Dynamic Synchronization Signal Relocation in LTE
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Solution Overview
Problem
In LTE systems, synchronization and broadcasting signals are vulnerable to interference in unlicensed environments, particularly from narrow-band interferers, leading to performance degradation due to their fixed location within the operating bandwidth.
Innovation Solution
The primary control signals, such as synchronization and broadcasting signals, can be relocated within the operating band to avoid interference by employing P contiguous subcarriers, allowing them to be placed at either end of the band or divided if interference occurs in the middle, with adaptive relocation based on changing interference conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronization signals and PBCH are fixed at the center of the operation channel, then system operation is simplified and reliable in licensed spectrum, but the system becomes vulnerable to narrow-band interference in unlicensed environments
Solution Approach 1:
The patent implements dynamic frequency positioning of synchronization signals and PBCH by allowing these signals to be transmitted at different frequency locations within the operation channel rather than being fixed at the center. The system can adaptively select frequency positions to avoid narrow-band interferers, making the transmission dynamic and flexible in response to changing interference conditions.
Solution Approach 2:
The patent changes the frequency parameter of synchronization signals and PBCH transmission by allowing variable frequency positioning within the operation channel. Instead of using a fixed center frequency, the system can shift the frequency location of these critical signals to avoid interference, thereby maintaining reliable operation in unlicensed spectrum environments.
2Device complexity
If synchronization signals and PBCH occupy a narrow bandwidth at a fixed location, then system complexity is reduced, but performance degrades when narrow-band interferers are present
Solution Approach 1:
The patent introduces dynamic frequency selection for synchronization signals and PBCH transmission, allowing the system to adaptively change the frequency position of these signals based on detected interference conditions. This dynamic approach maintains system performance without significantly increasing complexity by using straightforward frequency measurement and relocation mechanisms.
Data Source
AI summary
In a broadband wireless communication system, a primary control signal may be relocated within the operation band for transmission while avoiding interference. For example, if the primary control signal employs P contiguous subcarriers, the primary control signal can be placed in any section of the band that has P contiguous subcarriers. If a narrow-band interferer appears at one end of the band, the primary control signals can be placed at the other end. If the interferer appears in the middle, the primary can be relocated to either end of the band. The placement of primary control signals can be changed as the interference environment changes.