Line of Sight (LoS)

A direct, unobstructed path between transmitter and receiver allowing signals to travel without reflection or diffraction. LoS conditions typically provide best positioning accuracy and reliability. Many industrial environments have limited LoS due to equipment, racks, walls, and other obstructions. RTLS systems must be designed to handle non-line-of-sight (NLoS) conditions.

Unobstructed direct path between transmitter and receiver, critical factor affecting RTLS performance. LoS conditions provide: strongest signal strength (no attenuation from obstacles), most accurate ranging (single direct path vs. multipath), lowest latency (shortest signal path), and highest reliability (consistent signal reception). Non-line-of-sight (NLoS) conditions introduce: signal attenuation (obstacles absorb/reflect signals reducing strength), multipath propagation (multiple signal paths causing ranging errors), increased latency (longer signal paths), and reduced reliability (intermittent detection). Different technologies handle NLoS differently: UWB relatively robust to NLoS (operates through obstacles with some accuracy degradation, typically 30-50% error increase), BLE/Wi-Fi more sensitive to NLoS (accuracy degrading 2-5x in obstructed conditions), and IR/optical requiring strict LoS (complete signal loss if blocked). Industrial environments inherently challenging for LoS: metal equipment creates reflections and blockage, shelving and racking obstruct large areas, moving vehicles temporarily block signals, and facility layouts create obstructed zones. LoS planning strategies: (1) Anchor placement optimization - positioning infrastructure to maximize LoS to coverage areas (elevated mounting, strategic locations). (2) Redundancy - deploying additional anchors ensuring multiple LoS paths available (one path blocked, others remain). (3) NLoS mitigation - positioning algorithms detecting and compensating for NLoS conditions. (4) Technology selection - choosing technologies with good NLoS performance (UWB preferred over BLE/Wi-Fi in obstructed environments). Coverage gap remediation often involves improving LoS: repositioning existing anchors, adding anchors providing alternate LoS paths, or removing/relocating obstacles when feasible.