Coordinated Multi-Point HARQ Delay Mechanism
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Solution Overview
Problem
In LTE systems, the implementation of CoMP (Coordinated Multi-Point) transmission/reception for high data rates and improved cell-edge coverage is complicated by variable transmission times and significant delays in ACK/NACK signalling, especially in uplink scenarios, which can lead to data stalling and inefficient resource allocation.
Innovation Solution
Introducing an indirect-route delay in transmitting acknowledgement signals only when data is not properly received via the direct route, allowing for receipt via an indirect route, and using DTX signals to manage this delay, thereby enabling soft combining of data from multiple points without extending the HARQ round trip time unnecessarily.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CoMP transmission is implemented to improve data rates and cell-edge coverage, then communication reliability is improved, but ACK/NACK signalling delays increase causing data stalling
Solution Approach 1:
The patent applies dynamics by making the HARQ round trip time adjustable rather than fixed. The network can dynamically configure whether to use a first HARQ round trip time for normal operation or a second, extended HARQ round trip time when CoMP is active, allowing the system to adapt to varying transmission conditions and resolve the contradiction between reliability improvement and signalling delay
Solution Approach 2:
The patent changes the parameter of HARQ round trip time based on transmission conditions. By detecting whether a transmission is a CoMP transmission and accordingly selecting between different HARQ round trip time values, the system optimizes the balance between allowing sufficient time for coordinated transmission and maintaining efficient data flow, thus resolving the timing contradiction
2Reliability
If extended HARQ round trip time is used to accommodate CoMP transmission delays, then communication reliability is improved, but data packet delays increase
Solution Approach 1:
The system dynamically adjusts the HARQ round trip time based on the transmission type. For CoMP transmissions, an extended time is used to ensure reliable reception and combining of signals from multiple points. For normal transmissions, a standard time is maintained. This dynamic adjustment ensures that data packet delays are only introduced when necessary for CoMP operation, minimizing overall delay while maintaining reliability
Solution Approach 2:
The network detects whether a transmission requires CoMP processing before finalizing the HARQ timing. By preliminarily identifying CoMP transmissions and pre-configuring the appropriate extended HARQ round trip time, the system avoids unnecessary delays for non-CoMP traffic while ensuring sufficient time for CoMP signal combining and processing
3Reliability
If CoMP operation is introduced to improve cell-edge coverage, then communication reliability is improved, but system complexity increases
Solution Approach 1:
The patent segments the HARQ processing into distinct paths: a first HARQ process for normal transmissions and a second HARQ process for CoMP transmissions. This segmentation allows the system to handle CoMP complexity separately from standard operation, isolating the additional processing requirements to specific transmission contexts rather than affecting the entire system uniformly
Solution Approach 2:
The network introduces an intermediary detection mechanism that identifies CoMP transmissions and triggers the appropriate HARQ round trip time configuration. This intermediary layer (the detection and configuration mechanism) mediates between the CoMP transmission requirements and the HARQ processing, simplifying the overall system architecture by centralizing the coordination logic
Data Source
AI summary
A communication method in a first apparatus, in which the first apparatus receives data via a direct route from a second apparatus and transmits in response an acknowledgement signal, wherein if the same data has also been transmitted via an indirect route and the data is not properly received via the direct route, the first apparatus introduces an indirect-route delay in transmitting the acknowledgement signal to allow receipt of the data via the indirect route, and otherwise no indirect-route delay is introduced.