Base Station Spreading Code Allocation for Interference Control
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Solution Overview
Problem
The increasing density of small-cell and macro base stations leads to interference issues due to shared carrier frequencies and scrambling codes, which traditional methods struggle to mitigate without compromising coverage or data rates.
Innovation Solution
A method of allocating different spreading codes to neighboring base stations based on their operating characteristics, traffic demands, and quality of service requirements to minimize interference, using a hierarchical tree of orthogonal spreading codes to optimize channel performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If base stations are deployed in close proximity to increase network capacity, then network coverage and capacity are improved, but interference between base stations increases due to shared carrier frequencies
Solution Approach 1:
The patent segments the limited set of scrambling codes by organizing them into groups associated with different carrier frequencies. Each base station is assigned a specific scrambling code from its carrier's group, creating a structured segmentation that prevents random collisions and reduces interference while allowing dense deployment.
Solution Approach 2:
The patent changes the parameter assignment methodology by dynamically allocating scrambling codes based on carrier frequency associations rather than static assignments. This parameter change allows the system to adapt code assignments to minimize interference patterns while maintaining high network capacity.
2Area of stationary object
If carrier frequencies are reused to increase network density, then network coverage is improved, but transmission interference increases
Solution Approach 1:
The patent introduces carrier frequency as an intermediary parameter that mediates between scrambling code assignments and interference patterns. By associating specific scrambling code groups with specific carrier frequencies, the system creates an intermediary layer that coordinates resource usage and reduces direct interference between base stations using the same frequency.
3Ease of operation
If scrambling codes are shared among base stations to simplify network management, then ease of operation is improved, but interference mitigation capability deteriorates
Solution Approach 1:
The patent segments the scrambling code resource by creating distinct groups associated with different carrier frequencies. This segmentation maintains simplified management through group-based assignment while simultaneously enabling interference mitigation by ensuring that base stations on the same frequency use orthogonal codes from the same group.
Solution Approach 2:
The patent makes the scrambling code groups universal by associating each group with a carrier frequency that can be used across multiple base stations. This multi-functionality allows the same scrambling code group to serve multiple base stations on different frequencies without causing interference, simplifying resource management while maintaining interference avoidance.
Data Source
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AI summary
Methods and network nodes of a wireless telecommunications system are disclosed. One method of controlling transmissions with a base station of a wireless telecommunications system comprises the steps of: determining a set of neighbouring base stations, each base station in the set of neighbouring base stations utilising an identical carrier and scrambling code to support transmissions with that base station; and allocating base stations in the set of neighbouring base stations different spreading codes for transmissions with those base stations. By allocating each base station in the set of base stations sharing the same carrier and scrambling code different spreading codes, interference in transmissions between the base stations can be controlled.