Implications of time/frequency synchronization tradeoff of quasi-synchronous multi-carrier DS-CDMA for robust communications at lower VHF

Verma, Gunjan; Dagefu, Fikadu T.; Sadler, Brian M.; Spasojević, Predrag

doi:10.1109/milcom.2016.7795409

Cited by 4 publications

(3 citation statements)

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“…Motivated by low frequency CDMA, a comprehensive numerical search was conducted over a large collection of ZCZ code families that examined the best-and worst-achievable performance in terms of frequency-offset induced orthogonality loss. These codes were studied for QS multi-user networking applications at low VHF, including simulations and experiments on software-defined radios that have nontrivial frequency offsets [185], [186].…”

Section: A Quasi-synchronous Multi-carrier Cdmamentioning

confidence: 99%

“…However, MC-CDMA is more susceptible to frequency synchronization errors at the receiver than a single-carrier system. The time/frequency synchronization tradeoff for multi-carrier networks employing ZCZ codes is studied experimentally in [185], through software defined radio (SDR) experiments at low frequency, with low power transmission in densely cluttered environments. This work highlights the promise of QS-MC-CDMA signaling to enable low frequency multi-user communications.…”

Section: B Qs-mc-cdma Indoor/outdoor Experiments With Loosely Synchro...mentioning

confidence: 99%

“…Sporadic channel access allows one to capitalize on random code reuse and enable efficient nonorthogonal medium access [190]- [192]. This approach is appealing for low frequency operation with superior penetration, reduced multipath, and increased channel coherence time for near-ground communications and in complex environments [83], [185], [186]. The advent of miniature low frequency antennas enables practical device to device (D2D) applications, including small autonomous agents with limited power budget [194]- [196].…”

Section: B Scalable Sporadic Non-orthogonal Mac [193]mentioning

confidence: 99%

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Low Frequency Multi-Robot Networking

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et al. 2024

IEEE Access

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Autonomous teams of unmanned ground and air vehicles rely on networking and distributed processing to collaborate as they jointly localize, explore, map, and learn in sometimes difficult and adverse conditions. Co-designed intelligent wireless networks are needed for these autonomous mobile agents for applications including disaster response, logistics and transportation, supplementing cellular networks, and agricultural and environmental monitoring. In this paper we describe recent progress on wireless networking and distributed processing for autonomous systems using a low frequency portion of the electromagnetic spectrum, here defined as roughly 25 to 100 MHz with corresponding wavelengths of 3 to 12 meters. This research is motivated by the desire to support autonomous systems operating in dense and cluttered environments by harnessing low frequency propagation, where meters long wavelengths yield significantly reduced scattering and enhanced penetration of obstacles and structures. This differs considerably from higher frequency propagation, requiring different low frequency propagation models than those widely employed for other bands. Progress in use of low frequency for autonomous systems has resulted from combined advances in low frequency propagation modeling, networking, antennas and electromagnetics, geolocation, multi-antenna array distributed beamforming, and mobile collaborative processing. This article describes the breadth and the depth of interaction between areas, leading to new tools and methods, especially in physically complex indoor/outdoor, dense urban, and other challenging scenarios. We bring together key results, models, measurements, and experiments that describe the state of the art for new uses of low frequency spectrum for multi-agent autonomy.

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Section: A Quasi-synchronous Multi-carrier Cdmamentioning

confidence: 99%

Section: B Qs-mc-cdma Indoor/outdoor Experiments With Loosely Synchro...mentioning

confidence: 99%