Overlapping ACK Resource Reservation in LTE TDD
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Solution Overview
Problem
In LTE TDD systems, the overhead of reserved acknowledgement channel resources is high due to non-overlapping reservations for each subframe, especially when the number of uplink subframes is less than downlink subframes or vice versa, leading to inefficient use of system bandwidth.
Innovation Solution
A method where a base station reserves acknowledgement channel resources in a second subframe for each subframe in a first subframe set, allowing resources to completely or partly overlap, with the first subframe set comprising a subset and a complement part, where resources for the complement part overlap with those of the subset part, and non-overlapping resources are reserved for each subframe in the subset part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If non-overlapping acknowledgement channel resources are reserved for each subframe, then resource allocation is simplified and compatibility with earlier LTE TDD releases is maintained, but the overhead of acknowledgement channel resources increases significantly
Solution Approach 1:
The patent merges the acknowledgement channel resource reservations for multiple downlink subframes into a single uplink subframe. Specifically, multiple downlink subframes (e.g., 4 downlink subframes) are associated with one uplink subframe for ACK/NACK feedback, allowing their acknowledgement resources to overlap completely or partially in the time-frequency domain. This merging reduces the total number of separate resource reservations from 4 separate allocations to 1 shared allocation, thereby reducing overhead while maintaining proper acknowledgment functionality.
Solution Approach 2:
The patent makes a single uplink subframe serve multiple functions by having it carry acknowledgement information for multiple downlink subframes. The uplink subframe becomes a universal feedback channel that can accommodate ACK/NACK resources for several different downlink transmissions, rather than requiring dedicated resources in each downlink subframe. This multi-functionality approach reduces resource overhead while maintaining system compatibility.
2Productivity
If multiple downlink subframes are associated with the same uplink subframe, then system bandwidth utilization improves, but the complexity of resource management increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the associations between downlink subframes and uplink subframes using semi-static subframe ratio configurations. The network side device establishes the mapping relationships in advance through higher-layer signaling, so that when data transmission occurs, the acknowledgement resource associations are already determined. This preliminary configuration reduces the real-time complexity of resource management while enabling efficient bandwidth utilization through multiple downlink-to-uplink associations.
Data Source
AI summary
The present invention discloses a time division duplex TDD communication method, including: reserving, by a base station, in a second subframe, acknowledgment channel resources for each subframe in a first subframe set, where acknowledgement channel resources reserved for at least two subframes in the first subframe set completely or partly overlap; and transmitting, by the base station, in the first subframe set, data with a first user equipment. By using the method of the present invention, because acknowledgement channel resources reserved for at least two subframes in the first subframe set completely or partly overlap, overheads of acknowledgment channel resources reserved for the first subframe set are small when there are a large quantity of subframes in the first subframe set.