Flexible sTTI Resource Allocation via DCI Bit Field
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Solution Overview
Problem
Current wireless communication systems face challenges in reducing packet data latency, particularly in the context of short Transmission Time Intervals (TTIs), which limits system responsiveness and throughput, and existing resource allocation methods are not efficient in utilizing available resources for data transmission.
Innovation Solution
The implementation of flexible resource allocation for short TTIs, where unused Control Channel Elements (CCEs) within the Physical Downlink Control Channel (PDCCH) region are utilized for data transmission, allowing for efficient coexistence between different wireless devices and supporting both CRS-based and DMRS-based sPDCCH operations, with a bit field indicator determining resource usage in the Downlink Control Information (DCI) message.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional resource allocation methods are used in LTE subframes, then control channel resources are reserved for all wireless devices, but data transmission resources are reduced and resource utilization efficiency deteriorates
Solution Approach 1:
The patent implements dynamic resource allocation where the bit field in DCI messages enables the network to flexibly indicate whether sPDCCH candidates are used for control or data transmission. This dynamic switching allows the system to adapt resource usage based on traffic conditions, improving both control reliability and data transmission efficiency.
Solution Approach 2:
The patent makes sPDCCH resources multi-functional by allowing them to serve both control channel purposes (when bit field indicates control usage) and data transmission purposes (when bit field indicates data usage). This universal resource allocation resolves the contradiction between reserving control resources and maximizing data transmission resources.
2Reliability
If sPDCCH resources are allocated to all wireless devices for control channel transmission, then control signaling reliability is improved, but available resources for data transmission are reduced
Solution Approach 1:
The bit field mechanism enables dynamic indication of resource usage type. When control signaling is needed, sPDCCH resources are allocated; when data transmission is prioritized, the same resources can be repurposed. This dynamic allocation maintains control reliability when needed while maximizing data resources when control traffic is low.
Solution Approach 2:
The patent changes the state parameter of sPDCCH resources from fixed (always control) to variable (control or data based on bit field indication). This parameter change allows the system to optimize the balance between control signaling reliability and data transmission resource quantity based on instantaneous traffic conditions.
3Loss of time
If short TTI operation is implemented to reduce latency, then packet data latency is improved, but resource allocation complexity increases
Solution Approach 1:
The patent segments the sPDCCH region into individual candidates, each identifiable by a bit in the bit field. This segmentation allows precise control over which specific resources are used for control versus data, simplifying the allocation process compared to managing entire regions, while enabling fast latency-critical transmissions.
Solution Approach 2:
The bit field in DCI messages provides feedback information to wireless devices about resource usage. This feedback mechanism enables devices to quickly understand resource allocation decisions without complex signaling, reducing processing complexity while supporting fast short TTI operations for low latency.
4Productivity
If unused sPDCCH resources are utilized for data transmission, then resource utilization efficiency is improved, but risk of resource conflict between control and data channels increases
Solution Approach 1:
The bit field provides explicit feedback to wireless devices about whether sPDCCH candidates are allocated for control or data. This clear indication eliminates ambiguity and prevents resource conflicts, as devices can reliably determine resource usage type without complex coordination, enabling safe reuse of sPDCCH resources for data.
Solution Approach 2:
The bit field acts as an intermediary mechanism that mediates between control channel needs and data transmission needs. It provides a simple, unambiguous signal that resolves potential conflicts by clearly indicating resource usage intent, enabling efficient resource utilization without compromising reliability.
Data Source
AI summary
A network node, wireless device and methods for short transmission time interval, sTTI, resource allocation in a communication network are provided. The network node includes processing circuitry configured to determine a downlink control information, DCI, message. The DCI message includes a bit field of at least two bits. Each bit corresponds to a group of at least one short Control Channel Element, sCCE, of a configured sPDCCH region. The processing circuitry is configured to transmit the DCI message to a wireless device. The bit field indicates whether the group of at least one sCCE is used for data transmission to the wireless device.