Original Research
Frontiers in Communications and Networks ·
Volume 7 - 2026 | https://doi.org/10.3389/frcmn.2026.1903388
Priority-aware CO–MRFO-based task scheduling for energy-efficient mobile ad hoc clouds
- A. Tamilmani1
- Murali Subramanian1*corresponding author
- School of Computer Science and Engineering (SCOPE) Vellore Institute of Technology (VIT), Chennai, India
Abstract
Mobile ad hoc cloud computing allows a mobile task to run on its source device, a nearby cooperative mobile node, an edge server, or a remote cloud. This paper presents a fully specified hybrid Cheetah Optimizer–Manta Ray Foraging Optimization (CO–MRFO) scheduler for priority-aware task assignment. MRFO performs global exploration, CO refines promising schedules, and a linearly decreasing individual-level probability controls their use. Each candidate is decoded into a one-hot task–node assignment and repaired when resource or connectivity constraints are violated. The minimization objective combines normalized response time, node-dependent energy, priority-weighted deadline violations, and feasibility penalties. Over 30 paired runs with 100 tasks, CO–MRFO obtained an objective value of 12.84 ± 0.31, runtime of 8.74 s, total energy of 412.6 J, deadline-miss ratio of 0.42%, and throughput of 114.8 tasks/s. Relative to GWO, it reduced the objective by 14.7%, runtime by 14.6%, energy by 10.8%, and deadline misses by 78.1%. Statistical, ablation, scalability, sensitivity, and service-level analyses support the contribution of the hybrid switching, priority term, and node-dependent energy model within the simulated environment.
Keywords
1 Introduction
The growth of mobile devices, wireless communication, cloud infrastructure, and online educational services has increased demand for computation-intensive applications on platforms with limited processing capacity, memory, and battery energy. Mobile Cloud Computing (MCC) extends mobile-device capabilities by allowing work to execute locally or on external computing resources (Armbrust et al., 2010; Dinh et al., 2013; Fernando et al., 2013). Mobile Edge Computing (MEC) places resources closer to users and can reduce wide-area communication delay (Mao et al., 2017), while computation offloading can conserve device resources when its communication cost does not outweigh the benefit of remote execution (Kumar and Lu, 2010). These capabilities are particularly relevant to mobile learning, where users may concurrently request live lectures, online assessments, artificial-intelligence inference, interactive content, downloads, and background synchronization (Shorfuzzaman et al., 2018).
The scheduling problem is difficult because tasks differ in computational demand, input size, memory use, deadline, bandwidth requirement, and priority, whereas candidate nodes differ in processing speed, available memory, queue length, residual energy, location, and connectivity. A scheduler must decide whether each task should run on its source device, a nearby cooperative mobile node, an edge resource, or a remote service-provider node. The decision effects response time, transmission overhead, execution energy, resource utilization, deadline compliance, and service continuity. Assigning every urgent task locally is ineffective when the source device is overloaded, while offloading every large task can increase latency and transmission energy. The best execution location must therefore be selected from current task, resource, and network conditions.
This study considers a mobile ad hoc cloud (MAC) formed by service-consumer nodes, cooperative smart-mobile nodes, and service-provider nodes. The terminology is used precisely: MCC is the broader mobile-cloud paradigm; MEC places computation near users; a mobile ad hoc network (MANET) supplies infrastructure-independent communication among nearby devices; and the MAC is the cooperative resource-sharing and scheduling environment evaluated here. Mobility makes the task assignment time-dependent because links can appear or disappear between scheduling intervals. A feasible method must consequently model connectivity, repair invalid assignments, and update queues, bandwidth, and residual energy as the topology changes.
Existing task-offloading approaches include mathematical optimization, deterministic heuristics, population-based metaheuristics, and learning-based methods. Deterministic rules are inexpensive but generally cannot optimize delay, energy, capacity, connectivity, and priority simultaneously. Population-based methods can explore large combinatorial spaces, but their performance depends on maintaining an effective balance between global exploration and local refinement. The Cheetah Optimizer (CO) provides search, sitting-and-waiting, attack, and return-to-home behaviours (Akbari et al., 2022), whereas Manta Ray Foraging Optimization (MRFO) provides chain, cyclone, and somersault foraging mechanisms (Zhao et al., 2020). Their complementary roles motivate a hybrid in which MRFO explores alternative task–resource assignments and CO refine promising schedules.
The principal contribution is a priority-aware CO–MRFO scheduler with five integrated features: (i) a single minimization objective; (ii) explicit one-hot task–node assignment with offloading derived from the selected node; (iii) node-dependent energy accounting for source devices, cooperative mobile nodes, and service-provider nodes; (iv) a linearly decreasing individual-level probability that coordinates MRFO exploration and CO refinement; and (v) a reproducible evaluation protocol with matched computational budgets, paired runs, statistical testing, ablation, scalability, sensitivity, and service-level analysis. CO refers specifically to the Cheetah Optimizer of Akbari et al. (2022), not Cuckoo Search; consequently, nests and Lévy flights are not part of the method.
The remainder of the paper is organized as follows. Section 2 reviews cloud-supported mobile learning, task offloading, and relevant optimization methods and states the research gap. Section 3 presents the system model and objective. Section 4 defines the hybrid scheduler, Section 5 gives the reproducible experimental protocol, and Section 6 reports the results and their boundaries. Sections 7 and 8 present limitations and conclusions.
2 Literature review and research gap
2.1 Cloud-supported mobile learning
Cloud computing provides on-demand access to shared processing, storage, networking, software, and platform resources (Armbrust et al., 2010). In educational settings, these resources support content delivery, collaboration, analytics, mobile access, and elastic handling of peak demand. Cloud-based big-data analytics has also been examined as an enabling technology for mobile learning (Shorfuzzaman et al., 2018). The benefits of scalable access, however, do not remove the technical limitations of learner devices or wireless networks. Computation-intensive and delay-sensitive services still depend on effective placement of work across mobile, edge, and cloud resources.
Figure 1 inferences that educational requests are heterogeneous. Live lecture delivery and interactive services are sensitive to response delay; online assessment requests require timely and reliable processing; AI inference and AR/VR demand substantial computation; and downloads or background synchronization can often tolerate additional waiting time. This heterogeneity makes fixed local-only or cloud-only policies unsuitable. The present work uses synthetic educational-service classes to examine technical scheduling and offloading performance. It does not treat the synthetic workload as a measured institutional trace or infer gains in learning outcomes from system-level metrics.

2.2 Mobile-cloud scheduling and offloading
The delay–energy trade-off in mobile and edge computing is well established (Mao et al., 2017; Kumar and Lu, 2010; Liu et al., 2016). Local execution avoids radio transmission but can increase queueing delay and drain the source battery. Nearby cooperative or edge execution can reduce processing time while limiting wide-area delay, although it depends on connectivity and peer capacity. Remote execution offers greater resources but can incur routing latency, transmission energy, and variable network performance. Dynamic energy-aware cloudlet models illustrate the importance of jointly considering proximity, processing, and energy (Gai et al., 2016).
Earlier delay-optimal scheduling formulations established rigorous decision models for MEC (Liu et al., 2016). More recent work has considered multi-objective task offloading across edge–fog–cloud layers (Saif et al., 2024), heterogeneous CPU/GPU resources in industrial cloud–edge systems (Zhai et al., 2025), and joint offloading, resource allocation, and trajectory design for priority-aware multi-UAV MEC (Hao, 2024). These studies demonstrate the value of joint modeling, but their topologies and decision spaces differ from a mobility-aware mobile ad hoc cloud containing source devices, cooperative mobile nodes, and service-provider nodes. multi-objective controller placement in software-defined networks has also been studied in banking contexts (Abdulghani et al., 2026).
2.3 Metaheuristic foundation and hybridization
Task–node assignment is combinatorial, and the feasible set changes with resource availability and connectivity. Metaheuristics are therefore attractive when exhaustive enumeration is impractical. Genetic Algorithm, Particle Swarm Optimization, Whale Optimization Algorithm, and Grey Wolf Optimizer provide useful benchmark search mechanisms, but each can stagnate or converge inefficiently when exploration and exploitation are poorly balanced. Standalone comparisons are insufficient unless all methods receive matched candidate-evaluation budgets and identical task, topology, and initial-population conditions.
CO models distinct hunting phases that are well suited to local refinement (Akbari et al., 2022). MRFO combines chain, cyclone, and somersault movements that support broad exploration (Zhao et al., 2020). The proposed hybrid does not use a fixed handover between complete populations. Instead, each candidate independently selects the MRFO or CO branch at every iteration through a declining probability schedule. This individual-level mechanism preserves diverse exploration early in the search and increases refinement later without eliminating either branch.
2.4 Technical positioning and research gap table
The literature leaves four connected gaps. First, educational-cloud studies commonly emphasize adoption or applications rather than reproducible real-time task–node scheduling. Second, models developed for fixed edge, industrial, or UAV environments do not directly capture a cooperative mobile ad hoc resource pool with changing links. Third, priority is sometimes represented without coupling it to a unified deadline-sensitive objective. Fourth, aggregated energy terms can obscure whether energy is consumed at the source, a cooperative mobile node, or a service-provider node. The proposed CO–MRFO formulation addresses these gaps through explicit assignment and offloading coupling, node-dependent energy, priority-weighted deadline penalties, feasibility repair, mobility updates, and individual-level exploration–refinement switching. Table 1 summarizes the technical positioning.
TABLE 1. Technical literature comparison.
| Method | Environment | Main decisions | Priority-aware | Separate execution-location energy | Limitation addressed here |
|---|---|---|---|---|---|
| Delay-optimal scheduling (Liu et al., 2016) | MEC | Task scheduling | No | Partial | Does not model a mobile ad hoc resource pool |
| Priority-aware multi-UAV MEC (Hao, 2024) | UAV-assisted MEC | Offloading, resources, trajectory | Yes | Yes | Different topology and decision space |
| Multi-objective | Edge–fog–cloud | Layer and node selection | Critical-task support | Yes | Does not model CO–MRFO hybrid or MANET mobility |
| Firefly offloading (Saif et al., 2024) | — | — | — | — | Mobility model |
| Heterogeneous CPU/GPU offloading (Zhai et al., 2025) | Industrial cloud–edge | Offloading and resources | No | Yes | Hardware-specific industrial setting |
| CO–MRFO (this study) | Mobile ad hoc cloud | Task–node assignment and offloading | Yes | Local, SMN, SPN/cloud | Evaluated under matched budgets and the mobility-aware MAC model |
3 System model and problem formulation
3.1 Architecture and task model
Letdenote the set of computational tasks, and letdenote the set of service-consumer, smart-mobile, and service-provider nodes.
T = 1 , 2 , … , n
N = N S ∪ N M ∪ N P
Each task i is characterized by its computational requirement C i (cycles), input data size S i (bytes), memory requirement M i (MB), bandwidth requirement b i (bit/s), deadline D i (s), and priority weight
q i ∈ 1 , 2 , 3 .
Each node j is characterized by its processing capacity F j (cycles/s), maximum available memory M j max, available bandwidth B j max, queueing delay Q j t, and, for battery-powered nodes, residual energy E j r e s t. The structural organization of the proposed framework is depicted in Figure 1.
3.2 Assignment and offloading variables
The binary assignment variable is defined in Equation 1 as
y i j = 1 , if task i is assigned to node j , 0 , otherwise .
Each task must be assigned to exactly one node:
∑ j ∈ N y i j = 1 , ∀ i ∈ T (1)
Let s i denote the source node of task i. The offloading decision is not independent; it is derived from the assignment, as given in Equation 2:
o i = 1 − y i , s i (2)
Thus, o i = 0 indicates local execution at the source node, whereas o i = 1 indicates execution on an SMN or SPN. The priority value q i affects the cost associated with deadline violation but does not force a task to be assigned to a particular node.
3.3 Response-time model
For task i assigned to node j, the response time is defined asAccording to Equation 3, where R i j t is the effective data transmission rate between the source node and node j, and L i j t is the routing and protocol latency.
T i j = Q j t + C i F j + o i 8 S i R i j t + L i j t (3)
The deadline violation for task i is defined in Equation 4 as:
v i = max 0 , ∑ j ∈ N y i j T i j − D i (4)
Therefore, v i = 0 means that task i satisfies its deadline, while v i > 0 represents the amount of deadline violation.
3.4 Auditable node-dependent energy model
Energy consumption is calculated at the individual task level and subsequently aggregated according to the type of node executing the task.
For local execution on the source node, energy is given by Equation 5 as:where (Equation 5) P c p u s i is the CPU power consumption of the source node.
E i , s i l o c = P c p u s i C i F s i , j = s i , (5)
For execution on another mobile, edge, or cloud node, energy consumption is given by Equation 6 as:
E i j o f f = P t x s i 8 S i R i j t + P r x j 8 S i R i j t + P c p u j C i F j , j ≠ s i (6)
Here, P t x s i represents the transmission power of the source node, P r x j represents the receiving power of node j, and P c p u j represents the processing power of the node executing the task. Hence, the processing energy is explicitly node-dependent, and an SMN does not use a cloud-server power value.
The energy consumed by service-consumer nodes is given by Equation 7 as:
E S C N = ∑ i y i , s i E i , s i l o c (7)
For execution on smart-mobile and service-provider nodes, the energy is given by Equations 8a, b respectively as:
E S M N = ∑ i ∑ j ∈ N M y i j E i j o f f . (8a)
E S P N = ∑ i ∑ j ∈ N P y i j E i j o f f . (8b)
The total system energy consumption is therefore
E t o t = E S C N + E S M N + E S P N . (9)
Every reported total energy value must satisfy Equation 9.
For a battery-powered node, the available battery capacity in mAh is converted into joules usingwhere V is the declared nominal battery voltage.
E r e s = 3.6 V C m A h ,
3.5 Feasibility constraints
The assignment must satisfy the memory, computational, bandwidth, connectivity, and energy constraints of each node.
Per-node memory and CPU capacity constraints are given by Equations 10a, b as:
∑ i y i j M i ≤ M j max , ∀ j ∈ N . (10a)
∑ i y i j C i ≤ C j max t , ∀ j ∈ N . (10b)
Per-node bandwidth and connectivity constraints are given by Equations 11a, b as:
∑ i y i j b i ≤ B j max t , ∀ j ∈ N . (11a)
where
y i j ≤ a i j t (11b)
a i j t = 1 , if node j is reachable from the source and the link satisfies the minimum data ‐ rate requirement , 0 , otherwise .
For battery-powered nodes, the residual-energy constraint is given by Equation 12 as:
∑ i y i j E i j ≤ E j r e s t . (12)
SPNs are assumed to be mains-powered. Therefore, they are constrained by processing capacity, memory, queueing, bandwidth, and connectivity requirements rather than battery capacity.
3.6 Unified minimization objective
The proposed scheduler minimizes a unified objective function that jointly considers response time, energy consumption, priority-weighted deadline violation, and constraint violations. The scheduler minimizes the unified objective given in Equation 13:
J = w T T ^ + w E E ^ + w P P ^ + μ V (13)
The three normalized objective components - response time, total energy, and priority-weighted deadline violations - are given by Equations 14a, b, c respectively as: and
T ^ = ∑ i ∑ j y i j T i j T r e f (14a)
E ^ = E t o t E r e f (14b)
P ^ = ∑ i q i v i D i ∑ i q i (14c)
Here, T r e f and E r e f are reference values used for normalization.
The term V represents the normalized aggregate of memory, computational, battery, bandwidth, assignment, and connectivity violations. The fixed objective weights arewith the penalty coefficient
w T = 0.5 , w E = 0.3 , w P = 0.2 ,
μ = 1000 .
For sensitivity analysis, the combined time-priority emphasis is defined aswhile the energy emphasis is
α = w T + w P ,
β = w E .
Therefore,
α + β = 1 .
A lower value of J represents a better scheduling solution.
4 Proposed CO–MRFO scheduler
4.1 Continuous representation and decoding
The proposed CO–MRFO scheduler represents each candidate solution using a continuous vector
x ∈ − , 66 n
For task i, let F i t denote its ordered set of currently feasible nodes, and letdenote the number of feasible nodes.
m i = ∣ F i t ∣
The continuous variable x i is transformed into a discrete node index using the sigmoid function:
σ x = 1 1 + e − x
The decoded index is computed using Equation 15 as:
k i = min m i , − 1 ⌊ m i σ x i ⌋ (15)
The selected node is the k i-th element of F i t, and the corresponding assignment variable y i j is set to one.
The initial population is generated using independent uniform random samples within
− , 66 .
4.2 MRFO exploration
The MRFO branch is based on the Manta Ray Foraging Optimization strategy and employs three source-consistent operators: chain foraging, cyclone foraging, and somersault foraging (Zhao et al., 2020).
4.2.1 Chain foraging
Chain foraging updates a candidate from its predecessor and the current best, as given in Equation 16:where u ∼ U 0 , 1, x * t represents the current best solution, and
x r t + 1 = x r t + u x r − 1 t − x r t + α x * t − x r t (16)
α = 2 u ∣ ln u ∣ .
4.2.2 Cyclone Foraging
Cyclone foraging uses a spiral coefficient beta, as given in Equation 17:where the spiral coefficient iswith u 1 ∼ U 0 , 1.
x r t + 1 = x r t + u x r − 1 t − x r t + β x * t − x r t (17)
β = 2 exp u 1 I max − t + 1 I max sin 2 π u 1 ,
4.2.3 Somersault Foraging
Somersault foraging is given by Equation 18 as:
x r t + 1 = x r t + S u 2 x * t − u 3 x r t (18)
where
S = 2 ,
and u 2 , u 3 ∼ U 0 , 1.
Within the MRFO branch, the three operators are selected according to the following probabilities.
- Chain foraging: 0.40
- Cyclone foraging: 0.40
- Somersault foraging: 0.20
4.3 CO refinement
The CO branch follows the Cheetah Optimizer proposed by Akbari et al. (2022). The search operation is given by Equation 19 as:where r ^ r , d − 1 is a standard normal random variable and α t is a bounded local step.
x r , d t + 1 = x r , d t + r ^ r , d − 1 α t (19)
Sitting-and-waiting retains the current coordinate, as given in Equation 20:
x r , d t + 1 = x r , d t (20)
The attack operation is given by Equation 21 as:
x r , d t + 1 = x r , d t + r ˇ r , d β r , d t (21)
wherefor a randomly selected neighbouring candidate k ≠ r, and
β r , d t = x k , d t − x r , d t ,
r ˇ r , d = ∣ z ∣ exp z 2 sin 2 π z , z ∼ N 0 , 1
The return-to-home operation replaces a stagnated leader with its last successful best position and reinitializes one randomly selected candidate.
The four CO operations are selected using the following probabilities.
- Attack: 0.60
- Sit-and-wait: 0.20
- Search: 0.15
- Return-to-home: 0.05
4.4 Exploration–exploitation switching
To balance global exploration and local exploitation, the scheduler dynamically changes the probability of selecting the MRFO branch during optimization.
For each candidate and iteration, the switching probability is computed using Equation 22 as:
p t = p max − p max − p min t − 1 I max − 1 (22)
where
p max = 0.70 , p min = 0.30
For each candidate, ifwhere u ∼ U 0 , 1, the MRFO branch is selected. Otherwise, the CO branch is applied.
u < p t ,
Therefore, exploration is more frequent during the early iterations, whereas CO-based local refinement becomes increasingly dominant toward the end of the optimization process.
For sensitivity analysis, the midpoint probability is defined aswhile the probability span remains fixed at
p m i d = p max + p min 2 ,
p max − p min = 0.40
4.5 Boundary handling and repair
Updated coordinates are clipped to [−6,6], decoded by (Jain et al., 1984), and repaired in descending priority order. For an infeasible task, all currently connected nodes satisfying memory, compute, bandwidth, and battery constraints are evaluated. The task is reassigned to the node with the smallest incremental J. If no feasible node exists, it remains pending for the next interval and contributes to the drop and violation metrics. A candidate replaces its predecessor only when it has a lower J.
4.6 Mobility and termination
Because the system contains mobile nodes, node positions and the connectivity matrixare updated at every scheduling interval according to the Random Waypoint mobility model.
a i j t
If a selected communication link disappears before task execution, the task is returned to the pending queue and repaired using the current network topology.
The optimization process terminates when either of the following conditions is satisfied:orconsecutive iterations occur without improvement in the best objective value.
t = I max = 100 ,
H s t a l l = 20
Thus, the algorithm terminates after a maximum of 100 iterations or earlier when the optimization process stagnates for 20 consecutive iterations.
4.7 Computational complexity
When feasible-node lists are maintained, candidate decoding and objective evaluation requireoperations for n tasks.
O n
The repair mechanism evaluates multiple feasible nodes for infeasible tasks and has a worst-case complexity of
O n m ,
whereis the total number of nodes.
m = ∣ N ∣
With population size N p and maximum iteration count I max, the worst-case computational complexity is given by Equation 23 as:and the memory requirement is
O I max N p n m (23)
O N p n + n m .
Hence, the proposed scheduler maintains a population-based continuous optimization process while decoding each solution into a feasible task-to-node assignment and explicitly accounting for mobility, resource constraints, execution time, energy consumption, and deadline violations. Algorithm 1 flow can be traced back to Figure 2.

Algorithm 1 CO–MRFO scheduling.
5 Reproducible experimental protocol
5.1 Educational-service workload
The workload is synthetic and is not presented as a real educational trace. It contains the service classes in Table 2 so that priority and QoE can be evaluated explicitly.
TABLE 2. Task classes and simulation ranges.
| Task class | Priority qᵢ | Share | Input size | Computation | Memory | Deadline |
|---|---|---|---|---|---|---|
| Live lecture segment | 2 | 20% | 10–100 MB | 100–500 Mcycles | 128–512 MB | 1–4 s |
| Online assessment request | 3 | 15% | 0.1–5 MB | 10–100 Mcycles | 32–128 MB | 1–3 s |
| AI inference | 3 | 15% | 1–20 MB | 500–2000 Mcycles | 256–1024 MB | 0.2–1.0 s |
| Interactive AR/VR | 3 | 10% | 20–200 MB | 500–2500 Mcycles | 512–2048 MB | 0.5–1.5 s |
| Content download | 1 | 20% | 10–500 MB | 10–100 Mcycles | 32–128 MB | 10–60 s |
| Background synchronization | 1 | 20% | 0.1–5 MB | 1–50 Mcycles | 8–64 MB | 30–120 s |
Task attributes are sampled independently from uniform distributions over the stated ranges unless a trace is supplied. Arrivals follow a Poisson process; the default rate is selected to produce 25, 50, 100, 250, and 500-task windows. Table 3 summarize the system configuration in detail for further implementation of experimental protocol.
TABLE 3. System configuration.
| Setting | SCN | SMN | SPN |
|---|---|---|---|
| Number of nodes | 20 | 10 | 5 |
| Processing | 500–1500 MIPS | 2000–5000 MIPS | 10000–30000 MIPS |
| Memory | 512–2048 MB | 4096–8192 MB | 16384–65536 MB |
| Power source | 1500–4000 mAh, 3.7 V | 8000–12000 mAh, 3.7V | Mains powered |
| CPU power | 0.5–2.0 W | 2–8 W | 100–500 W |
| TX/RX power | 0.1–0.5/0.05–0.2 W | 0.1–0.5/0.05–0.2 W | Measured interface power |
5.2 Nodes, mobility, network, and power
The area is 1000 × 1000 m. Random Waypoint speed is 0–10 m/s with a 0–10 s pause. Transmission range is 100 m. Link bandwidth is 10–100 Mbps, and routing/protocol latency is 10–50 m. All ranges are sampled uniformly and recorded in the configuration file for each run. Table 4 explains the above discussed parameters in detail.
TABLE 4. Baselines and parameter settings.
| Method | Core settings | Evaluation status |
|---|---|---|
| CO–MRFO | p max = 0.70, p min = 0.30; MRFO 0.4/0.4/0.2; CO 0.60/0.20/0.15/0.05 | Proposed; 30 paired runs |
| Standalone CO | Original CO operators (Akbari et al., 2022); population 50; 100 iterations | Evaluated; 30 paired runs |
| Standalone MRFO | Original MRFO operators (Zhao et al., 2020); S = 2; population 50; 100 iterations | Evaluated; 30 paired runs |
| GA | Crossover 0.90; mutation 1/n; tournament size 2 | Evaluated; 30 paired runs |
| PSO | Inertia 0.9→0.4; c 1 = c 2 = 2 | Evaluated; 30 paired runs |
| WOA | Control coefficient a: 2→0 | Evaluated; 30 paired runs |
| GWO | Control coefficient a: 2→0 | Evaluated; 30 paired runs |
| SJF | Non-pre-emptive shortest feasible job first | Deterministic baseline |
| MFA offloading (Saif et al., 2024) | Re-implemented from (Saif et al., 2024) under the same workload and budget | Evaluated; 30 paired runs |
5.3 Algorithms and matched budgets
All stochastic methods use a population of 50 and 100 iterations, corresponding to 5000 candidate evaluations before repair re-evaluations. The same task set, topology sequence, and initial candidate population are used in each paired run.
5.4 Runs, software, seeds, and statistical analysis
Each method is evaluated in 30 paired runs. NumPy SeedSequence(20260730).spawn(30) generates the run seeds; the child seed and complete JSON configuration are saved for every run. The reference implementation uses Python 3.11.6, NumPy 1.24.3, NetworkX 3.1, SciPy, and Matplotlib on Ubuntu 22.04, Intel Core i7-12700K, and 32 GB RAM.
Report mean, standard deviation, median, and 95% confidence interval. For paired comparisons with CO–MRFO, apply a paired t-test when the paired differences are approximately normal and the Wilcoxon signed-rank test otherwise. Correct the family of baseline comparisons by Holm’s method (Holm, 1979). Report the adjusted p-value and paired effect size. Convergence must use archived per-iteration values rather than curves reconstructed from final means.
5.5 Reproducibility record and material availability
Independent numerical reproduction requires the implementation source, environment file, the master seed and 30 child-seed records, run-specific JSON configurations, task and topology files, task-level energy records, per-iteration objective histories, and table/figure generation scripts. These materials are not embedded in this Word manuscript. Accordingly, the manuscript is self-contained at the mathematical and protocol-specification level, but its numerical results cannot be independently reproduced from the DOCX alone. The complete record should accompany any resubmission as supplementary files or a public repository deposit.
5.6 Result-record and consistency controls
Each paired run is defined by a single record containing the task set, topology sequence, initial candidate population, terminal objective J, optimizer runtime, SCN/SMN/SPN energy, deadline violations, completed and dropped tasks, makespan, and the per-iteration best-objective history. A record is admissible only when every task has one assignment or an explicit pending status, all reported units match the definitions in Sections 3 and 5, and the unrounded energy identity E_tot = E_SCN + E_SMN + E_SPN holds within numerical tolerance.
All objective comparisons use the same minimization direction: a smaller J is better. Summary statistics must be calculated from the same 30 paired terminal records, while percentage improvement over comparator b is 100(J_b−J_CO–MRFO)/J_b for minimized metrics. Optimizer runtime is wall-clock search time; throughput is N_completed/T_makespan and is never calculated from optimizer runtime. Values displayed after rounding may differ from component sums only by the stated rounding precision.
6 Results and discussion
All values in this section are reported from 30 paired runs under the protocol in Section 5. Lower objective, runtime, energy, and deadline-miss values indicate better performance; higher throughput, fairness, and QoE indicate better service quality.
6.1 Main scheduling results
The node-dependent energy decomposition for the 100-task workload is shown in Figure 3. CO–MRFO achieved the lowest mean objective (12.84 ± 0.31), runtime (8.74 s), and total energy (412.6 J). Compared with GWO, the strongest conventional metaheuristic in Table 5 it reduced the objective by 14.7%, runtime by 14.6%, energy by 10.8%, and deadline misses by 78.1%, while increasing throughput by 11.8%.
TABLE 5. Main results for the 100-task workload (30 paired runs).
| Method | Mean ↓ | Runtime (s) ↓ | Total energy (J) ↓ | SCN energy (J) | SMN energy (J) | SPN energy (J) | Deadline misses (%) ↓ | Throughput (tasks/s) ↑ |
|---|---|---|---|---|---|---|---|---|
| CO–MRFO | 12.84 ± 0.31 | 8.74 | 412.6 | 132.4 | 138.9 | 141.3 | 0.42 | 114.8 |
| Standalone CO | 14.09 ± 0.45 | 9.51 | 438.7 | 141.5 | 147.3 | 149.9 | 1.08 | 108.3 |
| Standalone MRFO | 14.67 ± 0.52 | 9.83 | 447.9 | 145.6 | 150.7 | 151.6 | 1.35 | 106.4 |
| GA | 16.52 ± 0.73 | 11.36 | 498.5 | 161.8 | 166.5 | 170.2 | 3.84 | 94.7 |
| PSO | 15.84 ± 0.68 | 10.92 | 481.7 | 156.1 | 161.4 | 164.2 | 2.96 | 97.8 |
| WOA | 15.31 ± 0.61 | 10.47 | 469.2 | 151.7 | 156.5 | 161.0 | 2.34 | 100.5 |
| GWO | 15.06 ± 0.58 | 10.24 | 462.8 | 149.3 | 154.8 | 158.7 | 1.92 | 102.7 |
| SJF | 18.94 ± 0.84 | 13.18 | 541.6 | 176.4 | 181.9 | 183.3 | 6.51 | 87.2 |
| MFA (Saif et al., 2024) | 15.52 ± 0.63 | 10.61 | 474.5 | 153.2 | 158.1 | 163.2 | 2.58 | 99.3 |
Optimizer runtime is wall-clock scheduling time. System throughput is computed independently as Ncompleted/Tmakespan, where Tmakespan is the simulated service-completion interval; therefore, throughput is not calculated as the number of tasks divided by optimizer runtime.
The final 30-run objective distribution is summarized in Figure 4. Iteration-wise convergence trajectories must be generated directly from the archived per-iteration logs and must not be reconstructed from terminal means.


No claim about convergence speed is made from Figure 4. A convergence figure is valid only when the mean trajectory and its variability band are calculated directly from archived per-iteration histories for all 30 paired runs; terminal summary values must not be used to reconstruct such trajectories.
6.2 Statistical comparison
The prespecified paired comparisons were significant after Holm correction (adjusted p < 0.001). The objective improvement remained significant against both standalone components and GA, while energy and deadline-miss improvements were significant against the recent MFA, baseline and GWO, respectively. The large paired effect sizes indicate practical as well as statistical importance. All the above metrics comparitively listed in Table 6 which includes statistical metrics as discussed in this section.
TABLE 6. Paired statistical comparison with CO–MRFO.
| Metric | Comparator | Mean paired difference | 95% CI | Test used | Holm-adjusted p | Paired effect size | Decision |
|---|---|---|---|---|---|---|---|
| Objective | Standalone CO | −1.25 | [−1.56, −0.94] | Paired t-test | <0.001 | 1.84 (Cohen’s d) | Reject H0; CO–MRFO significantly better |
| Objective | Standalone MRFO | −1.83 | [−2.19, −1.47] | Paired t-test | <0.001 | 2.11 (Cohen’s d) | Reject H0; CO–MRFO significantly better |
| Objective | GA | −3.68 | [−4.12, −3.24] | Paired t-test | <0.001 | 3.26 (Cohen’s d) | Reject H0; CO–MRFO significantly better |
| Energy | MFA (Saif et al., 2024) | −61.9 J | [−71.6, −52.2] J | Wilcoxon signed-rank | <0.001 | 0.91 (r) | Reject H0; CO–MRFO significantly better |
| Deadline-miss ratio | GWO (best competing method) | −1.50% | [−1.88, −1.12] % | Wilcoxon signed-rank | <0.001 | 0.88 (r) | Reject H0; CO–MRFO significantly better |
6.3 Ablation study
Removing any proposed component degraded all three outcomes. The largest deterioration followed removal of node-dependent energy accounting, increasing the objective by 10.4%, energy by 32.7 J, and deadline misses by 0.96 percentage points. Standalone MRFO and CO were also inferior, confirming that the gain is not attributable to either parent optimizer alone. Table 7 exhaustively deals with ablation study in this regard.
TABLE 7. Ablation study.
| Variant | Mean ↓ | Energy (J) ↓ | Deadline misses (%) ↓ | Difference from full model | Interpretation |
|---|---|---|---|---|---|
| Full CO–MRFO | 12.84 ±0.31 | 412.6 | 0.42 | Reference | — |
| Without adaptive switching | 13.61 ±0.38 | 428.9 | 0.86 | +6.0% objective, +16.3 J energy, +0.44% deadline misses | Isolates the hybrid rule |
| Without priority penalty | 13.89 ±0.42 | 432.7 | 1.14 | +8.2% objective, +20.1 J energy, +0.72% deadline misses | Tests priority contribution |
| Without node-dependent energy | 14.18 ±0.47 | 445.3 | 1.38 | +10.4% objective, +32.7 J energy, +0.96% deadline misses | Tests energy formulation |
| MRFO only | 14.67 ±0.52 | 447.9 | 1.35 | +14.3% objective, +35.3 J energy, +0.93% deadline misses | Exploration-only reference |
| CO only | 14.09 ±0.45 | 438.7 | 1.08 | +9.7% objective, +26.1 J energy, +0.66% deadline misses | Refinement-only reference |
6.4 Scalability and sensitivity
Scalability of CO-MRFO and GWO across five workload sizes is shown in Figure 5. Runtime and energy increased with workload size, but CO–MRFO, retained lower objective, energy, and deadline-miss values than GWO, at every scale. At 500 tasks, it reduced runtime by 16.4%, objective by 15.5%, energy by 11.0%, and deadline misses by 63.2%.

The selected configuration used α = 0.7 and β = 0.3, population 50, 100 iterations, and switching midpoint p_mid = 0.50, corresponding to (p_max, p_min) = (0.70,0.30). Larger populations or longer runs produced only marginal objective gains at substantially higher runtime. the qualitative study of scalability and sensitivity showcased in Tables 8, 9.
TABLE 8. Scalability results.
| Tasks | Method | Runtime (s) | Mean ↓ | Energy (J) ↓ | Deadline misses (%) ↓ | Memory use (MB) |
|---|---|---|---|---|---|---|
| 25 | CO–MRFO/GWO | 2.18/2.49 | 4.86/5.43 | 108.4/118.9 | 0.00/0.24 | 44/41 |
| 50 | CO–MRFO/GWO | 4.36/4.98 | 7.42/8.19 | 206.8/224.3 | 0.15/0.68 | 52/49 |
| 100 | CO–MRFO/GWO | 8.74/10.24 | 12.8/15.06 | 412.6/462.8 | 0.42/1.92 | 68/63 |
| 250 | CO–MRFO/GWO | 22.05/25.97 | 28.71/33.65 | 1034.5/1161.7 | 1.38/4.26 | 101/95 |
| 500 | CO–MRFO/GWO | 44.83/53.61 | 57.92/68.54 | 2078.3/2335.8 | 2.81/7.64 | 149/141 |
TABLE 9. Parameter sensitivity.
| Parameter | Values | Mean ↓ | Energy (J) ↓ | Runtime (s) ↓ | Selected value and reason |
|---|---|---|---|---|---|
| Time–priority/energy emphasis (α = wT + wP, β = wE) | (0.8, 0.2), (0.7, 0.3), (0.6, 0.4) | 13.42/12.84/13.08 | 396.4/412.6/429.1 | 8.68/8.74/8.81 | (0.7, 0.3); lowest objective with balanced energy use |
| Population | 30, 50, 80 | 13.51/12.84/12.72 | 425.8/412.6/410.3 | 6.54/8.74/13.18 | 50; nearly the best solution quality with substantially lower runtime than 80 |
| Iterations | 50, 100, 150 | 13.64/12.84/12.71 | 424.2/412.6/410.9 | 4.86/8.74/12.53 | 100; additional iterations provide only marginal improvement while increasing runtime |
| Switching midpoint (pmid) | 0.30: (0.50, 0.10); 0.50: (0.70, 0.30); 0.70: (0.90, 0.50) | 13.26/12.84/13.05 | 419.4/412.6/416.7 | 8.62/8.74/8.89 | 0.50; best exploration–refinement balance |
6.5 Priority and educational-service performance
As we move on to analysis of service level QoE the Table 10 demonstrates executionable priorities of performance metrics. Service-class response time and QoE are shown in Figure 6. Across service classes, mean response time ranged from 0.46 to 1.24 s, deadline misses remained at or below 0.84%, and Jain fairness remained above 0.978. Priority-3 assessment, inference, and AR/VR tasks maintained low miss and drop rates without forcing a fixed execution location. Lower-priority background work experienced the largest delay, consistent with the priority-aware penalty.
TABLE 10. Service-level and QoE results by task class.
| Task class | Response time (s) ↓ | Waiting time (s) ↓ | Deadline-Miss ratio (%) ↓ | Drop rate (%) ↓ | Throughput (tasks/s) ↑ | Jain fairness ↑ | QoE score (1–5) ↑ |
|---|---|---|---|---|---|---|---|
| Live lecture | 0.46 | 0.08 | 0.12 | 0.04 | 118.6 | 0.992 | 4.92 |
| Online assessment | 0.53 | 0.11 | 0.18 | 0.06 | 116.9 | 0.989 | 4.90 |
| AI inference | 0.74 | 0.19 | 0.48 | 0.15 | 112.8 | 0.985 | 4.84 |
| AR/VR | 0.61 | 0.14 | 0.26 | 0.08 | 115.2 | 0.987 | 4.88 |
| Content download | 0.95 | 0.33 | 0.84 | 0.22 | 110.4 | 0.981 | 4.77 |
| Background sync | 1.24 | 0.51 | 0.52 | 0.34 | 108.1 | 0.978 | 4.72 |

Jain fairness is computed from completed-task rates z u of U users using Equation 24:
F J a i n = ∑ u = 1 U z u 2 U ∑ u = 1 U z u 2 (24)
where.
- Uis the total number of users.
- z uis the completed-task rate of user u .
- F J a i nis the Jain fairness index.
The class-level QoE score is fixed before analysis and computed as follows, where Rk and Wk are in seconds and Mk and Gk are deadline-miss and drop percentages expressed in percentage points:
The QoE score for service class k is as given in Equation 25:where clip 1 , 5 · restricts the resulting QoE value to the range 1–5.
Q o E k = clip 1 , 5 5 − 0.15 R k 1 s − 0.10 W k 1 s − 0.05 M k − 0.05 G k (25)
6.6 Discussion boundaries
The evidence supports improved simulated scheduling efficiency, not improved learning outcomes or deployment readiness. The results show lower objective, energy, and deadline misses under the declared workload and network model. Generalization to real educational platforms requires trace-driven and prototype evaluation.
6.7 Limitations
The workload is synthetic, the wireless channel model is simplified, and security and privacy are outside the objective. Although 30 paired endpoint runs are reported, any iteration-wise convergence figure must be regenerated from the archived logs rather than inferred from final summaries. Real educational traces, prototype deployment, richer channel models, and privacy-aware scheduling remain future work.
7 Conclusion
This study developed a reproducible CO–MRFO scheduler for priority-aware task assignment in mobile ad hoc clouds. CO is unambiguously the Cheetah Optimizer; MRFO performs exploration and CO performs refinement under the explicit switching schedule. The model couple’s assignment and offloading, accounts separately for SCN, SMN, and SPN energy, and includes feasibility, mobility, repair, complexity, and termination rules. In the 100-task experiment, CO–MRFO achieved the lowest objective, runtime, total energy, and deadline-miss ratio among the evaluated methods. Ablation and sensitivity analyses confirm the contributions of adaptive switching, priority weighting, and node-dependent energy accounting. These conclusions are limited to the simulated environment.
Correction note
This article has been corrected with minor changes. These changes do not impact the scientific content of the article.
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Footnotes
Edited by: Mauro Femminella, University of Perugia, Italy
Reviewed by: Nafees Akhter Farooqui, Integral University, India
Abdulrahman M. Abdulghani, Putra Malaysia University, Malaysia
Statements
- Conflict of interest
The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
- Funding
The author(s) declared that financial support was not received for this work and/or its publication.
- Data availability
The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.
- Author contributions
AT: Writing – original draft, Writing – review and editing, Conceptualization, Funding acquisition, Methodology, Project administration, Resources. MS: Data curation, Formal Analysis, Investigation, Software, Supervision, Validation, Visualization, Writing – review and editing.
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Citation
Tamilmani, A. & Subramanian, M. (2026). Priority-aware CO–MRFO-based task scheduling for energy-efficient mobile ad hoc clouds. Frontiers in Communications and Networks, Volume 7. https://doi.org/
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- 7 - 2026
Copyright
Copyright © 2026 Tamilmani and Subramanian.
License: https://creativecommons.org/licenses/by/4.0/
*Correspondence: Murali Subramanian
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