Base Station Co-Channel Interference Reduction via Power Loading
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current cellular telephone systems face limitations due to co-channel interference, particularly at cell edges, where estimating signal to interference plus noise ratio (SINR) for weak neighboring base stations is challenging, and feedback overhead is significant, making it difficult to implement effective interference reduction techniques like multiple base station transmit cooperation and single base station transmit nulling.
Innovation Solution
Identifying major interfering base stations without increasing subscriber station feedback, by exchanging transmission power levels through wired networks, and using power loading patterns to compute co-channel interference, allowing base stations to adjust their transmissions to minimize interference without additional overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple base station transmit cooperation and single base station transmit nulling are implemented to reduce co-channel interference, then co-channel interference reduction is improved, but feedback overhead becomes prohibitive due to the need to exchange SINR estimates for all base stations
Solution Approach 1:
The patent extracts only the essential information needed for interference reduction - the SINR of the desired base station and the received power of preamble sequences from interfering base stations - while discarding unnecessary feedback about all base stations. This selective extraction reduces feedback overhead while maintaining the capability to identify and mitigate major interferers.
Solution Approach 2:
The patent introduces an intermediary approach where base stations use preamble sequences as mediators to convey interference information. By measuring the received power of these standardized preamble sequences from interfering base stations, the system can infer interference characteristics without requiring direct SINR feedback from all base stations, thus reducing feedback complexity.
2Object-affected harmful factors
If SINR estimation for weak neighboring base stations is performed to enable interference reduction, then co-channel interference reduction is improved, but estimation accuracy deteriorates due to low preamble detection rate from weak base stations
Solution Approach 1:
The patent applies partial action by focusing SINR estimation and preamble detection only on the most critical interfering base stations rather than attempting to measure all base stations equally. By identifying and prioritizing the strongest interferers, the system achieves sufficient interference reduction without requiring accurate measurements from all weak neighboring base stations.
Solution Approach 2:
The patent changes the measurement parameter from direct SINR estimation (which fails for weak base stations) to received power measurement of preamble sequences (which remains reliable even for weak signals). This parameter transformation enables accurate interference characterization from weak base stations without requiring high SINR estimation accuracy.
3Object-affected harmful factors
If feedback of SINRs for all base stations is exchanged to enable multi-base station cooperation, then co-channel interference reduction is improved, but system complexity increases due to the cumbersome overhead
Solution Approach 1:
The patent segments the feedback information into two distinct components: (1) the SINR of the desired base station, which is always needed for link adaptation, and (2) the received power of preamble sequences from interfering base stations, which is needed for interference characterization. This segmentation allows the system to collect only the necessary information from each base station type, reducing overall feedback complexity while enabling effective multi-base station cooperation.
Data Source
AI summary
A base station may transmit at varied power levels. Subscriber stations receiving the power levels can transmit noise information back to the base station. As a result, co-channel interference can be determined from the varied power transmissions, either in the base station or in the subscriber station. In addition, in some embodiments, the transmissions may include different phases so that the phase of the co-channel interference may be determined as well.