AdaComm: Tracing Channel Dynamics for Reliable
Cross-Technology Communication
Weiguo Wang1, Xiaolong Zheng2, Yuan He1, Xiuzhen Guo1
1School of Software and BNRist, Tsinghua University
2School of Computer Science, Beijing University of Posts and Telecommunications
wwg18@mails.tsinghua.edu.cn, zhengxiaolong@bupt.edu.cn,
he@greenorbs.com, guoxz16@mails.tsinghua.edu.cn
Abstract—Cross-Technology Communication (CTC) is an
emerging technology to support direct communication between
wireless devices that follow different standards. In spite of
the many different proposals from the community to enable
CTC, the performance aspect of CTC is an equally important
problem but has seldom been studied before. We find this
problem is extremely challenging, due to the following reasons:
on one hand, a link for CTC is essentially different from a
conventional wireless link. The conventional link indicators like
RSSI (received signal strength indicator) and SNR (signal to noise
ratio) cannot be used to directly characterize a CTC link. On
the other hand, the indirect indicators like PER (packet error
rate), which is adopted by many existing CTC proposals, cannot
capture the short-term link behavior. As a result, the existing
CTC proposals fail to keep reliable performance under dynamic
channel conditions. In order to address the above challenge, we
in this paper propose AdaComm, a generic framework to achieve
self-adaptive CTC in dynamic channels. Instead of reactively
adjusting the CTC sender, AdaComm adopts online learning
mechanism to adaptively adjust the decoding model at the CTC
receiver. The self-adaptive decoding model automatically learns
the effective features directly from the raw received signals that
are embedded with the current channel state. With the lossless
channel information, AdaComm further adopts the fine tuning
and full training modes to cope with the continuous and abrupt
channel dynamics. We implement AdaComm and integrate it
with two existing CTC approaches that respectively employ
CSI (channel state information) and RSSI as the information
carrier. The evaluation results demonstrate that AdaComm can
significantly reduce the SER (symbol error rate) by 72.9% and
49.2%, respectively, compared with the existing approaches.
I.
INTRODUCTION
The ever-developing Internet of Things (IoT) brings the
widespread deployments as well as the rich diversity of
wireless technologies [1]–[3]. To directly interconnect the
heterogeneous devices that follow different wireless technolo-
gies, Cross-Technology Communication (CTC) is proposed
to enable the direct communication between incompatible
devices without extra hardware.
Despite the tremendous advances, existing CTC approaches
usually focus on enabling the communication between incom-
patible technologies. How to maintain the reliable performance
in the intrinsically dynamic channels has not received enough
attention. To convey data, existing CTC techniques usually
explore the mutually accessible information carrier such as the
energy and timing of packet transmissions [4]–[7], the state
variations of overlapped channels [8], [9], and the originally
incompatible but similar signals [10]–[12]. Since most CTC
leverages the signal patterns rather than the underlying raw
signals to convey data, the CTC links significantly differ from
the links in traditional wireless communication. Traditional
link quality indicators such as RSSI or CSI used by WiFi to
learn the channel state cannot reflect the quality of a CTC
link. So far there is not a link quality indicator to accurately
describe the CTC’s channel state.
Without an accurate CTC link indicator to learn the current
channel state, to cope with channel dynamics is a fundamental
but challenging task for CTC. Most of the existing CTC
approaches adopt indirect indicators, e.g. Packet Error Rate
(PER), to detect the changes of channel state. When there
is a significant variation in the PER, the CTC approaches
may reactively control the sender’s encoding behavior, so
as to enhance the features of encoded signals received by
the receiver. For example, WiZig [6] extends the symbol
window length and enlarges the differences of adjacent en-
coded amplitudes to enhance the features of CTC symbols.
FreeBee [4] increases the number of beacon repetitions per
symbol in the noisy channel, thus improving the highest fold
sum. ZigFi [8] controls the transmission power to maintain
Signal-to-Interference-plus-Noise-Ratio (SINR) perceived by
the receiver so that the CSI of ZigFi symbols still satisfy the
decoding model.
The reactive adjustments of CTC against channel dynamics,
unfortunately, suffer performance degradation and even failure
in practice. First, the indirect indicators of channel state only
reflect the long-term average channel quality but are insensitive
to the short-time channel dynamics. Therefore, adjusting CTC
according to those indicators can only achieve sub-optimal
performance. Second, existing decoding methods usually adopt
the threshold or machine learning model as the pattern recog-
nition methods. But features such as the RSSI threshold and
CSI variation predefined by the feature-based decoding model
cannot accurately describe the channel dynamics. For example,
the PHY information such as CSI can be affected by both the
intentional CTC transmissions and the channel-related factors
like multipath. The predetermined statistical features are not
necessarily effective to cover all possible cases, due to the
uncertainty of channel dynamics.
In order to address the above problems, in this paper we
propose AdaComm, a general and lightweight online adaptive