CCA Signal Generation for LAA Channel Assessment

The patent applies preliminary action by inserting a specific CCA signal at the beginning of the OFDM symbol (or at a known position before the actual data signal) to enable receiver equipment to perform channel assessment before the main signal transmission. This preliminary CCA signal allows receivers to quickly determine channel occupancy status without waiting for the middle-of-symbol signal arrival, thus resolving the identification capability issue while maintaining the flexible channel access benefit.

The patent implements dynamics by making the CCA signal transmission duration adaptive rather than fixed. The system dynamically adjusts the CCA signal duration based on the relationship between the first duration and OFDM symbol boundaries. When the first duration aligns with complete OFDM symbols, the CCA signal extends to include those complete symbols; otherwise, it uses only the first duration. This dynamic adjustment ensures reliable channel assessment while maintaining transmission simplicity through automated boundary detection.

The patent applies parameter changes by optimizing the frequency-domain density of the reference signal based on channel conditions and system requirements. Rather than using maximum density uniformly, the system adjusts the reference signal density parameter to achieve sufficient channel estimation accuracy while minimizing energy consumption. This is combined with energy information determination that allows the system to adaptively control reference signal transmission based on actual channel state, reducing unnecessary energy expenditure when high density is not required for adequate estimation.