Adaptive Spreading Factor and Chip Repetition for Interference Control
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Solution Overview
Problem
Conventional radio communication systems face challenges in achieving high frequency use efficiency in both multi-cell and isolated cell environments, particularly due to multiple-access interference and the need for bandwidth splitting, which limits the number of mobile stations that can be accommodated and reduces system capacity.
Innovation Solution
A base station and mobile station system that dynamically adjusts the spreading factor, number of chip repetitions, and unique phase based on cell structure, number of mobile stations, traffic type, radio parameters, and interference conditions, using a control information determining unit to optimize chip repetition and phase assignment for improved frequency domain orthogonality and reduced interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If DS-CDMA is used to reduce adjacent cell interference through spread spectrum gain, then frequency use efficiency is improved in multi-cell environments, but multiple-access interference increases in isolated cell environments due to accommodating a great number of signals
Solution Approach 1:
The patent applies dynamics by making the spreading factor and chip repetition factor adjustable and adaptive rather than fixed. The base station dynamically selects appropriate spreading factors and chip repetition factors for each mobile station based on channel conditions, traffic type, and interference levels, allowing the system to optimize performance across different cell environments and reduce multiple-access interference while maintaining frequency use efficiency.
Solution Approach 2:
The patent changes key parameters including spreading factor, chip repetition factor, and phase assignment to resolve the contradiction. By varying these parameters adaptively based on environmental conditions, the system achieves spread spectrum gain when needed while controlling multiple-access interference through optimized parameter selection for each specific scenario.
2Productivity
If the spreading factor is increased to accommodate more signals in isolated cell environments, then frequency use efficiency is improved, but information transmission speed decreases due to the 1/SF relationship
Solution Approach 1:
The system dynamically adjusts the spreading factor based on real-time conditions rather than using a fixed high value. The base station selects appropriate spreading factors adaptively, allowing the system to achieve high frequency use efficiency when many signals are present while maintaining higher transmission speeds when fewer signals are active, thus resolving the productivity-speed tradeoff.
Solution Approach 2:
Different spreading factors are assigned to different mobile stations based on their specific channel conditions, traffic requirements, and interference environments. This localized optimization allows each user to operate with the most appropriate spreading factor for their situation, achieving high overall frequency use efficiency without uniformly sacrificing transmission speed.
3Object-generated harmful factors
If chip repetition is increased to improve frequency domain orthogonality and reduce interference, then multiple-access interference is reduced, but system complexity increases due to additional control information and processing
Solution Approach 1:
The patent makes the chip repetition mechanism universally applicable across different cell environments and traffic types through a unified adaptive framework. The same chip repetition mechanism serves multiple functions: reducing multiple-access interference, improving frequency domain orthogonality, and adapting to various channel conditions, thereby justifying the added complexity through multi-functional benefits.
Solution Approach 2:
The base station uses feedback from channel quality indicators, interference measurements, and traffic conditions to adaptively determine the appropriate chip repetition factor for each mobile station. This feedback-driven approach ensures that chip repetition is applied optimally only when and where needed, reducing multiple-access interference effectively while avoiding unnecessary complexity in situations where simple spreading suffices.
Data Source
AI summary
A base station, a mobile station, a radio communications system, and a radio transmission method are disclosed. The base station includes a control information determining unit configured to determine control information that includes a spreading factor, the number of chip repetitions, and a phase unique to the mobile station, based on at least one ofinformation about the type of cell environments in which the mobile station is present,information about the number of mobile stations that are present in the cell,information about information rate required by the mobile station,information about a type of traffic,information about a radio parameter of the mobile station,information about a propagation path condition, andinformation about interference from an adjacent cell, andconfigured to transmit the spreading factor, the number of chip repetitions, and the unique phase of the mobile station that is determined to the mobile station.