Cell Search Method Prioritizing Normal Coverage Mode
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Solution Overview
Problem
Current LTE systems face challenges in efficiently managing cell search and selection, particularly for low-cost Machine Type Communications (MTC) devices in low data rate, delay-tolerant scenarios, where enhanced coverage is needed, leading to unnecessary operation in extended coverage mode, which consumes more resources and reduces spectral efficiency.
Innovation Solution
A method and apparatus for cellular communication devices to search for cells using pre-stored lists of frequencies, prioritizing normal coverage mode connections and switching to extended coverage mode only when necessary, by sequentially scanning frequencies and adjusting settings based on connection thresholds and system information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If devices perform comprehensive cell search in extended coverage mode, then coverage capability is improved, but resource consumption increases and spectral efficiency decreases
Solution Approach 1:
The system performs preliminary cell search in normal coverage mode before attempting extended coverage mode. The device first scans frequencies and evaluates cells using normal coverage criteria, and only if that fails does it proceed to extended coverage mode search, thereby avoiding unnecessary resource consumption in devices that can connect normally.
Solution Approach 2:
The cell search procedure dynamically adapts between normal and extended coverage modes based on real-time conditions. The system adjusts its search strategy, frequency scanning behavior, and connection thresholds dynamically, switching modes only when necessary based on whether normal coverage cell search succeeds or fails.
2Area of stationary object
If devices prioritize extended coverage mode operations, then coverage area is expanded, but spectral efficiency is reduced
Solution Approach 1:
The system performs preliminary evaluation of cell suitability in normal coverage mode before committing to extended coverage mode operations. By first attempting normal coverage mode cell search and connection, the system ensures that extended coverage mode is only activated when necessary, thereby preserving spectral efficiency while maintaining expanded coverage capability as a fallback.
Solution Approach 2:
The system applies different cell search and evaluation criteria locally depending on the coverage mode. Normal coverage mode uses standard cell evaluation parameters, while extended coverage mode uses relaxed criteria and different frequency scanning strategies. This local differentiation ensures that extended coverage resources are only consumed in areas where normal coverage is unavailable.
3Reliability
If devices scan all frequencies exhaustively, then cell detection completeness is improved, but search time increases
Solution Approach 1:
The frequency search space is segmented into normal coverage mode frequencies and extended coverage mode frequencies. The device first scans normal coverage frequencies exhaustively, and only if that fails does it proceed to scan extended coverage frequencies. This segmentation reduces overall search time by completing the more likely successful search first.
Solution Approach 2:
The system performs preliminary frequency scanning in normal coverage mode before attempting extended coverage mode scanning. By evaluating cells in normal coverage mode first and only proceeding to extended coverage mode if necessary, the system reduces average search time while maintaining complete cell detection capability across both modes.
Data Source
AI summary
A method of cell search for a cellular communication device capable of operation in a normal coverage mode and in an extended coverage mode is disclosed. The method comprises retrieving a first list of frequencies for cell search comprising at least one frequency item; searching for cells using the frequency items of the first list in consecutive order until either a cell, which enables connection in the normal coverage mode, is found or the first list is exhausted, wherein if a cell is found which enables connection in the normal coverage mode, connecting to said cell for operation in the normal coverage mode, or if the first list is exhausted, retrieving a second list of frequencies, searching for cells using the frequency items of the second list in consecutive order until either a cell is found which enables connection in the extended coverage mode or the second list is exhausted, wherein if a cell is found which enables connection in the extended coverage mode, connecting to said cell for operation in the extended coverage mode. Method for a base station, a cellular communication device, a base station, and computer program therefore are also disclosed.