finite MDP. The contextual UCB rule of Auer et al.
[13]
is nevertheless retained as a strong myopic learning
baseline, allowing the data to reveal whether long-horizon state coupling materially changes the decision.
Research question. Can a compact reinforcement-learning controller jointly adapt forwarding mode, RLNC
generation size, and redundancy to reduce tail latency while maintaining reliability and useful goodput under
changing narrowband multi-hop network conditions?
Methodological novelty boundary: DARC does not introduce a new RLNC coding theorem or a new Q-learning
update. Its contribution is the joint, interpretable, state-aware control architecture: forwarding mode, RLNC
generation size, and coded-packet redundancy are selected together from an 81-state context, the action affects
the subsequent load/queue transition, and the objective explicitly combines CVaR95 tail latency, residual loss,
coding overhead, and useful-goodput deficit. This differs from fixed coding or forwarding, RL-based coding that
does not jointly adapt forwarding in the present comparison, and a contextual-bandit controller that omits next-
state value.
The main contributions are as follows:
An 81-state representation that includes packet loss probability, load/queue pressure, hop count and message
size while retaining a compact 972-entry Q-table.
An action-dependent transition model in which the useful service rate affects the next queue/load state,
providing an explicit P(s_{t+1}|s_t,a_t) and a defensible MDP/Q-learning formulation.
A CVaR95 tail-latency estimator using a final 256-packet window, 256-packet warm-up and 32-packet update
stride is used; the choice is justified from the number of samples available in the 5% tail and is combined with
residual loss, coding overhead and goodput deficit after every term is normalized to [0,1].
An explicit RLNC model over GF(2^8), including finite-field rank probability, coefficient-header overhead,
source-only coding, generation-level cumulative ACK and rank-deficiency recovery.
A stronger benchmark suite: store-and-forward, fast-forward, reliability-biased RLNC, adaptive heuristic,
contextual UCB, greedy one-step control and an exact value-iteration MDP oracle.
Multi-seed learning-stabilization diagnostics over 120,000 transitions, confidence intervals, a full learned-
policy atlas, relative p95 gains, dual-axis-free ablation, message-size sensitivity, Pareto analysis and objective-
weight sensitivity.
A reproducibility package with code, transition and reward matrices, learned policy arrays, CSV data, and an
empirical-calibration template.
For traceability, Table 1 positions DARC against representative alternatives. The closed-loop MDP architecture
is defined in Fig. 1, and Algorithm 1 gives the online controller. Table 2 lists the state-bin boundaries, and Table
3 summarizes the state, action, learning, normalization, and transition parameters. Fig. 2 shows the results of
the multi-seed learning diagnostics; Fig. 3 shows all 81 learned decisions; and Figs. 4–10 present the
distributional, scaling, robustness, ablation, message-size, Pareto, and weight-sensitivity results. Tables 4–7
summarize representative baseline performance, exact discounted-policy performance, a dynamic-workload
stress test, and novelty-to-evidence traceability.
2. Related work and research gap
Earlier narrowband experiments by the authors,
[1,2,5,6]
together with independent studies of forwarding, network
coding, capacity, and delay in multi-hop wireless networks,
[3,4,7]
measured or analyzed how RTT/latency and
capacity vary with message size, route length, forwarding behavior, and coding/redundancy. In the present
study, the authors’ prior findings are used only to choose physically meaningful state variables and operating
ranges; the independent literature provides the broader comparison. Work on RLNC and wireless coding
[8–11]
establishes the basic trade-off between coded redundancy and recovery. ETX, ExOR, and low-power routing
standards
[16–21]
address path quality, opportunistic forwarding, and scheduled communication. Queueing and
stochastic network optimization
[22,23]
motivate representing load evolution and action-dependent service. The
6TiSCH minimal profile
[24]
and hard-real-time scheduling results
[25]
further motivate reproducible scheduling
assumptions and examination of deadlines and tail behavior rather than relying on mean throughput alone.
Recent studies provide several points of comparison. Learning-based network coding has been examined in
drone-assisted secure links and for selective RLNC in tactile-Internet scenarios.
[26,27]
Deep reinforcement
learning has also been used for link adaptation,
[28]
multi-hop offloading,
[29]
delay-aware resource allocation in
industrial IoT,
[30]
energy-aware forwarding,
[31]
and federated wireless control.
[32,33]
Nuwa-RL focuses on
application-sensitive congestion control in dynamic wireless networks.
[34]
Other works have evaluated RL rate
adaptation for time-critical Wi-Fi with a calibrated simulator
[35]
and multi-timescale DRL for delay reduction in
dynamic resource allocation.
[36]
Belief-state RL has recently been proposed for latency-robust wireless control
when observations are delayed or uncertain.
[37]
These contributions support adaptive decision making, but they