Papers by Arvind Merwaday
Integrating Sensing Into Cellular Systems: Architectural Requirements and Performance Enhancements
IEEE vehicular technology magazine, 2024
arXiv (Cornell University), Jun 26, 2015
In wireless cellular networks with densely deployed base stations, knowing the velocities of mobi... more In wireless cellular networks with densely deployed base stations, knowing the velocities of mobile devices is a key to avoid call drops and improve the quality of service to the user equipments (UEs). A simple and efficient way to estimate a UE's velocity is by counting the number of handovers made by the UE during a predefined time window. Indeed, handover-count based mobility state detection has been standardized since Long Term Evolution (LTE) Release-8 specifications. The increasing density of small cells in wireless networks can help in accurate estimation of velocity and mobility state of a UE. In this paper, we model densely deployed small cells using stochastic geometry, and then analyze the statistics of the number of handovers as a function of UE velocity, small-cell density, and handover count measurement time window. Using these statistics, we derive approximations to the Cramer-Rao lower bound (CRLB) for the velocity estimate of a UE. Also, we determine a minimum variance unbiased (MVU) velocity estimator whose variance tightly matches with the CRLB. Using this velocity estimator, we formulate the problem of detecting the mobility state of a UE as low, medium, or high-mobility, as in LTE specifications. Subsequently, we derive the probability of correctly detecting the mobility state of a UE. Finally, we evaluate the accuracy of the velocity estimator under more realistic scenarios such as clustered deployment of small cells, random way point (RWP) mobility model for UEs, and variable UE velocity. Our analysis shows that the accuracy of velocity estimation and mobility state detection increases with increasing small cell density and with increasing handover count measurement time window.
Handover Count Based UE Velocity Estimation in Hyper-Dense Heterogeneous Wireless Networks
In wireless cellular networks with densely deployed base stations, knowing the velocities of the ... more In wireless cellular networks with densely deployed base stations, knowing the velocities of the user equipments (UEs) is a key for efficient mobility management. A simple and efficient way to estimate a UE's velocity is by counting the number of handovers made by the UE during a predefined time window. Indeed, handover-count based mobility state detection has been standardized since Long Term Evolution (LTE) Release-8 specifications. The increasing density of small cells in wireless networks is advantageous, as it can help in accurate estimation of velocity and mobility state of a UE. In this paper, we model densely deployed small cells using stochastic geometry, and derive an approximation to the probability mass function of handover count as a function of UE velocity, small cell density, and time interval of handover count measurement. Then we derive Cramer-Rao lower bound (CRLB) for the velocity estimate of a UE, and also provide an unbiased estimator for the UE's velocity. Our analysis shows that the accuracy of velocity estimation increases with increasing small cell density and with increasing time interval of handover count measurement.
In recent years, the increase in the population of mobile users and the advances in computational... more In recent years, the increase in the population of mobile users and the advances in computational capabilities of mobile devices have led to an exponentially increasing traffic load on the wireless networks. This trend is foreseen to continue in the future due to the emerging applications such as cellular Internet of things (IoT) and machine type communications (MTC). Since the spectrum resources are limited, the only promising way to keep pace with the future demand is through aggressive spatial reuse of the available spectrum which can be realized in the networks through dense deployment of small cells. There are many challenges associated with such densely deployed heterogeneous networks (HetNets). The main challenges which are considered in this research work are capacity enhancement, velocity estimation of mobile users, and energy efficiency enhancement. We consider different approaches for capacity enhancement of the network. In the first approach, using stochastic geometry we theoretically analyze time domain inter-cell interference coordination techniques in a two-tier HetNet and optimize the parameters to maximize the capacity of the network. In the second approach, we consider optimization of the locations of aerial bases stations carried by the unmanned aerial vehicles (UAVs) to enhance the capacity of the network for public safety and emergency communications, in case of damaged network infrastructure. In the third approach, we introduce a subsidization scheme for the service providers through which the network capacity can be improved by using regulatory power of the government. Finally, we consider the approach of device-todevice communications and multi-hop transmissions for enhancing the capacity of a network. v Velocity estimation of high speed mobile users is important for effective mobility management in densely deployed small cell networks. In this research, we introduce two novel methods for the velocity estimation of mobile users: handover-count based velocity estimation, and sojourn time based velocity estimation. Using the tools from stochastic geometry and estimation theory, we theoretically analyze the accuracy of the two velocity estimation methods through Cramer-Rao lower bounds (CRLBs). With the dense deployment of small cells, energy efficiency becomes crucial for the sustained operation of wireless networks. In this research, we jointly study the energy efficiency and the spectral efficiency in a two-tier HetNet. We optimize the parameters of inter-cell interference coordination technique and study the trade-offs between the energy efficiency and spectral efficiency of the HetNet. vi USRP universal software radio peripheral Wireless Fidelity
On the performance of directional communications in ultra-dense networks
Extreme densification of base stations is imminent in the next generation of cellular networks to... more Extreme densification of base stations is imminent in the next generation of cellular networks to meet the exponentially increasing demand for mobile data traffic. In such ultra-dense networks (UDNs), the remarkably high inter-cell interference can reduce or even negate the densification gain. On the other hand, directional communications can significantly bring down the interference levels in UDNs. Hence, it is of importance to evaluate the network performance of UDNs with directional communications. Through Monte Carlo simulations, this paper analyzes the characteristics of coverage probability, area spectral efficiency (ASE), and per-user throughput with respect to extreme network densification. Our simulation results show that directional communications can deliver significantly higher network performance with tens of times higher ASE when compared to non-directional communications in UDNs.
Electronics Letters, May 1, 2016
Until recently, spectral efficiency (SE) has been considered as the major key performance indicat... more Until recently, spectral efficiency (SE) has been considered as the major key performance indicator of cellular networks. Nowadays, green evolution is becoming a major trend and the telecom industry is concerned about the energy costs and carbon footprint of their network infrastructure. These concerns will get more critical in the future due to the increasing base station densities. In such a scenario, minimising the network energy consumption while maximising the data sent to the users becomes crucial for the sustained operation of the network. In this letter, stochastic geometry is used to analyse the energy efficiency (EE) and SE in a two-tier long-term evolution-advanced heterogeneous network (HetNet). Range expansion and further-enhanced inter-cell interference coordination which have been standardised in third generation partnership project Release-11 are considered. System parameters of the HetNet are optimised and the trade-offs associated between EE and SE of the network are studied.
Sojourn Time-Based Velocity Estimation in Small Cell Poisson Networks
IEEE Communications Letters, Feb 1, 2016
Due to the increasing density of small cells, mobility management in heterogeneous networks has b... more Due to the increasing density of small cells, mobility management in heterogeneous networks has become a challenging task. One key challenge facing the development of advanced mobility management techniques is the accurate estimation of the users' velocity. One simple way to estimate a user's velocity is via the use of sojourn time samples. In this letter, the Cramer-Rao lower bound (CRLB) for the sojourn time-based velocity estimation is analyzed. Stochastic geometry is used for the spatial modeling of small cells, and the CRLB is derived using the tools from estimation theory. An asymptotically unbiased velocity estimator is also derived. Our analysis shows that the sojourn time-based velocity estimation exhibit a lower CRLB compared to the CRLB of classical velocity estimation using handover count.
UAV assisted heterogeneous networks for public safety communications
Communications play an important role during public safety operations. Since the current communic... more Communications play an important role during public safety operations. Since the current communication technologies heavily rely on the backbone network, the failure of base stations (BSs) due to natural disasters or malevolent attacks causes communication difficulties for public safety and emergency communications. Recently, the use of unmanned aerial vehicles (UAVs) such as quadcopters and unmanned gliders have gained attention in public safety communications. They can be used as unmanned aerial base stations (UABSs), which can be deployed rapidly as a part of the heterogeneous network architecture. However, due to their mobile characteristics, interference management in the network becomes very challenging. In this paper, we explore the use of UABSs for public safety communications during natural disasters, where part of the communication infrastructure becomes damaged and dysfunctional (e.g., as in the aftermath of the 2011 earthquake and tsunami in Japan). Through simulations, we analyze the throughput gains that can be obtained by exploiting the mobility feature of the UAVs. Our simulation results show that when there is loss of network infrastructure, the deployment of UABSs at optimized locations can improve the throughput coverage and the 5th percentile spectral efficiency of the network. Furthermore, the improvement is observed to be more significant with higher path-loss exponents.
Demo: Infrastructure Assisted Efficient Collective Perception Service for Connected Vehicles
Collective Perception Services (CPS) provided by roadside infrastructure is a promising way to ex... more Collective Perception Services (CPS) provided by roadside infrastructure is a promising way to extend the environment perception range of vehicles beyond their embedded sensors. However, sharing the perceived lists of objects can result in unacceptably high communication overhead, when the number of objects is large. We propose a Layered Costmap based novel perception sharing protocol to enable an overhead-efficient CPS, specifically in cases with many objects, such as crowded intersections. We demonstrate a CARLA-based collaborative autonomous vehicle simulation platform with realistic vehicular communications model, and evaluate costmap-based and object-list-based CPS in a T-junction scenario. Simulation results show that CPS from roadside infrastructure can significantly increase the perception coverage by 2.2x for T-junction scenario compared to on-board sensors’ perception. Moreover, layered costmap-based CPS outperforms object list-based CPS in efficiency enabling more than one order of magnitude overhead reduction for 40 or higher perceived objects.
Communication-Control Co-design for Robotic Manipulation in 5G Industrial IoT
2023 IEEE 21st International Conference on Industrial Informatics (INDIN)
On the performance of directional communications in ultra-dense networks
2017 IEEE International Conference on Communications Workshops (ICC Workshops), 2017
Extreme densification of base stations is imminent in the next generation of cellular networks to... more Extreme densification of base stations is imminent in the next generation of cellular networks to meet the exponentially increasing demand for mobile data traffic. In such ultra-dense networks (UDNs), the remarkably high inter-cell interference can reduce or even negate the densification gain. On the other hand, directional communications can significantly bring down the interference levels in UDNs. Hence, it is of importance to evaluate the network performance of UDNs with directional communications. Through Monte Carlo simulations, this paper analyzes the characteristics of coverage probability, area spectral efficiency (ASE), and per-user throughput with respect to extreme network densification. Our simulation results show that directional communications can deliver significantly higher network performance with tens of times higher ASE when compared to non-directional communications in UDNs.
Handover Count Based UE Velocity Estimation in Hyper-Dense Heterogeneous Wireless Networks
2015 IEEE Globecom Workshops (GC Wkshps), 2015
In wireless cellular networks with densely deployed base stations, knowing the velocities of the ... more In wireless cellular networks with densely deployed base stations, knowing the velocities of the user equipments (UEs) is a key for efficient mobility management. A simple and efficient way to estimate a UE's velocity is by counting the number of handovers made by the UE during a predefined time window. Indeed, handover-count based mobility state detection has been standardized since Long Term Evolution (LTE) Release-8 specifications. The increasing density of small cells in wireless networks is advantageous, as it can help in accurate estimation of velocity and mobility state of a UE. In this paper, we model densely deployed small cells using stochastic geometry, and derive an approximation to the probability mass function of handover count as a function of UE velocity, small cell density, and time interval of handover count measurement. Then we derive Cramer-Rao lower bound (CRLB) for the velocity estimate of a UE, and also provide an unbiased estimator for the UE's velocity. Our analysis shows that the accuracy of velocity estimation increases with increasing small cell density and with increasing time interval of handover count measurement.
Abstract—Traditional regulatory methods for spectrum licens-ing have been recently identified as ... more Abstract—Traditional regulatory methods for spectrum licens-ing have been recently identified as one of the causes for the under-utilization of the valuable radio spectrum. Governmental agencies such as the Federal Communications Commission (FCC) are seeking ways to remove stringent regulatory barriers and facilitate broader access to the spectrum resources. The goal is to allow for an improved and ubiquitous sharing of the precious radio spectrum between commercial service providers. In this paper, we propose a novel noncooperative game theo-retic approach, to show how to foster more sharing of the radio spectrum via the use of regulatory power. We define a two stage game in which the government regulators move first, followed by the providers. The providers are incentivized by lower spectrum allocation fees from the regulators in return for proof-of-sharing. The providers are offered discounted spectrum bands, potentially at different locations, but will be asked to provide covera...
Demo: Infrastructure Assisted Efficient Collective Perception Service for Connected Vehicles
2021 IEEE Vehicular Networking Conference (VNC), 2021
Collective Perception Services (CPS) provided by roadside infrastructure is a promising way to ex... more Collective Perception Services (CPS) provided by roadside infrastructure is a promising way to extend the environment perception range of vehicles beyond their embedded sensors. However, sharing the perceived lists of objects can result in unacceptably high communication overhead, when the number of objects is large. We propose a Layered Costmap based novel perception sharing protocol to enable an overhead-efficient CPS, specifically in cases with many objects, such as crowded intersections. We demonstrate a CARLA-based collaborative autonomous vehicle simulation platform with realistic vehicular communications model, and evaluate costmap-based and object-list-based CPS in a T-junction scenario. Simulation results show that CPS from roadside infrastructure can significantly increase the perception coverage by 2.2x for T-junction scenario compared to on-board sensors’ perception. Moreover, layered costmap-based CPS outperforms object list-based CPS in efficiency enabling more than one order of magnitude overhead reduction for 40 or higher perceived objects.
Methods and Apparatus to Perform Beam Selection for Wireless Communication
MISO- V: Misbehavior Detection for Collective Perception Services in Vehicular Communications
2021 IEEE Intelligent Vehicles Symposium (IV), 2021
Recently, Collective Perception Messages (CPM) that carry additional information about the surrou... more Recently, Collective Perception Messages (CPM) that carry additional information about the surrounding environment beyond Basic Safety Messages (BSM) or Cooperative Awareness Messages (CAM) have been proposed to increase the situational awareness for Connected and Automated Vehicles (CAV) in Intelligent Transportation Systems. However, blindly trusting perception information from neighbors that cannot be locally verified is dangerous given the safety impact that erroneous or malicious information might have. This paper addresses the data trust challenge of CPMs, proposing a misbehavior detection scheme called MISO- V (Multiple Independent Sources of Observations over V2X) that leverages the inherently overlapping nature of the perception observations from multiple vehicles to verify the semantic correctness of the V2X data and improve the data trust and robustness of V2X systems. CPM-enabled CAVs are implemented and MISO-V performance is evaluated in CARLA-based simulation tool, where falsified V2X packets presenting a ghost car are injected in a suburban T-junction scenario with other cars. The results show that MISO- V is very effective in detecting the ghost car attacks and removing the impact of such misbehavior from influencing the receiver and offers a conservative and sensible approach towards trustworthy Collective Perception Services for CAV s.
UAV-assisted edge infrastructure for challenged networks
2017 IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), 2017
Challenged Networks (CNs) are characterized by frequent varying network conditions and intermitte... more Challenged Networks (CNs) are characterized by frequent varying network conditions and intermittent connectivity. In general, CNs emerge in different scenarios including the disaster and emergency situations when the traditional cellular infrastructure is dysfunctional or unavailable as well as in the undeserved areas such as rural and developing regions. This paper aims to evaluate the performance of a mobile edge infrastructure adopting Unmanned Aerial Vehicles (UAVs) for CN scenarios. Specifically, we assume that the UAVs can host micro Base Stations (BSs) and edge computing resources, which can be dynamically moved over the zones where the terrestrial mobile network is not properly working. After presenting the proposed UAV-mounted edge architecture, we propose a simple model to evaluate the performance in terms of coverage to users. Our preliminary results show that the UAV-based mobile edge architecture can guarantee a good coverage to users, even if the number of traditional BSs that are not working correctly is large.
In recent years, the increase in the population of mobile users and the advances in computational... more In recent years, the increase in the population of mobile users and the advances in computational capabilities of mobile devices have led to an exponentially increasing traffic load on the wireless networks. This trend is foreseen to continue in the future due to the emerging applications such as cellular Internet of things (IoT) and machine type communications (MTC). Since the spectrum resources are limited, the only promising way to keep pace with the future demand is through aggressive spatial reuse of the available spectrum which can be realized in the networks through dense deployment of small cells. There are many challenges associated with such densely deployed heterogeneous networks (HetNets). The main challenges which are considered in this research work are capacity enhancement, velocity estimation of mobile users, and energy efficiency enhancement. We consider different approaches for capacity enhancement of the network. In the first approach, using stochastic geometry we theoretically analyze time domain inter-cell interference coordination techniques in a two-tier HetNet and optimize the parameters to maximize the capacity of the network. In the second approach, we consider optimization of the locations of aerial bases stations carried by the unmanned aerial vehicles (UAVs) to enhance the capacity of the network for public safety and emergency communications, in case of damaged network infrastructure. In the third approach, we introduce a subsidization scheme for the service providers through which the network capacity can be improved by using regulatory power of the government. Finally, we consider the approach of device-todevice communications and multi-hop transmissions for enhancing the capacity of a network. v Velocity estimation of high speed mobile users is important for effective mobility management in densely deployed small cell networks. In this research, we introduce two novel methods for the velocity estimation of mobile users: handover-count based velocity estimation, and sojourn time based velocity estimation. Using the tools from stochastic geometry and estimation theory, we theoretically analyze the accuracy of the two velocity estimation methods through Cramer-Rao lower bounds (CRLBs). With the dense deployment of small cells, energy efficiency becomes crucial for the sustained operation of wireless networks. In this research, we jointly study the energy efficiency and the spectral efficiency in a two-tier HetNet. We optimize the parameters of inter-cell interference coordination technique and study the trade-offs between the energy efficiency and spectral efficiency of the HetNet. vi USRP universal software radio peripheral Wireless Fidelity
IEEE Transactions on Wireless Communications, 2016
In wireless cellular networks with densely deployed base stations, knowing the velocities of mobi... more In wireless cellular networks with densely deployed base stations, knowing the velocities of mobile devices is a key to avoid call drops and improve the quality of service to the user equipments (UEs). A simple and efficient way to estimate a UE's velocity is by counting the number of handovers made by the UE during a predefined time window. Indeed, handover-count based mobility state detection has been standardized since Long Term Evolution (LTE) Release-8 specifications. The increasing density of small cells in wireless networks can help in accurate estimation of velocity and mobility state of a UE. In this paper, we model densely deployed small cells using stochastic geometry, and then analyze the statistics of the number of handovers as a function of UE velocity, small-cell density, and handover count measurement time window. Using these statistics, we derive approximations to the Cramer-Rao lower bound (CRLB) for the velocity estimate of a UE. Also, we determine a minimum variance unbiased (MVU) velocity estimator whose variance tightly matches with the CRLB. Using this velocity estimator, we formulate the problem of detecting the mobility state of a UE as low, medium, or high-mobility, as in LTE specifications. Subsequently, we derive the probability of correctly detecting the mobility state of a UE. Finally, we evaluate the accuracy of the velocity estimator under more realistic scenarios such as clustered deployment of small cells, random way point (RWP) mobility model for UEs, and variable UE velocity. Our analysis shows that the accuracy of velocity estimation and mobility state detection increases with increasing small cell density and with increasing handover count measurement time window.
IEEE Vehicular Technology Magazine, 2016
||| 53 C ommunications play an important role during public-safety operations. Because the curren... more ||| 53 C ommunications play an important role during public-safety operations. Because the current communication technologies heavily rely on the backbone network, the failure of base stations (BSs) due to natural disasters or malevolent attacks causes communication difficulties for public-safety and emergency communications. Recently, the use of unmanned aerial vehicles (UAVs), such as quadcopters and gliders, has gained attention in publicsafety communications (PSCs). They can be operated as unmanned image licensed by ingram publishing
Uploads
Papers by Arvind Merwaday