PUCCH Load Control via PDCCH Restrictions in LTE
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Solution Overview
Problem
In LTE networks, the existing load control methods for the physical uplink control channel (PUCCH) are inadequate in managing inter-cell and intra-cell interference, leading to reduced throughput and insufficient interference reduction, as they either underutilize resources or cause increased interference by allocating excessive bandwidth to PUCCH, thereby limiting the available resources for the physical uplink shared channel (PUSCH).
Innovation Solution
A scheduler at the base station controls the load on the PUCCH by mapping downlink assignments on the physical downlink control channel (PDCCH) to optimize the allocation of resources, ensuring that each PUCCH resource block (PRB) carries a manageable load of ACK/NACK responses, thereby dynamically adjusting the PUCCH utilization to minimize interference and maximize throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the bandwidth allocated to PUCCH is increased to handle more uplink control information, then the PUCCH can carry more ACK/NACK responses, but the available resources for PUSCH are reduced and interference increases
Solution Approach 1:
The patent segments the PUCCH resources into multiple PRBs and further divides the downlink control information into different CCE regions, mapping each region to specific PUCCH PRBs. This segmentation allows distributed load across multiple resources rather than concentrating all control information on a single channel, thereby reducing interference while maintaining capacity.
Solution Approach 2:
The patent implements dynamic scheduling where the eNodeB scheduler dynamically maps CCE regions to PUCCH PRBs based on current traffic conditions and interference levels. This dynamic allocation allows the system to adapt the PUCCH resource distribution in real-time, optimizing the balance between control information capacity and PUSCH availability.
2Adaptability or versatility
If the PUCCH load is increased to accommodate more wireless terminals, then more terminals can receive downlink data, but inter-cell and intra-cell interference increases
Solution Approach 1:
The patent assigns different qualities or characteristics to different CCE regions and maps them to specific PUCCH PRBs with different interference profiles. By locally optimizing the mapping based on the specific requirements and interference conditions of each region, the system can support more terminals while controlling interference through differentiated resource allocation.
3Object-affected harmful factors
If existing PUCCH load control methods are used, then some interference reduction is achieved, but throughput is reduced due to resource underutilization
Solution Approach 1:
The patent changes the mapping parameters between CCE regions and PUCCH PRBs dynamically based on current system conditions. By adjusting these mapping parameters, the system can optimize the balance between interference reduction and resource utilization, achieving both low interference and high throughput compared to static control methods.
Data Source
AI summary
Methods for scheduling downlink (DL) data on a downlink subframe from a base station directed to at least one wireless terminal in a wireless network are provided. The methods include selecting a control channel element (CCE) region for a physical downlink control channel (PDCCH) carried in a control region of the downlink subframe; determining whether a DL assignment corresponding to the DL data can be allocated on the selected CCE region based on a load imposed on a corresponding physical resource block (PRB) of a physical uplink control channel (PUCCH) of a future uplink subframe that will carry an ACK/NACK response corresponding to the DL assignment; and allocating the DL assignment on the selected CCE region when it is determined that the DL assignment can be allocated.