Master Cell Group Slot Reservation for NR LTE Coexistence
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Solution Overview
Problem
Dual connectivity schemes in wireless communications systems face coexistence issues between NR and LTE, particularly in scheduling conflicts and resource allocation, due to differences in radio access technologies and transmission characteristics.
Innovation Solution
Implementing a priority scheme for radio access technologies, where one cell group reserves slots and indicates them to the other, allowing independent scheduling and power control configurations to optimize NR and LTE coexistence, including hybrid automatic repeat request (HARQ) timing offset and dynamic power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dual connectivity scheme is implemented to improve throughput, then data transmission rate is improved, but scheduling conflicts and resource allocation issues arise between NR and LTE
Solution Approach 1:
The patent segments time resources by dividing slots into reserved slots for high priority RAT and non-reserved slots for low priority RAT. This temporal segmentation resolves scheduling conflicts by ensuring that high priority transmissions (e.g., URLLC) have guaranteed resources while low priority transmissions (e.g., eMBB) utilize remaining resources, thereby maintaining improved throughput without excessive scheduling complexity
Solution Approach 2:
The patent changes the parameter of slot reservation status from dynamic to semi-static. By semi-statically designating certain slots as reserved for high priority RAT, the system reduces real-time scheduling complexity while maintaining the throughput benefits of dual connectivity. The network can dynamically adjust which slots are reserved based on traffic patterns, balancing complexity and performance
2Productivity
If priority scheme is implemented for RATs with slot reservations, then resource allocation efficiency is improved, but system complexity increases due to additional signaling and coordination
Solution Approach 1:
The patent applies preliminary action by pre-reserving slots for high priority RAT before low priority RAT scheduling occurs. The network node determines in advance which slots will be reserved for high priority traffic and communicates this reservation status to the UE through signaling. This preliminary designation of reserved slots enables efficient resource allocation by preventing scheduling conflicts before they occur, while the signaling overhead is minimized through efficient indication mechanisms
Solution Approach 2:
The patent introduces a slot format indication (SFI) as an intermediary mechanism that carries reservation status information. The SFI efficiently conveys which slots are reserved for high priority RAT without requiring extensive separate signaling for each slot. This intermediary structure reduces signaling complexity by consolidating reservation information into a compact indication that the UE can process efficiently
3Productivity
If independent scheduling is allowed for non-reserved slots, then flexibility and throughput are improved, but interference and conflicts between RATs increase
Solution Approach 1:
The patent applies dynamics by allowing the classification of slots to change over time. Slots that are reserved for high priority RAT in one period can become non-reserved and available for low priority RAT in another period, depending on traffic conditions. This dynamic adjustment enables the system to maintain high throughput by flexibly allocating resources while preventing interference through time-division isolation when high priority traffic is active
Solution Approach 2:
The patent implements periodic action through the cyclic re-evaluation and re-assignment of slot reservation status. The network periodically assesses traffic patterns and adjusts which slots are reserved for high priority RAT versus available for low priority RAT. This periodic reconfiguration allows the system to maintain optimal throughput while systematically managing interference by ensuring that when high priority traffic dominates, dedicated reserved slots prevent interference to low priority transmissions
Data Source
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AI summary
Methods, systems, and devices for wireless communications are described. A wireless communications network may set priorities for cell groups in dual connectivity. A higher priority cell group (e.g. Master Cell Group, MCG or Secondary Cell Group, SCG) may reserve slots and indicate the reserved slots to the lower priority cell group (e.g. the complementary, i.e. SCG or MCG), for example by a backhaul connection. The high priority cell group may also indicate additional, non-reserved slots, which the lower priority cell group may reserve or use for scheduling. One of the cell groups may transmit a slot format indication (SFI) to a user equipment (UE) in the dual connectivity to indicate the slot reservations. In some cases, a hybrid automatic repeat request (HARQ) timing parameter may be based on a number of reserved slots. In some cases, power control may be varied based on whether the UE is capable of simultaneous uplink and downlink transmission.