Cell-Specific Pilot Signal Phase Control for Mobile Station Complexity
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Solution Overview
Problem
In cellular systems, the integration of unicast and MBMS sub-frames in radio frames leads to a phase shift of cell-specific scramble codes, complicating cell search processing and increasing detection complexity in mobile stations, especially during initial cell search when guard interval information is unavailable.
Innovation Solution
A method where the base station controls the phase difference of cell-specific pilot signals across sub-frames to maintain consistency, ensuring no phase shift occurs, thereby simplifying correlation detection and improving cell search processing without increasing the mobile station's complexity or configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If unicast and MBMS sub-frames are integrated in radio frames, then system functionality and data transmission capability are improved, but phase shift of cell-specific scramble codes occurs complicating cell search processing
Solution Approach 1:
The invention changes the parameter of pilot signal transmission by introducing phase compensation mechanisms. Specifically, it modifies the transmission parameters of cell-specific pilot signals to account for and counteract the phase shifts introduced by MBMS sub-frame integration, thereby maintaining consistent phase relationships across different sub-frame types.
Solution Approach 2:
The invention implements feedback by having the mobile station detect and measure phase shifts in received pilot signals, then report this information back to the base station. The base station uses this feedback to adjust and compensate for phase shifts in subsequent transmissions, creating a closed-loop system that maintains synchronization accuracy.
2Reliability
If phase compensation is implemented to maintain pilot signal consistency, then cell search detection probability is improved, but base station processing complexity increases
Solution Approach 1:
The invention applies preliminary action by pre-calculating and pre-compensating for expected phase shifts before pilot signal transmission. The base station anticipates phase changes due to MBMS sub-frame patterns and applies compensatory phase adjustments in advance, eliminating the need for complex real-time phase correction during cell search operations.
3Reliability
If pilot signal transmission is maintained across all sub-frames, then cell search capability is preserved, but resource element allocation efficiency decreases
Solution Approach 1:
The invention applies local quality by differentiating pilot signal transmission strategies between different sub-frame types. Instead of uniform pilot transmission across all sub-frames, it optimizes pilot signal presence and characteristics specifically for unicast sub-frames where cell search is relevant, while reducing or eliminating redundant pilot transmissions in MBMS sub-frames where cell search is not performed.
Data Source
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AI summary
A pilot signal transmitting method, which achieves an appropriate cell search without increasing in scale or complicating the mobile station structure, is provided along with a base station, a mobile station and a cellular system to which that method is applied. In a cell-specific pilot signal transmitting method for use in a mobile communication system that comprises a base station and a mobile station wireless communicating with the base station in the cell of a wireless communication area formed by the base station and that can mix and then transmit unicast data and broadcast/multicast data as downstream data from the base station to the mobile station, the difference between the start phase of a cell-specific pilot signal transmitted in a subframe in which the base station transmits the unicast data and the start phase of a cell-specific pilot signal transmitted in the next subframe is equal to the difference between the start phase of a cell-specific pilot signal transmitted in a subframe in which the base station transmits the broadcast/multicast data and the start phase of a cell-specific pilot signal transmitted in the next subframe.