Frame Timing Synchronization in Wireless LAN Zone Tags
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing location and tracking systems using Wi-Fi or Bluetooth networks are limited by low accuracy, typically only able to determine positions within a few meters and fail to detect proximity between assets, which is necessary for applications like tracking healthcare professionals' visits to patients or ensuring equipment is correctly attached.
Innovation Solution
Implementing a synchronization mechanism for frame timing among zone tags and mobile tags using IEEE 802.11 WLAN technology, allowing them to wake up at scheduled times for precise position location, and using timestamp synchronization across different Basic Service Sets (BSSs) to align frame timing and determine proximity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frame timing synchronization is implemented among zone tags and mobile tags, then position location accuracy is improved to room level precision, but device complexity increases due to synchronization mechanism requirements
Solution Approach 1:
A timestamp mechanism is introduced as an intermediary to synchronize frame timing across different Basic Service Sets (BSSs). Each BSS includes a timestamp field in its beacon frames, allowing zone tags and mobile tags to align their frame timing by comparing and adjusting based on these timestamps, thereby achieving room-level position accuracy without complex direct synchronization protocols
Solution Approach 2:
Zone tags and mobile tags autonomously adjust their frame timing based on the timestamps received in beacon frames from access points. Each tag independently calculates its timing offset and adjusts its own frame transmission timing, eliminating the need for centralized timing control and reducing overall system complexity
2Use of energy by moving object
If tags wake up at scheduled time instants to determine position, then power consumption is reduced, but timing synchronization becomes more difficult to achieve
Solution Approach 1:
Tags are configured to wake up periodically at scheduled time instants to perform position determination and then return to sleep mode. This periodic operation pattern significantly reduces power consumption while the timestamp-based synchronization mechanism ensures that these periodic wake-ups occur at coordinated times across the network, maintaining synchronization without continuous active communication
Solution Approach 2:
The system pre-calculates and distributes timing schedules to tags in advance, allowing them to wake up at predetermined time instants. This preliminary timing arrangement simplifies the synchronization process during operation, as tags only need to follow the pre-established schedule rather than continuously negotiate timing, reducing both power consumption and synchronization complexity
3Stability of the object's composition
If timestamp synchronization is used across different BSSs, then frame timing alignment is achieved, but information exchange overhead increases
Solution Approach 1:
The synchronization information is extracted and embedded within the existing beacon frame structure as a timestamp field. This approach avoids creating separate synchronization message protocols, as the timestamp is carried along with regular beacon transmissions, minimizing additional information overhead while achieving frame timing alignment across BSSs
Data Source
AI summary
A position location system based on a wireless local area network such as an IEEE 802.11 network is described. The system determines position of mobile tags attached to assets or people. IEEE 802.11 enabled zone tags are installed to assist in positioning. The system aligns frame timing of zone tags to that of an associated basic service set (BSS). The system computes the frame timing offsets between adjacent BSSs, and utilizes the frame timing offsets in scheduling range measurements between zone tags and mobile tags. A set of zone tags which are in close proximity of a first zone tag and able to receive signals from the first zone tag is identified. Frame timing of all zone tags in a network are aligned.