Optical Wireless Access Point Coordination for Interference Control
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Solution Overview
Problem
Existing optical wireless networks, particularly LiFi, face issues with interference and handover management due to overlapping coverage areas and the mobility of communication devices, with current coordination methods failing to adequately address these challenges.
Innovation Solution
A method and coordination device that allocate time slots to access points in an optical wireless network, ensuring each interface device in an exclusive area is assigned a time slot, and then allocates compatible devices in interference areas using various heuristics to minimize interference and facilitate seamless handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If access points transmit simultaneously in overlapping coverage areas, then network coverage is extended, but interference between access points increases
Solution Approach 1:
The patent segments the coverage area into exclusive sub-areas and interference sub-areas. Access points are allocated specific time slots to transmit in their exclusive sub-areas without interference, while coordinated transmission is managed in interference sub-areas. This spatial segmentation resolves the contradiction by allowing extended coverage through multiple access points while preventing interference through temporal and spatial separation.
Solution Approach 2:
The patent implements periodic time slot allocation where access points transmit in alternating time slots within interference sub-areas. This periodic transmission pattern ensures that only one access point transmits at a time in overlapping regions, eliminating interference while maintaining extended coverage through coordinated scheduling.
2Reliability
If handover between access points is implemented for mobile devices, then communication continuity is maintained, but coordination complexity increases
Solution Approach 1:
The patent performs preliminary allocation of time slots to access points before handover occurs. Mobile devices are pre-configured with knowledge of time slot allocations for different access points, enabling seamless handover without complex real-time coordination. This preliminary action reduces coordination complexity while maintaining communication continuity.
Solution Approach 2:
The patent implements feedback mechanisms where access points monitor device movements and communication quality, automatically adjusting time slot allocations to facilitate handovers. This feedback-driven coordination simplifies the handover process by using real-time information to make automated decisions, reducing overall coordination complexity while ensuring communication continuity.
3Measurement precision
If time slot allocation is optimized for interference avoidance, then signal quality improves, but network throughput may be reduced
Solution Approach 1:
The patent implements dynamic time slot allocation that adapts to real-time network conditions, device locations, and traffic demands. This dynamic approach allows the system to optimize signal quality in interference-prone areas while maximizing throughput in non-interfering areas, resolving the contradiction by making the allocation flexible rather than static.
Solution Approach 2:
The patent changes transmission parameters such as time slot duration, frequency of transmission, and power levels based on the specific conditions of each access point and its coverage area. By adjusting these parameters dynamically, the system maintains high signal quality where interference occurs while preserving high throughput where interference is minimal, thus resolving the contradiction between signal quality and network throughput.
Data Source
AI summary
A method coordinates access points having coverage areas each subdivided into an exclusive sub-area supplemented by an interference sub-area where they overlap and forming part of an optical wireless network. The method includes a procedure including, for each time channel, a first sub-procedure wherein each interface device located in an exclusive sub-area of an access point is allocated an authorized free time slot in the time channel, a second sub-procedure wherein, as long as there remains an interface device without an allocated time slot in an interference sub-area, for each free time slot: a set of interface devices compatible with it is determined, if this set is not empty, an interface device is allocated this free time slot which is compatible with an available access point according to a chosen heuristic, otherwise the time slot is not free, the second sub-step is performed again.