2 research outputs found
Saiyan: Design and Implementation of a Low-power Demodulator for LoRa Backscatter Systems
The radio range of backscatter systems continues growing as new wireless
communication primitives are continuously invented. Nevertheless, both the bit
error rate and the packet loss rate of backscatter signals increase rapidly
with the radio range, thereby necessitating the cooperation between the access
point and the backscatter tags through a feedback loop. Unfortunately, the
low-power nature of backscatter tags limits their ability to demodulate
feedback signals from a remote access point and scales down to such
circumstances. This paper presents Saiyan, an ultra-low-power demodulator for
long-range LoRa backscatter systems. With Saiyan, a backscatter tag can
demodulate feedback signals from a remote access point with moderate power
consumption and then perform an immediate packet retransmission in the presence
of packet loss. Moreover, Saiyan enables rate adaption and channel hopping-two
PHY-layer operations that are important to channel efficiency yet unavailable
on long-range backscatter systems. We prototype Saiyan on a two-layer PCB board
and evaluate its performance in different environments. Results show that
Saiyan achieves 5 gain on the demodulation range, compared with
state-of-the-art systems. Our ASIC simulation shows that the power consumption
of Saiyan is around 93.2 uW. Code and hardware schematics can be found at:
https://github.com/ZangJac/Saiyan
RF-Transformer: A Unified Backscatter Radio Hardware Abstraction
This paper presents RF-Transformer, a unified backscatter radio hardware
abstraction that allows a low-power IoT device to directly communicate with
heterogeneous wireless receivers at the minimum power consumption. Unlike
existing backscatter systems that are tailored to a specific wireless
communication protocol, RF-Transformer provides a programmable interface to the
micro-controller, allowing IoT devices to synthesize different types of
protocol-compliant backscatter signals sharing radically different PHY-layer
designs. To show the efficacy of our design, we implement a PCB prototype of
RF-Transformer on 2.4 GHz ISM band and showcase its capability on generating
standard ZigBee, Bluetooth, LoRa, and Wi-Fi 802.11b/g/n/ac packets. Our
extensive field studies show that RF-Transformer achieves 23.8 Mbps, 247.1
Kbps, 986.5 Kbps, and 27.3 Kbps throughput when generating standard Wi-Fi,
ZigBee, Bluetooth, and LoRa signals while consuming 7.6-74.2 less power than
their active counterparts. Our ASIC simulation based on the 65-nm CMOS process
shows that the power gain of RF-Transformer can further grow to 92-678. We
further integrate RF-Transformer with pressure sensors and present a case study
on detecting foot traffic density in hallways. Our 7-day case studies
demonstrate RFTransformer can reliably transmit sensor data to a commodity
gateway by synthesizing LoRa packets on top of Wi-Fi signals. Our experimental
results also verify the compatibility of RF-Transformer with commodity
receivers. Code and hardware schematics can be found at:
https://github.com/LeFsCC/RF-Transformer