1. Understanding the Handover Problem

When an AGV moves through a warehouse, it encounters multiple access points (APs) along its route. If the AGV doesn’t switch to the strongest AP quickly, it may:

• “Stick” to a weak signal

• Experience dropped packets

• Temporarily stop if safety thresholds are triggered

Key metric: Handover Time – the delay for the AGV to switch from one AP to the next.

Example: Enterprise Cisco APs with 802.11r/k/v fast roaming can achieve <50 ms handover. AGVs generally need <100 ms to avoid triggering emergency stop logic.

2. 802.11 Fast Roaming Standards

Tip: Verify that the AGV Wi-Fi module and firmware fully support 802.11r/k/v with your supplier.

3. Wi-Fi Architecture Strategy

Option A: Fat AP (Standalone)
       Pros: Simple, lower infrastructure cost
       Cons: Roaming depends on client logic; handover may be slower

Option B: Controller-Based (Centralized)
       Pros: Controller coordinates roaming, faster handoff, optimized channels
       Cons: Higher cost, slightly more complex to maintain

Best practice: Large warehouses with moving AGVs usually use controller-based architecture.

4. Handover Optimization Tips

• AP Placement & Overlap: 15–20% overlap; AGV paths should always be within 1–2 strong AP signals

• Signal Threshold Settings: Set minimum RSSI (e.g., -65 dBm) to prevent sticking

• Bandwidth & Channel Planning: Non-overlapping channels, prefer 5 GHz band

• Load Balancing: Ensure multiple AGVs don’t saturate a single AP

• Test Real Paths: Walk routes with Wi-Fi analyzer; log handover events and latency; adjust transmit power as needed

5. Monitoring & Diagnostics

• Use SNMP or controller logs to monitor roaming events

• RCS systems often log AGV connectivity drops

• Create Wi-Fi signal heatmaps of the warehouse

• Conduct dry-run AGV missions to validate handovers

✅ Key Insights

• Fast roaming support (802.11r/k/v) is critical for uninterrupted AGV operation

• Controller-based Wi-Fi generally outperforms standalone APs for fleets

• Tune handover thresholds and signal overlaps per aisle and blind turn

• Continuous RSSI and latency monitoring prevents “sticking” and safety stops

• Coordination between IT, AGV supplier, and warehouse ops is essential

Wi-Fi Roaming Optimization Checklist (Optional)

• AP placement map

• Signal threshold values

• Roaming test plan

• Handover latency logging template