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See detailTowards Massive Machine Type Communications in Ultra-Dense Cellular IoT Networks: Current Issues and Machine Learning-Assisted Solutions
Sharma, Shree Krishna UL; Wang, Xianbin

in IEEE Communications Surveys and Tutorials (2019)

The ever-increasing number of resource-constrained Machine-Type Communication (MTC) devices is leading to the critical challenge of fulfilling diverse communication requirements in dynamic and ultra-dense ... [more ▼]

The ever-increasing number of resource-constrained Machine-Type Communication (MTC) devices is leading to the critical challenge of fulfilling diverse communication requirements in dynamic and ultra-dense wireless environments. Among different application scenarios that the upcoming 5G and beyond cellular networks are expected to support, such as enhanced Mobile Broadband (eMBB), massive Machine Type Communications (mMTC) and Ultra-Reliable and Low Latency Communications (URLLC), the mMTC brings the unique technical challenge of supporting a huge number of MTC devices in cellular networks, which is the main focus of this paper. The related challenges include Quality of Service (QoS) provisioning, handling highly dynamic and sporadic MTC traffic, huge signalling overhead and Radio Access Network (RAN) congestion. In this regard, this paper aims to identify and analyze the involved technical issues, to review recent advances, to highlight potential solutions and to propose new research directions. First, starting with an overview of mMTC features and QoS provisioning issues, we present the key enablers for mMTC in cellular networks. Along with the highlights on the inefficiency of the legacy Random Access (RA) procedure in the mMTC scenario, we then present the key features and channel access mechanisms in the emerging cellular IoT standards, namely, LTE-M and Narrowband IoT (NB-IoT). Subsequently, we present a framework for the performance analysis of transmission scheduling with the QoS support along with the issues involved in short data packet transmission. Next, we provide a detailed overview of the existing and emerging solutions towards addressing RAN congestion problem, and then identify potential advantages, challenges and use cases for the applications of emerging Machine Learning (ML) techniques in ultra-dense cellular networks. Out of several ML techniques, we focus on the application of low-complexity Q-learning approach in the mMTC scenario along with the recent advances towards enhancing its learning performance and convergence. Finally, we discuss some open research challenges and promising future research directions. [less ▲]

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See detailCollaborative Distributed Q-Learning for RACH Congestion Minimization in Cellular IoT Networks
Sharma, Shree Krishna UL; Wang, Xianbin

in IEEE Communications Letters (2019), 23(4), 600-603

Due to infrequent and massive concurrent access requests from the ever-increasing number of machine-type communication (MTC) devices, the existing contention-based random access (RA) protocols, such as ... [more ▼]

Due to infrequent and massive concurrent access requests from the ever-increasing number of machine-type communication (MTC) devices, the existing contention-based random access (RA) protocols, such as slotted ALOHA, suffer from the severe problem of random access channel (RACH) congestion in emerging cellular IoT networks. To address this issue, we propose a novel collaborative distributed Q-learning mechanism for the resource-constrained MTC devices in order to enable them to find unique RA slots for their transmissions so that the number of possible collisions can be significantly reduced. In contrast to the independent Q-learning scheme, the proposed approach utilizes the congestion level of RA slots as the global cost during the learning process and thus can notably lower the learning time for the low-end MTC devices. Our results show that the proposed learning scheme can significantly minimize the RACH congestion in cellular IoT networks. [less ▲]

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See detailDevice Grouping for Fast and Efficient Channel Access in IEEE 802.11ah based IoT Networks
Bhandari, Sabin; Sharma, Shree Krishna UL; Wang, Xianbin

in Proc. IEEE Int. Conf. Communications 2018 (2018, July)

The recent advances in Internet of Things (IoT) have led to numerous emerging applications ranging from eHealthcare to industrial control, which often demand stringent Quality of Service (QoS ... [more ▼]

The recent advances in Internet of Things (IoT) have led to numerous emerging applications ranging from eHealthcare to industrial control, which often demand stringent Quality of Service (QoS) requirements such as low-latency and high system reliability. However, the ever-increasing number of connected devices in ultra-dense IoT networks and the dynamic traffic patterns increase the channel access delay and packet collision rate. In this regard, this paper proposes a sector-based device grouping scheme for fast and efficient channel access in IEEE 802.11ah based IoT networks such that the total number of the connected devices within each sector is dramatically reduced. In the proposed framework, the Access Point (AP) divides its coverage area into different sectors, and then each sector is further divided into distinct groups based on the number of devices and their location information available from the cloud-center. Subsequently, individual groups within a sector are assigned to specific Random Access Window (RAW) slots, and the devices within distinct groups in different sectors access the allocated RAW slots by employing a spatial orthogonal access mechanism. The performance of the proposed sectorized device grouping scheme has been analyzed in terms of system delay and network throughput. Our simulation results show that the proposed scheme can significantly enhance the network throughput while simultaneously decreasing the system delay as compared to the conventional Distributed Coordination Function (DCF) and IEEE 802.11ah grouping scheme. [less ▲]

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See detailDistributed Caching Enabled Peak Traffic Reduction in Ultra-Dense IoT Networks
Sharma, Shree Krishna UL; Wang, Xianbin

in IEEE Communications Letters (2018), 22(6), 1252-1255

The proliferation of massive machine-type communications devices and their random and intermittent transmissions have brought the new challenge of sporadic access-network congestion in ultra-dense ... [more ▼]

The proliferation of massive machine-type communications devices and their random and intermittent transmissions have brought the new challenge of sporadic access-network congestion in ultra-dense Internet of Things (IoT) networks. To address this issue, we propose an innovative approach of peak traffic reduction within the access network by utilizing distributed cache of IoT devices to coordinate their sporadic transmissions. The proposed technique is realized by employing a novel uplink transmission scheduling based on delay adaptation, in which distributed IoT devices adjust their transmission timings by utilizing embedded caching. An optimization problem is formulated for the minimization of peak data rate demand subject to delay tolerance levels, and is solved for the 3GPP-based traffic models by employing a gradient descent-based algorithm. Our results show that the proposed scheme can significantly reduce the peak data traffic in ultra-dense IoT networks. [less ▲]

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See detailCooperative sensing delay minimization in cloud-assisted DSA networks
Sharma, Shree Krishna UL; Wang, Xianbin

in Proc. IEEE PIMRC 2017 (2018, February 15)

Dynamic Spectrum Access (DSA) is considered as a promising solution to address the problem of spectrum scarcity in future wireless networks. However, the main challenges associated with this approach are ... [more ▼]

Dynamic Spectrum Access (DSA) is considered as a promising solution to address the problem of spectrum scarcity in future wireless networks. However, the main challenges associated with this approach are to acquire accurate spectrum usage information in a timely manner and to deal with the dynamicity of channel occupancy. Although Cooperative Sensing (CS) can provide significant advantages over individual device-level sensing in terms of sensing efficiency and the achievable throughput, the acquired channel occupancy information may become outdated in dynamic channel conditions due to the involved latency. In this regard, we propose to utilize a collaborative cloud-edge processing framework to minimize the CS delay in DSA networks. In this framework, the cloud-center can estimate channel occupancy parameters such as duty cycle based on the available historical sensing data by using a suitable spectrum prediction technique, and subsequently this prior knowledge can be utilized to adapt the sensing mechanism employed at the edge-side of a DSA network. Motivated by this, we formulate and solve the problem of minimizing CS delay in cloud-assisted DSA networks. A two-stage bisection search method is employed to solve this CS delay minimization problem. Our results show that the proposed cloud-assisted CS scheme can significantly reduce the CS delay in DSA networks. [less ▲]

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See detailLatency Minimization in Wireless IoT Using Prioritized Channel Access and Data Aggregation
Bhandari, Sabin; Sharma, Shree Krishna UL; Wang, Xianbin

in Proc. IEEE Global Communications (GLOBECOM) Conf. 2018 (2018, January)

Future Internet of Things (IoT) networks are expected to support a massive number of heterogeneous devices/sensors in diverse applications ranging from eHealthcare to industrial control systems. In highly ... [more ▼]

Future Internet of Things (IoT) networks are expected to support a massive number of heterogeneous devices/sensors in diverse applications ranging from eHealthcare to industrial control systems. In highly-dense deployment scenarios such as industrial IoT systems, providing reliable communication links with low-latency becomes challenging due to the involved system delay including data acquisition and processing latencies at the edge-side of IoT networks. In this regard, this paper proposes a priority-based channel access and data aggregation scheme at the Cluster Head (CH) to reduce channel access and queuing delays in a clustered industrial IoT network. First, a prioritized channel access mechanism is developed by assigning different Medium Access Control (MAC) layer attributes to the packets coming from two types of IoT nodes, namely, high-priority and low-priority nodes, based on the application-specific information provided from the cloud-center. Subsequently, a preemptive M/G/1 queuing model is employed by using separate low-priority and high- priority queues before sending aggregated data to the Cloud. Our results show that the proposed priority-based method significantly improves the system latency and reliability as compared to the non-prioritized scheme. [less ▲]

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See detailDynamic Spectrum Sharing in 5G Wireless Networks With Full-Duplex Technology: Recent Advances and Research Challenges
Sharma, Shree Krishna UL; Bogale, Tadilo Endeshaw; le, Long Bao et al

in IEEE Communications Surveys and Tutorials (2018), 20(1), 674-707

Full-duplex (FD) wireless technology enables a radio to transmit and receive on the same frequency band at the same time, and it is considered to be one of the candidate technologies for the fifth ... [more ▼]

Full-duplex (FD) wireless technology enables a radio to transmit and receive on the same frequency band at the same time, and it is considered to be one of the candidate technologies for the fifth generation (5G) and beyond wireless communication systems due to its advantages, including potential doubling of the capacity and increased spectrum utilization efficiency. However, one of the main challenges of FD technology is the mitigation of strong self-interference (SI). Recent advances in different SI cancellation techniques, such as antenna cancellation, analog cancellation, and digital cancellation methods, have led to the feasibility of using FD technology in different wireless applications. Among potential applications, one important application area is dynamic spectrum sharing (DSS) in wireless systems particularly 5G networks, where FD can provide several benefits and possibilities such as concurrent sensing and transmission (CST), concurrent transmission and reception, improved sensing efficiency and secondary throughput, and the mitigation of the hidden terminal problem. In this direction, first, starting with a detailed overview of FD-enabled DSS, we provide a comprehensive survey of recent advances in this domain. We then highlight several potential techniques for enabling FD operation in DSS wireless systems. Subsequently, we propose a novel communication framework to enable CST in DSS systems by employing a power control-based SI mitigation scheme and carry out the throughput performance analysis of this proposed framework. Finally, we discuss some open research issues and future directions with the objective of stimulating future research efforts in the emerging FD-enabled DSS wireless systems. [less ▲]

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See detailMulti-antenna based one-bit spatio-temporal wideband sensing for cognitive radio networks
Merlano Duncan, Juan Carlos UL; Sharma, Shree Krishna UL; Chatzinotas, Symeon UL et al

in Proceedings of IEEE International Conference on Communications (ICC) 2017 (2017, July 31)

Cognitive Radio (CR) communication has been considered as one of the promising technologies to enable dynamic spectrum sharing in the next generation of wireless networks. Among several possible enabling ... [more ▼]

Cognitive Radio (CR) communication has been considered as one of the promising technologies to enable dynamic spectrum sharing in the next generation of wireless networks. Among several possible enabling techniques, Spectrum Sensing (SS) is one of the key aspects for enabling opportunistic spectrum access in CR Networks (CRN). From practical perspectives, it is important to design low-complexity wideband CR receiver having low resolution Analog to Digital Converter (ADC) working at a reasonable sampling rate. In this context, this paper proposes a novel spatio-temporal wideband SS technique by employing multiple antennas and one-bit quantization at the CR node, which subsequently enables the use of a reasonable sampling rate. In our analysis, we show that for the same sensing performance requirements, the proposed wideband receiver can have lower power consumption than the conventional CR receiver equipped with a single-antenna and a high-resolution ADC. Furthermore, the proposed technique exploits the spatial dimension by estimating the direction of arrival of Primary User (PU) signals, which is not possible by the conventional SS methods and can be of a significant benefit in a CRN. Moreover, we evaluate the performance of the proposed technique and analyze the effects of one-bit quantization with the help of numerical results. [less ▲]

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See detailImpact of residual transceiver impairments on MMSE filtering performance of Rayleigh-product MIMO channels
Sharma, Shree Krishna UL; Papazafeiropoulos, Anastasios; Chatzinotas, Symeon UL et al

in Proc. IEEE International Workshop on Signal Processing Advances in Wireless Communications (SPAWC 2017) (2017, July)

ecent studies have demonstrated the presence of residual transceiver hardware impairments even after employing calibration and compensation techniques in different wireless systems. The effect of these ... [more ▼]

ecent studies have demonstrated the presence of residual transceiver hardware impairments even after employing calibration and compensation techniques in different wireless systems. The effect of these impairments becomes more severe in the systems involving a large number of inexpensive Radio Frequency (RF) chains such as massive Multiple Input Multiple Output (MIMO) systems due to the requirement of cost-efficient implementation. However, most of the existing studies consider ideal transceivers without incorporating the effect of residual hardware impairments. In this regard, this paper studies the impact of additive residual transceiver hardware impairments on the Minimum Mean Square Error (MMSE) filtering performance of Rayleigh-Product (RP) MIMO channels. Using principles from Random Matrix Theory (RMT), the MMSE filtering performance of the RP channels is analyzed and a tight lower bound is derived by taking the effects of residual additive transceiver impairments into account. Moreover, some useful insights on the performance of the considered system with respect to various parameters such as the transmit Signal to Noise Ratio (SNR), the number of scatterers and the severity of impairments on both the transmit and receive sides are provided. [less ▲]

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See detailCloud-Assisted Device Clustering for Lifetime Prolongation in Wireless IoT Networks
Bhandari, Sabin; Sharma, Shree Krishna UL; Wang, Xianbin

in Proc. IEEE 30th Canadian Conference on Electrical and Computer Engineering (CCECE) 2017 (2017, June 15)

One of the crucial challenges in the recently emerging Internet of Things (IoT) applications is how to handle the massive heterogeneous data generated from a large number of resource-constrained sensors ... [more ▼]

One of the crucial challenges in the recently emerging Internet of Things (IoT) applications is how to handle the massive heterogeneous data generated from a large number of resource-constrained sensors. In this context, cloud computing has emerged as a promising paradigm due to its enormous storage and computing capabilities, thus leading to the IoT-Cloud convergence. In such a framework, IoT devices can be grouped into several clusters and each cluster head can send the aggregated information to the cloud via a gateway for further processing. Although a number of clustering methods have been proposed for the conventional Wireless Sensor Networks (WSNs), it is important to consider specific IoT characteristics while adapting these techniques for wireless IoT networks. One of the important features of IoT networks that can be exploited while developing clustering techniques is the collaborations among heterogeneous IoT devices. In this regard, the network-wide knowledge at the cloud center can be useful to provide information about the device relations to the IoT gateway. Motivated by this, we propose and evaluate a cloud-assisted device interaction-aware clustering scheme for heterogeneous IoT networks. The proposed method considers the joint impact of residual energy and device closeness factor for the effective selection of cluster heads. Our results show that the proposed clustering scheme can significantly prolong the network lifetime, and enhance the overall throughput of a wireless IoT network. [less ▲]

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See detailLive Data Analytics with Collaborative Edge and Cloud Processing in Wireless IoT Network
Sharma, Shree Krishna UL; Wang, Xianbin

in IEEE Access (2017)

Recently, big data analytics has received important attention in a variety of application domains including business, finance, space science, healthcare, telecommunication and Internet of Things (IoT ... [more ▼]

Recently, big data analytics has received important attention in a variety of application domains including business, finance, space science, healthcare, telecommunication and Internet of Things (IoT). Among these areas, IoT is considered as an important platform in bringing people, processes, data and things/objects together in order to enhance the quality of our everyday lives. However, the key challenges are how to effectively extract useful features from the massive amount of heterogeneous data generated by resource-constrained IoT devices in order to provide real-time information and feedback to the endusers, and how to utilize this data-aware intelligence in enhancing the performance of wireless IoT networks. Although there are parallel advances in cloud computing and edge computing for addressing some issues in data analytics, they have their own benefits and limitations. The convergence of these two computing paradigms, i.e., massive virtually shared pool of computing and storage resources from the cloud and real-time data processing by edge computing, could effectively enable live data analytics in wireless IoT networks. In this regard, we propose a novel framework for coordinated processing between edge and cloud computing/processing by integrating advantages from both the platforms. The proposed framework can exploit the network-wide knowledge and historical information available at the cloud center to guide edge computing units towards satisfying various performance requirements of heterogeneous wireless IoT networks. Starting with the main features, key enablers and the challenges of big data analytics, we provide various synergies and distinctions between cloud and edge processing. More importantly, we identify and describe the potential key enablers for the proposed edge-cloud collaborative framework, the associated key challenges and some interesting future research directions. [less ▲]

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See detailImproving Robustness of Cyclostationary Detectors to Cyclic Frequency Mismatch Using Slepian Basis
Sharma, Shree Krishna UL; Bogale, Tadilo Endeshaw; Chatzinotas, Symeon UL et al

in Proceedings of IEEE PIMRC 2015 (2015, September)

Spectrum Sensing (SS) is one of the fundamental mechanisms required by a Cognitive Radio (CR). Among several SS techniques, cyclostationary feature detection is considered as an important technique due to ... [more ▼]

Spectrum Sensing (SS) is one of the fundamental mechanisms required by a Cognitive Radio (CR). Among several SS techniques, cyclostationary feature detection is considered as an important technique due to its robustness against noise variance uncertainty and its capability to distinguish among different systems on the basis of their cyclostationary features. However, one of the main limitations of this detector in practical scenarios is its performance degradation in the presence of cyclic frequency mismatch, which mainly arises due to the lack of knowledge about the transmitter clock/oscillator errors at the detector. In this context, this paper proposes a novel solution to address the cyclic frequency mismatch problem utilizing the Slepian basis expansion instead of the widely used Fourier basis expansion. It is shown that the proposed approach captures the deviation in the cyclic frequency caused by the aforementioned imperfections and hence provides a significant improvement in the sensing performance in the presence of cyclic frequency mismatch. [less ▲]

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See detailCognitive Radio Techniques under Practical Imperfections: A Survey
Sharma, Shree Krishna UL; Bogale, Tadilo Endeshaw; Chatzinotas, Symeon UL et al

in IEEE Communications Surveys and Tutorials (2015)

Cognitive Radio (CR) has been considered as a potential candidate for addressing the spectrum scarcity problem of future wireless networks. Since its conception, several researchers, academic institutions ... [more ▼]

Cognitive Radio (CR) has been considered as a potential candidate for addressing the spectrum scarcity problem of future wireless networks. Since its conception, several researchers, academic institutions, industries, regulatory and standardization bodies have put their significant efforts towards the realization of CR technology. However, as this technology adapts its transmission based on the surrounding radio environment, several practical issues may need to be considered. In practice, several imperfections such as noise uncertainty, channel/interference uncertainty, transceiver hardware imperfections, signal uncertainty, synchronization issues, etc. may severely deteriorate the performance of a CR system. To this end, the investigation of realistic solutions towards combating various practical imperfections is very important for successful implementation of the cognitive technology. In this direction, first, this survey paper provides an overview of the enabling techniques for CR communications. Subsequently, it discusses the main imperfections that may occur in the most widely used CR paradigms and then reviews the existing approaches towards addressing these imperfections. Finally, it provides some interesting open research issues. [less ▲]

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