4-Layer LDM Signal Transmission Using PN Sequence Insertion

The patent segments the LDM signal into distinct layers (UL, ML, LL, and new TL) with different power levels and modulation schemes. Each layer is independently modulated and transmitted, allowing the receiver to process and cancel layers sequentially. This segmentation enables the fourth layer to be added without fundamentally disrupting the reception of existing layers, as they can be separated through successive interference cancellation.

The patent extracts the fourth layer signal (TL) as a separate entity with distinct characteristics (different modulation scheme, power level, and PN sequence). By taking out the new layer as an independent component that can be identified and cancelled separately, the system allows high-capacity transmission of the fourth layer while preserving the reception quality of the original three layers through selective cancellation at the receiver.

The patent applies local quality by assigning different power levels and modulation characteristics to different layers. The fourth layer (TL) uses BPSK modulation with a specific power level that is locally optimized for its reception requirements, while the existing layers maintain their original characteristics. This local optimization allows each layer to be received with appropriate sensitivity without uniformly increasing noise across all layers.

The patent employs preliminary action through pre-insertion of PN sequences into the fourth layer signal before transmission. These PN sequences serve as identification markers that enable the receiver to detect and cancel the fourth layer signal before it interferes with the reception of existing layers. This preliminary preparation allows the system to handle higher fourth layer magnitudes without proportionally increasing interference to other layers.

The patent introduces PN sequences as intermediary elements that facilitate layer separation. These pseudo-random sequences act as mediators between the fourth layer signal and the receiver, enabling correlation-based detection and identification. The PN sequences provide a systematic way to distinguish the fourth layer from existing layers without requiring complex signaling protocols or coordination mechanisms.

The patent applies parameter changes by modifying the fourth layer signal with specific characteristics: BPSK modulation, predetermined power level relative to other layers, and inserted PN sequences with specific lengths and codes. These parameter changes create distinct fingerprints for the fourth layer, enabling efficient separation and detection. The systematic variation of these parameters provides a scalable approach to layer management that balances separation capability with implementation complexity.