Carrier Aggregation Extension Carrier Interference Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In heterogeneous networks (HetNet), cell range extension leads to high interference for user equipment (UEs) in the cell range extension zone, causing unreliable reception of the control channel and data channel, resulting in capacity loss and increased complexity with existing interference coordination techniques like Almost-Blank Subframes (ABS) and Low-Power Subframes (LPS).
Innovation Solution
Implementing carrier aggregation with extension carriers, where a new carrier type (NCT) lacks common control channels and signals, using a secondary component carrier with reduced power for selected symbols to align with the control region of a primary component carrier, allowing contemporaneous transmission by multiple base stations to reduce interference and increase macro eNB capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cell range extension is used to offload UEs to pico cell, then more UEs can connect to pico cell, but high interference is caused for UEs in cell range extension zone
Solution Approach 1:
The patent segments the subframe into different power levels by transmitting certain symbols at reduced power while other symbols are transmitted at full power. This allows the control region to be transmitted at lower power to reduce interference with pico cell UEs, while data regions can still transmit at full power to maintain capacity.
Solution Approach 2:
Different parts of the subframe are transmitted with different power levels. The control region symbols are transmitted at reduced power to minimize interference, while data symbols can be transmitted at full power. This local differentiation of power quality resolves the contradiction between interference reduction and capacity maintenance.
2Object-affected harmful factors
If Almost-Blank Subframes (ABS) are used to reduce interference, then interference is reduced for pico cell UEs, but system capacity is lost
Solution Approach 1:
Instead of making the entire subframe blank or low-power (which would cause capacity loss), the patent applies partial power reduction only to the control region symbols that cause interference, while maintaining full power transmission for data symbols. This partial action reduces interference without sacrificing capacity.
3Object-affected harmful factors
If Low-Power Subframes (LPS) are used to reduce interference, then interference is reduced, but capacity loss and increased complexity occur
Solution Approach 1:
The patent segments the subframe into control region symbols and data region symbols, applying different power levels to each segment. This segmentation allows interference reduction in the control region without requiring complex receivers, as the power differentiation is built into the transmission structure itself.
Data Source
AI summary
A first BS transmits a first set of aggregated carriers including a PCC having a first carrier frequency and an SCC having a second carrier frequency. Contemporaneously, a second BS transmits a second set of aggregated carriers including a PCC having the second carrier frequency and an SCC having the first carrier frequency. In one aspect, the first BS transmits on the SCC a subframe having a number of selected symbols of the subframe at a lower power than other symbols of the subframe, the selected symbols aligning at least in part with a number of symbols of a control region of a subframe transmitted by the second BS on the PCC having the second carrier frequency. In another aspect, a UE attached to the second BS receives at least control information on the PCC of the first BS and receives data on the PCC of the second BS.