Base Station HARQ Scheduling Under C-RAN Transmission Delay
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Solution Overview
Problem
In a centralized radio access network (C-RAN) for LTE systems, the increased bandwidth requirements for the Common Public Radio Interface (CPRI) due to 5th generation radio communication technologies lead to higher installation costs and transmission delays, which can reduce user data throughput and cause fluctuations in transmission delay, affecting HARQ processing and scheduling operations.
Innovation Solution
A mobile communication system that includes a central base station and a remote base station, where the central base station measures transmission delay and adjusts HARQ processing methods by increasing the number of HARQ processes and prioritizing quality information transmission to ensure timely and efficient data communication, even with significant transmission delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the bandwidth of CPRI is increased to support 5th generation radio communication technologies, then the peak rate is improved, but the installation cost increases
Solution Approach 1:
The patent segments the base station functionality by separating the BBU (baseband unit) from RRUs (remote radio units), allowing the system to support high peak rates through multiple RRUs connected via CPRI while managing installation costs through modular deployment. The BBU is centralized and can be upgraded independently, while RRUs are distributed and can be deployed incrementally.
2Speed
If the bandwidth of CPRI is increased to support 5th generation radio communication technologies, then the peak rate is improved, but the transmission delay increases
Solution Approach 1:
The patent implements preliminary action by having the BBU generate and transmit scheduling decisions and control information to RRUs in advance, allowing RRUs to prepare for upcoming transmissions. This reduces transmission delay by pre-positioning data and control information at the edge nodes (RRUs) before actual data transmission is needed.
3Productivity
If the transmission delay is reduced, then the user data throughput is improved, but the complexity of the system increases
Solution Approach 1:
The patent applies dynamics by making the HARQ (Hybrid Automatic Repeat Request) processing method adaptive. The system can dynamically switch between different HARQ processing modes (e.g., synchronous vs. asynchronous, with or without ACK/NACK) depending on the actual transmission delay conditions. This allows the system to optimize user data throughput by selecting the most appropriate HARQ configuration for current network conditions without requiring complex fixed infrastructure.
4Adaptability or versatility
If the transmission delay fluctuates, then the reliability of HARQ processing is worsened, but the adaptability of the system is improved
Solution Approach 1:
The patent implements feedback mechanisms where the BBU monitors transmission delay conditions and HARQ processing performance, then adjusts HARQ configuration parameters accordingly. RRUs provide feedback about actual transmission conditions and HARQ outcomes to the BBU, enabling closed-loop optimization. This feedback system allows the network to adapt to fluctuating transmission delays while maintaining reliable HARQ processing by adjusting parameters such as HARQ process numbers, timing configurations, and retransmission strategies.
Data Source
AI summary
A base station is provided. The base station includes a first reception unit configured to receive, from a user apparatus included in a mobile communication system including the base station, another base station communicating with the base station, and the user apparatus communicating with the base station, first data including quality information used for scheduling controlling performed by the other base station, and second data different from the first data. The base station also includes a transmission unit configured to transmit the first data to the other base station by giving higher priority to the first data than to the second data.