DMRS Sequence Modification for NOMA Interference Reduction
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Solution Overview
Problem
Current Non-Orthogonal Multiple Access (NOMA) systems face challenges in distinguishing between same DMRS sequences of different user equipment, leading to interference and reduced system performance due to limited orthogonal demodulation reference signals.
Innovation Solution
A method is introduced where user equipment receives multiple access signature information from a base station, which includes modification information to determine and modify its reference signal sequences, such as PN or ZC sequences, to reduce interference and improve system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of ports for orthogonal DMRS is limited in NOMA system, then the system structure remains simple, but different user equipment cannot distinguish and decode the same DMRS sequences
Solution Approach 1:
The patent modifies DMRS sequences by applying multiple access signature information (scrambling codes, cyclic shifts, orthogonal cover codes) to differentiate sequences across different user equipment. This changes the parameters of existing DMRS sequences rather than creating entirely new port structures, thereby improving distinguishability while maintaining structural simplicity
Solution Approach 2:
The patent segments the DMRS sequence generation process into multiple components: base sequence selection, scrambling code application, cyclic shift application, and orthogonal cover code application. Each component contributes to the overall differentiation capability, allowing the system to achieve high distinguishability through layered modification rather than structural complexity
2Object-affected harmful factors
If multiple access signature information is introduced to distinguish user equipment, then interference between user equipment is reduced, but system overhead increases
Solution Approach 1:
The patent makes the multiple access signature information serve multiple functions simultaneously: it differentiates user equipment, reduces interference, and enables sequence modification. By making this information multi-functional, the patent avoids additional overhead for separate differentiation mechanisms
Solution Approach 2:
The patent merges the DMRS sequence modification function with the multiple access signature information that already exists in the NOMA system. Instead of adding separate differentiation mechanisms, the patent combines sequence modification with existing access signatures, thereby reducing overall system overhead while achieving interference reduction
Data Source
AI summary
Provided by an embodiment of the present invention are a user equipment and base station that may be used in a wireless communication system, or a method performed by the user equipment and the base station. The user equipment according to the embodiment of the present invention includes: a receiving unit that is configured to receive multiple access signature information for the user equipment from a base station, wherein the multiple access signature information includes correction information indicating a reference signal sequence sent with respect to the user equipment; and a control unit that is configured to determine the reference signal sequence of the user equipment according to the received correction information.