H-ARQ Scheduling in Network MIMO Systems
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Solution Overview
Problem
In wireless communication systems, coordinating Hybrid Automatic Repeat Request (H-ARQ) across multiple network cells in a Network MIMO (N-MIMO) environment is challenging due to data distribution and inter-node coordination difficulties, particularly in synchronous H-ARQ scenarios where backhaul latency and outdated feedback can lead to inefficiencies and interference.
Innovation Solution
A method and apparatus for identifying and coordinating H-ARQ protocols across network nodes, utilizing a transmission scheduler to pre-schedule cooperative transmissions and re-transmissions, and employing asynchronous H-ARQ with delayed re-transmissions to manage latency-sensitive applications, ensuring timely feedback processing and minimizing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronous H-ARQ is used for coordinated multipoint transmission, then data reliability is improved through re-transmission mechanisms, but backhaul latency and outdated feedback cause coordination inefficiencies and interference
Solution Approach 1:
The system performs preliminary scheduling of H-ARQ re-transmissions by the scheduler before actual transmissions occur. The scheduler determines in advance which cells will transmit re-transmissions and when, based on pre-coordinated timing information. This preliminary action allows cells to prepare and execute re-transmissions without waiting for real-time feedback loops, thereby reducing the impact of backhaul latency while maintaining coordination efficiency and data reliability.
2Reliability
If H-ARQ coordination is implemented across multiple network nodes, then data accuracy is improved through cooperative re-transmissions, but inter-node coordination complexity increases
Solution Approach 1:
A centralized scheduler acts as an intermediary between multiple network nodes (cells) to coordinate H-ARQ operations. The scheduler receives feedback information, determines appropriate re-transmission strategies, and distributes coordinated scheduling decisions to participating cells. This intermediary approach simplifies inter-node coordination by centralizing the decision-making process, reducing the complexity of direct peer-to-peer coordination while maintaining improved data accuracy through cooperative re-transmissions.
3Object-affected harmful factors
If delayed re-transmissions are employed to manage latency-sensitive applications, then interference is reduced and timing is optimized, but re-transmission speed is decreased
Solution Approach 1:
The system dynamically adjusts re-transmission timing based on application requirements and system conditions. For latency-sensitive applications, the scheduler implements delayed re-transmissions at optimized times that reduce interference with other transmissions. The timing is not fixed but adapts to current system state, allowing re-transmissions to occur when channel conditions are favorable and interference is minimized. This dynamic approach balances the reduction of harmful interference with maintaining acceptable re-transmission speeds.
Data Source
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AI summary
Systems and methodologies are described herein that facilitate Hybrid Automatic Repeat Request (H-ARQ) scheduling and coordination in a wireless communication system. As described herein, a network node capable of cooperation with other nodes for communication to respective users can coordinate a cooperation strategy across nodes based on a H-ARQ protocol to be utilized for a given user. In the case of a synchronous H-ARQ protocol, communication can be scheduled as described herein such that initial transmissions to a user are conducted cooperatively and re-transmissions are conducted without inter-node cooperation. In the case of a H-ARQ protocol utilizing persistent assignments, transmission intervals can be calculated and utilized based on application latency requirements, backhaul link latency, or other factors. In the case of an asynchronous H-ARQ protocol, repeat transmissions can be coordinated in a similar manner to initial transmissions or conducted without inter-node cooperation based on latency sensitivity of an associated application.