Asynchronous HARQ Control for Low Latency Uplink
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Solution Overview
Problem
Current LTE systems face challenges in implementing low latency communication, particularly in uplink communication, due to statically determined HARQ transmission bundling numbers and insufficient flexibility in controlling HARQ processes, which limits latency reduction even with prioritization of services and MAC transmission across multiple carriers.
Innovation Solution
Implementing an asynchronous HARQ process control unit in user equipment and base stations to dynamically manage and identify HARQ processes during uplink communication, allowing for flexible transmission timing and bundling configurations, enabling the base station to identify transmitting HARQ processes and improve latency through asynchronous data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If synchronous HARQ transmission is used in uplink communication, then transmission timing is standardized and easy to manage, but flexibility in controlling HARQ processes is insufficient, limiting latency reduction
Solution Approach 1:
The patent transitions from static synchronous HARQ transmission to dynamic asynchronous HARQ transmission. The base station can now flexibly determine transmission timing for each HARQ process based on channel conditions, traffic patterns, and latency requirements, rather than being constrained by fixed periodic timing. This dynamic approach allows the system to adapt transmission schedules in real-time, resolving the contradiction between standardized timing and operational flexibility.
Solution Approach 2:
The invention changes the timing parameter from fixed (synchronous) to variable (asynchronous). By allowing transmission timing to vary based on system conditions and requirements, the patent enables both standardization through protocol definitions and flexibility through dynamic parameter adjustment. The base station can select appropriate timing parameters for each transmission scenario, achieving low latency while maintaining system manageability.
2Device complexity
If HARQ transmission bundling number is statically determined, then system complexity is reduced, but adaptability to different communication conditions is limited
Solution Approach 1:
The patent makes the HARQ transmission bundling number dynamic rather than static. The base station can adjust the bundling number based on channel quality, traffic characteristics, and latency requirements. This dynamic adjustment mechanism allows the system to optimize performance for different communication conditions without requiring complex reconfiguration, as the bundling number adapts automatically to current system state.
Solution Approach 2:
The invention enables the bundling number parameter to change based on communication conditions. By allowing this parameter to be adjusted dynamically while maintaining a relatively simple determination mechanism at the UE side, the patent achieves adaptability to different scenarios without significantly increasing system complexity. The base station performs the parameter adjustment based on predefined criteria and system state.
3Loss of time
If priority scheduling is applied to services with strict latency requirements, then latency is reduced for these services, but overall communication efficiency decreases in congested or low-quality radio environments
Solution Approach 1:
The patent applies different transmission strategies to different HARQ processes based on their specific requirements and channel conditions. Instead of uniform priority scheduling, the system tailors transmission timing, bundling numbers, and resource allocation to each process's needs. This localized optimization allows priority services to achieve low latency while non-priority services maintain efficient transmission, improving overall system productivity without sacrificing time-critical performance.
Solution Approach 2:
The invention implements selective priority handling rather than blanket priority scheduling. Only specific HARQ processes requiring low latency receive expedited treatment, while others follow standard scheduling. This partial application of priority scheduling reduces the negative impact on overall communication efficiency while still achieving latency reduction for services that truly require it, balancing time loss and productivity.
4Loss of time
If MAC transmission is performed across multiple carriers, then latency is reduced through diversity effect, but device complexity increases
Solution Approach 1:
The patent combines multiple HARQ processes across different component carriers under unified base station control. By coordinating transmissions across carriers and allowing flexible mapping of HARQ processes to carriers, the system achieves diversity effects that reduce latency. The base station manages the complexity of multi-carrier coordination, while UEs benefit from reduced latency without bearing the full burden of complex multi-carrier management.
Solution Approach 2:
The base station acts as an intermediary that manages the complexity of multi-carrier HARQ operations. It coordinates transmissions across multiple carriers, determines optimal carrier selection for each HARQ process, and handles the timing and resource allocation. This intermediary approach allows UEs to achieve low latency through multi-carrier diversity while the base station absorbs the management complexity, resolving the contradiction between latency reduction and device complexity.
Data Source
AI summary
Techniques for controlling HARQ processes in uplink communication to implement low latency communication are disclosed. One aspect of the present invention relates to user equipment, comprising: a transmission and reception unit configured to transmit and receive radio signals to/from a base station; and an HARQ process control unit configured to control multiple HARQ processes for uplink communication with the base station, wherein the HARQ process control unit asynchronously transmits uplink data from the multiple HARQ processes to the base station in accordance with a predetermined transmission method allowing the base station to identify a transmitting HARQ process of received uplink data.