{"title":"On Dynamic Regret and Constraint Violations in Constrained Online Convex Optimization","authors":"R. Vaze","doi":"10.23919/WiOpt56218.2022.9930613","DOIUrl":"https://doi.org/10.23919/WiOpt56218.2022.9930613","url":null,"abstract":"A constrained version of the online convex optimization (OCO) problem is considered. With slotted time, for each slot, first an action is chosen. Subsequently the loss function and the constraint violation penalty evaluated at the chosen action point is revealed. For each slot, both the loss function as well as the function defining the constraint set is assumed to be smooth and strongly convex. In addition, once an action is chosen, local information about a feasible set within a small neighborhood of the current action is also revealed. An algorithm is allowed to compute at most one gradient at its point of choice given the described feedback to choose the next action. The goal of an algorithm is to simultaneously minimize the dynamic regret (loss incurred compared to the oracle’s loss) and the constraint violation penalty (penalty accrued compared to the oracle’s penalty). We propose an algorithm that follows projected gradient descent over a suitably chosen set around the current action. We show that both the dynamic regret and the constraint violation is order-wise bounded by the path-length, the sum of the distances between the consecutive optimal actions. Moreover, we show that the derived bounds are the best possible.","PeriodicalId":228040,"journal":{"name":"2022 20th International Symposium on Modeling and Optimization in Mobile, Ad hoc, and Wireless Networks (WiOpt)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130288035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Energy-Optimal RAN Configurations for SWIPT IoT","authors":"G. Rizzo, M. Marsan, C. Esposito","doi":"10.23919/WiOpt56218.2022.9930622","DOIUrl":"https://doi.org/10.23919/WiOpt56218.2022.9930622","url":null,"abstract":"Internet of Things (IoT) devices often have batteries of limited capacity, which are not easily replaced or recharged. This implies very short device lifetimes, and calls for a very careful device configuration to achieve the optimal trade-off between performance and power consumption. SWIPT (Simultaneous Wireless Information and Power Transfer) deals with this problem by harvesting energy at IoT devices from the received RF signals. Studying the efficiency of SWIPT in dealing with the energy and data transfer demands of IoT nodes leads to a number of open issues. In this paper, we devise an analytical model based on stochastic geometry for a SWIPT radio access network with a dense population of IoT users. With our model, it is possible to accurately study the impact of the system parameters on the key system performance indicators, while accounting in a realistic manner for device performance, and for the statistics of time scheduling at base stations. This allows us to understand (not without some surprise) what are the most effective strategies to minimize energy consumption in a SWIPT network, and what is their potential for energy savings.","PeriodicalId":228040,"journal":{"name":"2022 20th International Symposium on Modeling and Optimization in Mobile, Ad hoc, and Wireless Networks (WiOpt)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126814245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Throughput and Energy Tradeoffs for Retransmission-based Random Access Protocols","authors":"Derya Malak","doi":"10.23919/WiOpt56218.2022.9930595","DOIUrl":"https://doi.org/10.23919/WiOpt56218.2022.9930595","url":null,"abstract":"The fifth-generation of wireless communication networks is required to support a range of use cases such as enhanced mobile broadband (eMBB), ultra-reliable, low-latency communications (URLLC), massive machine-type communications (mMTCs), with heterogeneous data rate, delay, and power requirements. The 4G LTE air interface is designed to support fewer devices with large payloads, and uses extra overhead to enable scheduled access, which is not justified for small payload sizes. In this paper, we employ a random access communication model with retransmissions for multiple users with small payloads at the low spectral efficiency regime. The radio resources are split non-orthogonally in the time and frequency dimensions. Retransmissions are combined via different Hybrid Automatic Repeat reQuest (HARQ) methods, namely Chase Combining and Incremental Redundancy with a finite buffer size constraint Cbuf, via a conventional matched filter receiver. We determine the best scaling of the spectral efficiency (SE) versus signal-to-noise ratio (SNR) ρ per bit and the scaling for the user density (number of users per real degrees of freedom, rdof) versus SNR per bit, for the sum-optimal regime and when the interference is treated as noise, using a Shannon capacity approximation. Numerical results show that the scaling results are applicable over a range of η, T, Cbuf, J, at low received SNR values. The proposed analytical framework can provide insights for resource allocation strategies in general random access systems and in specific 5G use cases for massive URLLC uplink access.","PeriodicalId":228040,"journal":{"name":"2022 20th International Symposium on Modeling and Optimization in Mobile, Ad hoc, and Wireless Networks (WiOpt)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127991084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Lower Bound on Load of Coded Caching Schemes for Finite Subpacketizations","authors":"Minquan Cheng, Youlong Wu","doi":"10.23919/WiOpt56218.2022.9930593","DOIUrl":"https://doi.org/10.23919/WiOpt56218.2022.9930593","url":null,"abstract":"Coded caching is a technique to create coded multicast opportunities for cache-aided networks. In coded caching problem, a fundamental but open question is: what is the minimum transmission load given any fixed subpacketization level? In this paper, we propose a lower bound on the transmission load for any fixed subpacketization by studying the combinatorial structure of corresponding placement delivery array, which was introduced by Yan et al. to reformulate the centralized coded caching schemes. Then we show that some schemes generated by the well known scheme proposed by Maddah-Ali and Niesen (MN), and some scheme generated by Packing (a classic concept of combinatorial design theory), can achieve our lower bound. This implies that our lower bound is tight for some cases.","PeriodicalId":228040,"journal":{"name":"2022 20th International Symposium on Modeling and Optimization in Mobile, Ad hoc, and Wireless Networks (WiOpt)","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131510852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Seyyidahmed Lahmer, A. Khoshsirat, M. Rossi, A. Zanella
{"title":"Energy Consumption of Neural Networks on NVIDIA Edge Boards: an Empirical Model","authors":"Seyyidahmed Lahmer, A. Khoshsirat, M. Rossi, A. Zanella","doi":"10.23919/WiOpt56218.2022.9930584","DOIUrl":"https://doi.org/10.23919/WiOpt56218.2022.9930584","url":null,"abstract":"Recently, there has been a trend of shifting the execution of deep learning inference tasks toward the edge of the network, closer to the user, to reduce latency and preserve data privacy. At the same time, growing interest is being devoted to the energetic sustainability of machine learning. At the intersection of these trends, in this paper we focus on the energetic characterization of machine learning at the edge, which is attracting increasing attention. Unfortunately, calculating the energy consumption of a given neural network during inference is complicated by the heterogeneity of the possible underlying hardware implementation. In this work, we aim at profiling the energetic consumption of inference tasks for some modern edge nodes by deriving simple but accurate models. To this end, we performed a large number of experiments to collect the energy consumption of fully connected and convolutional layers on two well-known edge boards by NVIDIA, namely, Jetson TX2 and Xavier. From these experimental measurements, we have then distilled a simple and practical model that can provide an estimate of the energy consumption of a certain inference task on these edge computers. We believe that this model can prove useful in many contexts as, for instance, to guide the search for efficient neural network architectures, as a heuristic in neural network pruning, to find energy-efficient offloading strategies in a split computing context, or to evaluate and compare the energy performance of deep neural network architectures.","PeriodicalId":228040,"journal":{"name":"2022 20th International Symposium on Modeling and Optimization in Mobile, Ad hoc, and Wireless Networks (WiOpt)","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133407238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Dual Gradient Descent EMF-Aware MU-MIMO Beamforming in RIS-Aided 6G Networks","authors":"Yi Yu, Rita Ibrahim, Dinh-Thuy Phan-Huy","doi":"10.23919/WiOpt56218.2022.9930548","DOIUrl":"https://doi.org/10.23919/WiOpt56218.2022.9930548","url":null,"abstract":"Reconfigurable Intelligent Surface (RIS) is one of the key technologies for the upcoming 6th Generation (6G) communications, which can improve the signal strength at the receivers by adding artificial propagation paths. In the context of Downlink (DL) Multi-User Multiple-Input Multiple-Output (MU-MIMO) communications, designing an appropriate Beamforming (BF) scheme to take full advantage of this reconfigured propagation environment and improve the network capacity is a major challenge. Due to the spatial dimension provided by MIMO systems, independent data streams can be transmitted to multiple users simultaneously on the same radio resources. It is important to note that serving the same subset of users over a period of time may lead to undesired areas where the average Electromagnetic Field Exposure (EMFE) exceeds regulatory limits. To address this challenge, in this paper, we propose a Dual Gradient Descent (Dual-GD)-based Electromagnetic Field (EMF)-aware MU-MIMO BF scheme that aims to optimize the overall capacity under EMFE constraints in RIS-aided 6G cellular networks.","PeriodicalId":228040,"journal":{"name":"2022 20th International Symposium on Modeling and Optimization in Mobile, Ad hoc, and Wireless Networks (WiOpt)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127519077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Online convex optimization in wireless networks and beyond: The feedback-performance trade-off","authors":"E. Belmega, P. Mertikopoulos, Romain Negrel","doi":"10.23919/WiOpt56218.2022.9930534","DOIUrl":"https://doi.org/10.23919/WiOpt56218.2022.9930534","url":null,"abstract":"The high degree of variability present in current and emerging mobile wireless networks calls for mathematical tools and techniques that transcend classical (convex) optimization paradigms. The aim of this short survey paper is to provide a gentle introduction to online learning and optimization algorithms that are able to provably cope with this variability and provide policies that are asymptotically optimal in hindsight-a property known as no regret. The focal point of this survey will be to delineate the trade-off between the information available as feedback to the learner, and the achievable regret guarantees starting with the case of gradient-based (first-order) feedback, then moving on to value-based (zeroth-order) feedback, and, ultimately, pushing the envelope to the extreme case of a single bit of feedback. We illustrate our theoretical analysis with a series of practical wireless network examples that highlight the potential of this elegant toolbox.","PeriodicalId":228040,"journal":{"name":"2022 20th International Symposium on Modeling and Optimization in Mobile, Ad hoc, and Wireless Networks (WiOpt)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129399123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Volume Spectral and Energy Efficiency of Ultra-Dense IoT Networks with Clustered Users","authors":"Hao Fu, T. O’Farrell","doi":"10.23919/WiOpt56218.2022.9930578","DOIUrl":"https://doi.org/10.23919/WiOpt56218.2022.9930578","url":null,"abstract":"The base station (BS) densification in Internet of Things (IoT) networks provides a viable pathway for enhancing network capacity to meet the ever increasing demand for data. Increasing the number of BSs also increases the energy consumption, which compromises the network energy efficiency (EE). This is important in 3 dimensional (3D) IoT deployments where volume spectral efficiency (VSE) and EE are key performance indicators (KPIs). In such networks, BS sleep modes provide an effective way to constrain both the interference and energy consumption, thereby improving the EE. In this paper, both the VSE and EE of a densified 3DIoT network are investigated when BS and UE counts follow independent 3D Homogeneous Poisson Point Process (HPPP) models and UEs are placed either uniformly or in clusters. The simulation results show that when unloaded BSs are turned off completely, including the backhaul, sufficiently densified 3DIoT networks can be made energy efficient.","PeriodicalId":228040,"journal":{"name":"2022 20th International Symposium on Modeling and Optimization in Mobile, Ad hoc, and Wireless Networks (WiOpt)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134045339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Aimi, F. Guillemin, Stéphane Rovedakis, Stefano Secci
{"title":"Traffic Control and Channel Assignment for Quality Differentiation in Dense Urban LoRaWANs","authors":"A. Aimi, F. Guillemin, Stéphane Rovedakis, Stefano Secci","doi":"10.23919/WiOpt56218.2022.9930551","DOIUrl":"https://doi.org/10.23919/WiOpt56218.2022.9930551","url":null,"abstract":"Service quality differentiation is gaining popularity in IoT networks, notably in LoRaWAN, with the rapid widespread of applications on connected devices. There is clearly a business demand for quality in IoT in the context of smart cities and network operators are urged by application designer to offer quality differentiation. However, those types of networks have been designed on the basis of a best effort service model. In particular, Packet Delivery Ratio (PDR) can dramatically decrease in dense scenarios. In this paper, we propose and evaluate traffic control and channel assignment solutions for PDR differentiation in dense deployments. Several performance criteria are defined in order to analyze the gain achieved by a network operator as well as end users. Numerical results show that both players can benefit from quality differentiation with ad-hoc pricing. This proves to be effective if penalizing low requirement devices, as they can create a bottleneck in the system. Namely, we show that in high density settings we can reach a 20% better PDR with one of the proposed policies, improving mean device servicing rate by 10% and the operator gain by 7.5%.","PeriodicalId":228040,"journal":{"name":"2022 20th International Symposium on Modeling and Optimization in Mobile, Ad hoc, and Wireless Networks (WiOpt)","volume":"100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134137395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Haßlinger, K. Ntougias, Frank Hasslinger, O. Hohlfeld
{"title":"Analysis of the LRU Cache StartUp Phase and Convergence Time and Error Bounds on Approximations by Fagin and Che","authors":"G. Haßlinger, K. Ntougias, Frank Hasslinger, O. Hohlfeld","doi":"10.23919/WiOpt56218.2022.9930556","DOIUrl":"https://doi.org/10.23919/WiOpt56218.2022.9930556","url":null,"abstract":"We compare exact and approximate performance evaluation methods of the Least Recently Used (LRU) caching strategy, which is widely applied in local caches and in distributed web cache architectures in core and edge networks. Based on the independent reference model (IRM), the LRU startup behaviour and convergence time (CT) is derived. The result is related to hit ratio approximations by Fagin and Che et al. We evaluate the precision of the approximations by identifying maximum errors, which are shown to decrease with the cache size. For different object sizes, we extend the analytical LRU hit ratio formula, which is tractable for small caches. The Che and CT approximations are subject to larger deviations for high variability of the object sizes and small caches due to partially unused cache space. We propose an estimation scheme for the fraction of unused LRU cache space, which is shown to improve the accuracy.","PeriodicalId":228040,"journal":{"name":"2022 20th International Symposium on Modeling and Optimization in Mobile, Ad hoc, and Wireless Networks (WiOpt)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126700118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}