Wireless Navigation Data Compression via Server-Side Tiling
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Solution Overview
Problem
Wireless client-server navigation systems face high data transmission costs due to the need to transmit large amounts of data for route searches and map generation, which is economically unsustainable.
Innovation Solution
The system reduces data transmission by generating and transmitting map-related features in a data-reduced format, using methods such as tiling, curve approximation, point removal, and data compression, as well as pregenerating turn instructions at the server, which are then sent to the client in a compressed format.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full-resolution map data is transmitted to mobile units, then navigation accuracy is improved, but data transmission costs increase significantly
Solution Approach 1:
The patent segments map data into hierarchical levels of detail (LOD), dividing comprehensive map data into multiple resolution tiers. Mobile units receive only the appropriate LOD level based on their specific needs, eliminating transmission of unnecessary high-resolution data while preserving navigation accuracy where required.
Solution Approach 2:
The patent applies local quality by transmitting high-resolution data only for specific local areas of interest (such as turn-by-turn navigation segments) while using lower-resolution data for broader regional contexts. This ensures navigation accuracy is maintained locally where critical while reducing overall data transmission volume.
2Adaptability or versatility
If complex route calculation algorithms are executed on mobile units, then routing flexibility is improved, but hardware requirements and costs increase
Solution Approach 1:
The patent performs preliminary route calculation and optimization on the server before transmitting results to mobile units. Complex algorithms pre-process routing options, constraints, and preferences server-side, then transmit only the optimized route recommendations to mobile devices. This preserves routing flexibility while eliminating the need for powerful onboard hardware.
Solution Approach 2:
The patent introduces the server as an intermediary between the user's navigation needs and the mobile unit. The server handles complex computational tasks, acting as a mediator that processes routing algorithms centrally and communicates simplified results to mobile devices, thereby reducing device complexity while maintaining routing versatility.
3Device complexity
If turn instruction data is pre-calculated and transmitted with routes, then client device capability requirements are reduced, but server processing requirements increase
Solution Approach 1:
The patent performs preliminary calculation of turn instructions and integrates them directly into the transmitted route data. All turn-by-turn navigation computations are completed in advance on the server, so mobile units receive ready-to-execute instructions without needing to perform complex calculations locally, reducing client device capability requirements.
4Measurement precision
If high-resolution map features are transmitted, then map display quality is improved, but transmission time increases
Solution Approach 1:
The patent segments map feature data by geometric complexity and resolution requirements. Simple linear features use efficient coordinate representations while complex curved features use approximation algorithms. This segmentation allows transmission of adequate map display quality without unnecessary high-resolution data, reducing transmission time.
Solution Approach 2:
The patent changes data representation parameters by converting high-resolution map features into compressed formats using geometric approximations. Curves are represented by control points rather than dense coordinate sequences, and resolution is adjusted based on display context, maintaining perceptible quality while dramatically reducing transmission time.
Data Source
AI summary
Methods and apparatus to reduce data transmission in a wireless client-server navigation system. A request for data representative of a map-related feature is received at a server from a mobile client. Data describing the feature is obtained in the form of coordinates of line segments. An operation is performed on the data to generate data representative of the feature in a data-reduced format, and the reduced data is forwarded to the client. The operation responsible for producing the data-reduced format includes the steps of: receiving map data; partitioning the map into a plurality of tiles; designating a reference point within each tile; representing the feature in the form of offsets from the reference points; and wherein the data-reduced format is based upon the reference points and offsets. The embodiment may also include sending precalculated turn instruction to the client rather than sending data necessary to generate turn instructions.