35 research outputs found
Sensing as a Service in 6G Perceptive Mobile Networks: Architecture, Advances, and the Road Ahead
Sensing-as-a-service is anticipated to be the core feature of 6G perceptive
mobile networks (PMN), where high-precision real-time sensing will become an
inherent capability rather than being an auxiliary function as before. With the
proliferation of wireless connected devices, resource allocation in terms of
the users' specific quality-of-service (QoS) requirements plays a pivotal role
to enhance the interference management ability and resource utilization
efficiency. In this article, we comprehensively introduce the concept of
sensing service in PMN, including the types of tasks, the
distinctions/advantages compared to conventional networks, and the definitions
of sensing QoS. Subsequently, we provide a unified RA framework in
sensing-centric PMN and elaborate on the unique challenges. Furthermore, we
present a typical case study named "communication-assisted sensing" and
evaluate the performance trade-off between sensing and communication procedure.
Finally, we shed light on several open problems and opportunities deserving
further investigation in the future
Sensing as a Service in 6G Perceptive Networks: A Unified Framework for ISAC Resource Allocation
In the upcoming next-generation (5G-Advanced and 6G) wireless networks,
sensing as a service will play a more important role than ever before.
Recently, the concept of perceptive network is proposed as a paradigm shift
that provides sensing and communication (S&C) services simultaneously. This
type of technology is typically referred to as Integrated Sensing and
Communications (ISAC). In this paper, we propose the concept of sensing quality
of service (QoS) in terms of diverse applications. Specifically, the
probability of detection, the Cramer-Rao bound (CRB) for parameter estimation
and the posterior CRB for moving target indication are employed to measure the
sensing QoS for detection, localization, and tracking, respectively. Then, we
establish a unified framework for ISAC resource allocation, where the fairness
and the comprehensiveness optimization criteria are considered for the
aforementioned sensing services. The proposed schemes can flexibly allocate the
limited power and bandwidth resources according to both S&C QoSs. Finally, we
study the performance trade-off between S&C services in different resource
allocation schemes by numerical simulations
Aiming in Harsh Environments: A New Framework for Flexible and Adaptive Resource Management
The harsh environment imposes a unique set of challenges on networking
strategies. In such circumstances, the environmental impact on network
resources and long-time unattended maintenance has not been well investigated
yet. To address these challenges, we propose a flexible and adaptive resource
management framework that incorporates the environment awareness functionality.
In particular, we propose a new network architecture and introduce the new
functionalities against the traditional network components. The novelties of
the proposed architecture include a deep-learning-based environment resource
prediction module and a self-organized service management module. Specifically,
the available network resource under various environmental conditions is
predicted by using the prediction module. Then based on the prediction, an
environment-oriented resource allocation method is developed to optimize the
system utility. To demonstrate the effectiveness and efficiency of the proposed
new functionalities, we examine the method via an experiment in a case study.
Finally, we introduce several promising directions of resource management in
harsh environments that can be extended from this paper.Comment: 8 pages, 4 figures, to appear in IEEE Network Magazine, 202
Energy-Efficient Beamforming Design for Integrated Sensing and Communications Systems
In this paper, we investigate the design of energy-efficient beamforming for
an ISAC system, where the transmitted waveform is optimized for joint
multi-user communication and target estimation simultaneously. We aim to
maximize the system energy efficiency (EE), taking into account the constraints
of a maximum transmit power budget, a minimum required
signal-to-interference-plus-noise ratio (SINR) for communication, and a maximum
tolerable Cramer-Rao bound (CRB) for target estimation. We first consider
communication-centric EE maximization. To handle the non-convex fractional
objective function, we propose an iterative quadratic-transform-Dinkelbach
method, where Schur complement and semi-definite relaxation (SDR) techniques
are leveraged to solve the subproblem in each iteration. For the scenarios
where sensing is critical, we propose a novel performance metric for
characterizing the sensing-centric EE and optimize the metric adopted in the
scenario of sensing a point-like target and an extended target. To handle the
nonconvexity, we employ the successive convex approximation (SCA) technique to
develop an efficient algorithm for approximating the nonconvex problem as a
sequence of convex ones. Furthermore, we adopt a Pareto optimization mechanism
to articulate the tradeoff between the communication-centric EE and
sensing-centric EE. We formulate the search of the Pareto boundary as a
constrained optimization problem and propose a computationally efficient
algorithm to handle it. Numerical results validate the effectiveness of our
proposed algorithms compared with the baseline schemes and the obtained
approximate Pareto boundary shows that there is a non-trivial tradeoff between
communication-centric EE and sensing-centric EE, where the number of
communication users and EE requirements have serious effects on the achievable
tradeoff
Waveform Design for Communication-Assisted Sensing in 6G Perceptive Networks
The integrated sensing and communication (ISAC) technique has the potential
to achieve coordination gain by exploiting the mutual assistance between
sensing and communication (S&C) functions. While the sensing-assisted
communications (SAC) technology has been extensively studied for high-mobility
scenarios, the communication-assisted sensing (CAS) counterpart remains widely
unexplored. This paper presents a waveform design framework for CAS in 6G
perceptive networks, aiming to attain an optimal sensing quality of service
(QoS) at the user after the target's parameters successively ``pass-through''
the SC channels. In particular, a pair of transmission schemes, namely,
separated S&C and dual-functional waveform designs, are proposed to optimize
the sensing QoS under the constraints of the rate-distortion and power budget.
The first scheme reveals a power allocation trade-off, while the latter
presents a water-filling trade-off. Numerical results demonstrate the
effectiveness of the proposed algorithms, where the dual-functional scheme
exhibits approximately 12% performance gain compared to its separated waveform
design counterpart
Seventy Years of Radar and Communications: The road from separation to integration
Radar and communications (R&C) as key utilities of electromagnetic (EM) waves have fundamentally shaped human society and triggered the modern information age. Although R&C had been historically progressing separately, in recent decades, they have been converging toward integration, forming integrated sensing and communication (ISAC) systems, giving rise to new highly desirable capabilities in next-generation wireless networks and future radars. To better understand the essence of ISAC, this article provides a systematic overview of the historical development of R&C from a signal processing (SP) perspective. We first interpret the duality between R&C as signals and systems, followed by an introduction of their fundamental principles. We then elaborate on the two main trends in their technological evolution, namely, the increase of frequencies and bandwidths and the expansion of antenna arrays. We then show how the intertwined narratives of R&C evolved into ISAC and discuss the resultant SP framework. Finally, we overview future research directions in this field
Seventy Years of Radar and Communications: The Road from Separation to Integration
Radar and communications (R&C) as key utilities of electromagnetic (EM) waves have fundamentally shaped human society and triggered the modern information age. Although R&C have been historically progressing separately, in recent decades they have been moving from separation to integration, forming integrated sensing and communication (ISAC) systems, which find extensive applications in next-generation wireless networks and future radar systems. To better understand the essence of ISAC systems, this paper provides a systematic overview on the historical development of R&C from a signal processing (SP) perspective. We first interpret the duality between R&C as signals and systems, followed by an introduction of their fundamental principles. We then elaborate on the two main trends in their technological evolution, namely, the increase of frequencies and bandwidths, and the expansion of antenna arrays. Moreover, we show how the intertwined narratives of R\&C evolved into ISAC, and discuss the resultant SP framework. Finally, we overview future research directions in this field
Probabilistic Constellation Shaping for OFDM-Based ISAC Signaling
Integrated Sensing and Communications (ISAC) has garnered significant
attention as a promising technology for the upcoming sixth-generation wireless
communication systems (6G). In pursuit of this goal, a common strategy is that
a unified waveform, such as Orthogonal Frequency Division Multiplexing (OFDM),
should serve dual-functional roles by enabling simultaneous sensing and
communications (S&C) operations. However, the sensing performance of an OFDM
communication signal is substantially affected by the randomness of the data
symbols mapped from bit streams. Therefore, achieving a balance between
preserving communication capability (i.e., the randomness) while improving
sensing performance remains a challenging task. To cope with this issue, in
this paper we analyze the ambiguity function of the OFDM communication signal
modulated by random data. Subsequently, a probabilistic constellation shaping
(PCS) method is proposed to devise the probability distributions of
constellation points, which is able to strike a scalable S&C tradeoff of the
random transmitted signal. Finally, the superiority of the proposed PCS method
over conventional uniformly distributed constellations is validated through
numerical simulations
Caracterizaci贸n de la adsorcion de amonio y fosfato mediante zeolitas sint茅ticas modificadas
En el contexto legal actual se exige una eliminaci贸n del f贸sforo y nitr贸geno casi completa en las aguas residuales. Por otro lado, conseguir recuperar estos nutrientes conllevar铆a beneficios tanto econ贸micos como ecol贸gicos ya que se cerrar铆a el ciclo natural de estos dos elementos evitando su acumulaci贸n y previniendo la eutrofizaci贸n en el medio acu谩tico.
El objetivo del presente proyecto es caracterizar el proceso de adsorci贸n de amonio y fosfato mediante una zeolita sintetizada a partir de cenizas volantes (Ze-Na), as铆 como las en su forma c谩lcica (Ze-Ca) y magn茅sica (Ze-Mg). Se han estudiado los par谩metros cin茅ticos y del equilibrio para los diferentes tipos de zeolitas. Se ha comprobado que la adsorci贸n se rige mediante el modelo cin茅tico de pseudo segundo orden mientras que el estudio del equilibrio muestra que los datos experimentales se ajustan al modelo de Langmuir.
Se ha observado que la Ze-Na no adsorbe fosfato y las modificaciones realizadas con calcio y magnesio son efectivas para mejorar esta carencia. Tambi茅n se ha visto que para una disoluci贸n monocomponente de amonio, la Ze-Na es la que tiene mayor capacidad de adsorci贸n en el equilibrio pero queda afectada significativamente con la presencia del fosfato en la disoluci贸n mientras que para la Ze-Ca la capacidad queda inalterada. En cuanto a la Ze-Mg muestra un ligero descenso de su capacidad de adsorci贸n de amonio por la presencia del fosfato.
Se ha estudiado el proceso de adsorci贸n de amonio y fosfato en cada zeolita resultando el intercambio i贸nico el mecanismo principal de la adsorci贸n de amonio en los tres tipos de zeolita mientras que la eliminaci贸n de fosfato se lleva a cabo mediante la formaci贸n de fosfato de calcio (Ze-Ca) y de estruvita (Ze-Mg).
Se han empleado diferentes t茅cnicas de caracterizaci贸n como la espectroscopia infrarroja por transformada de Fourier (FTIR en ingl茅s), la espectroscopia Raman, la isoterma de Brunauer-Emmett-Teller (BET en ingl茅s), el microscopio electr贸nico de barrido (SEM en ingl茅s) y la fluorescencia de rayos X (EDS en ingl茅s) para conocer la composici贸n de las zeolitas antes y despu茅s de saturarse con amonio y fosfato. Los resultados obtenidos muestran un aumento del contenido en calcio (Ze-Ca) y magnesio (Ze-Mg) en detrimento del porcentaje m谩sico del sodio despu茅s de la modificaci贸n. Tambi茅n se ha observado la disminuci贸n del porcentaje m谩sico de sodio (Ze-Na), de calcio (Ze-Ca) y de magnesio (Ze-Mg) en sus respectivas formas zeol铆ticas saturadas de los dos nutrientes