Shared Block ACK Session for Wireless Retransmission
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Solution Overview
Problem
Wireless communications systems face challenges in maintaining transmission reliability in conditions with fast-moving and rapidly changing sources of interference and blockage, where existing retransmission schemes can increase latency beyond acceptable limits.
Innovation Solution
The implementation of enhanced reliability techniques using shared block acknowledgment (ACK) sessions across multiple access points (APs), where a primary AP transmits protocol data units (PDUs) and secondary APs retransmit missing units on different channels, providing channel and spatial diversity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If retransmission schemes are used to increase transmission reliability, then reliability is improved, but latency increases beyond acceptable limits
Solution Approach 1:
The patent segments the retransmission function across multiple APs, where each AP handles specific PDUs. This allows parallel processing of retransmissions for different data units, reducing overall latency while maintaining reliability through distributed retransmission capabilities.
Solution Approach 2:
The patent implements preliminary action by having APs pre-identify and buffer missing PDUs before being requested for retransmission. The scoreboard mechanism pre-tracks which PDUs were successfully received, enabling immediate retransmission of only the missing units without waiting for complete acknowledgment cycles.
2Reliability
If multiple APs are used for retransmission with different channels, then reliability is improved through diversity, but device complexity increases
Solution Approach 1:
The patent implements universality by creating a shared block ACK session that multiple APs can participate in. Each AP in the member set can perform both primary transmission and retransmission functions, and can serve multiple STAs. The unified scoreboard and sequence space provide a universal state management mechanism across all participating APs, reducing the need for separate complex management systems for each AP.
Solution Approach 2:
The patent uses the unified scoreboard as an intermediary mechanism that mediates between multiple APs and the STA. The scoreboard maintains the state of PDU reception across all APs, allowing coordinated retransmissions without requiring complex direct communication and coordination between each AP pair. This intermediary state management simplifies the overall system complexity.
3Productivity
If a unified scoreboard and sequence space are maintained across APs, then resource utilization is improved, but device complexity increases
Solution Approach 1:
The patent merges the block ACK session state across multiple APs by maintaining a unified scoreboard and shared sequence space. This consolidation allows efficient resource utilization by enabling any AP in the member set to handle retransmissions for any PDU, rather than requiring separate state management at each AP. The merged state reduces redundancy and improves resource utilization while the standardization of the unified structure keeps complexity manageable.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. An access point (AP) and a station (STA) may identify an identifier for a shared block acknowledgment (ACK) session between the AP and the STA. The AP and the STA may further identify a set of member APs also for the shared block ACK session. For example, the STA may transmit a probe signal to discover the APs with which to associate. Additionally or alternatively, an AP may broadcast a probe signal to discover the STA. In one example transmission scheme, after associating, a primary AP may transmit a set of protocol data units (PDUs) to the APs, to which the AP may reply with a block ACK. The block ACK may indicate one or more PDUs that were not successfully received. One or more secondary APs may retransmit the PDUs determined to be missing.