IoT integrated with smart technologies enables the development of real-time critical systems for the timely processing and automation across various domains, e.g., vehicle interaction, healthcare, and agriculture [1–3]. Artificial Intelligence of Things (AIoT) networks continuously collect observed data and maintain seamless connectivity among devices and physical objects [4,5]. The integration of such technologies drives growth in modern ecosystems and fosters smarter interactions among research communities and industries [6–8]. In recent decades, edge computing has enabled smart cities to access resources near source devices and to provide distributed computing with minimal overhead, while enabling effective resource management [9,10]. AI-driven techniques and edge computing support timely decision-making for autonomous services and enable timely detection of malicious activities, leveraging existing security policies [11,12]. Despite this, most proposed approaches still lack privacy-preserving, lightweight authentication mechanisms for adaptive environments, and thus are unable to address issues of fault tolerance and efficient bandwidth utilization [13–15]. In addition, due to the rapid involvement of malicious devices in the IoT system over the insecure Internet, they are increasingly posing significant network threats, including involvement of untrusted devices, denial-of-service (DoS), and routing hole attacks [16–18]. In this research, we present a framework that integrates AI and blockchain technologies to increase intelligence at both the device and edge levels. It reduces additional computational costs in the constraint applications, and the involvement of the SDN controller helps optimize the decision-making system. It mitigates threats even in the presence of faulty IoT devices and enhances network-wide communication security through an authentic, authorized, and trusted system. The major contributions of our work are provided as follows. i.

A trust-aware routing mechanism integrating blockchain technology with SDN programmability is proposed to improve energy efficiency and enable real-time decision-making for AIoT networks.

The paper is structured into the following sub-sections. Related work is discussed in Section 2. Section 3 explains the functionalities of the proposed framework. Performance analysis is done in Section 4, and Section 5 provides the conclusion of our work with future directions.

Wireless devices and sensors are interconnected to develop real-time AIoT applications and generate large amounts of environmental data [19,20]. In smart cities, security against malicious attacks is a demanding requirement in most existing approaches that involve IoT systems and edge processing. It leads to compromised network integrity and unauthorized access during data transmission and decision-making [21–23]. Recent studies have explored blockchain for decentralized trust management [24,25], SDN for network programmability and centralized policy enforcement [26,27], and AI-driven approaches for threat detection and dynamic routing optimization [28,29]. However, most solutions often face scalability challenges, high computational costs, and limited end-to-end IoT security integration, motivating the need for a unified, lightweight framework. The proposed framework [30] integrates blockchain technology for decentralized, immutable data management, Artificial Intelligence for dynamic data analysis and threat detection, and advanced searchable encryption for secure, efficient queries. A patient-centered data access model that combines blockchain and trust chains enhances safety and efficiency, while also demonstrating a return on investment. The blockchain-based architecture ensures the integrity and immutability of medical data from IoMT devices, enabling decentralized, tamper-proof storage. In [31], the authors introduce a Free Node-based Routing Algorithm (FNRA) to provide efficient routing for the SIoT network. It compares the forwarding capabilities of relay and source nodes and distinguishes between in-community and out-of-community message forwarding. FNRA classifies devices into four structures and dynamically adopts forwarding strategies. The analysis of FNRA is evaluated through a range of experiments that demonstrate its superior performance compared to existing approaches. In [32], an Enhanced Energy Efficient Clustering and Routing protocol is proposed to address network issues. The protocol consists of three stages: selecting the best Cluster Head (CH) nodes using k-means clustering, designating a Super Cluster Head using an Adaptive Neuro Fuzzy Inference System, and determining the most energy-efficient multi-path routing strategy using the Black Widow Optimization algorithm. The proposed multi-level hierarchical secure and optimal routing (ML-HSOR) protocol [33] addresses network issues through four stages: registration, clustering, authentication, and optimal routing. Sensor nodes are registered with the base station using unique identities. A Markov model with adaptive weighting selects the optimal Cluster Head (CH) to improve network performance. Multi-level trust evaluation detects malicious nodes during authentication, and data transmission is optimized using the polarity learning-based chimp optimization algorithm (PL-COA). Authors [34] proposed BlockDLO, an IoT security approach combining blockchain technology with deep learning. The architecture consists of five phases: (1) network localization using chaotic map-based identification, (2) page rank-based clustering for edge computing, (3) shared-chain technique with deep distributed file system and Ethereum smart contracts for block creation and data security, (4) communication route optimization via page rank centrality, and (5) deep learning integration to detect malicious data using authenticated received data, forming an efficient intrusion detection system. In [35], the authors proposed a MANET-IoT architecture using Hybrid K-Mode Clustering (HKMC) for cluster building and Spider Monkey Optimization (SMO) to identify the optimal Cluster Head (CH). An Energy-aware Multi-Attribute Trust (EMAT) model, based on Multi-Agent Reinforcement Learning (MA-RL), computes trust values and selects optimal routes using the Secure & Energy Score (SES) methodology. To enhance data security, a Multi-Attribute Cryptography (MAC) approach is introduced, improving energy efficiency and security in MANET-IoT environments. Authors of [36] present a novel multiobjective SDN-based framework for IoT sensors, ensuring end-to-end (E2E) QoS across multiple domains with heterogeneous traffic service classes (TSC). The framework employs a two-layer SDN architecture to manage QoS based on specific service demands. An optimal additive weighting module (OAWM) ranks TSCs and prioritizes service parameters such as delay, PLR, and jitter. At the same time, global controller statistics enable E2E QoS provisioning by mapping service requests from IoT sensors. Table 1 summarizes the significant contributions and limitations of existing approaches for IoT systems and for achieving data privacy and integrity.

The proposed framework models an IoT deployment with edge nodes and an SDN controller as a time-varying graph, where devices make routing decisions aided by blockchain-backed trust and AI-based anomaly detection. Let V={v1,…,vN} denote IoT devices and edge nodes, and E(t) the set of wireless links at time t. Each node vi has coordinates (xi,yi), residual energy Ei(t), transmit/receive electronics energy per bit Eelec, and amplification factor εamp; links have distance dij and one-hop latency Lij(t). The maximum radio range is rmax, and packets have size s bits. Fig. 1 illustrates the architectural flow among the developed phases of the proposed framework.

To establish connectivity in physical space, the distance dij between two nodes, vi and vj, is defined as the Manhattan distance, expressed in Eq. (1). (1)dij=|xi−xj|+|yi−yj|

A link is considered available if the two nodes are within communication range of each other. The binary link indicator aij(t) captures the condition, as defined in Eq. (2). (2)aij(t)={1,dij≤rmax,0,otherwise.

The energy to transmit s bits over distance dij follows a standard radio model with path-loss exponent γ≥2. The per-transmission energy is defined in Eq. (3), while the reception consumes only electronic energy, and the per-reception energy at node vj is given in Eq. (4). (3)Etx(i→j)=Eelec⋅s+εamp⋅s⋅dijγ (4)Erx(j)=Eelec⋅s

The nodes’ residual energy is updated after a single transmit-receive exchange to track their lifetimes using Eq. (5). (5)Ei(t+1)=Ei(t)−⊮{i tx}Etx(i→j)−⊮{i rx}Erx(i)where ⊮{⋅} is an indicator function that determines whether node i transmitted or received during the current time slot. Specifically, ⊮{i tx} subtracts the energy consumed by transmission Etx(i→j), and ⊮{i rx} subtracts the energy consumed by reception Erx(i).

In the proposed framework, the link reliability over a sliding window of W packets is measured as the successful delivery ratio, capturing short-term wireless quality. The reliability Rij(t) is defined as the fraction of packets that were successfully received within the window and can be formulated using Eq. (6). (6)Rij(t)=∑τ=t−W+1t⊮{pkt (i,j,τ)∈𝒮}Wwhere ⊮{⋅} is an indicator function, and 𝒮 is the set of successfully received packets during time slot τ. A node’s local forwarding reliability aggregates its incident links to stabilize trust against fluctuations in the reliability of individual links. The neighborhood-averaged reliability is computed based on Eq. (7). (7)R¯i(t)=1|𝒩i(t)|∑j∈𝒩i(t)Rij(t)where 𝒩i(t)={j|aij(t)=1} is the neighbor set.

In addition, the proposed framework integrates blockchain to contribute an auditable record of behavior. Let Bi(t) represent the blockchain-derived trust component for node i, which is updated using exponential smoothing based on the ratio of valid on-chain events. The trust update is given in Eq. (8). (8)Bi(t)=αBi(t−1)+(1−α)⋅Vi(t)Ti(t),α∈[0,1]where α is the smoothing factor, Vi(t) is the number of valid events for node i at time t, and Ti(t) is the total number of events for node i at time t. Each block k records the hashed state and transactions to ensure immutability. With the previous block’s hash hk−1, timestamp tk, node set digest Sk, and transaction list Txk, the block hash is computed as given in Eq. (9). (9)hk=H(hk−1∥tk∥Sk∥Txk∥noncek)where H(⋅) is a cryptographic hash function, and ∥ denotes concatenation.

The proposed framework explores Proof of Authority (PoA) as the consensus algorithm for establishing and maintaining the blockchain network. The following parameters are considered for blockchain operations: i.

A time needed to generate a new block is denoted by Block Time (Tblock) and varies based on the network conditions and consensus algorithm. It is typically fixed for PoA, but can change with realistic, distributed loads.

Thus, the blockchain overhead OBC(t) is the sum of the block verification and broadcast times as given in Eqs. (10) to (12). (10)Overify(t)=τverify(t) (11)Obroadcast(t)=τbroadcast(t) (12)OBC(t)=Overify(t)+Obroadcast(t)

Edge-hosted AI assigns an anomaly score Ai(t) using logistic regression [37] to each node based on its feature vector fi(t), which can include metrics like inter-arrival variance, drop burst, and trust transition. The score is computed using a logistic regression head on an encoder function g(⋅) as given in Eq. (13). (13)Ai(t)=σ(w⊤g(fi(t))+b)where σ(z) is the sigmoid function, defined as given in Eq. (14). (14)σ(z)=11+e−z

The trust score Ti(t) of node i at time t is computed as a combination of node reliability R¯i(t), blockchain-derived trust Bi(t), and anomaly score Ai(t), subject to β1+β2+β3=1, as defined in Eq. (15). (15)Ti(t)∈{β1R¯i(t)+β2Bi(t)+β3(1−Ai(t))∣β1+β2+β3=1}

It represents the trust score Ti(t) of node i at time t, where R¯i(t) denotes the reliability or reputation of node i, Bi(t) represents the blockchain-derived trust component for node i, and Ai(t) is the anomaly score, indicating the likelihood of abnormal behavior, subject to the constraint β1+β2+β3=1. The node reliability R¯i(t), blockchain-derived trust Bi(t), and anomaly score Ai(t) are integrated to compute the trust score Ti(t) of node i at time t, while β1+β2+β3=1.

Also the proposed framework determines link-wise latency Lij(t), and it the combination of transmission (Tijtx(t)) that represents the associated with the link from device i to j at time t, propagation (Tijprop(t)) that measures the time taken in traveling the signal from device i to device j, queuing (Tijqueue(t)) measures a time that a packet waits in the queue for for transmission, and processing delays (Tijproc(t)) indicates the time needed for the data to be processed, as shown in Eq. (16). (16)Lij(t)=[Tijtx(t)Tijprop(t)Tijqueue(t)Tijproc(t)]

In Eq. (17), a composite cost is computed by penalizing the factors such as delay, low energy, low trust, and blockchain overhead. The weighted parameters α, β, γ, and δ are combined with the parameters for balanced contribution such that (α,β,γ,δ≥0). (17)wij(t)=α⋅Lij(t)+β⋅1Ej(t)+ε+γ⋅1Tj(t)+ε+δ⋅OBC(t)

Delay of the link between nodes i and j is denoted by Lij(t)r, the energy depletion represents by Ej(t), Tj(t) is the trust score, and blockchain overhead is denoted by OBC(t). Also, to avoid undefined values in computations, a small constant ε is introduced. At the end, SDN determines the minimum-cost route under the current state as given in Eq. (18) for a path P. (18)P⋆(t)=arg⁡minP∈𝒫  C(P,t),C(P,t)=∑(i,j)∈Pwij(t)

To ensure end-to-end service guarantees, the data-plane delay of the selected route is monitored and sent back to the controller for reconfiguration, as given in Eq. (19). (19)De2e(P⋆,t)=∑(i,j)∈P⋆Lij(t)where De2e(P⋆,t) is the total delay of the selected route P⋆ at time t, and Lij(t) is the delay on the link between nodes i and j. Table 2 summarizes the definitions and values of the key parameters used in the tests.

Algorithm 1 computes trust for IoT devices using blockchain technology to achieve more reliable, trustworthy communication. It enables distributed route establishment and lightweight computing while incurring the least overhead on the IoT system. O(|V|) is used to evaluate the time complexity, where |V | represents the number of nodes. Algorithm 2 governs the optimization of task distribution across network edges and provides energy-efficient communication integrated blockchain technology. O(|V|+|N|) is used for time complexity to validate the block, where |N| is the number of edge nodes and |V | is the number of trusted nodes.

This section presents the experimental results of the proposed framework as compared to FNRA [31] and ML-HSOR [33], conducted using the NS-3 simulator. The deployed environment is composed of edge devices, IoT sensors, SDN controller, and sink nodes. IoT devices are resource-constrained, with static edges, limited processing power for intensive computing, and limited support for other resources. SDN controllers act as centralized managers, collecting global information about devices and optimizing decision-making. The dimension area is fixed to 2000 m × 2000 m, with 10–50 malicious devices, and 100–1000 sensors. The parameters considered for evaluating performance in a simulated environment are illustrated in Table 3.

Real-time applications play a vital role in sensing and processing the collected data from the observed environment. IoT, along with emerging technologies, has led to the development and growth of smart cities. These systems are composed of sensors and many physical objects deployed in the sensing field to periodically gather data and forward it to the edge/cloud for further analysis in harsh environments. This research proposed a blockchain-assisted framework integrated with AI techniques to optimize network performance and security. In addition, intelligence is provided at the edges via lightweight computing to enhance decision-making and evenly distribute load across data forwarders and constraint devices. The network behavior and device conditions are frequently reevaluated for dynamic trust computation, thereby offering a more trustworthy system even in the presence of malicious threats. The consideration of multiple factors in route selection involves addressing energy holes across network boundaries by efficiently maintaining routes. In future work, we intend to incorporate a deep learning model to improve system stability under dynamic conditions and enhance distributed threat detection, thereby enhancing the security of the proposed framework in a large-scale IoT system.