Bluetooth Beacon for Indoor Positioning-Deployment Solution

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Bluetooth Beacon for Indoor Positioning-Deployment Solution [Copy link]

Beacon positioning principle

Ibeacon is a low-energy Bluetooth technology. Its working principle is similar to the previous Bluetooth technology. Beacon transmits signals, and Bluetooth devices receive and feedback signals. When users enter, exit or wander in the area, Beacon broadcasts have the ability to spread, and the distance between the user and Beacon can be calculated (can be calculated by RSSI). Therefore, as long as there are three Beacon devices, positioning can be achieved.

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Trilateration positioning algorithmBasic principle

Trilateration (three-sided measurement) is a commonly used positioning algorithm:

• The positions of three points are known (x1, y1), (x2, y2), (x3, y3)
• The unknown point is known (x0, y0) Distances to three points d1, d2, d3

Draw three circles with radii d1, d2, d3. According to the Pythagorean theorem, we can get the formula for calculating the position of the intersection point, i.e. the unknown point:

( x1 - x0 )2 + ( y1 - y0 )2 = d12 ( x2 - x0 )2 + ( y2 - y0 )2 = d22 ( x3 - x0 )2 + ( y3 - y0 )2 = d32 Solution derivation

Suppose the unknown point is at (x, y), let the center coordinates of the first sphere P1 be (0, 0), P2 is at the same ordinate, the center coordinates are (d, 0), P3 is at (i, j), the radii of the three spheres are r1, r2, r3, and z is the height of the intersection of the three spheres and the horizontal plane. Then we have:r12 = x2 + y2 + z2 r22 = (x - d)2 + y2 + z2 r32 = (x - i)2 + (y - j)2 + z2 When z = 0, the three circles intersect at one point on the horizontal plane. First solve for x:x = (r12 - r22 + d2) / 2d Transform formula 2, substitute z2 from formula 1 into formula 2, and then substitute into formula 3 to get y Calculation formula:

y = (r12 - r32 - x2 + (x - i)2 + j2) / 2j Bluetooth Beacon Requirements

Under the premise that the battery working time is stable and the environmental structure is not too complex, Bluetooth beacons that meet the following standards can be better supported: 1. Protocol: Comply with the ibeacon standard protocol (Apple official) 2. UUID, major, minor: fixed 3. Antenna: omnidirectional antenna 4. Encryption: Non-encrypted Bluetooth beacon is required 5. Signal transmission period: Generally 100ms-200ms is required 6. Power: It is required to be stable and the default is 0db. For devices without enhancement, the signal effective radius is about 5m, and the deployment spacing is recommended to be 5-8m. Detection tool: ibeaconDetector (Android), used to determine whether the UUID, major, and minor meet the requirements and whether the power is stable.

Bluetooth Beacon deployment planDeployment principles

1) Bluetooth Beacon ground height: 3m Height H: Generally between 2.5 and 3m. If the on-site installation location is high, it is necessary to consider increasing the attenuation budget. Alternatively, use ground or wall deployment to ensure that the height is within 3m.

2) Horizontal spacing of Bluetooth Beacon: 4-8 m One-dimensional positioning scenario: suitable for corridors with high isolation. In theory, only one row of Beacons with a spacing of 4-8 m need to be deployed in sequence. General positioning scenario (open area): Bluetooth Beacons are evenly deployed in a triangle, requiring 3 or more Bluetooth Beacons. The distance between each other is 4-8 m.

Deployment solutions for different scenarios

A. For general indoor environments, the Beacon spacing is controlled at about 4-8m. The deployment should be uniform. B. The deployment of Bluetooth Beacons needs to avoid obstructions as much as possible. Do not deploy near corners or obstacles. C. In open areas, the distance between each other should be about 5m, and the entire space should be covered in a triangular grid-like staggered distribution. D. For room entrances, indoor route intersections, and path turning points, deployment is required to improve user experience. E. Inside the room, a smaller room or a room that does not require precise positioning can be deployed in the center. For larger rooms, consider using a triangular grid-like staggered distribution similar to open areas. F. Indoor corridors can be deployed in single or double rows depending on the width. For relatively closed corridors (about 3m wide), deployment can be considered along the center line of the corridor; for wider corridors, deployment can be staggered in double rows. G. In the parking lot driving lane area, try to deploy in an unobstructed area above, with a spacing of about 5m, and can be deployed in single or double rows according to the width. For parking spaces, it is recommended to deploy 1-2 Beacons per parking space (generally 2.5m*5.5m, and 1-2 Beacons can be deployed as needed. H. Lobbies or areas with high floor heights (floor height>4m), hollows, etc. must not be deployed on the ceiling. It can be deployed along the wall or on near-ground building structures at a spacing of about 5m. I. Beacon deployment density can be increased or decreased as needed, but it is generally recommended that a spacing range of 4-6m can achieve better positioning accuracy. A spacing greater than 6-8m will result in poor positioning results.

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