A Multi-Tier Vehicular Edge–Fog Framework for Real-Time Traffic Management in Smart Cities
Abstract
1. Introduction
- In Section 3.1, we present a decentralized vehicle management framework that segments an urban region into multiple operational areas, each managed by the respective proxy servers via RSUs.
- In Section 3.2, we employed a microservice-based application approach for implementing the proposed distributed framework. The proposed application design enables dynamic placement and scaling [16] of application modules across multiple network nodes. Moreover, this approach enables the integration of various modular strategies in the system.
- In Section 4.2, a mobility management algorithm is presented for the provision of the efficient migration of services while considering the position and speed of the vehicle, along with the availability of RSUs. Correspondingly, the selection of intermediate nodes to facilitate service migration in the absence of RSUs is also considered.
- In Section 4.3, a dynamic vehicular clustering algorithm is presented that groups the RSUs based on proximity, communication range, and latency, to ensure efficient, low-latency, and reliable V2I communication.
- In Section 4.4, a dynamic microservice assignment algorithm is presented that effectively places microservices according to the location and resource availability.
- In Section 6, we evaluate the effectiveness of our proposed schemes on multiple scales on the EUA dataset. Our evaluation demonstrates enhanced performance with significant improvements in latency, network consumption, execution cost, and energy efficiency, as compared to existing schemes.
2. Related Work
3. System Architecture
3.1. Adaptive Area-Based Traffic Management Framework
- Cloud Layer: This is the uppermost layer of the proposed architecture, containing the cloud server, the most resourceful entity of the architecture. The cloud server is responsible for the processing of the tasks requiring resources not available at the lower layers. The cloud server stores historical traffic information for predictive analysis to forecast congestion. All the microzones are connected to this layer for the overall management of the urban area.
- Proxy layer: This layer consists of multiple proxy servers, with each proxy server acting as a supervisory head to each microzone. The purpose of the proxy server is to manage traffic within its designated microzone. For effective vehicular management and the seamless exchange of traffic information, all proxy servers are interconnected with each other. Moreover, all proxy servers are connected to the centralized cloud server for the execution of tasks requiring extra resources.
- RSU Layer: This layer comprises fog nodes acting as RSUs in the proposed framework. These RSUs are responsible for the collection and processing of vehicular information. For real-time traffic management, multiple RSUs are assigned to each microzone. All the RSUs are associated with the proxy server of the microzone. Similarly, they are also interconnected and are utilized for the calculation of the shortest path between multiple network components.
- Traffic Layer: This layer consists of all the traffic monitoring equipment and vehicles. The vehicles in the network are equipped with OBUs and act as a mobile edge computing (MEC) node. The nodes present in this layer are utilized for the transmission and reception of real-time vehicular information for efficient traffic management. Additionally, it executes the commands received from fog and proxy servers to manage the traffic flow.
3.2. Application Model
- Storage Microservice: This module is responsible for storing the information requiring long-term usage. In smart traffic control environments, the critical traffic information, e.g., historical traffic data, accidents, etc., is needed for predictive traffic schemes and forensic analysis.
- Microzone Traffic Microservice: This microservice is initially placed at proxy servers to process the traffic information of the assigned area. This module requires more processing resources, as it applies advanced artificial intelligence techniques on the acquired information for real-time traffic management. Moreover, the proxy servers not only have to process the allocated microzone information but also have to coordinate with other areas for efficient traffic management. This microservice is also responsible for the transmission of signals to the Emergency Control Module as per requirements.
- Data Collection Microservice: This module is initially assigned to the fog nodes working as RSUs. This microservice preprocesses the real-time traffic information gathered from the smart vehicles. These modules preprocess that information and forward the outcomes to the Microzone Traffic Microservice and Vehicle Microservice.
- Vehicle Microservice: This microservice is placed on the smart vehicles as an OBU to collect and exchange real-time vehicular and traffic information with nearby vehicles (i.e., V2V) and roadside infrastructure (i.e., V2I). This module interacts with the Data Collection Microservice at the RSUs to ensure the real-time exchange of safety messages, congestion information, and emergency alerts.
- Emergency Control Microservice: This microservice is placed on different actuators to display information about traffic incidents or accidents, identifying traffic disruptions such as accidents or road closures.
4. Methodology
4.1. Mathematical Model
- returns the coverage radius of an RSU f, denoted as .
- returns the communication range of RSU f, denoted as .
- returns the current load (e.g., number of active services/sessions).
- returns the maximum admissible load .
- returns the latency between vehicle i and RSU .
- returns the remaining resource vectors = .
4.1.1. Mobility Management Conditions
| Algorithm 1 Vehicle mobility management |
|
4.1.2. Clustering Conditions
- ← =
- ← the maximum admissible communication distance
- ← the latency threshold.
| Algorithm 2 Dynamic vehicular clustering (DVC) algorithm |
|
4.1.3. Microservice Placement Constraints
| Algorithm 3 Dynamic microservice assignment (DMA) algorithm |
|
4.1.4. Latency and Cost-Oriented Objective
- : end-to-end delay of loop sS;
- : network usage for loops s;
- : execution cost for loop s.
4.2. Vehicle Mobility Management Algorithm
4.3. Dynamic Vehicular Clustering Algorithm
4.4. Dynamic Microservice Assignment Algorithm
5. Simulation Setup
- Edgeward: this placement technique only considers the vertical scalability of application modules without taking fog node clustering and horizontal scalability-based load balancing into consideration [31].
- DMA-clustering: this approach makes use of both the dynamic vehicular clustering (DVC) algorithm [32] and the dynamic microservice assignment (DMA) scheme.
5.1. Scenario 1
5.2. Scenario 2
6. Results and Discussion
6.1. Results for Scenario 1
6.1.1. Latency
6.1.2. Network Usage
6.1.3. Energy Consumption
6.1.4. Execution Cost
6.2. Results for Scenario 2
6.2.1. Network Utilization
6.2.2. Energy Consumption
6.2.3. Execution Cost
7. Conclusions
7.1. Limitations
7.2. Future Directions
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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| Ref. | Methodology | Limitations | Implementation | Technologies | Achievements |
|---|---|---|---|---|---|
| [17] 2020 | Fog–cloud IoT framework for real-time monitoring, congestion detection, and traffic light management. | Limited fog capacity, scalability issues, and reliance on IoT sensors. | Real-time monitoring system with congestion detection, adaptive traffic lights, and Twitter-based alerts. | IoT, Fog, Cloud, ThingSpeak, Twitter API, Ultrasonic Sensors. | Faster response, higher bandwidth efficiency, and real-time alerts. |
| [19] 2021 | Multi-agent traffic light control on fog nodes using Q-learning for adaptive signal timing. | Multi-intersection coordination challenges, dependence on fog nodes, and limited scalability. | An adaptive traffic light system adjusts green time and secures vehicle data. | Fog, Q-learning, IoT, Security Protocols. | Improved regulation efficiency, reduced delays, and enhanced security. |
| [20] 2022 | Edge computing-based congestion prediction using fuzzy inference and hybrid OWNB. | Scalability concerns, longer training time, and reliance on expert guidance. | Real-time congestion prediction and direction detection for faster decisions. | Edge, IoT, Fuzzy Logic, Hybrid OWNB. | High accuracy and precision and fast decision-making. |
| [21] 2022 | Fog-based traffic light management with fuzzy inference and V2I communication. | Needs strong fog–cloud infra, privacy concerns, and no emergency vehicle prioritization. | Real-time signal management optimizes waiting time and traffic flow. | Fog, Fuzzy Logic, V2I, GPS. | 45% less vehicle delay, 35% shorter total delay, 30% higher throughput, and 8% fuel savings. |
| [13] 2024 | Software-defined fog computing (SDFC) framework with clustering, load balancing, and intelligent controller placement in VANETs. | Frequent handovers, scalability, controller placement, and dynamic network conditions. | Resource-optimized vehicular network with better data flow and latency control. | Fog, SDN, CRAN, Dynamic Clustering. | 28% faster response, 23% lower latency, and 25% faster convergence. |
| [22] 2024 | Four-layer fog–cloud–IoT architecture using machine learning (ANN, Logistic Regression) for traffic prediction, adaptive timing, and routing. | Scalability issues, infra dependency, sensor accuracy, and high computational cost. | Situation-aware traffic management with adaptive signals and re-routing. | IoT, Fog, Cloud, ANN, Logistic Regression, GPS. | Adaptive phase planning, real-time routing, better load balancing, and improved safety. |
| [23] 2024 | Hybrid IoT–Fog–Cloud architecture with dynamic load balancing and resource allocation. | Simulation-based validation, unstable networks, scalability challenges, and privacy concerns. | A hybrid system distributing processing tasks across IoT, fog, and cloud. | IoT, Fog, Cloud, Machine Learning. | 20–30% lower latency, 25% better resource use, 15% improved decision-making, and stronger privacy. |
| [24] 2025 | Fog–cloud-based navigation for emergency vehicles using IoT data for real-time routing and traffic signal adjustments. | Infra dependency, privacy risks, frequent updates, and scalability issues. | Smart EV navigation ensures priority routes and dynamic signal control. | Fog, Cloud, IoT, Priority Control. | Faster emergency response, improved safety, and efficient traffic management. |
| Ref. | Year | Area-Based Segmentation | Service Migration | Clustering Strategy | Microservice Orchestration | Architecture | Real Dataset Integration | Scale of Evaluation |
|---|---|---|---|---|---|---|---|---|
| [17] | 2020 | × | Not supported | None | Monolithic IoT services | Cloud + Fog | × | Small-scale IoT sensors |
| [19] | 2021 | × | Not supported | None | Monolithic traffic-light logic | Fog-only | × | Single/multi-intersection |
| [20] | 2022 | × | Not supported | None | Rule-based components | Edge + IoT | × | Local congestion points |
| [21] | 2022 | × | Not supported | None | Centralized fuzzy systems | Fog + V2I | × | Intersection-level |
| [13] | 2024 | × | Only SDN-based handover | Latency-driven RSU/VANET clustering | SDN functions, not microservices | Fog + SDN | × | Moderate-scale VANET |
| [22] | 2024 | × | Not supported | Latency-aware resource grouping | ML modules, not microservices | Fog-Cloud-IoT | × | Multi-intersection |
| [23] | 2024 | × | Occasional reallocation | Local-based resource grouping | Semi-moduler | Fog-Cloud-IoT | × | Medium-scale simulation |
| [24] | 2025 | × | Not supported | None | Monolithic navigation logic | Fog + Cloud | × | Emergency vehicle routing |
| Proposed | 2025 | ✓ (microzones) | ContinuousRSU proxy → RSU migration via VMM | Dynamic latency + range-based vehicular clustering | Fully microservice-based orchestration with DMA | Cloud + Proxy + Fog (multi-tier VEFC) | ✓ | Large-scale (118 RSUs, multi microzones, 10–60 vehicles) |
| Resource Type | Cloud Server | Proxy Server | RSUs | Smart Vehicles |
|---|---|---|---|---|
| Numbers | 1 | 3 | 13 | 10–60 |
| Speed (MIPS) | 44,800 | 2800 | 2800 | 200 |
| RAM (GB) | 40 | 4 | 4 | 2 |
| Uplink (MBPS) | 100 | 10,000 | 10,000 | 10,000 |
| Downlink (MBPS) | 10,000 | 10,000 | 10,000 | 270 |
| Busy Power (MJ) | 107.339 | 107.339 | 107.339 | 87.530 |
| Idle Power (MJ) | 83.433 | 83.433 | 83.433 | 82.440 |
| Module | RAM(MB) | CPU Length (MI) | Size (MB) |
|---|---|---|---|
| Vehicle | 128 | 150 | 100 |
| Data Collection | 512 | 250 | 200 |
| Microzone Traffic | 512 | 350 | 200 |
| Emergency Control | 512 | 350 | 200 |
| Storage | 128 | 250 | 200 |
| Algorithm | Primary Function | Performance Gains | Improvement |
|---|---|---|---|
| VMM | Seamless service migration based on vehicle speed, location, and RSU load | Contributes to 86.4% latency reduction and 53.3% lower network usage | Improves RSU assignment and reduces handover delay |
| DVC | Groups RSUs based on proximity, communication range, and latency | Contributes to 59.2% network reduction and 5% energy reduction | Enhances V2I performance and cluster-based RSU efficiency |
| DMA | Resource-aware microservice placement and migration | Achieves 59.2% network reduction, 5% energy savings, and 38.4% execution cost reduction | Reduces inter-tier communication and improves load balancing |
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Hassan, S.R.; Mehmood, A. A Multi-Tier Vehicular Edge–Fog Framework for Real-Time Traffic Management in Smart Cities. Mathematics 2025, 13, 3947. https://doi.org/10.3390/math13243947
Hassan SR, Mehmood A. A Multi-Tier Vehicular Edge–Fog Framework for Real-Time Traffic Management in Smart Cities. Mathematics. 2025; 13(24):3947. https://doi.org/10.3390/math13243947
Chicago/Turabian StyleHassan, Syed Rizwan, and Asif Mehmood. 2025. "A Multi-Tier Vehicular Edge–Fog Framework for Real-Time Traffic Management in Smart Cities" Mathematics 13, no. 24: 3947. https://doi.org/10.3390/math13243947
APA StyleHassan, S. R., & Mehmood, A. (2025). A Multi-Tier Vehicular Edge–Fog Framework for Real-Time Traffic Management in Smart Cities. Mathematics, 13(24), 3947. https://doi.org/10.3390/math13243947

