HARQ Coding Units for WLAN Retransmission Efficiency
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Solution Overview
Problem
Current WLAN protocols make the use of Hybrid Automatic Repeat Request (HARQ) impractical due to their PPDU formats, which require retransmission of all aggregated MPDUs if any one is not correctly received, leading to inefficient use of radio resources.
Innovation Solution
The proposed solution involves generating PHY data units with individually encoded HARQ coding units of a common length, each including a set of MPDUs, and a PHY preamble with a HARQ signal field that includes common and specific parameters for each coding unit, allowing for efficient retransmission of only necessary data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple MPDUs are aggregated and transmitted within one PPDU with joint encoding, then transmission efficiency is improved through aggregation, but HARQ becomes impractical requiring retransmission of all MPDUs
Solution Approach 1:
The patent divides the aggregated MPDUs into separate HARQ coding units, each with its own encoding. This segmentation allows individual MPDUs to be retransmitted independently through HARQ without requiring retransmission of the entire aggregate, thus maintaining transmission efficiency while enabling practical HARQ operations.
Solution Approach 2:
The patent applies different encoding strategies to different HARQ coding units within the same PPDU. Each coding unit can be individually encoded and treated, allowing selective retransmission of only the problematic units rather than treating the entire aggregate uniformly, thereby improving both efficiency and HARQ feasibility.
2Device complexity
If all MPDUs in an aggregate are jointly encoded, then encoding complexity is reduced, but radio resources are wasted when only one MPDU needs retransmission
Solution Approach 1:
The patent segments the aggregate into separate HARQ coding units, each with its own encoding. This allows the system to encode only the necessary portions for HARQ operations rather than the entire aggregate, reducing radio resource waste while maintaining manageable encoding complexity through standardized coding unit structures.
Solution Approach 2:
The patent applies encoding selectively to HARQ coding units that require it, rather than encoding the entire aggregate. This partial action approach ensures that encoding resources are used only where necessary for HARQ functionality, avoiding waste while maintaining sufficient encoding complexity for reliable operation.
3Productivity
If individual MPDUs are individually encoded, then HARQ retransmission efficiency is improved, but PHY data unit format complexity increases
Solution Approach 1:
The patent segments the PHY data unit into standardized HARQ coding units with consistent structures. This segmentation enables individual encoding and efficient HARQ operations while managing format complexity through standardization, making the increased complexity predictable and manageable rather than arbitrary and uncontrolled.
Solution Approach 2:
The patent designs HARQ coding units with universal structures that can serve multiple functions: they carry MPDU data, support HARQ retransmission, and provide encoding flexibility. This multi-functionality reduces the need for separate specialized structures, thereby limiting the increase in format complexity while maintaining high HARQ efficiency.
Data Source
AI summary
A wireless communication device generates physical layer (PHY) protocol service data units (PSDUs), and, in response to determining that the PHY data unit is to be transmitted according to a HARQ process, generates HARQ coding units of a common length, each of the HARQ coding units including a respective set of one or more PSDUs, and individually encodes the HARQ coding units. The wireless communication device also generates a HARQ signal field to the included in a PHY preamble of the PHY data unit. The HARQ signal field includes i) a common information subfield to indicate one or more parameters that commonly apply to each of at least some of the one or more HARQ coding units and ii) a respective HARQ coding unit information subfield for each of the HARQ coding units to indicate one or more parameters that apply to only the corresponding HARQ coding unit.