609 research outputs found
Decentralized Collaborative Learning Framework for Next POI Recommendation
Next Point-of-Interest (POI) recommendation has become an indispensable
functionality in Location-based Social Networks (LBSNs) due to its
effectiveness in helping people decide the next POI to visit. However, accurate
recommendation requires a vast amount of historical check-in data, thus
threatening user privacy as the location-sensitive data needs to be handled by
cloud servers. Although there have been several on-device frameworks for
privacy-preserving POI recommendations, they are still resource-intensive when
it comes to storage and computation, and show limited robustness to the high
sparsity of user-POI interactions. On this basis, we propose a novel
decentralized collaborative learning framework for POI recommendation (DCLR),
which allows users to train their personalized models locally in a
collaborative manner. DCLR significantly reduces the local models' dependence
on the cloud for training, and can be used to expand arbitrary centralized
recommendation models. To counteract the sparsity of on-device user data when
learning each local model, we design two self-supervision signals to pretrain
the POI representations on the server with geographical and categorical
correlations of POIs. To facilitate collaborative learning, we innovatively
propose to incorporate knowledge from either geographically or semantically
similar users into each local model with attentive aggregation and mutual
information maximization. The collaborative learning process makes use of
communications between devices while requiring only minor engagement from the
central server for identifying user groups, and is compatible with common
privacy preservation mechanisms like differential privacy. We evaluate DCLR
with two real-world datasets, where the results show that DCLR outperforms
state-of-the-art on-device frameworks and yields competitive results compared
with centralized counterparts.Comment: 21 Pages, 3 figures, 4 table
Model-Agnostic Decentralized Collaborative Learning for On-Device POI Recommendation
As an indispensable personalized service in Location-based Social Networks
(LBSNs), the next Point-of-Interest (POI) recommendation aims to help people
discover attractive and interesting places. Currently, most POI recommenders
are based on the conventional centralized paradigm that heavily relies on the
cloud to train the recommendation models with large volumes of collected users'
sensitive check-in data. Although a few recent works have explored on-device
frameworks for resilient and privacy-preserving POI recommendations, they
invariably hold the assumption of model homogeneity for parameters/gradients
aggregation and collaboration. However, users' mobile devices in the real world
have various hardware configurations (e.g., compute resources), leading to
heterogeneous on-device models with different architectures and sizes. In light
of this, We propose a novel on-device POI recommendation framework, namely
Model-Agnostic Collaborative learning for on-device POI recommendation (MAC),
allowing users to customize their own model structures (e.g., dimension \&
number of hidden layers). To counteract the sparsity of on-device user data, we
propose to pre-select neighbors for collaboration based on physical distances,
category-level preferences, and social networks. To assimilate knowledge from
the above-selected neighbors in an efficient and secure way, we adopt the
knowledge distillation framework with mutual information maximization. Instead
of sharing sensitive models/gradients, clients in MAC only share their soft
decisions on a preloaded reference dataset. To filter out low-quality
neighbors, we propose two sampling strategies, performance-triggered sampling
and similarity-based sampling, to speed up the training process and obtain
optimal recommenders. In addition, we design two novel approaches to generate
more effective reference datasets while protecting users' privacy
PERSONALIZED POINT OF INTEREST RECOMMENDATIONS WITH PRIVACY-PRESERVING TECHNIQUES
Location-based services (LBS) have become increasingly popular, with millions of people using mobile devices to access information about nearby points of interest (POIs). Personalized POI recommender systems have been developed to assist users in discovering and navigating these POIs. However, these systems typically require large amounts of user data, including location history and preferences, to provide personalized recommendations.
The collection and use of such data can pose significant privacy concerns. This dissertation proposes a privacy-preserving approach to POI recommendations that address these privacy concerns. The proposed approach uses clustering, tabular generative adversarial networks, and differential privacy to generate synthetic user data, allowing for personalized recommendations without revealing individual user data. Specifically, the approach clusters users based on their fuzzy locations, generates synthetic user data using a tabular generative adversarial network and perturbs user data with differential privacy before it is used for recommendation.
The proposed approaches achieve well-balanced trade-offs between accuracy and privacy preservation and can be applied to different recommender systems. The approach is evaluated through extensive experiments on real-world POI datasets, demonstrating that it is effective in providing personalized recommendations while preserving user privacy. The results show that the proposed approach achieves comparable accuracy to traditional POI recommender systems that do not consider privacy while providing significant privacy guarantees for users.
The research\u27s contribution is twofold: it compares different methods for synthesizing user data specifically for POI recommender systems and offers a general privacy-preserving framework for different recommender systems. The proposed approach provides a novel solution to the privacy concerns of POI recommender systems, contributes to the development of more trustworthy and user-friendly LBS applications, and can enhance the trust of users in these systems
Differentially Private Trajectory Analysis for Points-of-Interest Recommendation
Ubiquitous deployment of low-cost mobile positioning devices and the widespread use of high-speed wireless networks enable massive collection of large-scale trajectory data of individuals moving on road networks. Trajectory data mining finds numerous applications including understanding users' historical travel preferences and recommending places of interest to new visitors. Privacy-preserving trajectory mining is an important and challenging problem as exposure of sensitive location information in the trajectories can directly invade the location privacy of the users associated with the trajectories. In this paper, we propose a differentially private trajectory analysis algorithm for points-of-interest recommendation to users that aims at maximizing the accuracy of the recommendation results while protecting the privacy of the exposed trajectories with differential privacy guarantees. Our algorithm first transforms the raw trajectory dataset into a bipartite graph with nodes representing the users and the points-of-interest and the edges representing the visits made by the users to the locations, and then extracts the association matrix representing the bipartite graph to inject carefully calibrated noise to meet ϵ-differential privacy guarantees. A post-processing of the perturbed association matrix is performed to suppress noise prior to performing a Hyperlink-Induced Topic Search (HITS) on the transformed data that generates an ordered list of recommended points-of-interest. Extensive experiments on a real trajectory dataset show that our algorithm is efficient, scalable and demonstrates high recommendation accuracy while meeting the required differential privacy guarantees
Privacy-Preserving Individual-Level COVID-19 Infection Prediction via Federated Graph Learning
Accurately predicting individual-level infection state is of great value
since its essential role in reducing the damage of the epidemic. However, there
exists an inescapable risk of privacy leakage in the fine-grained user mobility
trajectories required by individual-level infection prediction. In this paper,
we focus on developing a framework of privacy-preserving individual-level
infection prediction based on federated learning (FL) and graph neural networks
(GNN). We propose Falcon, a Federated grAph Learning method for
privacy-preserving individual-level infeCtion predictiON. It utilizes a novel
hypergraph structure with spatio-temporal hyperedges to describe the complex
interactions between individuals and locations in the contagion process. By
organically combining the FL framework with hypergraph neural networks, the
information propagation process of the graph machine learning is able to be
divided into two stages distributed on the server and the clients,
respectively, so as to effectively protect user privacy while transmitting
high-level information. Furthermore, it elaborately designs a differential
privacy perturbation mechanism as well as a plausible pseudo location
generation approach to preserve user privacy in the graph structure. Besides,
it introduces a cooperative coupling mechanism between the individual-level
prediction model and an additional region-level model to mitigate the
detrimental impacts caused by the injected obfuscation mechanisms. Extensive
experimental results show that our methodology outperforms state-of-the-art
algorithms and is able to protect user privacy against actual privacy attacks.
Our code and datasets are available at the link:
https://github.com/wjfu99/FL-epidemic.Comment: accepted by TOI
Improving privacy preserving in modern applications
The thesis studies the privacy problems in various modern applications, such as recommendation system, Internet of Things, location-based service and crowdsourcing system. The corresponding solutions are proposed, and the proposed solutions not only protect the data privacy with guaranteed privacy level, but also enhancing the data utility
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