Candidate-Specific Uncertainty-Aware Predictive Handover for Dense Mobile Networks ()
1. Introduction
NR mobility management combines measurement configuration, handover control, and execution procedures [1]. Radio-resource control specifies the reporting and control messages that carry those decisions [2]. A predictive policy must therefore distinguish the information available at decision time from radio outcomes observed only after execution.
A scalar uncertainty penalty shared by every candidate cannot influence target ranking or a target-serving comparison. UAPHO instead estimates a distinct uncertainty state for each user-cell pair, evaluates cell-specific margins, recomputes occupancy after executed handovers, and scores failure over a short post-handover interval.
The study asks whether cell-specific forecast residual uncertainty can stabilize short-horizon mobility decisions and what portion of the result comes from the return-cell, load, and viability guards. It does not assume future channel values. Figure 1 shows the measurement, forecast, decision, and execution sequence.
Figure 1. UAPHO pipeline with candidate-specific residual uncertainty, guarded decisions, and post-handover execution assessment.
2. Related Work
The channel model follows the distance-loss and correlated-shadowing concepts documented for 0.5 - 100 GHz evaluation [3]. Dense 5G systems motivate small cells, directional links, and frequent mobility events [4], while higher-frequency propagation increases sensitivity to blockage and geometry [5].
Recursive prediction methods formalize estimation from noisy observations [6]. UAPHO uses a transparent local trend rather than a trained model so that residual uncertainty and every decision term remain inspectable. Packet-level LTE simulation [7] and learned radio coordination [8] offer richer alternatives but would obscure the specific guardrail question addressed here.
Velocity and mobility-state inference can use handover histories [9]. IMT-2020 requirements identify mobility and user-experienced data rate as linked evaluation dimensions [10]. Heterogeneous-network studies [11] and media-independent handover standards [12] further motivate ping-pong and failure analysis. The NR system text [13] supplies broader architectural context. Simulation limits are reported explicitly in line with established cautions about synthetic network models [14].
Recent studies predict mobility-management demand from operational signaling [15], optimize handover jointly with load distribution [16], and reduce association churn through soft handover in cell-free systems [17]. Load-sensitive parameterization remains important in heterogeneous 5G networks [18], while multi-agent learning [19] and proportionally fair mobility control [20] illustrate broader stability-throughput objectives. Self-optimization of handover parameters [21] and predictive mechanisms for 5G and beyond [22] further motivate transparent forecast uncertainty and guardrail analysis.
3. Mobility and Radio Model
Figure 2 depicts the 6 km wraparound corridor with nine sites spaced 750 m apart. Users move at one of three speed ranges through a correlated shadowing field. Each trace is generated once per seed-density-speed scenario and replayed for every policy.
Figure 2. Synthetic nine-site mobility corridor used for all handover-policy comparisons.
Table 1 lists the radio and mobility assumptions. The model is intentionally controlled: it is designed to test decision logic, not to reproduce a specific operator deployment.
Table 1. Radio and mobility assumptions.
Parameter |
Value |
Sites |
9, spaced 750 m |
Corridor |
6 km with wraparound |
Trace duration |
50 s |
Decision interval |
0.5 s |
Users |
40, 80, 120 |
Speed ranges |
40 - 70, 70 - 100, 100 - 130 km/h |
Shadowing |
4 dB correlated Gaussian |
Bandwidth |
20 MHz per cell |
RSRP model |
−43 − 30.5 log10(max(10, d)/10) + X dBm |
Shadowing SD |
4 dB |
Shadowing temporal correlation |
0.94 per 0.5-s step |
Candidate-cell set |
All 9 cells |
Interference abstraction |
Strongest non-serving cell |
SINR-like offset |
1.5 dB |
Explicit carrier frequency |
Not modeled |
Explicit Tx power/antenna gains |
Not modeled |
Thermal noise/noise figure |
Not modeled |
3.1. Radio Propagation and Measurement Model
The study uses a controlled received-power abstraction rather than a complete 3GPP link-budget model. Carrier frequency, absolute transmit power, antenna gains and heights, thermal-noise power, and receiver noise figure are not represented as separate parameters. Their aggregate effect is absorbed into the synthetic RSRP-distance relationship so that the study can isolate handover-decision behavior.
For user
and cell
, the modeled RSRP is
(1)
where
is the one-dimensional user-site distance in meters and
is the shadowing term. Distances below 10 m are clipped to 10 m.
Initial shadowing is sampled independently as
Thereafter, shadowing follows the temporal first-order process
with
The model therefore uses temporal correlation of 0.94 per 0.5-s measurement interval rather than a fixed spatial correlation distance. Because user speeds vary, the implied traveled distance over one correlation step also varies.
All nine cells are measurable candidates for every user at each decision epoch. Interference is represented by the strongest non-serving-cell RSRP rather than by a full sum of received interference powers. A synthetic SINR-like margin is computed as
Thus, this simulation is intended to compare handover control policies under a common radio trace; it is not a calibrated carrier-frequency-specific radio-access-network model.
3.2. Mobility Trace Generation
For each seed-density-speed scenario, the mobility trace is generated once and replayed unchanged across all eight handover policies. User initial positions are independently sampled from a uniform distribution over the 6-km wraparound corridor:
All users move in the positive corridor direction; travel direction is not independently randomized. Initial speed is sampled uniformly within the configured scenario range:
after conversion from km/h to m/s.
At every 0.5-s step, speed evolves according to
where
Position is then updated as
The initial serving cell is the cell with the highest modeled RSRP at the first recorded measurement:
This pairing ensures that every policy evaluated for a common seed-density-speed scenario sees the same user positions, speeds, shadowing process, and RSRP trace.
4. Candidate Specific Forecast Uncertainty
4.1. Observable Forecast and Residual Variance
At each decision epoch
, separated by
, the controller computes the local RSRP trend for user
and cell
as
Two forecasts are derived from the same observable trend. The handover decision uses a 1.5-s-ahead forecast:
Uncertainty estimation uses a separate one-step forecast for the next 0.5-s measurement:
At epoch
, the matured one-step residual is therefore
The candidate-specific residual variance is updated as
(2)
The initial residual variance is 9 dB2. Thus, no 1.5-s prediction is evaluated prematurely: the 1.5-s forecast drives the handover decision, while uncertainty is estimated from matured 0.5-s forecast errors.
4.2. Lower Confidence Margin
Occupancy/load term:
where
.
For serving cell s and candidate j, Equation (3) is evaluated with candidate-specific and serving-cell variances. The uncertainty term can no longer cancel because
varies by candidate and the combined margin changes the handover condition.
(3)
Full UAPHO uses
and
. A candidate becomes eligible when
dB for two consecutive decision epochs.
4.3. Guardrails and Execution
Handover persistence is evaluated at the 0.5-s decision interval. When a candidate first satisfies the handover margin, the persistence timer begins. The same candidate must continue satisfying the margin for two consecutive decision epochs, corresponding to 1.0 s, before handover execution is initiated.
Once a handover is executed at epoch
, the post-handover viability window begins with the first subsequent measurement and spans the next four 0.5-s measurement intervals, i.e., epochs
through
. Failure is recorded if the target violates either the absolute-power or relative-margin criterion at any point within this 2.0-s execution-assessment window.
or
Cell occupancy is recomputed after all handovers and failures in the interval. Equation (4) then shares cell bandwidth among the updated occupants.
(4)
where
MHz is the per-cell bandwidth and
is the post-handover number of users attached to user i’s serving cell.
A user that executes a handover during the interval receives 90% of the calculated rate, representing a 50-ms interruption during the 0.5-s service interval.
Table 2 defines the baselines and ablations. Forecast-only intentionally omits every guard so that prediction instability is visible.
Table 2. Policies and ablations.
Policy |
Uncertainty |
Return guard |
Load |
Viability |
A3 baseline |
No |
No |
No |
Execution only |
Load-aware A3 |
No |
No |
Yes |
Execution only |
Full UAPHO |
Cell specific |
Yes |
Yes |
Yes |
No uncertainty term |
κ = 0 |
Yes |
Yes |
Yes |
No return guard |
Cell specific |
No |
Yes |
Yes |
No load penalty |
Cell specific |
Yes |
No |
Yes |
No viability guard |
Cell specific |
Yes |
Yes |
No |
Forecast only |
No |
No |
No |
No |
These values are held fixed across all reported seeds, densities, and speed ranges. The uncertainty coefficient κ is additionally evaluated from 0 to 2 in the predefined sensitivity experiment.
Parameter |
Value |
Rationale |
Decision interval |
0.5 s |
Common measurement/control interval |
Decision forecast |
1.5 s |
Anticipates conditions three control intervals ahead |
Residual forecast |
0.5 s |
Allows residual to mature at the next measurement |
Residual EWMA β |
0.86 |
Smooths short-term forecast-error variation |
Initial variance |
9 dB2 |
Initial 3-dB residual standard deviation |
κ |
1.0 |
Central value of predefined 0–2 sweep |
λ |
2.8 |
Moderate load penalty |
UAPHO decision threshold |
2.8 dB |
Requires material lower-confidence advantage |
A3 threshold |
3.0 dB |
Fixed baseline comparison threshold |
TTT |
1.0 s |
Two qualifying 0.5-s intervals |
Return guard |
8 s |
Longer than 5-s ping-pong window |
Viability threshold |
−107 dBm |
Rejects predicted weak target |
Failure power threshold |
−112 dBm |
Severe post-HO degradation |
Failure relative threshold |
−11 dB |
Target collapse vs strongest competitor |
HO interruption |
50 ms |
Successful-handover service loss |
Failure interruption |
180 ms |
Failed-HO recovery penalty |
4.4. Baseline Decision Rules
The A3 baseline uses current measured RSRP. At each decision epoch, the target is the cell with the highest instantaneous RSRP:
The A3 advantage is
A handover is initiated when the target differs from the serving cell and
dB for two consecutive 0.5-s decision intervals, corresponding to a 1.0-s time-to-trigger.
Load-aware A3 uses the same 3.0-dB threshold and 1.0-s time-to-trigger but adjusts target ranking using cell occupancy. Let
denote the number of users currently attached to cell
, and define the pseudocount-adjusted occupancy
. The load term for candidate
relative to serving cell
is
The load-adjusted score is
and the target is
. Handover occurs when the target’s load-adjusted advantage over the serving cell exceeds 3.0 dB for 1.0 s.
5. Experimental Design and Statistics
Table 3 records the executed factorial design. Each policy sees the same RSRP trace within a seed-density-speed scenario. The sensitivity experiment reruns the principal scenario at κ values from 0 to 2.
Table 3. Executed design.
Factor |
Values |
Seeds |
20, numbered 2001-2020 |
Densities |
40, 80, 120 users |
Speed ranges |
40 - 70, 70 - 100, 100 - 130 km/h |
Policies |
8 |
Main records |
1440 |
Kappa sensitivity |
5 values × 20 seeds = 100 records |
Primary outcomes |
Failure, ping-pong, outage, P10 throughput |
Equation (5) gives paired 95% confidence intervals. All means and standard deviations are calculated across fixed seeds.
(5)
Differences are formed seed by seed before the mean and standard error are calculated.
6. Results
6.1. Principal Scenario
Figure 3 reports post-handover failures at 80 users and 70 - 100 km/h. Full UAPHO failed 1.08% of handovers (SD 0.82); no uncertainty failed 2.03% (SD 1.42). The paired full-minus-no-uncertainty difference was −0.95 percentage points (95% CI −1.60 to −0.29).
Figure 4 isolates ping-pong behavior. Full UAPHO recorded 0.00% and the no-return-guard ablation recorded 3.48%. The paired difference was −3.48 points (95% CI −4.30 to −2.67). This comparison, rather than the full-policy zero alone, quantifies the return guard’s effect.
Figure 5 shows lower-tail service. Full UAPHO produced 1.51 Mbit/s (SD 0.17); A3 produced 1.98 Mbit/s (SD 0.15). The paired difference was −0.46 Mbit/s (95% CI −0.56 to −0.36).
Handover-failure rate is calculated as
Figure 3. Mean post-handover failure rate in the principal scenario.
Figure 4. Ping-pong rate with and without the return-cell and other guardrails.
Ping-pong rate is
Figure 5. Tenth-percentile throughput after recomputing post-handover occupancy.
For each seed, handover-failure rate is
Ping-pong rate is
Outage rate is computed over all user-decision intervals. An interval is classified as outage when the serving-cell RSRP is below −110 dBm or when the SINR-like margin
is below −7 dB:
The reported tenth-percentile throughput is the 10th percentile of all user-interval throughput samples accumulated over the trace.
Table 4 consolidates failure rate, ping-pong rate, outage rate, and tenth-percentile throughput.
Table 4. Principal scenario results.
Policy |
Mean HOs ± SD |
Total HOs |
Failed HOs |
Ping-pong events |
Failure mean ± SD (%) |
Ping-pong
(%) |
Outage
(%) |
P10
Mbit/s |
A3 baseline |
136.4 ± 5.1 |
2728 |
1 |
12 |
0.04 ± 0.17 |
0.43 |
0.49 |
1.98 |
Load-aware A3 |
137.7 ± 4.6 |
2754 |
0 |
18 |
0.00 ± 0.00 |
0.64 |
0.56 |
2.08 |
Full UAPHO |
133.9 ± 3.8 |
2677 |
29 |
0 |
1.08 ± 0.82 |
0.00 |
4.85 |
1.51 |
No uncertainty term |
153.1 ± 5.7 |
3061 |
62 |
0 |
2.03 ± 1.42 |
0.00 |
1.39 |
2.08 |
No return guard |
139.2 ± 4.8 |
2783 |
31 |
98 |
1.11 ± 0.82 |
3.48 |
4.76 |
1.53 |
No load penalty |
132.1 ± 3.5 |
2642 |
28 |
0 |
1.07 ± 0.83 |
0.00 |
4.47 |
1.46 |
No viability guard |
140.2 ± 4.6 |
2804 |
26 |
0 |
0.93 ± 0.70 |
0.00 |
1.72 |
2.00 |
Forecast only |
479.0 ± 23.9 |
9580 |
969 |
5178 |
10.11 ± 0.87 |
53.98 |
5.57 |
0.95 |
Failure and ping-pong percentages are computed within each seed and then averaged across the 20 seeds; therefore, the displayed mean percentages need not exactly equal the ratios calculated from pooled event totals.
6.2. Stability-Throughput Trade-Off
Full UAPHO eliminated measured ping-pong in the principal scenario and reduced failure relative to the no-uncertainty predictive variant (1.08% versus 2.03%). That stability did not translate into across-the-board service gains. A3 and load-aware A3 had lower failure rates (0.04% and 0.00%) and higher tenth-percentile throughput (1.98 and 2.08 Mbit/s) than full UAPHO (1.51 Mbit/s). The principal result is therefore a stability-throughput trade-off: uncertainty-aware guardrails suppress unstable predictive handovers but can retain a weaker serving cell long enough to reduce lower-tail service.
The no-return-guard result attributes the zero ping-pong rate to the explicit dwell constraint, while the full-versus-no-uncertainty comparison isolates the effect of the candidate-specific confidence term. Together, the ablations show that forecast uncertainty and dwell protection address predictive instability, but neither should be interpreted as a general replacement for conventional A3 in this model.
6.3. Speed and Density Sensitivity
Figure 6 compares failure rate across speed ranges. Figure 7 reports full-UAPHO lower-tail throughput for every density-speed cell. These plots use all 20 seeds per cell.
6.4. Uncertainty Coefficient Sensitivity
Figure 8 shows that κ changes failure, ping-pong, and lower-tail throughput. A larger uncertainty penalty suppresses marginal handovers but can retain a degrading serving cell too long. Table 5 provides the executed means.
Table 5. Kappa sensitivity.
Kappa |
Failure (%) |
Ping-pong (%) |
P10 Mbit/s |
Outage (%) |
0.0 |
2.03 |
0.00 |
2.08 |
1.39 |
0.5 |
1.58 |
0.00 |
1.80 |
3.47 |
1.0 |
1.08 |
0.00 |
1.51 |
4.85 |
1.5 |
0.58 |
0.00 |
1.25 |
5.68 |
2.0 |
0.52 |
0.00 |
0.97 |
6.60 |
Figure 6. Handover-failure sensitivity across the three vehicle-speed ranges at 80 users.
Figure 7. Full-UAPHO tenth-percentile throughput across all density and speed combinations.
Figure 8. Sensitivity of the principal scenario to the candidate-specific uncertainty coefficient.
6.5. Resource Sharing after Handover
Figure 9 reports mean throughput calculated from occupancy recomputed after handover decisions, so each interval’s resource sharing reflects the executed serving-cell assignments.
Figure 9. Mean throughput using post-handover cell occupancy in the principal scenario.
7. Discussion
Candidate-specific uncertainty affects both the margin and the executed decision set. The results do not justify a universal superiority claim. In this controlled corridor, κ = 0 can outperform κ = 1 on some throughput or failure metrics, indicating that uncertainty calibration matters as much as including the term.
The return-cell guard is the direct cause of the full policy’s ping-pong suppression. The no-return ablation restores ping-pong while leaving the uncertainty estimator intact. The method’s novelty therefore lies in the combined, auditable decision rule and the separation of each guard’s contribution, not in attributing a mechanically enforced zero to prediction.
The viability guard is evaluated prospectively from present information, while failure is scored from a later execution interval. This temporal separation removes future leakage. Recomputed occupancy also exposes the throughput cost when many users select the same target.
8. Threats to Validity and Limitations
The corridor is one-dimensional, the channel equation is simplified, sites share equal bandwidth, and the model omits beam management, scheduler details, core-network delay, and signaling contention. Results are simulation outcomes rather than field measurements. The model intentionally abstracts explicit carrier frequency, transmit power, antenna characteristics, thermal noise, and summed inter-cell interference; therefore, absolute throughput values should be interpreted as internally consistent simulation metrics for policy comparison rather than operator-specific 5G performance predictions.
Residual variance is an EWMA of matured 0.5-s one-step forecast errors and is used as an engineering uncertainty proxy for the separate 1.5-s decision forecast. It is not a calibrated probabilistic confidence interval. The lower-confidence expression uses that variance as an engineering penalty. Trace-driven or packet-level evaluation is required before interpreting κ as a confidence level.
Twenty seeds quantify within-model variation but do not cover all road layouts or fading processes. Failure thresholds and execution-window length are explicit sensitivity candidates for future work.
9. Conclusion
UAPHO uses cell-specific residual uncertainty, recomputes load after handovers, and evaluates target viability over a four-step execution window. In the principal scenario, full UAPHO recorded 1.08% failures, 0.00% ping-pong, and 1.51 Mbit/s tenth-percentile throughput. It reduced failure relative to the no-uncertainty predictive variant, and the no-return ablation demonstrates that the return guard accounts for the ping-pong result. Conventional A3 policies nevertheless achieved lower failure and better lower-tail throughput. The contribution is therefore control of prediction-induced instability under uncertain forecasts, with an explicit stability-throughput trade-off rather than across-the-board superiority.
Data and Code Availability
The study uses no proprietary or personal data. The complete simulation source, fixed random-seed ranges, seed-level result files, aggregated tables, and publication figures are included in the accompanying reproducibility package. The code regenerates all numerical results and figures reported in this manuscript.
Author Contributions
Utham Kumar Anugula Sethupathy: Conceptualization, methodology, software, validation, formal analysis, investigation, data curation, writing—original draft, writing—review and editing, and visualization. Vijayanand Ananthanarayanan: Validation, formal analysis, writing—review and editing.
Appendix. Reproduction Procedure
Run the supplied Python file using the following command: python run_experiments.py --study cn. The script generates the nine scenario cells, eight-policy comparisons, five-level κ sweep, figures, seed-level CSVs, and grouped summaries; Table A1 lists the expected checks.
Table A1. Reproduction checks.
Check |
Expected value |
Seed range |
2001-2020 |
Main records |
1440 |
Sensitivity records |
100 |
Occupancy timing |
After handover execution |
Future state used by decision |
No |
Decision interval |
0.5 s |
Decision forecast horizon |
1.5 s |
Residual forecast horizon |
0.5 s |
Residual EWMA |
|
A3 threshold |
3.0 dB |
UAPHO threshold |
2.8 dB |
TTT |
1.0 s |
Return guard |
8 s |
Ping-pong window |
5 s |
Viability threshold |
−107 dBm |
Failure power threshold |
−112 dBm |
Failure relative margin |
−11 dB |
Post-HO assessment |
4 × 0.5 s |
Successful HO interruption |
50 ms |
Failed HO interruption |
180 ms |
Candidate cells |
All 9 |