Cross-Correlation Nulling for Flexible MIMO Resource Allocation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless communication systems face challenges in efficiently resolving uplink interference, particularly in scenarios involving femto and macro base stations, where existing methods like CoMP, fractional frequency reuse, and ICIC techniques are inefficient or require significant resources, and fail to effectively mitigate interference in a coordinated manner.
Innovation Solution
An access node system that includes multiple radio modules and a processor module to derive local reference signals and estimate channel transfer functions by correlating expected reference signals, allowing for on-demand uncoordinated uplink multipoint interference resolution without requiring coordinated scheduling or extensive antenna resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coordinated multipoint (CoMP) with fractional frequency reuse is used to combat uplink interference, then interference resolution capability is improved, but resource utilization efficiency deteriorates due to the need for coordinated scheduling and one base station not scheduling UL resources while the other is using them
Solution Approach 1:
The patent segments the frequency spectrum into multiple subbands and processes each subband independently through separate FFT operations. This allows different base stations to schedule UL resources in different subbands simultaneously without requiring coordinated scheduling, thus improving resource utilization while maintaining interference resolution capability
Solution Approach 2:
The patent applies partial interference cancellation by processing only certain subbands with full interference resolution while allowing other subbands to use simpler processing. This reduces the overall resource overhead compared to applying CoMP to all subbands, improving resource utilization efficiency
2Reliability
If beamforming is used to coordinate UL resources spatially, then interference resolution capability is improved, but device complexity increases due to significant antenna resources required
Solution Approach 1:
The patent transitions from spatial dimension interference resolution (beamforming requiring multiple antennas) to frequency dimension interference resolution through subband processing. This allows interference resolution without requiring significant antenna resources, reducing device complexity while maintaining capability
Solution Approach 2:
The patent replaces the mechanical/physical beamforming system (requiring multiple antennas and complex hardware coordination) with a signal processing-based frequency domain approach. This substitution reduces hardware complexity while achieving similar interference resolution goals
3Reliability
If joint reception is used where both base stations receive the same data from an individual UE, then interference resolution capability is improved, but resource utilization deteriorates since the resources of both base stations are tied up with the same reception
Solution Approach 1:
The patent segments the frequency spectrum into multiple subbands and allocates different subbands to different base stations for reception. This allows both base stations to utilize their resources simultaneously for different subbands, improving overall resource utilization while maintaining interference resolution through the segmented processing approach
4Reliability
If robust modulation and coding schemes are used to combat interference, then reliability is improved, but productivity deteriorates due to inefficient data transmission
Solution Approach 1:
The patent applies different processing qualities to different subbands based on local interference conditions. Subbands with high interference receive full interference cancellation processing, while subbands with low interference use simpler processing. This allows the use of more efficient modulation schemes overall while maintaining reliability where needed
Data Source
AI summary
An access node in a wireless communication network receives a transmission that includes first and second signals. The first and second signals may be layers of a multiple-input multiple-output transmission and may also be from first and second terminal nodes. The access node derives first and second local reference signals from the transmission received using first and second antennas and estimates channel transfer functions associated with the channel through with the transmission is received. Estimating the channel transfer function can include correlating at least a portion of an expected reference signal associated with the first signal with a corresponding portion of the first local reference signal and correlating at least a portion of an expected reference signal associated with the second signal with a corresponding portion of the second local reference signal. The expected reference signal portions used to estimate the channel transfer functions may be non-orthogonal.