Secondary Sync Channel Scrambling for OFDM Interference Reduction
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Solution Overview
Problem
In radio communications systems using OFDM for downlink, the Secondary Synchronization Channel (S-SCH) experiences interference and increased Peak-to-Average Power Ratio (PAPR), leading to decreased detection probability and degraded cell search performance in inter-station synchronization systems.
Innovation Solution
A base station apparatus and mobile station apparatus are designed to generate and transmit a secondary sync channel with a scramble code, where cell-specific information is included, and the mobile station descrambles and detects this information to improve S-SCH detection probability and reduce PAPR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the S-SCH is transmitted without scramble code in inter-station synchronization systems, then the transmission process is simple, but the PAPR increases and detection probability decreases
Solution Approach 1:
The patent applies scramble codes to the S-SCH transmission, which changes the signal parameters to reduce PAPR. The scramble code modifies the signal characteristics in a way that lowers peak power while maintaining detection performance, directly resolving the contradiction between transmission simplicity and detection reliability.
2Device complexity
If the S-SCH is transmitted without scramble code, then the transmission structure is simple, but interference increases in inter-station synchronization systems
Solution Approach 1:
The scramble code changes the signal parameters to provide better interference characteristics. By scrambling the S-SCH with cell-specific codes, the patent reduces mutual interference between cells in synchronization systems while keeping the transmission structure relatively simple.
3Stability of the object's composition
If multiple cells use the same S-SCH sequence in inter-station synchronization systems, then the system is easy to synchronize, but interference occurs and detection probability decreases
Solution Approach 1:
The patent applies different scramble codes to different cells, creating local differentiation in the S-SCH transmission. This allows cells to maintain synchronized timing while having distinct signal characteristics that reduce interference, resolving the contradiction between synchronization stability and interference reduction.
Data Source
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AI summary
A mobile station adapted to communicate with a base station apparatus using an OFDM scheme in downlink, the mobile station comprises a receiver adapted to receive a multi-carrier signal from the base station apparatus; a first detector adapted to detect a primary sync channel included in the multi-carrier signal received by the receiver; and a second detector adapted to detect a secondary sync channel included in the multi-carrier signal received by the receiver, based on the primary sync channel detected by the first detector, wherein the first detector is adapted to detect the primary sync channel that is generated based on a primary sync channel sequence number, and wherein the second detector is adapted to detect the secondary sync channel such that, in the secondary sync channel, two types of short codes to be alternately arranged in a frequency domain are scrambled by using corresponding mutually different two types of scramble sequences, and the scramble sequence used for scrambling the secondary sync channel corresponds to the primary sync channel sequence number.