Subcarrier Block Power Assignment for SIR Homogeneity
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Solution Overview
Problem
In wireless communication systems without power control, the average signal-to-interference ratio (SIR) varies significantly due to mobile station geometries, leading to inaccurate Dynamic Channel Assignment (DCA) and Adaptive Modulation and Coding (AMC) operations, resulting in reduced data rates and increased transmission delays.
Innovation Solution
The method involves grouping subcarrier blocks into sets and assigning distinct transmission power levels to each radio cell, allowing for a mapping of power levels to subcarrier block sets or vice versa, to balance interference distribution across cells, thereby compensating for geometry-related SIR variations without introducing additional estimation or measurement delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If distinct transmission power levels are assigned to subcarrier block sets in adjacent radio cells to balance interference distribution, then SIR homogeneity is improved, but device complexity increases
Solution Approach 1:
The frequency spectrum is segmented into multiple subcarrier block sets, each assigned to different transmission power levels. This segmentation allows interference balancing across adjacent cells by ensuring that subcarrier blocks using the same physical channels are mapped to the same subcarrier block set with consistent power levels, thereby improving SIR homogeneity without requiring complex per-channel power control
Solution Approach 2:
Different subcarrier block sets are assigned different transmission power levels based on local interference conditions. By mapping physical channels to specific subcarrier block sets with appropriate power levels, the system achieves localized interference balancing, improving SIR homogeneity for mobile stations at cell edges while maintaining overall system performance
2Productivity
If multiple transmission power levels are used for subcarrier block sets, then data rate homogeneity is improved, but the complexity of power level assignment increases
Solution Approach 1:
Transmission power levels are pre-assigned to subcarrier block sets before actual channel assignment occurs. This preliminary configuration ensures that when physical channels are mapped to subcarrier blocks, the power levels are already optimized for interference balancing, improving data rate homogeneity while avoiding complex real-time power level calculation and assignment
3Object-affected harmful factors
If subcarrier blocks are grouped into subcarrier block sets with different power levels, then interference distribution is balanced, but system configuration complexity increases
Solution Approach 1:
The system changes the power level parameter for different subcarrier block sets rather than controlling power on an individual channel basis. This parameter-level control approach balances interference distribution across cells while reducing configuration complexity compared to per-channel power control, as power levels are assigned at the subcarrier block set level and automatically applied to all physical channels mapped to that set
Data Source
AI summary
The present invention relates to a method for balancing the distribution of interference between radio cells in a wireless communication system comprising cells in which subcarrier blocks are used for communication. A number of adjacent cells build a cell cluster. Moreover, the present invention relates to a corresponding method adapted for use in a system in which multi beam antennas or multiple antennas are used. Furthermore, the present invention relates to base stations performing the above method as well as a communication system comprising the base stations. To reduce the large average SIR variations without causing additional SIR estimation, measurement and calculation problem as introduced with power control the invention suggests to group subcarrier blocks into a plurality of subcarrier block sets in each cell of a cell cluster, to determine transmission power levels for each of the cells of said cell cluster, and to assign transmission power levels to the subcarrier block sets.