Symbiotic Radio: A New Communication Paradigm for Passive Internet-of-Things (1810.13068v1)

Abstract: In this paper, a novel technique, called symbiotic radio (SR), is proposed for passive Internet-of-Things (IoT), in which a backscatter device (BD) is integrated with a primary transmission. The primary transmitter is designed to assist the primary and BD transmissions, and the primary receiver decodes the information from the primary transmitter as well as the BD. We consider a multiple-input single-output (MISO) SR and the symbol period for BD transmission is designed to be either the same as or much longer than that of the primary system, resulting in parasitic or commensal relationship between the primary and BD transmissions. We first derive the achievable rates for the primary system and the BD transmission. Then, we formulate two transmit beamforming optimization problems, i.e., the weighted sum-rate maximization problem and the transmit power minimization problem, and solve these non-convex problems by applying semi-definite relaxation technique. In addition, a novel transmit beamforming structure is proposed to reduce the computational complexity of the solutions. Simulation results show that when the BD transmission rate is properly designed, the proposed SR not only enables the opportunistic transmission for the BD via energy-efficient passive backscattering, but also enhances the achievable rate of the primary system by properly exploiting the additional signal path from the BD.

• The paper proposes Symbiotic Radio (SR) as a new paradigm for passive IoT, analytically modeling and optimizing its performance under Parasitic (PSR) and Commensal (CSR) setups.
• Numerical results demonstrate that SR enhances primary system performance and improves spectral efficiency through the use of backscatter-induced signal paths, without compromising primary communication.
• Symbiotic Radio offers fresh perspectives on spectrum and energy-efficient strategies crucial for next-generation IoT, potentially prompting a paradigm shift towards integrated network designs.

Evaluating the Paradigm of Symbiotic Radio for Passive Internet-of-Things

This academic essay provides an analysis of the paper "Symbiotic Radio: A New Communication Paradigm for Passive Internet-of-Things" by Ruizhe Long et al., where the authors explore a novel communication framework in the context of the burgeoning Internet-of-Things (IoT) ecosystem. As IoT continues to expand, it presents unique challenges related to energy consumption and spectrum availability. The authors propose Symbiotic Radio (SR) as a compelling solution to enhance spectral efficiency while addressing the energy constraints of passive IoT devices.

Conceptual Framework

Symbiotic Radio leverages a shared spectrum and receiver architecture, integrating a passive backscatter device (BD) with a primary wireless communication network. The SR system is designed to support both the primary transmission and the BD transmission, creating potential synergies between the two. The integration is realized through two setups: Parasitic Symbiotic Radio (PSR), where the BD acts as an interference source, and Commensal Symbiotic Radio (CSR), which treats the BD's signal as a beneficial multipath component for the primary transmission.

Analytical Contributions

The paper provides rigorous analytical treatment concerning achievable rate performances under both PSR and CSR setups. It introduces a multiple-input single-output (MISO) model and derives the achievable rates for both the primary system and the BD transmission. For PSR, the interference management techniques are explored, whereas, for CSR, the potential multipath gain is capitalized upon.

Optimization Framework

Two primary optimization problems are formulated to evaluate the SR performance further:

1. Weighted Sum-Rate Maximization (WSRM): This addresses the trade-off between maximizing the combined rate of both primary and BD transmissions by applying a weighted sum-rate objective function.
2. Transmit Power Minimization (TPM): This targets the reduction of the primary transmitter's power consumption, ensuring compliance with predetermined rate constraints.

The solution to these non-convex optimization problems is facilitated by a semi-definite relaxation (SDR) approach, serving as a pathway to achieving suboptimal management of beamforming operations.

Numerical Validation

Simulation results demonstrate that SR can enhance the primary system's performance by utilizing backscatter-induced signal paths. For CSR, the additional signal path conferred by BD improves spectral efficiency, indicating that such systems can be implemented without sacrificing the performance of ongoing primary communication systems. The competitive analysis between conventional solutions and proposed low-complexity beamforming structures illustrates the practicality of deploying SR technologies in large-scale environments.

Implications and Future Directions

The research introduces fresh perspectives on spectrum and energy-efficient communication strategies crucial for the advancement of next-generation IoT networks. The introduction of SR could prompt a paradigm shift towards more integrated network designs catering to passive IoT requirements, with potential effectiveness in urban connectivity and smart home applications. As future developments in AI and machine learning continue to redefine signal processing techniques, the integration of intelligent network adaptations with SR frameworks could yield further performance enhancements. Exploratory research into AI-driven optimization of SR could unravel additional insights into managing interference and enhancing throughput in dense IoT environments.

In conclusion, the work by Long et al. pioneers an important step towards addressing the dual challenges of energy and spectrum constraints in IoT. Such innovations bring to light novel methodologies that highlight the essential interplay between passive device communications and primary network services, paving the way for more robust, sustainable network architecture designs in an era characterized by the explosive growth of connected devices.