Group-common SPS Activation via MAC-CE for Missed PDCCH Recovery
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Solution Overview
Problem
In the context of 3GPP New Radio (NR) specification, there is a need to implement semi-persistent scheduling (SPS) for group-common Physical Downlink Shared Channel (PDSCH) transmissions in wireless communication networks, particularly addressing issues related to activation/deactivation, multiple configurations per UE, uplink feedback configuration, and retransmission within the SPS framework, especially when some UEs miss the initial activation message or cannot receive simultaneous PDCCH activation.
Innovation Solution
A method is introduced where a command is prepared to activate or release SPS for a group of wireless devices, including a group identifier, slot index, and physical layer information, which is transmitted via PDCCH or PDSCH, allowing for recovery of missed activations and enabling all UEs to receive SPS transmissions synchronously, even if they missed the initial activation message, by using MAC-CE for carrying activation/release information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If PDCCH is used for SPS activation/deactivation in group scheduling, then dynamic control capability is improved, but reliability deteriorates when UEs miss the activation message
Solution Approach 1:
The patent introduces HARQ feedback mechanism where UEs send acknowledgment (ACK/NACK) for SPS activation and release messages received on PDCCH. The network monitors this feedback and can detect when activation is missed, enabling retransmission or alternative activation methods to ensure reliable delivery of SPS configuration to all UEs in the group.
Solution Approach 2:
The patent introduces an intermediate mechanism (MAC-CE or PDSCH-based activation) that acts as a backup or alternative to PDCCH activation. When PDCCH activation is missed or unreliable, this intermediary pathway provides a fallback method to deliver SPS activation information, ensuring that UEs can still join the group-common SPS transmission even if they miss the initial PDCCH command.
2Stability of the object's composition
If SPS is activated for all UEs simultaneously, then synchronization is improved, but device complexity increases to manage individual UE configurations
Solution Approach 1:
The patent applies a universal SPS configuration approach where a single SPS configuration is shared by all UEs in the multicast group through group-common PDCCH or PDSCH. This multi-functional mechanism allows the same SPS parameters (periodicity, time slot, frequency resources) to be simultaneously applied to multiple UEs, achieving synchronization while avoiding the complexity of individual UE-specific configurations for each UE.
Solution Approach 2:
The patent segments the SPS configuration into group-common parameters (shared by all UEs) and UE-specific parameters (individual adjustments). This segmentation allows the network to manage synchronization efficiently at the group level while still accommodating individual UE requirements through minimal UE-specific modifications, reducing overall configuration management complexity.
3Reliability
If fallback to PDCCH-based scheduling is used for retransmission, then retransmission capability is improved, but resource efficiency deteriorates due to loss of SPS framework benefits
Solution Approach 1:
The patent applies preliminary action by pre-configuring SPS parameters (periodicity, time slot, frequency resources, HARQ process) before actual data transmission. This allows subsequent transmissions to occur without dynamic PDCCH scheduling, reducing control signaling overhead and improving resource efficiency. The SPS framework is established in advance, enabling efficient semi-persistent transmissions while maintaining the ability to fallback to PDCCH-based scheduling when needed.
Data Source
AI summary
A method of operating a network node includes preparing a command that activates or releases semi-persistent scheduling, SPS, of a group-common SPS transmission for a group of wireless devices, and transmitting the command to a wireless device in the group of wireless devices. A method of operating a wireless device includes receiving a command that activates or releases SPS of a group-common SPS transmission, and activating or releasing the group-common SPS transmission in response to the command. Related network nodes and wireless devices are disclosed.