A practical guide to chirp spread spectrum for acoustic underwater communication in shallow waters

Steinmetz, Fabian; Heitmann, Jan; Renner, Christian

doi:10.1145/3291940.3291964

Cited by 14 publications

(14 citation statements)

References 13 publications

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“…We conclude a practical limitation of a few kbit/s using FSK. Chirp signals-already employed to some extent by commercial acoustic underwater modems and known from, e.g., radar applications-are an appealing modulation alternative that we have already started exploring from a scientific point of view in Reference [66]. We also found that low-power communication with only a few watts of transmit power at distances of several hundred meters is achievable.…”

Section: Discussionmentioning

confidence: 66%

“…A promising approach is to use chirp spread spectrum (CSS) for modulation-possibly in combination with FSK or PSK-to make communication more resilient. The advantages of CSS for underwater acoustics are discussed in References [40] and [66]; its main disadvantage is the computation complexity of demodulation. While modulation is an integral part of communication, we argue that our goal is not to present the best possible acoustic modem but a research platform that will enable and trigger practically backed research on, e.g., the best possible modulation scheme for underwater communication.…”

Section: Modulation Techniquesmentioning

confidence: 99%

“…To enable basic communication and localization for μAUVs as part of our ongoing research [33,64,66], we implemented a reference communication stack, ranging from modulation to encoding. We discuss the stack subsequently and provide a detailed evaluation in Section 5 and Section 6.…”

Section: Acoustic Communication Stackmentioning

confidence: 99%

“…We discuss the stack subsequently and provide a detailed evaluation in Section 5 and Section 6. Due to the complexity of building a fully operational communication stack, we constrained ourselves to a choice of robust techniques, leaving optimization (e.g., other modulation techniques) to follow-up work; e.g., we are currently investigating chirp spread spectrum [66] and performed a comparison of modulation techniques in Reference [67]. Following this path allows research from modulation over medium access to localization but also employment in applications.…”

Section: Acoustic Communication Stackmentioning

confidence: 99%

“…Second, it simplifies and enables real-world experiments in the domain of autonomous μAUV swarms and their communication for both industry and academia at an affordable price point, with readily available components and with the freedom to modify hardware and software components, as we intend to release the ahoi modem as open source. Being a software-defined device, the ahoi modem enables comparison and testing of, e.g., novel modulation schemes [66] on real hardware. With this device at hand, thorough analysis of real-world acoustic communication and localization, in static and mobile use cases, is enabled and conducted.…”

Section: Introductionmentioning

confidence: 99%

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ahoi

Renner

Heitmann

Steinmetz

2020

ACM Trans. Sen. Netw.

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The recent development of small, cheap AUVs enables a plethora of underwater near-and inshore applications. Among these are monitoring of wind parks, detection of pollution sources, water-quality inspection, and the support of divers during disaster management. These tasks profit from online reporting, control, and AUV swarm interaction; yet they require underwater communication. Unfortunately, commercial devices are prohibitively expensive and typically closed-source, hampering their application in affordable products and research. Therefore, we developed the open-source 1 ahoi acoustic modem. It is (i) small enough to be carried by micro AUVs, (ii) consumes little enough energy to not diminish operation times of its host, (iii) comes at an attractive unit cost below $600, (iv) can reliably communicate at distances of 150 m and more, and (v) supports ranging without additional hardware. Due to its modular build, the modem can be customized and is suitable as research platform to analyze, e.g., MAC and routing protocols. We conducted extensive real-world studies and present results of communication range, packet reception rate, ranging accuracy, and efficient and reliable self-localization. Finally, we draw conclusions regarding acoustic communication, ranging, and localization with inexpensive and low-power devices that go beyond a particular device. Our study, hence, encompasses general insights, observations, and recommendations.

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Section: Discussionmentioning

confidence: 66%

Section: Modulation Techniquesmentioning

confidence: 99%

Section: Acoustic Communication Stackmentioning

confidence: 99%

Section: Acoustic Communication Stackmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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ahoi

Renner

Heitmann

Steinmetz

2020

ACM Trans. Sen. Netw.

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Modeling and Simulation of SWARA Path Loss Model for Underwater Acoustic Communication in Multipath Environment

Bartakke²,

Agrawal

2023

Wireless Pers Commun

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The propagation loss varies with underwater channel conditions which might considered to be random phenomena. Modeling propagation loss will become meaningful iff mathematical model includes parameters namely viz projector's transmit voltage response (TVR), hydrophone's open circuit receiving response (OCRR), directivity patterns of both, channel parameters such as salinity, temperature, pressure, enclosure boundary conditions along with placements of Tx & Rx nodes & their operating frequency. To best of our knowledge, existing simulators are unable to trace eigen rays for very short range i.e. less than 0.1 km and therefore they are not suitable for computation of such short-range propagation losses. We have made an attempt to overcome limitations of existing simulators wherein we proposed mathematical model SWARA which includes parameters as mentioned above to study very short-range propagation losses using plane wave theory. To validate simulated propagation loss, we conducted tank trials at UWAA Lab, CARE, IIT Delhi to investigate effects of placements of projector & hydrophone on occurrence of transmission loss. The Simulated results of SWARA mathematical model shows that simulated maximum transmission loss is -0.18 to 0.10 times experimental maximum transmission loss, whereas simulated minimum transmission loss is -0.36 to 0.19 times experimental minimum transmission loss for placements of projector (ITC 1042) and hydrophone (Keltron 8240000001) at depths varying from 0.3m-1.2m & range varying from 2m-3.2m in uw tank facility of 3.85m long 2.4 wide 2m deep for 30kHz chirp signal (10kHz bandwidth) under static channel conditions.

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Doppler Shift and SFO Robust Synchronization for LoRa-Like Acoustic Underwater Communication

Steinmetz,

Renner

2023

IEEE Access

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Frequency shift chirp modulation (FSCM) is the modulation technique utilized by the LoRa physical layer, a widely used and relatively new communication technique for radio low-power wide area networks (LPWANs). In this paper, we adapt and implement FSCM for low-power acoustic underwater communication. Opposed to over-water communication based on the electromagnetic wave, the acoustic wave in water travels much slower. Therefore, acoustic underwater communication is more sensitive to motion-based Doppler shifts. For a resilient acoustic underwater communication Doppler tracking and removal is mandatory. In this paper, we mathematically derive the effect of Doppler shifts to FSCM symbols. Afterwards, we describe a novel algorithm for a low-power receiver to track Doppler shifts without modification of the transmitted packet. Finally, we evaluate and compare our algorithm to another Doppler estimation algorithm from literature and study the effect on the bit error rate (BER). We show, that our algorithm can improve with lightweight additional computational overhead the BER by a factor of more than 10 4 in some cases.

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A practical guide to chirp spread spectrum for acoustic underwater communication in shallow waters

Cited by 14 publications

References 13 publications

ahoi

ahoi

Modeling and Simulation of SWARA Path Loss Model for Underwater Acoustic Communication in Multipath Environment

Doppler Shift and SFO Robust Synchronization for LoRa-Like Acoustic Underwater Communication

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