| 1. |
- Alegria, Juan Vidal, et al.
(author)
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Channel Orthogonalization with Reconfigurable Surfaces
- 2022
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In: 2022 IEEE GLOBECOM Workshops, GC Wkshps 2022 - Proceedings. - 9781665459754 ; , s. 37-42
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Conference paper (peer-reviewed)abstract
- Orthogonal multi-user multiple-input multiple-output (MU-MIMO) channels allow for optimum performance with simplified precoding/equalization, and they achieve maximum multiplexing gain which is shared fairly among users. Reconfigurable intelligent surface (RIS) constitutes a promising cost-efficient solution to improve the wireless channel, since they consist of passive reflecting elements able to adjust the phases of the incoming waves. However, it is still widely unclear how these surfaces can improve spatial-multiplexing. In fact, the common RIS model cannot achieve perfect orthogonalization of MU-MIMO channels with a reasonable number of elements. Furthermore, efficient channel estimation algorithms for RIS, which are key for taking advantage of its benefits, are still a matter of research. We study two types of reconfigurable surfaces (RSs), namely amplitude-reconfigurable intelligent surface (ARIS) and fully-reconfigurable intelligent surface (FRIS), with extended capabilities over RIS. We show how these RSs allow for perfect channel orthogonalization, and, by minimizing the applied power, we show that they can potentially be implemented without the need of amplification. We also present an efficient channel estimation method for each of them that allows the base station (BS) to select the desired propagation channel.
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| 2. |
- Guo, Hao, 1992, et al.
(author)
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Electromagnetic Field Exposure Avoidance thanks to Non-Intended User Equipment and RIS
- 2022
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In: GLOBECOM - IEEE Global Telecommunications Conference. - 9781665459754 ; , s. 1537-1542
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Conference paper (peer-reviewed)abstract
- On the one hand, there is a growing demand for high throughput which can be satisfied thanks to the deployment of new networks using massive multiple-input multiple-output (MIMO) and beamforming. On the other hand, in some countries or cities, there is a demand for arbitrarily low electromagnetic field exposure (EMFE) of people not concerned by the ongoing communication, which slows down the deployment of new networks. Recently, it has been proposed to take the opportunity, when designing the future 6th generation (6G), to offer, in addition to higher throughput, a new type of service: arbitrarily low EMFE. Recent works have shown that a reconfigurable intelligent surface (RIS), jointly optimized with the base station (BS) beamforming can improve the received throughput at the desired location whilst reducing EMFE everywhere. In this paper, we introduce a new concept of a non-intended user (NIU). An NIU is a user of the network who requests low EMFE when he/she is not downloading/uploading data. An NIU lets his/her device, called NIU equipment (NIUE), exchange some control signaling and pilots with the network, to help the network avoid exposing NIU to waves that are transporting data for another user of the network: the intended user (IU), whose device is called IU equipment (IUE). Specifically, we propose several new schemes to maximize the IU throughput under an EMFE constraint at the NIU (in practice, an interference constraint at the NIUE). Several propagation scenarios are investigated. Analytical and numerical results show that proper power allocation and beam optimization can remarkably boost the EMFE-constrained system's performance with limited complexity and channel information.
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| 3. |
- Khodakhah, Farnaz, et al.
(author)
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Design and Resource Allocation of NOMA-based Transmission Scheme for Industrial Collaborative AR
- 2022
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In: 2022 IEEE GLOBECOM Workshops, GC Wkshps 2022 - Proceedings. - : IEEE conference proceedings. - 9781665459754 ; , s. 1604-1609
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Conference paper (peer-reviewed)abstract
- Collaborative augmented reality (AR), which enables interaction and consistency in multi-user AR scenarios, is a promising technology for AR-guided remote monitoring, optimization, and troubleshooting of complex manufacturing processes. However, for uplink high data rate demands in collaborative-AR, the design of an efficient transmission and resource allocation scheme is demanding in resource-constrained wireless systems. To address this challenge, we propose a collaborative non-orthogonal multiple access (C-NOMA)-enabled transmission scheme by exploiting the fact that multi-user interaction often leads to common and individual views of the scenario (e.g., the region of interest). C-NOMA is designed as a two-step transmission scheme by treating these views separately and allowing users to offload the common views partially. Further, we define an optimization problem to jointly optimize the time and power allocation for AR users, with an objective of minimizing the maximum rate-distortion of the individual views for all users while guaranteeing a target distortion of their common view for its mutual significance. For its inherent non-linearity and non-convexity, we solve the defined problem using a primal-dual interior-point algorithm with a filter line search as well as by developing a successive convex approximation (SCA) method. The simulation results demonstrate that the optimized C-NOMA outperforms the non-collaborative baseline scheme by 23.94% and 77.28% in terms of energy consumption and achievable distortion on the common information, respectively.
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| 4. |
- Ullah, Syed Ali, et al.
(author)
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Deep RL-assisted Energy Harvesting in CR-NOMA Communications for NextG IoT Networks
- 2022
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In: 2022 IEEE GLOBECOM Workshops, GC Wkshps 2022 - Proceedings. - : IEEE conference proceedings. - 9781665459754 ; , s. 74-79
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Conference paper (peer-reviewed)abstract
- Zero-energy radios in energy-constrained devices are envisioned as key enablers to realizing the next-generation Internet-of-things (NG-IoT) networks for ultra-dense sensing and monitoring. This paper presents analytical modeling and analysis of the energy-efficient uplink transmission of an energyconstrained secondary sensor operating opportunistically among several primary sensors. The considered scenario assumes that all primary sensors transmit in a round-robin, time division multiple access-based schemes, and the secondary sensor is admitted in the time slot of each primary sensor using a nonorthogonal multiple access technique, inspired by cognitive radio. The energy efficiency of the secondary sensor is maximized by exposing it to a deep reinforcement learning-based algorithm, recognized as a deep deterministic policy gradient (DDPG). Our results demonstrate that the DDPG-based transmission scheme outperforms the conventional random and greedy algorithms in terms of energy efficiency at different operating conditions.
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