Cloud Wi-Fi Central Unit Preemptive ACK Diversity Combining
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Solution Overview
Problem
Cloud-based Wi-Fi networks face propagation delays between the central unit (CU) and access points (APs), which are not accounted for in existing decentralized networks, leading to performance degradation due to interference from densely deployed APs and increased time overhead when trying to accommodate these delays.
Innovation Solution
Implementing a cloud-based Wi-Fi network architecture with a central unit that performs baseband-signal-level cooperative diversity combining using multiple APs, where the CU preemptively transmits an ACK frame before data decoding and selects APs based on signal-to-noise ratio (SNR) levels to mitigate propagation delays and interference, while maintaining backward compatibility with IEEE 802.11 protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cloud-based Wi-Fi network architecture is implemented with centralized baseband processing, then network resource management efficiency is improved, but propagation delay between CU and APs increases
Solution Approach 1:
The patent applies preliminary action by having the CU preemptively transmit ACK frames before completing data decoding. When the CU receives data from an AP, it immediately sends an ACK frame to confirm receipt without waiting for full decoding completion. This anticipatory acknowledgment reduces the effective propagation delay impact on throughput by eliminating the waiting time for decoding confirmation, while still maintaining centralized resource management benefits.
2Area of stationary object
If multiple APs are densely deployed to improve coverage, then network coverage area is improved, but interference between APs increases
Solution Approach 1:
The patent applies merging by implementing cooperative diversity combining at the CU, where data received from multiple APs are combined together. The CU collects data from multiple APs covering the same geographic area and combines them using diversity combining techniques (such as maximal ratio combining). This merging approach allows dense AP deployment for extended coverage while mitigating interference through constructive combination of signals, transforming the harmful interference into a beneficial diversity effect.
Solution Approach 2:
The patent converts the harmful effect of interference into a benefit by utilizing diversity combining. When multiple APs transmit to the same client, their signals interfere with each other in traditional systems. However, this patent deliberately receives and combines these interfering signals at the CU, where the diversity combining process extracts the useful signal components while suppressing the interference, thereby converting the harmful multi-path and multi-AP interference into improved signal reliability and throughput.
3Measurement precision
If ACK transmission is delayed to accommodate propagation delay, then decoding accuracy is improved, but time overhead increases
Solution Approach 1:
The CU performs preliminary action by initiating ACK transmission before the data decoding process is fully complete. Instead of waiting for decoding to finish and then sending ACK, the system sends the ACK frame in advance based on preliminary reception confirmation. This preliminary ACK transmission reduces the effective time overhead while the decoding process continues in parallel, maintaining decoding accuracy without the penalty of extended waiting time.
Data Source
AI summary
A cloud-based Wi-Fi network architecture consisting of a CU and RAUs is proposed as an improvement on the conventional Wi-Fi architecture with traditional access points (APs). In addition, a method for uplink data transmission in a cloud-based Wi-Fi network is proposed. In a conventional Wi-Fi network with independently operating APs, APs close to each other may not be able to utilize the same frequency band efficiently because of significant amounts of interference. However, in a cloud-based Wi-Fi network, the CU coordinates RAUs so that they can operate in the same frequency band by transmitting or receiving signals through the shared wireless medium to improve spectral efficiency. For each frequency band, the proposed system utilizes a diversity combining that combines multiple signals and introduces a single improved signal with high signal-to-noise ratio for uplink transmission in the cloud-based Wi-Fi network. In proposed uplink transmission method for a cloud-based Wi-Fi network, diversity combining is utilized with the immediate acknowledgement (ACK) transmission method that transmits the ACK frame to the client immediately before decoding. The proposed uplink data transmission method mitigates the performance degradation caused by the fronthaul propagation delay between the CU and RAUs, without significant modification of the IEEE 802.11 standard.