What the work must achieve
Entrance detection means using a Bluetooth beacon, NFC tag, or QR code at a doorway to register that a visitor has crossed into a venue. A welcome message is the notification, screen content, or audio prompt triggered by that detection. The two are often assumed to be the same thing, but they are distinct: you can detect an entrance without sending any message at all, and you can send a welcome without reliable entrance detection.
In practice, most retail and venue deployments use a beacon mounted near the entrance, broadcasting at a configured transmit power and advertising interval. A visitor's phone receives the signal, and if the accompanying app is installed with the correct permissions granted, the app estimates distance using the received signal strength indicator (RSSI). When that value crosses a defined threshold, the system logs an entrance event and, if the campaign logic allows, pushes a notification.
The consent chain is the first practical barrier. Before any welcome message can arrive, the visitor must have downloaded the app, enabled Bluetooth, granted location permissions, and accepted push notifications. In a typical high-street retail environment, the proportion of footfall meeting all four conditions is often very small. Entrance detection works reliably only for that subset of visitors, which limits its usefulness as a general footfall counter.
An entrance is also not a point. It is a zone with depth, width, and often a threshold line that people cross at different speeds and angles. A beacon placed directly on the door frame will produce different RSSI readings for someone walking straight through versus someone pausing to check a bag or speak to a greeter. Treating the entrance as a precise trigger line is a common source of error.
Implementation choices and evidence
Retail environments
In a shop, the most common use is a loyalty-oriented welcome: recognising a returning customer and surfacing their points balance, a personalised offer, or a reminder of an abandoned basket. The value depends entirely on whether the message is relevant to that moment. A generic "Welcome to [Store]" notification adds nothing and trains users to dismiss future prompts.
Placement matters more than transmit power. Mounting the beacon on the ceiling, roughly one to two metres inside the entrance and offset from the door swing, gives a more consistent RSSI curve than a tag stuck to the door frame itself. The exact position should be tested during a pilot with real footfall, not decided from a floor plan alone.
Museums and visitor attractions
Here, the entrance message often serves an orientation purpose: a link to the floor plan, today's events, or accessibility information. Because museum visitors are more likely to have deliberately installed the venue's app, the consent gap is narrower than in general retail. The message should answer a question the visitor already has at that point, such as "Where do I start?" or "What's on today?"
Events and temporary venues
At conferences or exhibitions, entrance detection can trigger a schedule download or badge-related information. The infrastructure is temporary, so beacons are typically mounted on stands, truss, or temporary partitions. The main complication is that multiple events may share a venue in quick succession, requiring beacon identifiers to be reprogrammed or physically swapped between setups.
Defining the entrance zone
Rather than a single RSSI threshold, most practical systems define an outer boundary and an inner boundary. The outer boundary filters out people walking past on the street outside. The inner boundary confirms the person has actually entered. A detection is logged only when the signal crosses both thresholds in the correct sequence within a reasonable time window. This two-stage approach reduces false positives but requires calibration on site.
Staff and repeat-entry handling
Staff passing through the entrance multiple times per shift will generate repeated detection events unless their device identifiers are excluded. Similarly, a customer who steps outside for a phone call and returns should not receive a second welcome message within a short period. Frequency capping, typically set at one welcome per visit session or per number of hours, is essential to avoid notification fatigue.
Acceptance, records and review triggers
Treating the welcome as the objective
The welcome message is a means, not an end. If the campaign brief starts with "we want to send a welcome notification" rather than "we want to solve this specific visitor problem at the entrance," the result is usually a low-engagement message that damages future notification open rates. The question to ask first is: what does the visitor need at the exact moment they cross the threshold?
Ignoring the street-side false-positive problem
A beacon mounted too close to an open shopfront will be detected by people on the pavement. In a covered shopping centre this is less of an issue, but on a high street with a single-glazed shop window, Bluetooth signal passes through with surprisingly little attenuation. Testing with a phone held outside the premises, at pavement distance, is a basic check that is frequently skipped.
Over-relying on a single beacon
One beacon at a wide entrance will produce inconsistent results. The RSSI at the left-hand door may differ from the right-hand door by a considerable margin depending on the beacon's position. For entrances wider than roughly three metres, two beacons with overlapping zones give more reliable detection than one central unit.
Not accounting for door behaviour
Automatic doors, swing doors, and open archways all affect the radio environment differently. A glass swing door can reflect Bluetooth signals, creating momentary RSSI spikes as it moves. An open archway offers no attenuation at all. The physical door type should be recorded during site survey and factored into placement decisions.
Key checks before going live
- Walk past the entrance from outside at normal pavement distance and confirm no false trigger occurs.
- Walk through the entrance at different speeds, including pausing in the doorway, and check that detection logs consistently.
- Test with the door in its various positions: open, closed, mid-swing.
- Verify that staff devices are excluded from welcome-message triggers.
- Confirm that a visitor who exits and re-enters within the capping window does not receive a duplicate message.
- Check that the message content renders correctly on both iOS and Android, as notification formatting and deep-link behaviour differ between the two platforms.
- Review the message copy for actual usefulness: does it tell the visitor something they could not already see?
When entrance detection is the wrong approach
If the primary goal is to count total footfall, beacons are the wrong tool. Thermal counters or camera-based systems handle anonymous counting far more reliably because they do not depend on app installation or consent. If the goal is to greet every visitor, the consent gap means beacons will only ever reach a fraction. Entrance detection with welcome messages works best when the objective is to deliver a personalised, app-dependent action to a known visitor at the moment they arrive. Anything broader than that will underperform expectations.
