HARQ Interleaving Sequence Variation for Wi-Fi Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current 802.11 wireless communication standards lack support for Hybrid Automatic Repeat Request (HARQ), which limits the effectiveness of retransmissions due to the absence of frequency diversity, as the same interleaving sequence is used for all transmissions, resulting in limited noise averaging and diversity gains.
Innovation Solution
Implementing a transmitting device and receiving device that change the interleaving sequence between retransmissions, allowing bits/QAMs to experience a different channel, thereby introducing frequency diversity and improving performance through HARQ combining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the same interleaving sequence is used for all transmissions, then the system maintains simplicity and compatibility with existing 802.11 standards, but frequency diversity and noise averaging benefits are lost
Solution Approach 1:
The patent applies dynamics by making the interleaving sequence variable rather than static. Different interleaving sequences are used for initial transmission and retransmissions, allowing the system to adapt to changing channel conditions and achieve frequency diversity without requiring complex reconfiguration
Solution Approach 2:
The patent changes the interleaving sequence parameter between transmissions. By varying this parameter, the system achieves frequency diversity and improves noise averaging, directly enhancing packet detection probability while maintaining compatibility with existing 802.11 frameworks
2Reliability
If HARQ combining is implemented without changing interleaving sequences, then the receiving device can store and combine LLRs, but the diversity gain is limited due to identical channel experience
Solution Approach 1:
The patent introduces dynamics by changing the interleving sequence between initial transmission and retransmission. This allows the same data to experience different frequency mappings and channel conditions, providing the adaptability needed for frequency diversity while enabling effective HARQ combining at the receiver
Solution Approach 2:
The patent varies the interleving sequence parameter across transmissions. This parameter change ensures that retransmissions experience different channel characteristics, providing both the adaptability for frequency diversity and the improved SNR needed for reliable packet detection
3Productivity
If retransmissions use identical interleaving as initial transmission, then implementation is straightforward, but thermal noise cannot be effectively averaged and diversity gains are minimal
Solution Approach 1:
The patent applies dynamics by implementing different interleving sequences for initial transmission and retransmissions. This dynamic approach allows thermal noise to be averaged across different frequency mappings, reducing its impact and improving throughput through more successful packet detection
Solution Approach 2:
The patent changes the interleving sequence parameter between transmissions to enable effective noise averaging. By varying this parameter, the system reduces thermal noise impact and achieves the productivity improvements needed for higher throughput
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates to Hybrid Automatic Repeat Request (HARQ) in wireless communication technologies, particularly HARQ for IEEE 802.11, i.e. HARQ for Wi-Fi. To this end, the invention proposes a transmitting device and a receiving device, respectively, both configured to support such HARQ in Wi-Fi. The transmitting device is configured to: select a first interleaving sequence; interleave a data unit using the first interleaving sequence to obtain a first interleaved data unit to be transmitted to a receiving device. Accordingly, the receiving device is configured to: receive a first interleaved data unit; select a first de-interleaving sequence according to a first interleaving sequence; and de-interleave the first interleaved data unit using the first de-interleaving sequence to obtain the data unit.