Wireless Multicast Signaling Overhead Reduction via Grouped Retransmission
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Solution Overview
Problem
In wireless multicast systems, the Hybrid Automatic Repeat Request (HARQ) protocol increases data latency and can lead to network congestion due to multiple retransmission requests from receiving devices, prompting the disabling of HARQ mechanisms, which in turn increases error susceptibility of broadcast data.
Innovation Solution
A method is introduced where a first group of wireless devices is selected based on their retransmission request numbers, with a second group having a higher number of requests and a third group having fewer requests, and each device is assigned a delay time based on its retransmission request count. A timer is started for devices in the first group when a data packet is not received, and the device with the shortest delay time sends a retransmission request when its timer expires, thereby coordinating retransmissions to reduce signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ protocol is enabled for retransmission requests, then transmission reliability is improved, but data latency increases and network congestion occurs
Solution Approach 1:
The system performs preliminary classification of wireless devices into groups based on their retransmission request counts before actual data transmission. This preliminary action allows the system to pre-determine which devices should send retransmission requests and with what timing, thereby avoiding reactive delays and reducing overall data latency while maintaining transmission reliability.
Solution Approach 2:
The system dynamically adjusts the behavior of different device groups based on real-time transmission conditions. Devices in the first group (with higher retransmission counts) are assigned different delay parameters than devices in the second group (with lower retransmission counts), creating a dynamic, adaptive retransmission strategy that reduces latency while preserving reliability.
2Reliability
If HARQ protocol is enabled for retransmission requests, then transmission reliability is improved, but network congestion and signaling overhead increase
Solution Approach 1:
The system segments wireless devices into distinct groups (first group with higher retransmission counts, second group with lower counts) and applies different retransmission strategies to each segment. This segmentation reduces the total number of simultaneous retransmission requests, thereby decreasing network congestion and signaling overhead while maintaining transmission reliability through targeted retransmissions.
Solution Approach 2:
Different quality parameters (delay times, retransmission thresholds) are assigned to different device groups based on their specific characteristics. Devices in the first group receive different treatment than devices in the second group, optimizing the balance between reliability and reducing signaling overhead for each local subgroup rather than applying a uniform approach to all devices.
3Object-generated harmful factors
If HARQ mechanism is disabled to reduce signaling overhead, then network congestion is reduced, but error susceptibility of broadcast data increases
Solution Approach 1:
Instead of completely disabling HARQ or applying it uniformly to all devices, the system applies partial HARQ action selectively to specific device groups. Devices in the first group (with higher retransmission counts) are more likely to receive retransmission requests than devices in the second group, reducing overall signaling overhead while maintaining sufficient error protection where most needed.
Data Source
AI summary
At least one retransmission request is received from each of a plurality of wireless devices receiving a multicast broadcast, and a number of retransmission requests received from each of the plurality of wireless devices is determined. A first group of wireless devices is selected from among the plurality of wireless devices, and a delay time is determined for each wireless device in the first group based on the respective number of retransmission requests from each wireless device. When a data packet is not received at the one or more wireless devices of the first group, a timer is started at each of the wireless devices of the first group using the respective delay times. When the shortest delay time expires, another retransmission request is received from the wireless device comprising the shortest delay time of the one or more wireless devices.