| 1. |
- Lopes Batista, Rodrigo, et al.
(author)
-
Joint Opportunistic Scheduling of Cellular and Device-to-Device Communications
- 2017
-
In: Journal of communication and information systems. - Brazil : Journal of Communication and Information Systems. - 1980-6604.
-
Journal article (peer-reviewed)abstract
- The joint scheduling of cellular and D2D communications to share the same radio resource is a complex task.In one hand, D2D links provide very high throughputs. In the other hand, the intra-cell interference they cause impacts on the performance of cellular communications.Therefore, designing algorithms and mechanisms that allow an efficient reuse of resources by the D2D links with a reduced impact on cellular communications is a key problem.In general, traditional Radio Resource Management (RRM) schemes (D2D grouping and mode selection) focus on finding the most compatible D2D pair for an already scheduled cellular User Equipment (UE).However, such approach limits the number of possible combinations to form the group (composed by a cellular UE and a D2D pair) to be scheduled in the radio resource.To overcome that, in this work a unified Joint Opportunistic Scheduling (JOS) of cellular and D2D communications, which is able to improve the total system throughput by exploiting the spatial compatibility among cellular and D2D UEs, is proposed.But more complexity is brought to the scheduling problem.Thus, a low-complexity suboptimal heuristic Joint Opportunistic Assignment and Scheduling (JOAS) is also elaborated.Results show that it is possible to reduce the computational complexity but still improve the overall performance in terms of cellular fairness and total system throughput with less impact on cellular communications.
|
|
| 2. |
- B. da Silva Jr., Jose Mairton, 1990-, et al.
(author)
-
Fast-Lipschitz Power Control and User-Frequency Assignment in Full-Duplex Cellular Networks
- 2017
-
In: IEEE Transactions on Wireless Communications. - : IEEE Communications Society. - 1536-1276 .- 1558-2248. ; 16:10, s. 6672-6687
-
Journal article (peer-reviewed)abstract
- In cellular networks, the three-node full-duplex transmission mode has the po-tential to increase spectral efficiency without requiring full-duplex capability ofusers. Consequently, three-node full-duplex in cellular networks must deal with self-interference and user-to-user interference, which can be managed by power controland user-frequency assignment techniques. This paper investigates the problem ofmaximizing the sum spectral efficiency by jointly determining the transmit powersin a distributed fashion, and assigning users to frequency channels. The problem is for-mulated as a mixed-integer nonlinear problem, which is shown to be non-deterministicpolynomial-time hard. We investigate a close-to-optimal solution approach by dividingthe joint problem into a power control problem and an assignment problem. The powercontrol problem is solved by Fast-Lipschitz optimization, while a greedy solution withguaranteed performance is developed for the assignment problem. Numerical resultsindicate that compared with the half-duplex mode, both spectral and energy efficienciesof the system are increased by the proposed algorithm. Moreover, results show that thepower control and assignment solutions have important, but opposite roles in scenarioswith low or high self-interference cancellation. When the self-interference cancellationis high, user-frequency assignment is more important than power control, while powercontrol is essential at low self-interference cancellation.
|
|
| 3. |
- B. da Silva Jr., Jose Mairton, 1990-, et al.
(author)
-
How to Split UL/DL Antennas in Full-DuplexCellular Networks
- 2018
-
In: IEEE International Conference on Communication (ICC’18). - Kansas City, MO, USA : IEEE Communications Society.
-
Conference paper (peer-reviewed)abstract
- To further improve the potential of full-duplex com-munications, networks may employ multiple antennas at thebase station or user equipment. To this end, networks thatemploy current radios usually deal with self-interference andmulti-user interference by beamforming techniques. Althoughprevious works investigated beamforming design to improvespectral efficiency, the fundamental question of how to split theantennas at a base station between uplink and downlink infull-duplex networks has not been investigated rigorously. Thispaper addresses this question by posing antenna splitting as abinary nonlinear optimization problem to minimize the sum meansquared error of the received data symbols. It is shown that thisis an NP-hard problem. This combinatorial problem is dealt withby equivalent formulations, iterative convex approximations, anda binary relaxation. The proposed algorithm is guaranteed toconverge to a stationary solution of the relaxed problem with muchsmaller complexity than exhaustive search. Numerical resultsindicate that the proposed solution is close to the optimal in bothhigh and low self-interference capable scenarios, while the usuallyassumed antenna splitting is far from optimal. For large numberof antennas, a simple antenna splitting is close to the proposedsolution. This reveals that the importance of antenna splittingdiminishes with the number of antennas.
|
|
| 4. |
- B. da Silva Jr., Jose Mairton, 1990-, et al.
(author)
-
On the Spectral Efficiency and Fairness in Full-Duplex Cellular Networks
- 2017
-
In: 2017 IEEE International Conference on Communications (ICC). - Paris : Institute of Electrical and Electronics Engineers (IEEE). - 9781467389990 ; , s. 1-6
-
Conference paper (peer-reviewed)abstract
- To increase the spectral efficiency of wireless networks without requiring full-duplex capability of user devices, a potential solution is the recently proposed three-node full-duplex mode. To realize this potential, networks employing three-node full-duplex transmissions must deal with self-interference and user-to-user interference, which can be managed by frequency channel and power allocation techniques. Whereas previous works investigated either spectral efficient or fair mechanisms, a scheme that balances these two metrics among users is investigated in this paper. This balancing scheme is based on a new solution method of the multi-objective optimization problem to maximize the weighted sum of the per-user spectral efficiency and the minimum spectral efficiency among users. The mixed integer non-linear nature of this problem is dealt by Lagrangian duality. Based on the proposed solution approach, a low-complexity centralized algorithm is developed, which relies on large scale fading measurements that can be advantageously implemented at the base station. Numerical results indicate that the proposed algorithm increases the spectral efficiency and fairness among users without the need of weighting the spectral efficiency. An important conclusion is that managing user-to-user interference by resource assignment and power control is crucial for ensuring spectral efficient and fair operation of full-duplex networks.
|
|
| 5. |
- B. da Silva Jr., Jose Mairton, 1990-
(author)
-
Optimization and Fundamental Insights in Full-Duplex Cellular Networks
- 2019
-
Doctoral thesis (other academic/artistic)abstract
- The next generations of cellular networks are expected to provide explosive data rate transmissions and very low latencies. To meet such demands, one of the promising wireless transmissions candidates is in-band full-duplex communications, which enable wireless devices to simultaneously transmit and receive on the same frequency channel. Full-duplex communications have the potential to double the spectral efficiency and reduce the transmission delays when compared to current half-duplex systems that either transmit or receive on the same frequency channel. Until recently, full-duplex communications have been hindered by the interference that leaks from the transmitter to its own receiver,the so-called self-interference. However, advances in digital and analog self-interference suppression techniques are making it possible to reduce the self-interference to manageable levels, and thereby make full-duplex a realistic candidate for advanced wireless systems.Although in-band full-duplex promises to double the data rates of existing wireless technologies, its deployment in cellular networks must be gradual due to the large number of legacy devices operating in half-duplex mode. When half-duplex devices are deployed in full-duplex cellular networks, the user-to-user interference may become the performance bottleneck. In such new interference situation, the techniques such as user pairing, frequency channel assignment, power control, beamforming, and antenna splitting become even more important than before, because they are essential to mitigate both the user-to-user interference and the residual self-interference. Moreover, introduction of full- duplex in cellular networks must comply with current multi-antenna systems and, possibly, transmissions in the millimeter-wave bands. In these new scenarios, no comprehensive analysis is available to understand the trade-offs in the performance of full-duplex cellular networks.This thesis investigates the optimization and fundamental insights in the design of spectral efficient and fair mechanisms in full-duplex cellular networks. The novel analysis proposed in this thesis suggests new solutions for maximizing full-duplex performance in the sub-6 GHz and millimeter-wave bands. The investigations are based on an optimization theory approach that includes distributed and nonconvex optimization with mixed integer-continuous variables, and novel extensions of Fast-Lipschitz optimization. The analysis sheds lights on fundamental questions such as which antenna architecture should be used and whether full-duplex in the millimeter-wave band is feasible. The results establish fundamental insights in the role of user pairing, frequency assignment, power control and beamforming; reveal the special behaviour between the self-interference and user- to-user interference; analyse the trade-offs between antenna sharing and splitting for uplink/downlink signal separation; and investigate the role of practical beamforming design in full-duplex millimeter-wave systems. This thesis may provide input to future standardization process of full-duplex communications.
|
|
| 6. |
- B. da Silva Jr., Jose Mairton, 1990-
(author)
-
Spectral Efficiency and Fairness Maximization in Full-Duplex Cellular Networks
- 2017
-
Licentiate thesis (other academic/artistic)abstract
- Future cellular networks, the so-called 5G, are expected to provide explosive data volumes and data rates. To meet such a demand, the research communities are investigating new wireless transmission technologies. One of the most promising candidates is in-band full-duplex communications. These communications are characterized by that a wireless device can simultaneously transmit and receive on the same frequency channel. In-band full-duplex communications have the potential to double the spectral efficiencywhen compared to current half duplex systems. The traditional drawback of full-duplex was the interference that leaks from the own transmitter to its own receiver, the so- called self-interference, which renders the receiving signal unsuitable for communication.However, recent advances in self-interference suppression techniques have provided high cancellation and reduced the self-interference to noise floor levels, which shows full-duplex is becoming a realistic technology component of advanced wireless systems.Although in-band full-duplex promises to double the data rate of existing wireless technologies, its deployment in cellular networks is challenging due to the large number of legacy devices working in half-duplex. A viable introduction in cellular networks is offered by three-node full-duplex deployments, in which only the base stations are full-duplex, whereas the user- or end-devices remain half-duplex. However, in addition to the inherent self-interference, now the interference between users, the user-to-user interference, may become the performance bottleneck, especially as the capability to suppress self-interference improves. Due to this new interference situation, user pairing and frequency channel assignment become of paramount importance, because both mechanisms can help to mitigate the user-to-user interference. It is essential to understand the trade-offs in the performance of full-duplex cellular networks, specially three-node full-duplex, in the design of spectral and energy efficient as well as fair mechanisms.This thesis investigates the design of spectral efficient and fair mechanisms to improve the performance of full-duplex in cellular networks. The novel analysis proposed in this thesis suggests centralized and distributed user pairing, frequency channel assignment and power allocation solutions to maximize the spectral efficiency and fairness in future full-duplex cellular networks. The investigations are based on distributed optimization theory with mixed integer-real variables and novel extensions of Fast-Lipschitz optimization. The analysis sheds lights on two fundamental problems of standard cellular networks, namely the spectral efficiency and fairness maximization, but in the new context of full-duplex communications. The results in this thesis provide important understanding in the role of user pairing, frequency assignment and power allocation, and reveal the special behaviourbetween the legacy self-interference and the new user-to-user interference. This thesis can provide input to the standardization process of full-duplex communications, and have the potential to be used in the implementation of future full-duplex in cellular networks.
|
|
| 7. |
- B. da Silva Jr., Jose Mairton, 1990-, et al.
(author)
-
Spectral Efficient and Fair User Pairing for Full-Duplex Communication in Cellular Networks
- 2016
-
In: IEEE Transactions on Wireless Communications. - : IEEE Press. - 1536-1276 .- 1558-2248. ; 15:11, s. 7578-7593
-
Journal article (peer-reviewed)abstract
- —A promising new transmission mode in cellular networks is the three-node full-duplex mode, which involves a base station with full-duplex capability and two half-duplex user transmissions on the same frequency channel for uplink and downlink. The three-node full-duplex mode can increase spectral efficiency, especially in the low transmit power regime, without requiring full-duplex capability at user devices. However, when a large set of users is scheduled in this mode, self-interference at the base station and user-to-user interference can substantially hinder the potential gains of full-duplex communications. This paper investigates the problem of grouping users to pairs and assigning frequency channels to each pair in a spectral efficient and fair manner. Specifically, the joint problem of user uplink/downlink frequency channel pairing and power allocation is formulated as a mixed integer nonlinear problem that is solved by a novel joint fairness assignment maximization algorithm. Realistic system level simulations indicate that the spectral efficiency of the users having the lowest spectral efficiency is increased by the proposed algorithm, while a high ratio of connected users in different loads and self-interference levels is maintained.
|
|
| 8. |
- Sousa, Diego Perdigão, et al.
(author)
-
Leakage Detection In Water Distribution Networks : Efficient Training By Data Clustering
- 2022
-
In: IWA World Water Congress & Exhibition, Sep. 2022. - : IWA Publishing.
-
Conference paper (peer-reviewed)abstract
- This work proposes a reliable leakage detection methodology for water distribution networks based on machine learning techniques. The design is developed through real data acquisition from a municipal area of a water distribution network. We propose to combine both unsupervised learning (K-means and cluster validation techniques) and supervised learning (LVQ-type algorithms) for the efficient design of prototype-based classifiers. We investigated several metrics aiming to define the optimal number of clusters, in which we succeeded in reporting attractive classification accuracies (approximately 90%) on scenarios of severely limited number of prototypes.
|
|
| 9. |
- Tavangaran, Nima, et al.
(author)
-
On differential privacy for federated learning in wireless systems with multiple base stations
- 2024
-
In: IET Communications. - 1751-8628 .- 1751-8636.
-
Journal article (peer-reviewed)abstract
- In this work, we consider a federated learning model in a wireless system with multiple base stations and inter-cell interference. We apply a differentially private scheme to transmit information from users to their corresponding base station during the learning phase. We show the convergence behavior of the learning process by deriving an upper bound on its optimality gap. Furthermore, we define an optimization problem to reduce this upper bound and the total privacy leakage. To find the locally optimal solutions of this problem, we first propose an algorithm that schedules the resource blocks and users. We then extend this scheme to reduce the total privacy leakage by optimizing the differential privacy artificial noise. We apply the solutions of these two procedures as parameters of a federated learning system where each user is equipped with a classifier and communication cells have mostly fewer resource blocks than numbers of users. The simulation results show that our proposed scheduler improves the average accuracy of the predictions compared with a random scheduler. In particular, the results show an improvement of over 6%. Furthermore, its extended version with noise optimizer significantly reduces the amount of privacy leakage.
|
|
