Synchronous HARQ Process Configuration in TDD Wireless Systems
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Solution Overview
Problem
In Time Division Duplex (TDD) wireless communication systems, synchronous Hybrid Automatic Repeat Request (HARQ) faces challenges in determining time parameters for HARQ retransmissions and feedback packets due to asymmetrical data exchange, leading to inefficiencies and increased signaling overhead.
Innovation Solution
A method and system for configuring multiple HARQ processes in TDD systems, where data bursts are transmitted in specific subframes, and HARQ feedback is used to determine whether retransmissions are needed, optimizing the number of HARQ processes based on the number of uplink subframes between transmission and retransmission subframes, without explicit HARQ process identification, to minimize signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If synchronous HARQ is used in TDD systems with asymmetrical data exchange, then data transmission can be supported, but determining time parameters for HARQ retransmissions and feedback packets becomes difficult
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the number of HARQ processes based on the uplink-downlink configuration. Specifically, the system configures different numbers of HARQ processes (e.g., 4, 5, or 8 processes) according to the TDD uplink-downlink configuration, which directly changes the system parameters to adapt to asymmetrical data exchange requirements while simplifying time parameter determination.
Solution Approach 2:
The patent implements dynamics by making the HARQ process configuration adaptive rather than fixed. The system dynamically selects and configures the appropriate number of HARQ processes based on the current TDD configuration and traffic patterns, allowing the system to flexibly respond to changing asymmetrical data exchange requirements without increasing complexity.
2Productivity
If multiple HARQ processes are configured to handle asymmetrical traffic, then transmission efficiency improves, but signaling overhead increases
Solution Approach 1:
The patent reduces signaling overhead by optimizing the HARQ process ID assignment parameters. Instead of using explicit signaling for every HARQ process identification, the system uses implicit parameter-based assignment where the HARQ process ID is determined by mathematical relationships (e.g., modulo operations) on the subframe index and configured parameters, thereby minimizing the information that needs to be explicitly signaled.
Solution Approach 2:
The patent implements self-service by enabling the receiving end to autonomously determine the HARQ process ID through pre-configured parameters and mathematical calculations without requiring explicit signaling from the transmitting end. The receiving end uses the subframe index and configured HARQ parameters to self-determine which process is being used, eliminating the need for additional signaling overhead.
3Productivity
If the number of HARQ processes is increased to reduce wasted transmission slots, then throughput improves, but system complexity increases
Solution Approach 1:
The patent optimizes the number of HARQ processes as a configurable parameter based on the specific TDD configuration and traffic requirements. Rather than using a fixed large number of processes that would increase complexity, the system selects an appropriate number (e.g., 4, 5, or 8) that balances throughput improvement with manageable complexity for the given scenario.
Solution Approach 2:
The patent applies dynamics by allowing the system to adapt the number of active HARQ processes based on current traffic conditions and TDD configuration. The system can dynamically adjust which HARQ processes are active and how they are assigned to different uplink subframes, optimizing throughput while keeping the management complexity proportional to the actual needs rather than a fixed maximum.
Data Source
AI summary
A method for operating synchronous HARQ between a transmitting station and a receiving station in a TDD communication system, includes configuring a plurality of HARQ processes at the transmitting station, and transmitting a data burst in a first subframe to the receiving station via one of the plurality of HARQ processes and using a frame structure including a plurality of regions of subframes. The method also includes receiving a second subframe transmitted from the receiving station and containing a HARQ feedback indicative of whether the data burst was correctly received at the receiving station. Further, the method includes determining whether the HARQ feedback is an acknowledgement (ACK) or a negative acknowledgement (NACK), and retransmitting, via the one of the plurality of HARQ processes, the data burst in a third subframe to the receiving station if it is determined that the HARQ feedback is a NACK. A total number of plurality of HARQ processes is determined based on a total number of uplink subframes between the first subframe and the third subframe.