| 1. |
- Fountoulakis, Emmanouil, et al.
(författare)
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AoI minimization with Timely-Throughput Constraints over Time-Correlated Wireless Channels
- 2023
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Ingår i: ICC 2023 - IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS. - : IEEE. - 9781538674628 - 9781538674635 ; , s. 5959-5964
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Konferensbidrag (refereegranskat)abstract
- In this work, we consider mixed traffic with time-sensitive users; a deadline-constrained user, and an AoI-oriented user. To develop an efficient scheduling policy, we cast a novel optimization problem formulation for minimizing the average AoI while satisfying the timely throughput constraints. The optimization problem is a Constrained Markov Decision Process (CMDP). We relax the constrained problem to an unconstrained Markov Decision Process (MDP) problem by utilizing Lyapunov optimization theory. The unconstrained problem is solved for each frame by applying backward dynamic programming. Simulation results show that the timely throughput constraints are satisfied while minimizing the average AoI. Also, simulation results show the convergence of the algorithm for different values of the weighted factor and the trade-off between the AoI and the timely throughput.
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| 2. |
- Fountoulakis, Emmanouil, 1991-, et al.
(författare)
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Dynamic power control for time-critical networking with heterogeneous traffic
- 2021
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Ingår i: ITU Journal on Future and Evolving Technologies. - 2616-8375. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- Future wireless networks will be characterized by heterogeneous traffic requirements. Examples can be low-latency or minimum-througput requirements. Therefore, the network has to adjust to different needs. Usually, users with low-latency requirements have to deliver their demand within a specific time frame, i.e., before a deadline, and they coexist with throughput oriented users. In addition, mobile devices have a limited-power budget and therefore, a power-efficient scheduling scheme is required by the network. In this work, we cast a stochastic network optimization problem for minimizing the packet drop rate while guaranteeing a minimum throughput and taking into account the limited-power capabilities of the users. We apply tools from Lyapunov optimization theory in order to provide an algorithm, named Dynamic Power Control (DPC) algorithm, that solves the formulated problem in real time. It is proved that the DPC algorithm gives a solution arbitrarily close to the optimal one. Simulation results show that our algorithm outperforms the baseline Largest-Debt-First (LDF) algorithm for short deadlines and multiple users.
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| 3. |
- Fountoulakis, Emmanouil, et al.
(författare)
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Information Freshness and Packet Drop Rate Interplay in a Two-User Multi-Access Channel
- 2021
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Ingår i: 2020 IEEE INFORMATION THEORY WORKSHOP (ITW). - : IEEE. - 9781728159621
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Konferensbidrag (refereegranskat)abstract
- In this work, we combine the two notions of timely delivery of information to study their interplay; namely, deadline-constrained packet delivery due to latency constraints and freshness of information. More specifically, we consider a two-user multiple access setup with random-access, in which user 1 is a wireless device with a queue and has external bursty traffic which is deadline-constrained, while user 2 monitors a sensor and transmits status updates to the destination. We provide analytical expressions for the throughput and drop probability of user 1, and an analytical expression for the average Age of Information (AoI) of user 2 monitoring the sensor. The relations reveal that there is a trade-off between the average AoI of user 2 and the drop rate of user 1: the lower the average AoI, the higher the drop rate, and vice versa. Simulations corroborate the validity of our theoretical results.
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| 4. |
- Fountoulakis, Emmanouil, et al.
(författare)
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Information Freshness and Packet Drop Rate Interplay in a Two-User Multi-Access Channel
- 2022
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Ingår i: Journal of Communications and Networks. - : Korean Institute of Communication Sciences. - 1229-2370 .- 1976-5541. ; 24:3, s. 357-364
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we combine the two notions of timely delivery of information to study their interplay; namely, deadline -constrained packet delivery due to latency constraints and freshness of information. More specifically, we consider a two -user multiple access setup with random access, in which user 1 is a wireless device with a buffer and has external bursty traffic which is deadline-constrained, while user 2 monitors a sensor and transmits status updates to the destination. We provide analytical expressions for the throughput and drop probability of user 1. For user 2, we derive in closed form the age of information distribution, the average age of information (AoI), and the probability the AoI to be larger than a certain value for each time slot. The relations reveal a trade-off between the average AoI of user 2 and the drop rate of user 1: the lower the average AoI, the higher the drop rate, and vice versa. Simulations corroborate the validity of our theoretical results.
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| 5. |
- Fountoulakis, Emmanouil, et al.
(författare)
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Optimal Sampling Cost in Wireless Networks with Age of Information Constraints
- 2020
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Ingår i: IEEE INFOCOM 2020 - IEEE CONFERENCE ON COMPUTER COMMUNICATIONS WORKSHOPS (INFOCOM WKSHPS). - : IEEE. - 9781728186955 ; , s. 918-923
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Konferensbidrag (refereegranskat)abstract
- We consider the problem of minimizing the time average cost of sampling and transmitting status updates by users over a wireless channel subject to average Age of Information constraints (AoI). Errors in the transmission may occur and the scheduling algorithm has to decide if the users sample a new packet or attempt for retransmission of the packet sampled previously. The cost consists of both sampling and transmission costs. The sampling of a new packet after a failure imposes an additional cost in the system. We formulate a stochastic optimization problem with time average cost in the objective under time average AoI constraints. To solve this problem, we apply tools from Lyapunov optimization theory and develop a dynamic algorithm that takes decisions in a slot-by-slot basis. The algorithm decides if a user: a) samples a new packet, b) transmits the old one, c) remains silent. We provide optimality guarantees of the algorithm and study its performance in terms of time average cost and AoI through simulation results.
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| 6. |
- Fountoulakis, Emmanouil, et al.
(författare)
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Resource Allocation for Heterogeneous Traffic with Power Consumption Constraints
- 2021
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Ingår i: IEEE CONFERENCE ON COMPUTER COMMUNICATIONS WORKSHOPS (IEEE INFOCOM WKSHPS 2021). - : IEEE. - 9781665404433 - 9781665447140
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Konferensbidrag (refereegranskat)abstract
- Future wireless networks will be characterized by users with heterogeneous requirements. Such users can require low-latency or minimum-throughput requirements. In addition, due to the limited-power budget of the mobile devices, a power-efficient scheduling scheme is required by the network. In this work, we cast a stochastic network optimization problem for minimizing the packet drop rate while guaranteeing a minimum throughput and taking into account the limited-power capabilities of the users.
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| 7. |
- Fountoulakis, Emmanouil, et al.
(författare)
-
Scheduling Policies for AoI Minimization With Timely Throughput Constraints
- 2023
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Ingår i: IEEE Transactions on Communications. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0090-6778 .- 1558-0857. ; 71:7, s. 3905-3917
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Tidskriftsartikel (refereegranskat)abstract
- In 5G and beyond communication systems, the notion of latency gets great momentum in wireless connectivity as a metric for serving real-time communications requirements. However, in many applications, research has pointed out that latency could be inefficient to handle applications with data freshness requirements. Recently, Age of Information (AoI) metric, which can capture the freshness of the data, has attracted a lot of attention. In this work, we consider mixed traffic with time-sensitive users; a deadline-constrained user, and an AoI-oriented user. To develop an efficient scheduling policy, we cast a novel optimization problem formulation for minimizing the average AoI while satisfying the timely throughput constraints. The formulated problem is cast as a Constrained Markov Decision Process (CMDP). We relax the constrained problem to an unconstrained Markov Decision Process (MDP) problem by utilizing the Lyapunov optimization theory and it can be proved that it is solved per frame by applying backward dynamic programming algorithms with optimality guarantees. In addition, we provide a low-complexity algorithm guaranteeing that the timely-throughput constraint is satisfied. Simulation results show that the timely throughput constraints are satisfied while minimizing the average AoI. Simulation results show the convergence of the algorithms for different values of the weighted factor and the trade-off between the AoI and the timely throughput.
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| 8. |
- He, Qing, 1979-, et al.
(författare)
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Optimal Scheduling for Emptying a Wireless Network : Solution Characterization, Applications, Including Deadline Constraints
- 2020
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Ingår i: IEEE Transactions on Information Theory. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9448 .- 1557-9654. ; 66:3, s. 1882-1892
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Tidskriftsartikel (refereegranskat)abstract
- Link scheduling, i.e., which links should transmit together and for how long, has been and remains a cornerstone optimization problem in wireless networking. In minimum-time scheduling, the task is to minimize the amount of time before emptying the data demand residing at the source nodes. We derive a complete structural characterization of the solution that unifies and significantly extends the known results. First, we approach link scheduling with a general system model without restrictions on the shape of the achievable rate region. Then, we give and prove a solution characterization of optimality that is conceptually simple yet powerful. We demonstrate several applications of this characterization for analysis of optimality and problem tractability. Next, we consider a significant extension by including deadline constraints, under which optimal scheduling becomes much more complex. Yet, we show how our formulation yields a solution description for that problem as well.
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| 9. |
- Kosta, Antzela, et al.
(författare)
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Non-linear Age of Information in a Discrete Time Queue: Stationary Distribution and Average Performance Analysis
- 2020
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Ingår i: ICC 2020 - 2020 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC). - : IEEE. - 9781728150895
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Konferensbidrag (refereegranskat)abstract
- This paper considers a status update communication system consisting of a source-destination link with timeliness requirements. First, we study the properties of a sample path of the age of information (AoI) process at the destination. Under the assumption of ergodicity, we obtain a general formula of the stationary distribution of the AoI. We relate this result to a discrete time queueing system and provide a general expression of the generating function of AoI in relation with the system time and the peak age of information (PAoI). Furthermore, we consider the first-come-first-served (FCFS) Geo/Geo/1 queue and we obtain closed-form expressions of the generating functions and the stationary distributions of the AoI and the PAoI. We built upon these results to provide a methodology for analyzing general non-linear age functions for this type of systems.
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| 10. |
- Kosta, Antzela, et al.
(författare)
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The Age of Information in a Discrete Time Queue : Stationary Distribution and Non-Linear Age Mean Analysis
- 2021
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Ingår i: IEEE Journal on Selected Areas in Communications. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0733-8716 .- 1558-0008. ; 39:5, s. 1352-1364
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we investigate information freshness in a status update communication system consisting of a source-destination link. Initially, we study the properties of a sample path of the age of information (AoI) process at the destination. We obtain a general formula of the stationary distribution of the AoI, under the assumption of ergodicity. We relate this result to a discrete time queueing system and provide a general expression of the generating function of AoI in relation with the system time and the peak age of information (PAoI) metric. Furthermore, we consider three different single-server system models and we obtain closed-form expressions of the generating functions and the stationary distributions of the AoI and the PAoI. The first model is a first-come-first-served (FCFS) queue, the second model is a preemptive last-come-first-served (LCFS) queue, and the last model is a bufferless system with packet dropping. We build upon these results to provide a methodology for analyzing general non-linear age functions for this type of systems, using representations of functions as power series.
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