Scrambling Sequence Initialization for CoMP Transmissions
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Solution Overview
Problem
In coordinated multi-point (CoMP) transmission networks, existing methods for initializing scrambling sequences in LTE-A systems result in complex control channel signaling and overhead, particularly when multiple cells serve the same user equipment (UE) concurrently, leading to different scrambling sequences across cells and increased operational complexity.
Innovation Solution
A shared initialization code is generated and used across all cells involved in CoMP operations, incorporating a virtual serving cell identifier, virtual UE identifier, and shared codeword and slot indices, to ensure identical scrambling sequences for all cells, reducing complexity and overhead by aligning on common parameters like serving cell IDs and virtual indices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate scrambling sequences are used for each cell in CoMP transmission, then cell-specific data transmission is enabled, but control channel signaling complexity and overhead increase
Solution Approach 1:
The patent merges the scrambling sequence initialization across multiple cells by using a common virtual cell ID and shared codeword indices. Instead of maintaining separate scrambling sequences for each cell, the system combines the initialization process using common parameters (virtual cell ID, shared slot indices, shared RB indices) while preserving cell-specificity through the serving cell's unique identifier in the PDCCH address space.
Solution Approach 2:
The patent creates a universal scrambling sequence initialization mechanism that serves multiple cells simultaneously. The same initialization parameters (c_init, slot index, RB index) are used across all CoMP cells, allowing the system to handle both single-cell and multi-cell transmissions with a unified approach, reducing the need for cell-specific signaling configurations.
2Reliability
If multiple cells transmit to the same UE concurrently, then signal to noise ratio at UE increases, but scrambling sequence management complexity increases
Solution Approach 1:
The patent applies local quality by maintaining cell-specific characteristics where needed (PDCCH addressing, serving cell identification) while using common quality parameters for scrambling initialization (virtual cell ID, shared codeword indices). This allows each cell to contribute to improving SNR at the UE while the scrambling management remains standardized and less complex.
3Reliability
If cell-specific scrambling sequences are used, then data transmission security is maintained, but operational complexity between single-point and multi-point transmissions increases
Solution Approach 1:
The patent introduces dynamic adaptability by using a virtual cell ID that can represent different cells in different transmission modes. When switching between single-point and multi-point transmissions, the system dynamically adjusts which cell's parameters are used for initialization, but the underlying mechanism remains the same, simplifying the operational complexity of mode switching.
Data Source
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AI summary
A user equipment, UE, comprising: means for initializing a scrambling sequence based on a virtual serving cell identifier that is distinct from a serving cell identifier of a serving base station; means for scrambling data using the scrambling sequence; and means for transmitting the scrambled data on a physical uplink shared channel, PUSCH as well as a corresponding method and a corresponding computer product.