results derived from real-world datasets show that the proposed data sharing scheme achieves good accuracy, high efficiency and enhanced security.

13 February 2020 in IEEE Transactions on Vehicular Technology
Verified
Journal Article
Closed access
YLYunlong Lu
Yunlong Lu
XHXiaohong Huang
Xiaohong Huang
KZKe Zhang
Ke Zhang
SMSabita Maharjan
Sabita Maharjan
YZYan Zhang
Yan Zhang
In Internet of Vehicles (IoV), data sharing among vehicles for collaborative analysis can improve the driving experience and service quality. However, the security and privacy issues hinder data providers from participating in the data sharing process. In addition, due to the intermittent and unreliable communications in IoV, the efficiency and reliability of data sharing need to be further enhanced. In this paper, we propose a new architecture for data sharing based on blockchain and federated learning. To enhance the efficiency and security of data sharing, we develop a hybrid blockchain architecture which consists of the permissioned blockchain and the local Directed Acyclic Graph (DAG). Moreover, we propose an asynchronous federated learning scheme by adopting Deep Reinforcement Learning (DRL) for node selection to improve the efficiency. The reliability of shared data is also guaranteed by integrating learned models into blockchain and executing a two-stage verification. Numerical results show that the proposed data sharing scheme provides both higher learning accuracy and convergence efficiency.

11 October 2018 in IEEE Internet of Things Journal
Verified
Journal Article
Closed access
JKJiawen Kang
Jiawen Kang
RYRong Yu
Rong Yu
Xumin HuangXumin Huang
Xumin Huang
MWMaoqiang Wu
Maoqiang Wu
SMSabita Maharjan
Sabita Maharjan
YZYan Zhang
Yan Zhang
The drastically increasing volume and the growing trend on the types of data have brought in the possibility of realizing advanced applications such as enhanced driving safety, and have enriched existing vehicular services through data sharing among vehicles and data analysis. Due to limited resource of vehicles, mobile edge computing integrated with vehicular networks gives rise to Vehicular Edge COmputing and Networks (VECONs) for providing powerful computing and massive storage resources. However, vehicular edge computing servers consisted of roadside units cannot be fully trusted, which may result in serious security and privacy challenges. We exploit consortium blockchain and smart contract technologies to achieve secure data storage and sharing in vehicular edge networks. These technologies efficiently prevent data sharing without authorization. In addition, we propose a reputation based data sharing scheme to ensure high-quality data sharing among vehicles. A three-weight subjective logic model is utilized for precisely managing reputation of the vehicles. Numerical results based on a real dataset show that our schemes achieve reasonable efficiency and high-level security for data sharing in VECONs.

18 August 2020 in IEEE Transactions on Industrial Informatics
Verified
Journal Article
Closed access
YLYunlong Lu
Yunlong Lu
XHXiaohong Huang
Xiaohong Huang
KZKe Zhang
Ke Zhang
SMSabita Maharjan
Sabita Maharjan
YZYan Zhang
Yan Zhang
Emerging technologies such as digital twins and 6th Generation mobile networks (6G) have accelerated the realization of edge intelligence in Industrial Internet of Things (IIoT). Federated learning has been regarded as a promising solution in wireless networks. However, unreliable communication channels and limited resources hinder its application in IIoT. In this paper, we introduce Digital Twin Wireless Networks (DTWN) to migrate real-time data processing and computation to the edge plane. Then, we propose a blockchain empowered federated learning framework running in the DTWN for collaborative computing. To balance the learning accuracy and time cost of the proposed scheme, we formulate an optimization problem for edge association by jointly considering digital twin association, training data batch size, and bandwidth allocation. We exploit multi-agent reinforcement learning to find an optimal solution. Numerical results on real-world dataset show that the proposed scheme yields improved efficiency and reduced cost compared to benchmark learning method.

25 July 2020 in Mobile Networks and Applications
Verified
Journal Article
Closed access
PDF file
LLLei Liu
Lei Liu
Chen ChenChen Chen
Chen Chen
Qingqi PeiQingqi Pei
Qingqi Pei
SMSabita Maharjan
Sabita Maharjan
YZYan Zhang
Yan Zhang

16 October 2018 in IEEE Internet of Things Journal
Verified
Journal Article
Closed access
YDYueyue Dai
Yueyue Dai
DXDu Xu
Du Xu
SMSabita Maharjan
Sabita Maharjan
YZYan Zhang
Yan Zhang
The emergence of computation intensive and delay sensitive on-vehicle applications makes it quite a challenge for vehicles to be able to provide the required level of computation capacity, and thus the performance. Vehicular Edge Computing (VEC) is a new computing paradigm with a great potential to enhance vehicular performance by offloading applications from the resource-constrained vehicles to lightweight and ubiquitous VEC servers. Nevertheless, offloading schemes where all vehicles offload their tasks to the same VEC server, can limit the performance gain due to overload. To address this problem, in this paper, we propose integrating load balancing with offloading, and study resource allocation for a multi-user multi-server VEC system. First, we formulate the joint load balancing and offloading problem as a mixed integer non-linear programming problem to maximize system utility. Particularly, we take IEEE 802.11p protocol into consideration for modeling the system utility. Then, we decouple the problem as two subproblems and develop a low-complexity algorithm to jointly make VEC server selection, and optimize offloading ratio and computation resource. Numerical results illustrate that the proposed algorithm exhibits fast convergence and demonstrates the superior performance of our joint optimal VEC server selection and offloading (JSCO) algorithm compared to the benchmark solutions.