Neighboring Cell Assistance for Interference Mitigation
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Solution Overview
Problem
In wireless communication systems, especially in LTE networks, user equipment (UE) devices face difficulties in accessing and decoding signals from macrocells due to interference from nearby small cells, particularly Closed Subscriber Group (CSG) cells, which are stronger than macrocell signals, leading to challenges in establishing communication links.
Innovation Solution
The method involves small cells transmitting assistance information to UEs, including synchronization, system frame number alignment, radio frame boundary offsets, and interference cancellation details, allowing UEs to acquire and decode neighbor cell signals effectively, even when not registered with the small cell network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If small cells transmit at lower power than macrocells, then macrocell coverage area is improved, but small cell signals may still cause strong interference to UE at macrocell cell edges
Solution Approach 1:
The patent applies preliminary action by having the small cell transmit assistance information about its interfering signals before the UE attempts to decode macrocell signals. This allows the UE to prepare interference cancellation in advance by obtaining scheduling information, resource allocations, and transmission parameters of the small cell, enabling effective interference mitigation when receiving weak macrocell signals at cell edges
Solution Approach 2:
The patent uses an intermediary approach by introducing assistance information as a mediator between the small cell and the UE. This assistance information acts as a bridge that enables the UE to understand and cancel small cell interference without requiring direct interaction between the UE and small cell, facilitating successful macrocell signal reception in the presence of small cell transmissions
2Reliability
If UE attempts to decode macrocell signals in presence of strong small cell interference, then communication link establishment is attempted, but decoding fails due to interference
Solution Approach 1:
The patent converts the harmful small cell interference into a beneficial situation by providing the UE with assistance information about the interfering signals. The UE uses this information to perform interference cancellation, transforming the previously harmful small cell transmissions into predictable, cancelable signals that actually help the UE identify and decode macrocell signals more reliably
3Productivity
If UE performs initial cell acquisition without assistance information, then cell search procedure is executed, but time and power consumption increase
Solution Approach 1:
The patent applies preliminary action by providing the UE with pre-configured assistance information from the small cell before the UE needs to perform exhaustive cell search procedures. This assistance information includes synchronization parameters, frame structure details, and resource allocation patterns that would otherwise require time-consuming blind detection, thereby reducing both acquisition time and power consumption
Data Source
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AI summary
Certain aspects of the present disclosure relate to methods and apparatus for employing a neighboring cell's assistance information for interference mitigation (e.g., by conveying the information to a user equipment). A base station (BS) may determine assistance information for a neighboring cell and convey it to a user equipment (UE). A UE may receive assistance information for a neighboring cell and use that information for performing interference cancellation or suppression on received signals. The UE may receive the assistance information from a serving cell or a non-serving cell. The assistance information may be valid for a particular transmission instance, for a known period of time, or until updated by a BS.