Comprehensive Overview of Indoor Positioning Technologies and Their Challenges

GPS and cellular base‑station positioning satisfy most outdoor location service needs, but because people spend about 80% of their time indoors, indoor positioning has become a critical focus, driven by its vast application and commercial potential.

Outdoor positioning technologies include satellite (GPS, GLONASS, Galileo, BeiDou) and cellular base‑station methods, each with distinct principles, components, accuracy, power consumption, and cost considerations.

Indoor positioning faces unique challenges such as dynamic environments, high precision requirements, coverage, reliability, cost, power consumption, scalability, and response time. Solutions must balance these factors based on specific use cases.

Common indoor positioning techniques are categorized by principle and observation type, including:

Proximity detection

Centroid method

Multilateration

Triangulation

Polar coordinate method

Fingerprinting

Dead‑reckoning (navigation)

Key observation measurements include RSSI, TOA, TDOA, AOA, and direction‑distance, each supporting different indoor positioning approaches.

Major indoor positioning technologies covered:

Wi‑Fi positioning : Uses signal strength or fingerprint databases; widely deployed but limited by accuracy and maintenance overhead.

Cellular (LBS) positioning : Relies on signal strength from multiple base stations; fast but coarse accuracy.

RFID positioning : Reads tags via readers using proximity or multilateration; offers centimeter‑level accuracy over short ranges.

Infrared positioning : Employs active tags and sensors; high precision in line‑of‑sight scenarios but costly and sensitive to obstacles.

Ultrasonic positioning : Uses acoustic ranging; high precision but limited range.

Bluetooth (BLE) positioning : Based on RSSI; supports network‑side and device‑side models, offering low power consumption.

Inertial navigation : Leverages accelerometers and gyroscopes; drift requires periodic correction (e.g., with Wi‑Fi).

UWB (Ultra‑Wideband) positioning : Provides high‑accuracy ranging via nanosecond pulses; emerging with strong indoor performance.

Visible Light (LED) positioning : Encodes IDs in LED light, captured by camera; offers high accuracy without extra infrastructure.

Geomagnetic positioning : Utilizes indoor magnetic field variations; can achieve sub‑meter accuracy after mapping.

Visual positioning : Uses cameras and reference models or markers; supports various reference schemes.

Each technology has distinct strengths and weaknesses, and the optimal solution often combines multiple methods to meet specific accuracy, coverage, cost, and power requirements.

定位技术

GPS定位

LBS定位

原理

卫星定位

基站定位

精度

精度高（5‑10m）

精度较低（市区20‑200m；郊区1000‑2000m）

耗电量

很大，需要高压供电

低，基站采集数据即可

优点

精度高，覆盖广

定位快，不受天气影响，功耗低

缺点

需室外视野，受天气影响，耗电高，成本高

需基站信号，精度低

In summary, indoor positioning technologies are diverse, each suited to particular scenarios; selecting or combining them based on specific requirements yields the most effective solution.