Asynchronous HARQ Base Station Scheduling Flexibility
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Solution Overview
Problem
Conventional persistent scheduling in mobile communication systems lacks flexibility in retransmission control and fixed radio resource allocation, leading to inefficiencies and delays, especially when combined with synchronous HARQ and competing transmission timings.
Innovation Solution
Implementing asynchronous HARQ with dynamic process number determination and flexible radio resource allocation, allowing retransmissions at any timing within a persistent scheduling period, and notifying scheduling information at any time to avoid delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronous HARQ is used with persistent scheduling, then retransmission timing is fixed and predictable, but flexibility in retransmission opportunities is reduced and delays occur when competing with broadcast or MBMS channels
Solution Approach 1:
The patent transitions from synchronous HARQ with fixed retransmission timing to asynchronous HARQ where retransmission timing is dynamic and flexible. The base station can determine retransmission timing based on current system conditions, allowing retransmissions to occur at optimal times without being constrained by predetermined slots, thus resolving the contradiction between reliability and adaptability.
Solution Approach 2:
The patent changes the parameter of retransmission timing from fixed (synchronous) to variable (asynchronous). By allowing the retransmission timing parameter to be dynamically adjusted based on system conditions and channel availability, the system achieves both reliable retransmission control and flexibility in selecting retransmission opportunities.
2Device complexity
If radio resources are fixedly assigned to mobile stations in persistent scheduling, then resource allocation is simple and predictable, but the ability to change radio resources for each persistent scheduling period is lost
Solution Approach 1:
The patent implements dynamic radio resource allocation where resources can be changed for each persistent scheduling period based on system conditions. The base station determines whether to maintain fixed allocation or switch to dynamic allocation, allowing the system to adapt resource assignment flexibility while managing complexity through conditional decision-making.
Solution Approach 2:
The patent creates a universal resource allocation mechanism that can operate in multiple modes: fixed allocation for simplicity and dynamic allocation for flexibility. This multi-functional approach allows the system to select the appropriate allocation strategy based on traffic characteristics and system conditions, resolving the contradiction between device complexity and adaptability.
3Adaptability or versatility
If notification of transmission opportunity assignment is done through HS-SCCH at each TTI, then scheduling flexibility is maintained, but signaling channel overhead becomes too large for efficient operation
Solution Approach 1:
The patent implements persistent scheduling where transmission opportunity assignments are made periodically at predetermined intervals rather than at every TTI. This periodic notification approach significantly reduces signaling channel overhead while maintaining scheduling flexibility through the base station's ability to determine assignments based on persistent scheduling information and current conditions.
Solution Approach 2:
The patent extracts the essential scheduling information and transmits it periodically through persistent scheduling, rather than transmitting complete scheduling information at every TTI through HS-SCCH. This extraction approach reduces signaling overhead by only notifying changes or critical information while maintaining scheduling flexibility.
Data Source
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AI summary
A base station according to the present invention includes: a scheduling unit configured to perform a persistent scheduling for transmitting data at a predetermined timing; and a scheduling information generating unit configured to generate scheduling information and to notify the scheduling information to a predetermined mobile station, when the persistent scheduling is performed. The scheduling information includes resource assignment information that indicates a radio resource assigned to the predetermined mobile station at the predetermined timing in the persistent scheduling.