Short Physical Downlink Control Channel for Ultralow Delay 5G
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current 5G systems face challenges in achieving ultralow delay transmission due to limitations in supporting short Transmission Time Intervals (TTIs) with fewer OFDM symbols, particularly in effectively utilizing the downlink control channel.
Innovation Solution
The proposed solution involves determining and utilizing a second downlink control channel, such as the Short Physical Downlink Control Channel (SPDCCH), within a short TTI, which is either out of the scheduling range of the first downlink control channel or defined by pre-definition or system configuration information, to enhance resource multiplexing and reduce processing delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the number of OFDM symbols in a TTI is reduced to shorten TTI duration, then the air interface delay is reduced to meet ultralow delay requirements, but the existing downlink control channel cannot well support the short TTI with new granularity
Solution Approach 1:
The patent divides the downlink control channel into two types: first downlink control channel (PDCCH) for long TTI scheduling and second downlink control channel (SPDCCH) for short TTI scheduling. This segmentation allows each control channel to be optimized for its specific TTI duration, enabling the system to support both long and short TTIs effectively while reducing air interface delay for short TTIs.
Solution Approach 2:
The patent introduces dynamic TTI length configuration where the system can flexibly switch between long TTI and short TTI modes based on service requirements. The downlink control channel structure adapts dynamically by selecting appropriate control channels (PDCCH or SPDCCH) and configuring corresponding parameters, enabling the system to meet varying delay requirements without compromising control channel support capability.
2Adaptability or versatility
If a second downlink control channel is introduced to support short TTI, then short TTI can be effectively scheduled, but the system complexity increases due to multiple control channel types
Solution Approach 1:
The patent designs the second downlink control channel (SPDCCH) with multi-functionality to handle various short TTI scheduling scenarios. The SPDCCH can schedule both downlink and uplink resources, support different short TTI durations, and work in conjunction with the first control channel for seamless service transition. This universal design reduces the need for multiple specialized control channels, thereby limiting complexity increase.
Solution Approach 2:
The patent applies different control channel structures and parameters locally according to TTI duration requirements. For long TTIs, the traditional PDCCH structure is used with conventional parameters. For short TTIs, the SPDCCH structure is applied with optimized parameters such as reduced cyclic prefix length and adjusted resource element allocation. This localized optimization enables effective short TTI scheduling while avoiding unnecessary complexity in long TTI handling.
3Productivity
If resource multiplexing strategies are optimized for short TTI, then resource utilization efficiency is improved, but the scheduling flexibility is reduced
Solution Approach 1:
The patent implements dynamic resource multiplexing strategies that adapt to different service types and traffic conditions. For delay-sensitive services using short TTI, aggressive resource allocation and tighter scheduling intervals are applied to maximize efficiency. For services requiring flexibility, the system dynamically adjusts resource allocation parameters and scheduling granularity. This dynamic approach enables the system to achieve high resource utilization efficiency for short TTI while maintaining scheduling flexibility through parameter adaptation.
Data Source
AI summary
A downlink control method and apparatus are disclosed. The method includes: a base station determining at least one downlink control channel in a first downlink control channel and a second downlink control channel, including: determining to use the second downlink control channel in a short transmission time interval (TTI) which is out of a scheduling range of the first downlink control channel, or determining the downlink control channel used in the short TTI according to pre-definition or system configuration information; and the base station transmitting downlink control information (DCI) by using the determined downlink control channel.