LTE Carrier Aggregation Supplementary PDCCH for Congestion Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
LTE systems operating in license exempt bands face interference from secondary users, leading to Physical Downlink Control Channel (PDCCH) congestion and performance degradation, which conventional methods like increasing signal-to-noise ratio cannot adequately address.
Innovation Solution
Implementing methods and apparatuses for aggregating component carriers in licensed and license exempt spectrums, where control information is processed in a wireless transmit/receive unit (WTRU) to manage PDCCH congestion by enabling PDCCH transmission on supplementary component carriers and adjusting aggregation levels based on signal-to-interference-plus-noise ratio (SINR) values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If PDCCH is signaled on the supplementary component carrier (SuppCC) in license exempt band, then the LTE system can utilize additional spectrum resources, but the PDCCH experiences interference from primary users operating in adjacent channels and secondary users sharing the same channel
Solution Approach 1:
The patent segments the control signaling function by introducing a supplementary PDCCH (sPDCCH) on the SuppCC that operates independently from the primary PDCCH on the licensed carrier. This segmentation allows the system to utilize unlicensed spectrum resources while isolating the control channel from interference affecting the primary carrier, thereby resolving the contradiction between spectrum utilization and interference avoidance.
Solution Approach 2:
The patent introduces an intermediary mechanism where the sPDCCH on SuppCC acts as a mediator for control signaling. Instead of having the primary PDCCH directly handle all control functions (which would be blocked by interference), the sPDCCH serves as an intermediate control channel that can operate in the unlicensed band, receiving control information from the network and forwarding it to the user equipment, thus bypassing the interference problem on the primary carrier.
2Reliability
If the signal to noise ratio (SNR) is increased to overcome interference, then PDCCH performance may improve, but a simple increase in SNR is not enough to address the PDCCH performance degradation caused by congestion and blocking
Solution Approach 1:
The patent transitions from a single-dimension approach (increasing SNR on one carrier) to a multi-dimensional solution by introducing a second control channel dimension (sPDCCH on SuppCC). This dimensional change allows control signaling to occur on a separate carrier that is not subject to the same congestion and blocking conditions, thereby improving reliability without relying solely on SNR enhancement.
Solution Approach 2:
The patent changes the operational parameters of the control channel by moving it from the licensed band primary carrier to the unlicensed band supplementary carrier. This parameter change (carrier frequency, band type, interference characteristics) fundamentally alters the channel conditions, allowing the control signaling to operate in an environment with different interference and congestion characteristics, thus improving overall performance.
3Ease of operation
If cross-carrier scheduling is used from the primary cell to allocate supplementary cell resources, then resource allocation can be centralized, but PDCCH congestion and blocking occur within the system
Solution Approach 1:
The patent segments the resource allocation function by introducing separate control channels for different carriers. Instead of having all resource allocation decisions funneled through a single PDCCH on the primary cell (which causes congestion), the sPDCCH on the SuppCC handles control signaling specific to supplementary cell resources. This segmentation distributes the control signaling load across multiple carriers, maintaining ease of operation while improving PDCCH availability.
Solution Approach 2:
The patent adds another dimension to resource allocation by implementing control signaling on a second carrier (SuppCC). This dimensional addition allows resource allocation to occur in parallel across different frequency dimensions, reducing the congestion on the primary PDCCH while maintaining centralized control through coordinated scheduling between primary and supplementary carriers.
Data Source
AI summary
Methods and devices may be provided for aggregating component carriers in the licensed spectrum with at least one component carriers in the licensed exempt spectrum. Control information may be processed in a wireless transmit/receive unit (WTRU) while receiving and sending information on a primary component carrier (PCC) and a supplementary component carrier (SuppCC). A PCC subframe with a control portion and a data portion may be received. Resource assignment information associated with a downlink shared channel on the PCC may be embedded in the control portion of the subframe. Based on the resource assignment information on the PCC, resource assignment information associated with a downlink shared channel on the SuppCC may be identified in the data portion of the PCC subframe. A SuppCC subframe of the shared channel on the SuppCC may be processed as per the identified resource assignment information associated with the downlink shared channel on the SuppCC.