Supporting real-time wireless traffic through a high-throughput side channel

Abstract

Performance of modern cognitive and interactive mobile applications highly depends on the data transmission delay in the wireless link that is vital to supporting real-time wireless traffic. To eliminate wireless network congestion caused by large amounts of concurrent network traffic and support such real-time traffic, traditional schemes adopt various flow control and QoS-aware traffic scheduling techniques, but fail when the amount of network traffic further increases. In this paper, we present a novel design of high-throughput wireless side channel, which operates concurrently with the existing wireless network channel over the same spectrum but dedicates to real-time traffic. Our key idea of realizing such a side channel is to exploit the excessive SNR margin in the wireless network to encode data as patterned interference. We design such patterned interference in form of energy erasure over specific subcarriers in an OFDM-based wireless network, and achieve a data rate of 1.25 Mbps in the side channel without affecting the existing wireless network links. Experimental results over software-defined radio platforms demonstrate the effectiveness of our side channel design in reducing the latency of real-time wireless traffic, while providing sufficient data throughput for such traffic.

Enabling Out-of-Band Coordination of Wi-Fi Communications on Smartphones

“…HoWiES [27] builds a WiFi-ZigBee side channel, by using different Wi-Fi transmission patterns, to disseminate control information from Wi-Fi AP to ZigBee radio. Lu and Gao [15] exploit the in-band SNR margin to encode data as patterned interference, and create a side channel that operates concurrently with the OFDM main channels to support high-throughput real-time traffic. In contrast, our OBC establishes a side channel for only homogeneous Wi-Fi clients.…”

DeltaVR

“…However, these designs cannot scale to mobile VR, because its requirements of high resolution and low response latency make it impossible to stream game scenes at real-time. Other schemes enable multi-Gbps wireless communication to VR headsets via mmWave wireless technology [9,10] or propose new technologies to improve the wireless network throughput under fluctuating channel conditions [35,36], but rely on specialized hardware support and line-of-sight connectivity. These techniques are orthogonal to the major focus of DeltaVR, which aims to provide high VR performance using commodity wireless networks with low bandwidth.…”

EasyPass

“…Prior designs of the in-band side channel are mainly applied for delivering coordination and control information, so as to improve the network performance without introducing extra costs compared to the out-of-band approaches. Most schemes hide information into the side channel for private communication, by alternating the physical characteristics of the main channel such as signal duration [10], the position of interfered chips [62], timing of periodic beacon frames [30], intentionally corrupted checksums [40] and the position of the blank subcarriers [38]. These side channel designs can only provide limited throughputs and do not support multi-access operations due to their dependency with the main channel.…”

“…The major challenge of using a wireless side channel in IoT, however, is to support multiple access to the side channel from many IoT devices. Most of existing research builds the side channel over WiFi [15,38] and ZigBee [63] by alternating the main channel characteristics [10,21,25,27,41,56], but limits the side channel to be operated by the same device that operates the main channel. The RF signal of the side channel, when being transmitted from multiple devices, will be appended to the main channel signal as extra interference and difficult to be correctly demodulated.…”