Mapping Downlink Control to Uplink Resources for Interference Reporting
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Solution Overview
Problem
In heterogeneous wireless communication networks, user equipment (UE) in RRC IDLE mode faces challenges in reporting severe interference from closed subscriber group (CSG) femto cells to the macro eNB, leading to potential interference and communication disruptions, especially when the UE is not allowed access to the CSG cell.
Innovation Solution
Mapping downlink common control information to unused uplink resources in the macro network, allowing the UE to send dedicated control information about interference or D2D communication needs, thereby enabling early interference reporting and resource allocation optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE in RRC IDLE mode does not report interference information, then network complexity is reduced, but interference from CSG cells cannot be mitigated and communication disruptions occur
Solution Approach 1:
The patent introduces an intermediary mechanism where the UE autonomously determines and reports interference information based on measured signal characteristics. The network uses this reported information to configure ABS patterns, creating a mediator role for the UE in the interference management process between CSG cells and macro cells.
Solution Approach 2:
The patent enables preliminary interference reporting by allowing UEs in RRC IDLE mode to measure and report interference information before establishing full communication. This preliminary action allows the network to pre-configure protection mechanisms (ABS patterns) before actual data transmission begins, preventing interference proactively rather than reactively.
2Productivity
If UE reports interference information proactively, then resource allocation is optimized, but additional uplink resources are consumed
Solution Approach 1:
The patent applies partial action by having UEs report only specific interference-related control information rather than all possible measurement data. The UE selectively reports parameters such as reference signal received power (RSRP) and signal to interference plus noise ratio (SINR) only when interference thresholds are exceeded, avoiding unnecessary resource consumption while maintaining effective resource allocation optimization.
Solution Approach 2:
The patent changes the parameters of uplink resource usage by mapping interference reporting to existing downlink control information resources. Instead of allocating dedicated uplink resources for all reporting, the system repurposes existing control channels, changing the resource allocation parameters to be more efficient and reducing overall uplink resource consumption.
3Area of stationary object
If macro eNB transmits in all subframes, then network coverage is maximized, but interference to femto cells and D2D communications increases
Solution Approach 1:
The patent segments the downlink transmission time into different types of subframes: normal subframes for macro coverage and almost-blank subframes (ABS) for femto cell protection. This segmentation allows the macro eNB to maximize coverage during normal subframes while providing targeted interference protection during ABS periods, balancing coverage and interference mitigation.
Solution Approach 2:
The patent introduces dynamic ABS configuration where the macro eNB can flexibly adjust the timing and duration of almost-blank subframes based on real-time interference conditions and UE reports. This dynamic approach allows the network to adapt the protection mechanism to actual operational needs, maximizing coverage when interference is low and providing protection when needed.
Data Source
AI summary
Downlink common control information communicated in a first network (such as a macro network or a small cell) between a first/macro access node and a user equipment UE is mapped to an uplink resource. The first/macro access node and UE then tune to the mapped uplink resource to send or receive dedicated control information about the UE concerning a second network (an underlay network such as a femto CSG or D2D network). In one embodiment the DCI may be within a downlink assignment indicated by P-RNTI, RA-RNTI, or SI-RNTI; and the mapping uses a control channel element which carries the P-RNTI or the RA-RNTI or the SI-RNTI. In another the mapped uplink resource is a format 1a or format 1b PUCCH and the common control information requires neither an acknowledgement nor a negative acknowledgement. The dedicated control information may inform about interference experienced by the UE with the second network.