Channel Estimation for Interference Cancellation in Heterogeneous Networks
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Solution Overview
Problem
In heterogeneous wireless communication networks, accurate channel estimation for interference cancellation during cell search procedures is challenging due to varying output power levels and interference between different network nodes, leading to sub-optimal detection of low power cells.
Innovation Solution
A method for wireless communication devices that selects the most suitable known signal sequences for channel estimation based on signal quality measures like SNR, SIR, and SINR, and performs interference cancellation using a combination of primary and secondary synchronization signals, with dynamic weighting factors to minimize correlation with interfering cells, enabling robust channel estimation and detection of low power cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If frequency separation between layers is applied to avoid interference, then interference between layers is avoided and cell splitting gain is achieved, but inefficient resource utilization results when there is low activity in a lower layer cell
Solution Approach 1:
The patent implements dynamic resource allocation where the lower layer cell can switch between using dedicated frequency resources and sharing resources with higher layer cells based on traffic conditions. When lower layer activity is low, resources are released for higher layer utilization; when activity increases, resources are dynamically allocated to the lower layer, eliminating the need for static frequency separation.
2Productivity
If the same carrier frequency is used across layers with ICIC coordination, then efficient resource utilization is achieved, but time synchronization between network nodes of different layers is required which complicates the system
Solution Approach 1:
The patent segments the interference cancellation process into distinct stages: first detecting known signal sequences from higher layer cells, then using these detections to cancel interference before detecting lower layer cell signals. This segmentation allows frequency reuse across layers without requiring complex inter-layer time synchronization, as each layer's signal detection is processed independently through the interference cancellation stage.
3Illumination intensity
If high power network nodes transmit synchronization signals, then strong signal coverage is achieved, but strong interference is created that prevents detection of low power network nodes
Solution Approach 1:
The patent converts the harmful interference from high power network nodes into a beneficial detection mechanism by detecting known signal sequences (PSS/SSS) from these high power nodes first, then using this detected information to actively cancel their interference contribution. This allows the system to leverage the strong high power signals as reference information for interference cancellation, transforming them from obstacles into aids for detecting low power cells.
Solution Approach 2:
The patent performs preliminary detection of known signal sequences from higher layer (high power) cells before attempting to detect lower layer (low power) cell signals. By预先 detecting and characterizing the interference sources, the system can prepare appropriate cancellation parameters and weights, enabling effective interference removal in subsequent processing stages and facilitating low power cell detection.
4Device complexity
If standard channel estimation is used for interference cancellation, then processing simplicity is maintained, but accurate channel estimation becomes difficult when known signal sequences experience large interference
Solution Approach 1:
The patent implements an iterative feedback-based channel estimation process where initial channel estimates are obtained using known signal sequences, then interference cancellation is performed using these estimates, and the cancelled signal is fed back for refined channel estimation. This feedback loop continuously improves estimation accuracy by removing interference contributions from previous estimation rounds, allowing accurate channel estimation even in high interference environments without requiring overly complex processing.
Data Source
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AI summary
A method of a wireless communication device for a cellular communication system is disclosed. According to the method, a signal comprising a first known signal sequence and a second known signal sequence for each of one or more first cells of the cellular communication system is received, and the first and second known signal sequences of each of the one or more first cells are detected based on the received signal. For at least one of the one or more first cells, one of the first known signal sequence, the second known signal sequence, and a combination of the first and second known signal sequences is selected for channel estimation. The selection is based on the detected first and second known signal sequences of the one or more cells. Channel estimation of the at least one of the one or more first cells is performed based on the signal sequence selection. In some examples, the method may further comprise performing interference cancellation of at least one of the first and second known signal sequences of the at least one of the one or more first cells based on the channel estimation and detecting one or more second cells of the cellular communication system after the interference cancellation. Corresponding computer program product, arrangement and wireless communication device are also disclosed.