IEEE Access (Jan 2018)
Cloud-Based Wi-Fi Network Using Immediate ACK in Uplink Data Transmissions
Abstract
In a cloud-based network architecture, the central unit (CU) at the cloud coordinates wireless nodes such as the remote access units (RAUs) at the edges of the network and manages most functions for providing wireless connectivity services to clients. The CU facilitates efficient communication resource management such as radio frequency or transmission power of RAUs by global resource coordination. In this paper, we propose a cloud-based Wi-Fi network architecture consisting of a CU and RAUs as an improvement on the conventional Wi-Fi architecture with traditional access points (APs). We then propose a method for uplink data transmission in a cloud-based Wi-Fi network. 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 our proposed uplink transmission method for a cloud-based Wi-Fi network, we utilize diversity combining 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. Using an IEEE 802.11n standard-compliant simulation and experiments with software-defined radio equipment, we verify the goodput performance of the proposed method for a cloud-based Wi-Fi network architecture.
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