Dual Receiving Window for ARQ HARQ Contradiction
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Solution Overview
Problem
In wireless communications systems, the use of a single sliding window for both ARQ and HARQ operations leads to inefficient data transmission due to unnecessary retransmissions and delayed NACK status reports, particularly in systems like LTE where RLC and MAC layers are combined, causing radio resource wastage and transmission delays.
Innovation Solution
Implementing a dual window approach, where a first receiving window provides Automatic Retransmission Request (ARQ) functionality and a second receiving window detects missing Sequence Numbers, and similarly, a dual transmitting window approach with a first window for ARQ and a second for Hybrid Automatic Repeat Request (HARQ), to timely request retransmissions and avoid radio resource wastage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sliding window is used for both ARQ and HARQ operations, then device complexity is reduced, but transmission efficiency deteriorates due to unnecessary retransmissions and delayed NACK status reports
Solution Approach 1:
The single sliding window is segmented into two separate windows: a first sliding window dedicated to ARQ operations and a second sliding window dedicated to HARQ operations. This segmentation allows each window to independently manage its respective protocol's packet reception and acknowledgment status, preventing interference between ARQ and HARQ processes, thereby eliminating unnecessary retransmissions and reducing NACK status report delays while maintaining manageable device complexity through modular window management
Solution Approach 2:
The patent introduces an intermediary mechanism where the first sliding window acts as a mediator for ARQ-level packet tracking and the second sliding window mediates HARQ-level packet tracking. This intermediary structure enables independent operation of each protocol layer, allowing the system to distinguish between packets that need ARQ retransmission versus those handled by HARQ, thus improving transmission efficiency without significantly increasing overall system complexity
2Reliability
If a timer mechanism is used to detect HARQ PDU loss, then reliability of retransmission detection is improved, but transmission efficiency deteriorates due to delayed NACK status reports
Solution Approach 1:
The patent applies preliminary action by pre-configuring the second sliding window with knowledge of HARQ packet status before ARQ status reports are generated. By maintaining separate tracking of HARQ packets in the second window, the system can proactively identify which packets are already being handled by HARQ retransmission, allowing the ARQ status report to be generated immediately without waiting for timer expiration, thus reducing NACK delay while maintaining reliable detection of actual packet loss
Solution Approach 2:
The patent implements a feedback mechanism where the second sliding window continuously provides status information about HARQ packet reception to the ARQ layer. This real-time feedback allows the system to immediately know when a packet has been successfully received or is under HARQ retransmission, enabling the ARQ entity to send NACK status reports only when truly necessary, thereby improving both detection reliability and reducing unnecessary delays
Data Source
AI summary
A method for enhancing data transmission efficiency in a wireless communications system includes using a first receiving window and a second receiving window in a receiver side of an entity operating in Acknowledgement Mode, wherein the first receiving window provides a function of Automatic Retransmission Request and the second receiving window is utilized for detecting missing Sequence Numbers.