Interference Control in Heterogeneous Networks via Subframe Puncturing
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Solution Overview
Problem
In heterogeneous network environments, time-domain inter-cell interference control techniques using almost blank sub-frames struggle to mitigate interference caused by the transmission of important system information, such as cell-specific reference signals, due to overlapping cell coverage between high and low power nodes.
Innovation Solution
The method involves transmitting information about punctured sub-frame resources to user equipment, specifically setting and informing about sub-frames with reduced resources for system information transmission, and using dedicated resources for critical signals like CRS, PSS, SSS, PBCH, and paging messages, while allowing other sub-frames to maintain full resource allocation for PDSCH data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an almost blank sub-frame (ABS) is used for time-domain inter-cell interference control, then interference from data transmission is reduced, but interference from system information transmission (CRS, PSS, SSS, PBCH) cannot be avoided
Solution Approach 1:
The sub-frame resources are segmented into two categories: punctured resources (where ABS is applied to reduce interference) and non-punctured resources (where system information is transmitted). This segmentation allows the base station to selectively apply interference mitigation only to data transmission resources while preserving system information transmission resources, thereby resolving the contradiction between reducing data interference and maintaining system information reliability.
Solution Approach 2:
Different quality characteristics are applied to different resource regions within the sub-frame. The punctured resources have reduced transmission power or are left blank to minimize interference, while the non-punctured resources maintain full transmission quality for reliable system information delivery. This local differentiation resolves the contradiction by allowing interference reduction in specific regions without compromising overall system information transmission reliability.
2Area of stationary object
If all sub-frame resources are used for system information transmission, then system information coverage is maintained, but inter-cell interference increases in heterogeneous networks
Solution Approach 1:
The sub-frame is segmented into punctured and non-punctured resource regions. The non-punctured resources are dedicated to system information transmission to maintain coverage, while the punctured resources are used to reduce interference to neighboring cells. This segmentation enables the network to achieve both full system information coverage and reduced inter-cell interference simultaneously.
Solution Approach 2:
The base station periodically transmits system information in non-punctured resources while applying puncturing in other resources. This periodic pattern allows receiving cells to anticipate and prepare for interference-free system information transmission intervals, maintaining coverage while managing interference through regular, predictable resource allocation.
3Loss of information
If punctured sub-frame information is not communicated to UE, then signaling overhead is reduced, but UE cannot properly receive data in punctured resources
Solution Approach 1:
The base station preliminarily informs the UE about the punctured sub-frame patterns through pre-configured parameters (such as abs-PBCH-Config). This advance notification allows the UE to prepare its reception strategy beforehand, knowing which resources will be punctured and which will contain system information. This preliminary action ensures complete data reception without requiring complex real-time signaling, thereby resolving the contradiction between information completeness and signaling overhead.
Data Source
AI summary
Disclosed is a method for controlling interference in a heterogeneous network environment. The method for controlling the inter-cell interference of a base station according to one aspect of the present invention comprises the following steps: transmitting, to a terminal, information relating to subframes in which a portion of a resource is to be punctured; transmitting, to the terminal, a relevant subframe in which a portion of a resource is punctured on the basis of the information relating to said subframes. A method for controlling the inter-cell interference of a base station according to another aspect of the present invention comprises the following steps: setting a resource for transmitting system information; and transmitting system information using only said resource for transmitting system information, or preferentially using said resource for transmitting system information when transmitting system information using a subframe designated as an almost blank subframe (ABS). Accordingly, inter-cell interference problems may be alleviated even in the event pieces of important system information, such as CRS, should be transmitted using an ABS.