Synchronous HARQ Feedback Mapping 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 inefficiencies due to the need for explicit HARQ process identification information, which increases signaling overhead and decreases system efficiency, especially when handling multiple HARQ processes within restricted uplink and downlink time slots.
Innovation Solution
The method configures multiple HARQ processes without including HARQ process identification information in data packets or feedback packets, allowing for mapping of feedback packets to their corresponding processes, enabling efficient synchronous HARQ operations by determining feedback and transmission time slots and optimizing the number of HARQ processes based on the frame structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If explicit HARQ process identification information is included in data packets and feedback packets, then HARQ processes can be correctly matched, but signaling overhead increases and system efficiency decreases
Solution Approach 1:
The patent extracts and removes the explicit HARQ process identification information from the data packets and feedback packets. Instead of including process IDs in the signaling, the system uses the inherent time slot structure and synchronous timing to implicitly identify which HARQ process a packet belongs to, thereby eliminating redundant signaling overhead while maintaining correct process matching
Solution Approach 2:
The patent makes the time slot structure serve multiple functions: it not only carries data transmission timing but also implicitly encodes HARQ process identification. The same time slot allocation that organizes data transmission also serves as the identifier for matching HARQ processes, eliminating the need for separate identification signaling
2Productivity
If multiple HARQ processes are handled within restricted uplink and downlink time slots, then system throughput increases, but complexity of managing process mapping increases
Solution Approach 1:
The patent applies periodic action by establishing fixed, periodic time slot allocations for different HARQ processes. Each HARQ process is assigned specific periodic time slots for transmission and feedback, creating a predictable pattern that simplifies mapping logic. The periodic structure allows the system to handle multiple processes efficiently by relying on the regular timing pattern rather than complex dynamic mapping
Solution Approach 2:
The patent performs preliminary action by pre-configuring the time slot allocations and HARQ process mappings before actual data transmission begins. The system establishes the mapping relationship between time slots and HARQ processes in advance, so that during operation, simple timing-based identification can be used without requiring complex real-time mapping decisions
3Productivity
If HARQ feedback packets are received in downlink slots, then uplink transmission capacity is preserved, but feedback timing flexibility is reduced
Solution Approach 1:
The patent merges the feedback timing with the existing TDD frame structure by receiving feedback packets in designated downlink slots. This combines the feedback function with the downlink transmission capability, allowing the system to maintain preserved uplink capacity while using the downlink period for feedback. The merging of feedback reception into the downlink slot structure eliminates the need for separate feedback channels
Data Source
AI summary
A method of operating synchronous Hybrid Automatic Repeat Request (HARQ) between a transmitting station and a receiving station in a Time-Division Duplex (TDD) communication system includes configuring, at the transmitting station, a plurality of HARQ processes; transmitting data packets to the receiving station using the plurality of HARQ processes, wherein the data packets do not include HARQ process identification information; receiving, from the receiving station, a plurality of HARQ feedback packets indicative of whether the data packets were correctly received at the receiving station, wherein the plurality of HARQ feedback packets do not include HARQ process identification information and wherein the plurality of HARQ feedback packets are received in a downlink slot; and mapping, by the transmitting station, the plurality of HARQ feedback packets to the plurality of HARQ processes.