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  • 1.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Battery Lifetime-Aware Base Station Sleeping Control with M2M/H2H Coexistence2016In: 2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2016, article id 7841624Conference paper (Refereed)
    Abstract [en]

    Fundamental tradeoffs in green cellular networkswith coexistence of machine-oriented and human-oriented trafficsare investigated. First, we present a queuing system to modelthe uplink transmission of a green base station which servestwo types of distinct traffics with strict requirements on delayand battery lifetime. Then, the energy-lifetime and energydelaytradeoffs are introduced, and closed-form expressions forenergy consumption of the base station, average experienceddelay in data transmission, and expected battery lifetime ofmachine devices are derived. Furthermore, we extend the derivedresults to the multi-cell scenario, and investigate the impacts ofsystem and traffic parameters on the energy-lifetime and energydelaytradeoffs using analytical and numerical results. Numericalresults show the impact of energy saving for the access network onthe introduced tradeoffs, and figure out the ways in which energycould be saved by compromising on the level of performance.

  • 2.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Energy Efficient MAC for Cellular-Based M2M Communications2014In: Signal and Information Processing (GlobalSIP), 2014 IEEE Global Conference on, IEEE conference proceedings, 2014, p. 128-132Conference paper (Refereed)
    Abstract [en]

    In Machine-to-Machine (M2M) networks, an energyefficient scalable medium access control (MAC) is crucial forserving massive battery-driven machine-type devices. In thispaper, we investigate the energy efficient MAC design to minimizebattery power consumption in cellular-based M2M communications.We present an energy efficient MAC protocol that notonly adapts contention and reservation-based protocols for M2Mcommunications in cellular networks, but also benefits frompartial clustering to handle the massive access problem. Then weinvestigate the energy efficiency and access capacity of contentionbasedprotocols and present an energy efficient contention-basedprotocol for intra-cluster communication of the proposed MAC,which results in huge power saving. The simulation results showthat the proposed MAC protocol outperforms the others in energysaving without sacrificing much delay or throughput. Also, thelifetimes of both individual nodes and the whole M2M networkare significantly extended.

  • 3.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Fundamental Tradeoffs in Resource Provisioning forIoT Services over Cellular Networks2017In: Proceedings of the 2017 IEEE International Conference on Communications, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7996885Conference paper (Refereed)
    Abstract [en]

    Performance tradeoffs in resource provisioningfor mixed internet-of-things (IoT) and human-orientedcommunications(HoC) services over cellular networks are investigated.First, we present a low-complexity model of cellularconnectivity in the uplink direction in which both accessreservation and scheduled data transmission procedures areincluded. This model is employed subsequently in derivinganalytical expressions for energy efficiency, spectral efficiency,and experienced delay in data transmission of connected devicesas well as energy consumption of base stations. The derivedexpressions indicate that the choice of uplink resource provisioningstrategy introduces tradeoffs between battery lifetime forIoT communications, quality of service (QoS) for HoC, spectralefficiency and energy consumption for the access network. Then,the impacts of system and traffic parameters on the introducedtradeoffs are investigated. Performance analysis illustrates thatimproper resource provisioning for IoT traffic not only degradesQoS of high-priority services and decreases battery lifetime ofIoT devices, but also increases energy consumption of the accessnetwork. The presented analytical and simulations results figureout the ways in which spectral/energy efficiency for the accessnetwork and QoS for high-priority services could be traded toprolong battery lifetimes of connected devices by compromisingon the level of provisioned radio resources.

  • 4.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Lifetime-Aware Scheduling and Power Control for Cellular-based M2M Communications2015In: Wireless Communications and Networking Conference (WCNC), 2015 IEEE: , IEEE conference proceedings, 2015, p. 1171-1176Conference paper (Refereed)
    Abstract [en]

    In this paper the uplink scheduling and transmit powercontrol is investigated to minimize the energy consumption forbattery-driven devices deployed in cellular networks. A lifetimemetric based on the accurate energy consumption model for cellularbasedmachine devices is provided and used to formulate theuplink scheduling and power control problems as network lifetimemaximization problems. Then, lifetime-aware uplink scheduling andpower control protocols which maximize the overall network lifetimeare investigated based on the different lifetime definitions. Besidesthe exact solutions, the low-complexity suboptimal solutions arepresented in this work which can achieve near optimal performancewith much lower computational complexity. The performance evaluationshows that the network lifetime is significantly extended underproposed protocols.

  • 5.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Lifetime-Aware Scheduling and Power Control for M2M Communications in LTE Networks2015In: Vehicular Technology Conference (VTC Spring), 2015 IEEE 81st, IEEE conference proceedings, 2015Conference paper (Refereed)
    Abstract [en]

    In this paper the scheduling and transmit powercontrol are investigated to minimize the energy consumptionfor battery-driven devices deployed in LTE networks. To enableefficient scheduling for a massive number of machine-typesubscribers, a novel distributed scheme is proposed to let machinenodes form local clusters and communicate with the base-stationthrough the cluster-heads. Then, uplink scheduling and powercontrol in LTE networks are introduced and lifetime-aware solu-tions are investigated to be used for the communication betweencluster-heads and the base-station. Beside the exact solutions,low-complexity suboptimal solutions are presented in this workwhich can achieve near optimal performance with much lowercomputational complexity. The performance evaluation showsthat the network lifetime is significantly extended using theproposed protocols.

  • 6.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Network Life time Maximization for Cellular-Based M2M Networks2017In: IEEE Access, E-ISSN 2169-3536, Vol. 5, p. 18927-18940, article id 8045999Article in journal (Refereed)
    Abstract [en]

    High energy efficiency is critical for enabling massive machine-type communications (MTC) over cellular networks. This paper is devoted to energy consumption modeling, battery lifetime analysis, lifetime-aware scheduling, and transmit power control for massive MTC over cellular networks. We consider a realistic energy consumption model for MTC and model network battery-lifetime. Analytic expressions are derived to demonstrate the impact of scheduling on both the individual and network battery lifetimes. The derived expressions are subsequently employed in the uplink scheduling and transmit power control for mixed-priority MTC traffic in order to maximize the network lifetime. Besides the main solutions, low complexity solutions with limited feedback requirement are investigated, and the results are extended to existing LIE networks. In addition, the energy efficiency, spectral efficiency, and network lifetime tradeoffs in resource provisioning and scheduling for MTC over cellular networks are investigated. The simulation results show that the proposed solutions can provide substantial network lifetime improvement and network maintenance cost reduction in comparison with the existing scheduling schemes.

  • 7.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Network Lifetime Maximization for Cellular-Based M2M Networks2017In: IEEE Access, E-ISSN 2169-3536Article in journal (Refereed)
    Abstract [en]

    High energy efficiency is critical for enabling massivemachine-type communications (MTC) over cellular networks.This work is devoted to energy consumption modeling,battery lifetime analysis, lifetime-aware scheduling and transmitpower control for massive MTC over cellular networks. Weconsider a realistic energy consumption model for MTC andmodel network battery-lifetime. Analytic expressions are derivedto demonstrate the impact of scheduling on both the individualand network battery lifetimes. The derived expressions aresubsequently employed in uplink scheduling and transmit powercontrol for mixed-priority MTC traffic in order to maximizethe network lifetime. Besides the main solutions, low-complexitysolutions with limited feedback requirement are investigated,and the results are extended to existing LTE networks. Also,the energy efficiency, spectral efficiency, and network lifetimetradeoffs in resource provisioning and scheduling for MTC overcellular networks are investigated. The simulation results showthat the proposed solutions can provide substantial networklifetime improvement and network maintenance cost reductionin comparison with the existing scheduling schemes.

  • 8.
    Azari, Amin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Stefanovic, Cedomir
    Aalborg University.
    Popovski, Petar
    Aalborg University.
    Latency-Energy Tradeoff based on Channel Scheduling and Repetitions in NB-IoT Systems2018In: 2018 IEEE Global Communications Conference, GLOBECOM 2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018, article id 8648024Conference paper (Refereed)
    Abstract [en]

    Narrowband Internet of Things (NB-IoT) is the latest IoT connectivity solution presented by the 3rd generation partnership project (3GPP). NB-IoT introduces coverage classes and offers a significant link budget improvement by allowing repeated transmissions by nodes that experience high path loss. However, those repetitions necessarily increase the energy consumption and the latency in the whole NB-IoT system. The extent to which the whole system is affected depends on the scheduling of the uplink and downlink channels. We address this question, not treated previously, by developing a tractable model of NB-IoT access protocol operation, comprising message exchanges in random-access, control, and data channels, both in the uplink and downlink The model is then used to analyze the impact of channel scheduling as well as the interaction of coexisting coverage classes, through derivation of the expected latency and battery lifetime for each coverage class. These results are subsequently employed in investigation of latency-energy tradeoff in NB-IoT channel scheduling as well as determining the optimized operation points. Simulations results show validity of the analysis and confirm that channel scheduling and coexistence of coverage classes significantly affect latency and battery lifetime performance of NB-IoT devices.

  • 9.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. Aalborg University.
    Popovski, Petar
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Stefanovic, Cedomir
    Grant-Free Radio Access for Short-Packet Communications over 5G Networks2017In: 2017 IEEE Global Communications Conference, GLOBECOM 2017 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2017Conference paper (Refereed)
    Abstract [en]

    Radio access management plays a vital role in delay and energy consumption of connected devices. The radio access in existing cellular networks is unable to efficiently support massive connectivity, due to its signaling overhead. In this paper, we investigate an asynchronous grant-free narrowband data transmission protocol that aims to provide low energy consumption and delay, by relaxing the synchronization/reservation requirement at the cost of sending several packet copies at the transmitter side and more complex signal processing at the receiver side. Specifically, the timing and frequency offsets, as well as sending of multiple replicas of the same packet, are exploited as form of diversities at the receiver-side to trigger successive interference cancellation. The proposed scheme is investigated by deriving closed-form expressions for key performance indicators, including reliability and battery-lifetime. The performance evaluation indicates that the scheme can be tuned to realize long battery lifetime radio access for low-complexity devices. The obtained results indicate existence of traffic load regions, where synchronous access outperforms asynchronous access and vice versa.

  • 10.
    Chang, Peiliang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Area Spectral and Energy Efficiency Analysis of Cellular Networks with Cell DTX2015In: IEEE Globecom 2015 , San Diego, December 6th-10th, 2015, IEEE conference proceedings, 2015, p. 1-6Conference paper (Refereed)
    Abstract [en]

    Cell discontinuous transmission (DTX) has been proposed as an effective solution to reduce energy consumption of cellular networks. In this paper, we investigate the impact of network traffic load on area spectral efficiency (ASE) and energy efficiency (EE) of cellular networks with cell DTX. Closedform expressions of ASE and EE as functions of traffic load for cellular networks with cell DTX are derived. It is shown that ASE increases monotonically in traffic load, while EE depends on the power consumption of base stations in sleep mode. If this power consumption is larger than a percentage of the active-mode power consumption, EE increases monotonically with traffic load and is maximized when the network is fully loaded. Otherwise, EE first increases and then decreases in traffic load. In this case, ASE and EE are maximized with different loads. The percentage threshold only depends on the path loss exponent of radio propagation environment and is calculated to be 56.2% when the path loss exponent is 4.

  • 11.
    Chang, Peiliang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Energy and Spectral Efficiency of Cellular Networks with Discontinuous Transmission2017In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 16, no 5, p. 2991-3002Article in journal (Refereed)
    Abstract [en]

    Cell discontinuous transmission (DTX) has been proposed as a solution to reduce energy consumption of cellular networks. This paper investigates the impact of network traffic load on spectral and energy efficiency of cellular networks with DTX. The SINR distribution as a function of traffic load is derived firstly. Then sufficient condition for ignoring thermal noise and simplifying the SINR distribution is investigated. Based on the simplified SINR distribution, the network spectral and energy efficiency as functions of network traffic load are derived. It is shown that the network spectral efficiency increases monotonically in traffic load, while the optimal network energy efficiency depends on the ratio of the sleep-mode power consumption to the active-mode power consumption of base stations. If the ratio is larger than a certain threshold, the network energy efficiency increases monotonically with network traffic load and is maximized when the network is fully loaded. Otherwise, the network energy efficiency firstly increases and then decreases in network traffic load. The optimal load can be identified with a binary search algorithm. The power ratio threshold depends solely on the path loss exponent α, e.g. 56% for α = 4. All these analytic results are further validated by the numerical simulations.

  • 12.
    Chang, Peiliang
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Energy-Efficient Resource Allocation in Multi-Carrier NOMA SystemsManuscript (preprint) (Other academic)
    Abstract [en]

    5G cellular networks are expected to support heterogeneous services with the same level of energy dissipation as current cellular networks. As a key enabler of 5G [1], the energy efficiency performance of non-orthogonal multiple access (NOMA) is of paramount importance. In NOMA systems, the system performance, e.g., spectral efficiency and energy efficiency are largely affected by resource allocation, i.e., sub-carrier assignment and power allocation. This paper studies the joint sub-carrier assignment and power allocation for the downlink transmission of multi-carrier NOMA systems to maximize the system energy efficiency (SEE). We first formulate an energyefficiency maximization problem while assuring the connectivity requirements of all users. The original optimization problem is a mixed integer programming problem and is NP hard. In order to develop optimal solutions with low complexity, the formulated problem is decomposed into three sub-problems: sub-carrier assignment, power allocation across sub-carriers and power allocation among users sharing the same sub-carrier. Given subcarrier assignment, we first obtain the optimal power allocation among users on one sub-carrier and then the optimal power allocation across sub-carriers. To find the optimal sub-carrier assignment, a greedy search solution based on the intrinsic structure of the transmitted power is proposed to minimize the overall required power to support the connectivity requirements of all users. Numerical simulations are implemented to validate the analytical findings. The results show that our proposed algorithms achieve better system energy efficiency and lower user blocking rate than the state-of-the-art solutions in the literature.

  • 13.
    Chang, Peiliang
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Interference-aware Distributed Control of Cell Discontinuous Transmission2018In: 2018 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC), IEEE , 2018Conference paper (Refereed)
    Abstract [en]

    As a main enabler for the next generation (5G) cellular networks, network densification faces challenges in intercell interference and energy consumption. Cell discontinuous transmission (DTX) can be employed to reduce both energy consumption of base stations (BSs) and inter-cell interference. In this paper we study the control problem of cell DTX in dense small cell networks (DSCNs). We firstly formulate the network energy efficiency optimization problem. Then a centralized heuristic DTX control algorithm is presented. In order to address the issues of complexity and scalability of the centralized solution, an interference-aware distributed DTX control algorithm is proposed. Discussions on algorithm complexity and implementation are provided. The proposed algorithms are evaluated with numerical simulations. Results show that at high load region, the proposed algorithms can not only enhance network capacity by reducing inter-cell interference by up to 60% but also increase network energy efficiency by switching BSs into micro-sleep mode by 67%.

  • 14.
    Chang, Peiliang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Joint Optimization of Base Station Deep-Sleep and DTX Micro-Sleep2016In: 2016 IEEE Globecom Workshops, GC Wkshps 2016 - Proceedings, IEEE conference proceedings, 2016, article id 7848943Conference paper (Refereed)
    Abstract [en]

    When both base station (BS) deep-sleep and discontinuous transmission (DTX) are applied to improve network energy efficiency (EE), switching BS into deep-sleep mode would increase the load of remaining active BSs and thereby reduce their energy savings via DTX. This paper studies the optimal BS operation strategy when both deep-sleep and DTX are employed. Queuing theory and stochastic geometry are jointly applied to model network performance with consideration of both traffic dynamics and channel quality variations. Analytical expressions of average BS load and network EE are derived. Both analytical and simulation results show that there is a trade-off between deep-sleep energy saving and DTX energy saving when the energy saving capacity of DTX is considerable. Analytical expression of the optimal percentage of deep-sleep BSs is provided.

  • 15.
    Chang, Peiliang
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Optimal Operation of Base Stations With Deep Sleep and Discontinuous TransmissionIn: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359Article in journal (Refereed)
    Abstract [en]

    Traffic-aware base station (BS) sleeping is a promising approach to increase the energy efficiency (EE) of cellular networks. Both deep sleep and discontinuous transmission (DTX)can be applied to improve network EE. This paper studies the optimal BS operation when both deep sleep and DTX are employed. Queuing theory and stochastic geometry theory are jointly applied to model network performance considering both traffic dynamics and stochastic channel quality. We firstly propose a scaling law of transmit power that assures network coverage. Then, we characterize the resource utilization of active BSs when various percent-ages of BSs are switched into deep sleep, and analyze the overload probability of the remaining active BSs. Finally, we investigate the impact of BS deep sleep and DTX micro sleep on network EE. Both analytical and simulation results show that there is a trade-off between deep sleep and DTX micro sleep. Switching BSs into deep sleep would increase the load of the remaining active BSs and reduce their energy saving achieved with DTX. When the power consumption of BS in DTX micro-sleep mode is considerably low, switching BSs into deep sleep might increase the overall energy consumption, and it is not always the best practice to switch as many BSs into deep sleep as possible to maximize network EE.

  • 16.
    Chang, Peiliang
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Resource Provision for Energy-Efficient Mobile Edge Computing2018In: 2018 IEEE Global Communications Conference, GLOBECOM 2018 - Proceedings, IEEE Communications Society, 2018, article id 8648008Conference paper (Refereed)
    Abstract [en]

    Mobile Edge Computing (a.k.a Fog computing) is recently proposed to provide computing service for delay-sensitive mobile applications. Despite various benefits, deploying edge servers in cellular networks would increase their energy consumption. In this paper, we investigate the provision of resources, including both communication and computation resources, of Mobile Edge Computing (MEC) systems to improve their energy efficiency (EE). In a MEC system, both the communication subsystem, which allows mobile users to access Internet and offload their computing tasks, and the computation subsystem, which accomplishes the offloaded computing tasks, affect the service latency and consume energy. Modelling the whole system as tandem queues, we study the trade-offs between these two subsystems on energy consumption and service latency. Based on the analysis results, we propose an algorithm to determine the optimal provision of both communication and computation resources to minimize the overall energy consumption without sacrificing the performance on service latency. Numerical results are provided to validate our analytical findings.

  • 17.
    Costa, J.
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Context-Aware Framework for Energy Efficient Machine-to-Machine CommunicationsIn: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896Article in journal (Refereed)
    Abstract [en]

    Cellular network based Machine-to-Machine(M2M) communications have been growing rapidly in recentyears, being used in a wide range of services such as security,metering, health, remote control, tracking and so on. A criticalissue that needs to be considered in M2M communications isthe energy efficiency, typically the machines are powered bybatteries of low capacity and it is important to optimize the waythe power is consumed. In search of better M2M systems, wepropose a context-aware framework for M2M communicationsso the machine type communication (MTC) devices dynamicallyadapt their settings depending on a series of characteristicssuch as data reporting mode and quality of service (QoS)features so higher energy efficient is achieved, extending theoperating lifetime of the M2M network. Simulations results willbe provided for four commonly used M2M applications: homesecurity, telehealth, climate and smart metering, showing thatconsiderable energy savings and operating lifetime extension onthe network can be achieved. Thus, contexts play an importantrole on the energy efficiency of a M2M system.

  • 18.
    Costa, Javier Mendonca
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Context-Aware Machine-to-Machine Communications2014In: 2014 IEEE CONFERENCE ON COMPUTER COMMUNICATIONS WORKSHOPS (INFOCOM WKSHPS), IEEE , 2014, p. 730-735Conference paper (Refereed)
    Abstract [en]

    As a key enabler of Internet of things, cellular network based Machine-to-Machine (M2M) communications have been growing rapidly in recent years, being used in a wide range of services such as security, metering, health, remote control, tracking, and so on. A critical issue in M2M communications is the energy efficiency as typically the machine devices are powered by batteries of low capacity and thus, it is the key to optimize their consumption. To achieve higher energy efficiency, this paper proposes the adoption of contexts through a generic context-aware framework for M2M communications. With this framework, machine devices dynamically adapt their settings depending on a series of characteristics such as data reporting mode, QoS features, and network conditions to achieve higher energy efficiency and extend the operating lifetime of M2M networks. Simulation results are provided for four commonly used M2M applications. The results demonstrate considerable energy savings and operating lifetime extension on the network when the proposed context-aware framework is used. Thus, it is shown that contexts play an important role on the energy efficiency of M2M systems.

  • 19. Gao, Deyun
    et al.
    Foh, Chuan Heng
    Vu, Hai
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wireless Vehicular Sensor and Ad Hoc Networks2014In: International Journal of Distributed Sensor Networks, ISSN 1550-1329, E-ISSN 1550-1477, Vol. 2014, p. 769067-Article in journal (Refereed)
  • 20. Han, Q.
    et al.
    Yang, B.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Chen, C.
    Wang, X.
    Guan, X.
    Backhaul-Aware User Association and Resource Allocation for Energy-Constrained HetNets2017In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 66, no 1, p. 580-593, article id 7422839Article in journal (Refereed)
    Abstract [en]

    Growing attention has been paid to renewable-or hybrid-energy-powered heterogeneous networks (HetNets). In this paper, focusing on backhaul-aware joint user association and resource allocation for this type of HetNets, we formulate an online optimization problem to maximize the network utility reflecting proportional fairness. Since user association and resource allocation are tightly coupled not only on resource consumption of the base stations (BSs) but in the constraints of their available energy and backhaul as well, the closed-form solution is quite difficult to obtain. Thus, we solve the problem distributively by employing certain decomposition methods. Specifically, at first, by adopting the primal decomposition method, we decompose the original problem into a lower level resource-allocation problem for each BS and a higher level user-association problem. For the optimal resource allocation, we prove that a BS either assigns equal normalized resources or provides an equal long-term service rate to its served users. Then, the user-association problem is solved by the Lagrange dual decomposition method, and a completely distributed algorithm is developed. Moreover, applying results of the subgradient method, we demonstrate the convergence of the proposed distributed algorithm. Furthermore, to efficiently and reliably apply the proposed algorithm to the future wireless networks with an extremely dense BS deployment, we design a virtual user association and resource allocation scheme based on the software-defined networking architecture. Finally, numerical results validate the convergence of the proposed algorithm and the significant improvement on network utility, load balancing, and user fairness.

  • 21. Hwang, T.
    et al.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Park, H.
    Kwon, Y.
    Himayat, N.
    Green Radio2015In: Green Communications: Principles, Concepts and Practice, Wiley-Blackwell, 2015, p. 119-134Chapter in book (Other academic)
    Abstract [en]

    This chapter gives a comprehensive introduction to state-of-the-art energy-efficient communications, focusing on the physical (PHY) and medium access control (MAC) layers of wireless communication systems. The PHY layer consists of RF circuits, modulation, power control, and channel coding units, and so on and delivers data transmission as reliably as possible. The MAC layer ensures network-wide efficient resource management while maintaining quality of service (QoS) requirements of individual users. As wireless is a shared communication medium, with wireless communications, device energy consumption is not only affected by the designs of different layers of the point-to-point communicating link but also by the interactions of all links in the network. A system approach is therefore necessary for energy-efficient wireless communications system design. The focus of this chapter is on wireless system design, analysis, and optimization emphasizing energy efficiency enhancement while meeting given performance requirements. Since the design of all protocol layers impact energy consumption, this chapter introduces cross-layer energy-efficient techniques to reduce redundant message transfers and the associated energy consumption. Cross-layer techniques exploit interactions between different layers to significantly improve energy efficiency and adaptability to service, traffic, and environment dynamics.

  • 22.
    Kim, Yunesung
    et al.
    Yonsei University.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Hwang, Taewon
    Yonsei University.
    Energy Efficient Pilot and Link Adaptation for Mobile Users in TDD Multi-User MIMO Systems2014In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 13, no 1, p. 382-393Article in journal (Refereed)
    Abstract [en]

    In this paper, we develop an uplink pilot and downlink link adaptation approach to improve the energy efficiency (EE) of mobile users in time division duplexing (TDD) multi-user multiple input and multiple output (MU-MIMO) systems. Assuming reciprocity between uplink and downlink channels, the downlink transmission is based on uplink channel estimation. While more uplink pilot power ensures more accurate channel estimation and better downlink performance, it incurs higher energy consumption of mobile users. This paper reveals the relationship and tradeoff among pilot power, channel estimation, and downlink link adaptation that achieves the highest energy efficiency for mobile users. We show that the energy efficiency of different users can be decoupled because the downlink average throughput of each user is independent of the pilot powers of other users and energy-efficient design can be done on a per-user basis. Based on the analysis, we propose an uplink pilot and downlink link adaptation algorithm to improve the EE of mobile users. Simulation results are finally provided to demonstrate the significant gain in energy efficiency for mobile users.

  • 23.
    Kwon, Younggap
    et al.
    Yonsei Univ, Sch Elect & Elect Engn, Seoul 120749, South Korea.;Agcy Def Dev, Daejeon 305600, South Korea..
    Park, Hyunsung
    Yonsei Univ, Sch Elect & Elect Engn, Seoul 120749, South Korea..
    Oh, Jintaek
    Yonsei Univ, Sch Elect & Elect Engn, Seoul 120749, South Korea..
    Miao, Guowang
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Hwang, Taewon
    Yonsei Univ, Sch Elect & Elect Engn, Seoul 120749, South Korea..
    Energy-Efficient Routing and Link Adaptation for 2D Wireless Relay Networks in the Wideband Regime2018In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, no 11, p. 7325-7339Article in journal (Refereed)
    Abstract [en]

    We discuss the globally optimal energy-efficient design of a 2D relay network. Different from the existing routing protocols on energy saving, which finds the minimal energy route for a given data rate, the proposed algorithm jointly optimizes routing and data rate to maximize energy efficiency (EE) defined as the achievable data rate per power consumption. We propose a low-complexity algorithm to circumvent the huge complexity of the exhaustive search for the network EE maximization and prove its global optimality. Moreover, the proposed algorithm is implemented in a distributed fashion because each relay needs to send its routing information only to the relays in its adjacent tiers, which significantly reduces the signaling overhead of the centralized implementation. Our analysis on the worst-case complexity in a fading channel shows that the complexity of the proposed algorithm increases linearly while that of the exhaustive search increases exponentially as the tier index increases. Simulation results confirm that the proposed algorithm outperforms the existing routing protocols on energy saving and achieves the globally optimal network EE at a significantly lower complexity than the exhaustive search.

  • 24. Liu, Lingjia
    et al.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Zhang, Jianzhong(Charlie)
    Energy-Efficient Scheduling for Downlink Multi-User MIMO2012In: IEEE International Conference on Communications (ICC) 2012, IEEE conference proceedings, 2012, p. 4390-4394Conference paper (Refereed)
    Abstract [en]

    Multi-user MIMO is the enabling technology forLTE-Advanced systems to meet IMT-Advanced targets. The gainof multi-user MIMO is achieved partially through advanced usergrouping,user-scheduling, and precoding. Traditionally, multiuserMIMO scheduling focuses solely on spectral-efficiency [1].That is, the scheduler will strike to balance the cell-edge userspectral-efficiency as well as the cell-average spectral-efficiency.Similar to spectral-efficiency, energy-efficiency is becoming increasinglyimportant for wireless communications. The energyefficiency is measured by a classical measure, “throughput perJoule”, while both RF transmit power and device electronic circuitpower consumptions are considered. In this paper, an energyefficientproportional-fair scheduling is proposed for downlinkmulti-user MIMO systems. To specific, the scheduling algorithmis proposed to balance cell-edge energy-efficiency and the cellaverageenergy-efficiency. The energy-efficient proportional-fairmetric is defined and the optimal power allocation maximizingthe performance measure is identified. System level evaluationsuggests that multi-user MIMO could improve the energyefficiencyof a wireless communication system significantly.

  • 25.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Energy-Efficient Uplink Multi-User MIMO2013In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 12, no 5, p. 2302-2313Article in journal (Refereed)
    Abstract [en]

    This paper addresses optimal energy-efficient design for uplink (UL) MU-MIMO in a single cell environment. The energy efficiency is measured by throughput per Joule, while both RF transmission power and device electronic circuit power are considered. We define the energy efficiency (EE) capacity for UL MU-MIMO and study the power allocation that achieves this capacity. First we assume all users consume a fixed amount of circuit power and show that user antennas should be used only when the corresponding spatial channels are sufficiently good and using them improves the overall network EE. Mobile devices may have improved circuit management capability and turn off circuit operations when some antennas are not used to reduce circuit power consumption. Therefore we further study energy-efficient UL MU-MIMO with improved circuit management and show that some antennas should not be used even when their channel states are good because turning them on consumes too much circuit power. Based on theoretical analysis, we further develop low-complexity yet globally optimal energy-efficient power allocation algorithms that converge to the optimum exponentially. Simulation results are provided to demonstrate the significant gain in network energy efficiency.

  • 26.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Energy-Efficient Uplink Multi-User MIMO with Dynamic Antenna Management2012In: 2012 IEEE Global Communications Conference (Globecom), IEEE , 2012, p. 3437-3442Conference paper (Refereed)
    Abstract [en]

    Energy efficiency is important for mobile devices because battery technology development has not kept up with the growing demand of ubiquitous broadband communications. This paper addresses optimal energy-efficient design for uplink (UL) MU-MIMO in a single cell environment. We assume mobile devices have dynamic antenna management capability and can turn off circuit operations when some antennas are not used to save power. We show that some antennas should not be used even when their channel states are good because turning them on consumes too much circuit power. This indicates a single antenna system could perform better than a multi-antenna system in terms of energy efficiency. Based on theoretical analysis, we further develop low-complexity yet globally optimal algorithms that converge to the optimum exponentially.

  • 27.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    On Optimal Energy-Efficient Multi-User MIMO2011In: 2011 IEEE Global Telecommunications Conference (GLOBECOM 2011), IEEE conference proceedings, 2011, p. 1-6Conference paper (Refereed)
    Abstract [en]

    Energy efficiency is becoming increasingly importantfor mobile devices because battery technology has notkept up with the growing demand of ubiquitous multimediacommunications. Since multi-user multiple-input multiple-output(MU-MIMO) is a key technology in next-generation wirelesscommunications, this paper addresses optimal energy-efficientdesign for MU-MIMO. The energy efficiency is measured by aclassic metric, “throughput per Joule”, while both RF transmitpower and device electronic circuit power are considered. Wedefine the energy efficiency (EE) capacity for MU-MIMO andstudy the power allocation that achieves this capacity. We showthat user antennas should be used only when the correspondingsubchannels are sufficiently good and using them improves theoverall network EE. Based on theoretical analysis, we further developlow-complexity yet globally optimal energy-efficient powerallocation algorithms that converge to the optimum exponentially.Finally comprehensive simulation results are provided todemonstrate the significant gain in network energy efficiency.

  • 28.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Scalable Device-to-Device Communications ForFrequency Reuse >> 1In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248Article in journal (Refereed)
    Abstract [en]

    Proximity based applications are becoming fastgrowing markets suggesting that Device-to-Device (D2D) communicationsis becoming an essential part of future mobiledata networks. We present three solutions for coordinating theinterferences that aim at maximizing the density of D2D linkswhile considering different levels of complexity and availablechannel state information (CSI).We analyze the performance of D2D communications in multicellenvironments to gain valuable insights on important limitingfactors of the system scalability and spectral efficiency.The results show that the proposed low complexity interferencecoordination schemes achieve high spectral efficiency and goodscalability while assuring low outage probability to provide QoSfor all users.

  • 29.
    Miao, Guowang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Azari, Amin
    KTH, School of Information and Communication Technology (ICT).
    Hwang, Taewon
    E2-MAC: Energy Efficient Medium Access for Massive M2M Communications2016In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 64, no 11, p. 4720-4735Article in journal (Refereed)
    Abstract [en]

    In this paper, we investigate energy-efficient clustering and medium access control (MAC) for cellular-based M2M networks to minimize device energy consumption and prolong network battery lifetime. First, we present an accurate energy consumption model that considers both static and dynamic energy consumptions, and utilize this model to derive the network lifetime. Second, we find the cluster size to maximize the network lifetime and develop an energy-efficient cluster-head selection scheme.

    Furthermore, we find feasible regions where clustering is beneficial in enhancing network lifetime. We further investigate communications protocols for both intra- and inter-cluster communications. While inter-cluster communications use conventional cellular access schemes, we develop an energy-efficient and load-adaptive multiple access scheme, called n-phase CSMA/CA, which provides a tunable tradeoff between energy efficiency, delay, and spectral efficiency of the network. The simulation results show that the proposed clustering, cluster-head selection, and communications protocol design outperform the others in energy saving and significantly prolong the lifetimes of both individual nodes and the whole M2M network.

  • 30.
    Miao, Guowang
    et al.
    School of ECE, Georgia Institute of Technology.
    Himayat, Nageen
    Wireless Communications Lab., Intel Labs.
    Li, Geoffrey Ye
    School of ECE, Georgia Institute of Technology.
    Talwar, Shilpa
    Wireless Communications Lab., Intel Labs.
    Low-Complexity Energy-Efficient Scheduling for Uplink OFDMA2012In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 60, no 1, p. 112-120Article in journal (Refereed)
    Abstract [en]

    Energy-efficient wireless communication is very important for battery-constrained mobile devices. For mobile devices in a cellular system, uplink power consumption dominates the wireless power budget because of RF power requirements for reliable transmission over long distances. Our previous work in this area focused on optimizing energy efficiency by maximizing the instantaneous bits-per-Joule metric through iterative approaches, which resulted in significant energy savings for uplink cellular OFDMA transmissions. In this paper, we develop energy efficient schemes with significantly lower complexity when compared to iterative approaches, by considering time-averaged bits-per-Joule metrics. We consider an uplink OFDMA system where multiple users communicate to a central scheduler over frequency-selective channels with high energy efficiency. The scheduler allocates the system bandwidth among all users to optimize energy efficiency across the whole network. Using time-averaged metrics, we derive energy optimal techniques in "closed forms" for per-user link adaptation and resource scheduling across users. Simulation results show that the proposed schemes not only have low complexity but also perform close to the globally optimum solutions obtained through exhaustive search.

  • 31.
    Miao, Guowang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Himayat, Nageen
    Talwar, Shilpa
    Probabilistic interference mitigation for wireless cellular networks2007Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    An interference mitigation system randomizes transmissions to cell-edge users by carefully controlling the probability of transmission to these users, thereby creating a virtual fractional frequency system that does not require extensive frequency management and coordination across the network. In some embodiments, the interference mitigation system identifies severely interfered links and reduces the probability of transmission on these links, with the result being a reduced probability of interference.

  • 32.
    Miao, Guowang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Li, Ye (Geoffrey)
    Swami, Ananthram
    Channel-Aware Distributed Medium Access Control2012In: IEEE/ACM Transactions on Networking, ISSN 1063-6692, E-ISSN 1558-2566, Vol. 20, no 4, p. 1290-1303Article in journal (Refereed)
    Abstract [en]

    In this paper, we solve a fundamental problem: how to use distributed random access to achieve the performance of centralized schedulers. We consider wireless networks with arbitrary topologies and spatial traffic distributions, where users can receive traffic from or send traffic to different users and different communication links may interfere with each other. The channels are assumed heterogeneous, and the random channel gains of different links may have different distributions. To resolve the network contention in a distributed way, each frame is divided into contention and transmission periods. The contention period is used to resolve conflicts, while the transmission period is used to send payload in collision-free scenarios. We design a multistage channel-aware Aloha scheme for the contention period to enable users with relatively better channel states to have higher probabilities of contention success while assuring fairness among all users. We show analytically that the proposed scheme completely resolves network contention and achieves throughput close to that of centralized schedulers. Furthermore, the proposed scheme is robust to any uncertainty in channel estimation. Simulation results demonstrate that it significantly improves network performance while maintaining fairness among different users. The proposed random access approach can be applied to different wireless networks, such as cellular, sensor, and mobile ad hoc networks, to improve quality of service.

  • 33.
    Miao, Guowang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Song, Guocong
    Energy and Spectrum Efficient Wireless Network Design2014 (ed. 1)Book (Refereed)
    Abstract [en]

    Covering the fundamental principles and state-of-the-art cross-layer techniques, this practical guide provides the tools needed to design MIMO- and OFDM-based wireless networks that are both energy- and spectrum-efficient. Technologies are introduced in parallel for both centralized and distributed wireless networks to give you a clear understanding of the similarities and differences between their energy- and spectrum-efficient designs, which is essential for achieving the highest network energy saving without losing performance. Cutting-edge green cellular network design technologies, enabling you to master resource management for next-generation wireless networks based on MIMO and OFDM, and detailed real-world implementation examples are provided to guide your engineering design in both theory and practice. Whether you are a graduate student, a researcher or a practitioner in industry, this is an invaluable guide. 

  • 34.
    Miao, Guowang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Västberg, Anders
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Energy Efficiency in the Wideband Regime2013In: 2013 IEEE Wireless Communications And Networking Conference (WCNC), IEEE Communications Society, 2013, p. 510-515Conference paper (Refereed)
    Abstract [en]

    In this paper we discuss globally optimal energy-efficient communications in the wideband regime that is characterized by wide signal bandwidth and low spectral efficiency. An end-to-end multiple-hop system with one sender, one receiver, and multiple relays is considered. We discover the globally optimal link adaptation as well as relay deployment strategies such that the whole system can run with the highest energy efficiency. The technologies proposed can be used in various communication systems, such as the deployment and communication of wired core networks and wireless broadband relay backhauls, to improve their energy efficiency.

  • 35.
    Miao, Guowang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Västberg, Anders
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Energy Efficiency in the Wideband Regime2013In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 12, no 8, p. 4102-4109Article in journal (Refereed)
    Abstract [en]

    End-to-end communication is the fundamental building block of communication networks. In this paper, we discuss globally optimal energy efficient design for end-to-end communications. An end-to-end multiple-hop system with one sender, one receiver, and multiple relays is considered. We first study in detail energy-efficient designs in the wideband regime that is characterized by wide signal bandwidth and low spectral efficiency, and later briefly those in the narrowband regime. We will reveal the globally optimal link adaptation as well as relay deployment strategies such that the whole system can achieve the highest energy efficiency. The technologies proposed can be used in various communication systems, such as the deployment and communication of wired core networks and wireless relay networks, to improve their energy efficiency. While this paper focuses on a linear end-to-end network topology, the methodology can be easily extended to two-dimensional network topologies for energy-efficient designs of the whole network

  • 36.
    Miao, Guowang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Slimane, Slimane Ben
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Fundamentals of Mobile Data Networks2016Book (Other academic)
    Abstract [en]

    This unique text provides a comprehensive and systematic introduction to the theory and practice of mobile data networks. Covering basic design principles as well as analytical tools for network performance evaluation, and with a focus on system-level resource management, you will learn how state-of-the-art network design can enable you flexibly and efficiently to manage and trade-off various resources such as spectrum, energy, and infrastructure investments. Topics covered range from traditional elements such as medium access, cell deployment, capacity, handover, and interference management, to more recent cutting-edge topics such as heterogeneous networks, energy and cost-efficient network design, and a detailed introduction to LTE (4G). Numerous worked examples and exercises illustrate the key theoretical concepts and help you put your knowledge into practice, making this an essential resource whether you are a student, researcher, or practicing engineer.

  • 37.
    Miao, Guowang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Zhang, J.
    Apparatus and method for channel measurement in radio link monitoring in a wireless network2010Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A subscriber station is configured to perform a channel measurement on a communication channel in restricted sub-frames for DRX and NON-DRX modes. The subscriber station includes a receiver configured to receive signals from a base station. The subscriber station also includes processing circuitry. When the receiver receives higher layer signaling indicating that channel quality measurement is to be performed in restricted sub-frames for measurement (RFSM), the processing circuitry is configured to extend an evaluation period for monitoring a quality of the communication channel.

  • 38.
    Pradini, Aidilla
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Fodor, Gabor
    KTH, School of Electrical Engineering (EES), Automatic Control. Ericsson Research, Sweden .
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Belleschi, M.
    Near-optimal practical power control schemes for D2D communications in cellular networks2014In: EuCNC 2014 - European Conference on Networks and Communications, IEEE Computer Society, 2014, p. 6882666-Conference paper (Refereed)
    Abstract [en]

    Device-to-device (D2D) communication has the potential of increasing the system capacity, energy efficiency and achievable peak rates while reducing the end-to-end latency. To realize these gains, recent works have proposed resource allocation (RA) and power control (PC) approaches that show near optimal performance in terms of spectral or energy efficiency. However, the proposed schemes either consider a single cell environment or assume instantaneous channel state information (CSI) and/or rely on iterative algorithms that require excessive inter-node message exchange and suffer from slow convergence time. For D2D user equipment (UE), we propose a distributed utility optimization based PC scheme that relies on locally available measurement data and is made practical by constraining the number of iterations and the interference caused to the cellular receiver, while legacy UEs employ the standard Long Term Evolution (LTE) PC. We investigate the performance of the proposed PC scheme when combined with two RA schemes that differ in terms of the required channel state information. We find that when properly tuned, this practical PC scheme combined with a RA algorithm that requires limited channel knowledge, not only shows near optimal performance, but it also constraints the impact of D2D communications on the cellular layer.

  • 39.
    Shalmashi, Serveh
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Han, Zhu
    University of Houston.
    Slimane, Ben
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Interference Constrained Device-to-Device Communications2014In: 2014 IEEE International Conference on Communications, ICC 2014, IEEE Computer Society, 2014, p. 5245-5250Conference paper (Refereed)
    Abstract [en]

    This paper considers a scenario in which multiple device-to-device (D2D) users can reuse the uplink resources of a cellular network to transmit directly to their corresponding receivers. The aggregated interference from the D2D users is limited by applying a threshold on the allowable interference in the base station. The problem is solved under two types of constraints, namely, the peak interference and average interference constraints. In the former, we assume that full channel state information (CSI) is available at the base station, and we optimize the allowable transmit power for the D2D users so that the number of coexisting D2D communications is maximized. We further define a quality-of-service constraint for the D2D users. In practice, however, it is difficult to have complete CSI at the base station as it imposes heavy signaling overhead. Therefore, in the latter scenario, we assume that no knowledge about the location of D2D users and their CSI are available at the base station. This approach does not impose any signaling overhead. Our results show that even with no CSI knowledge, we are able to improve the system performance in terms of throughput by allowing coexisting D2D communications while satisfying the cellular user's constraints.

  • 40.
    Shalmashi, Serveh
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Slimane, Ben
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Interference management for multiple device-to-device communications underlaying cellular networks2013In: 2013 IEEE 24th International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), IEEE conference proceedings, 2013, p. 223-227Conference paper (Refereed)
    Abstract [en]

    We study the problem of interference management for device-to-device (D2D) communications where multiple D2D users may coexist with one cellular user. The problem is to optimize the transmit power levels of D2D users to maximize the cell throughput while preserving the signal-to-noise-plus-interference ratio (SINR) performance for the cellular user. This is the so-called multi rate power control problem. We investigate the problem under two assumptions, the availability of the instantaneous or average channel state information (CSI) at the base station. In the first case, D2D transmit power levels adapt to fast fading, whereas in the second case, they only adapt to slow fading. In the latter assumption, the cellular user has a maximum outage probability requirement. With numerical results, we study the trade-off between the signaling overhead, that is frequent CSI feedbacks, and the overall system performance, that is the maximum achievable cell capacity, for D2D communications underlying cellular networks.

  • 41.
    Thanos, Anastasios
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Shalmashi, Serveh
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Network-Assisted Discovery for Device-to-Device Communications2013In: 2013 IEEE Globecom Workshops (GC Wkshps), IEEE Computer Society, 2013, p. 660-664Conference paper (Refereed)
    Abstract [en]

    Network-assisted device-to-device (D2D) communications allow two devices to communicate with each other directly using one bidirectional link. Exchange of signaling messages with the base station allows the establishment of D2D communications. The discovery of D2D pairs of devices is an essential part of D2D communications as it provides the base station with all the information necessary to evaluate the possibility of D2D communication for the pair. This paper proposes two discovery algorithms, the centralized fully network-dependent and the semi centralized semi-network-dependent algorithms to identify D2D pairs through the exchange of a number of signaling messages. A comparison between those algorithms is performed with respect to delay and signaling overhead. Simulation results show that the second discovery algorithm is faster and more efficient than the first one in discovering new D2D pairs.

  • 42.
    Tombaz, Sibel
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Friman, Erik
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Energy Efficiency in Network Level: Definition, Measurement and PredictionManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, network level energy efficiency assessment issues are described in wireless access networks. High level definitions of energy efficiency are introduced and existing heterogeneous metrics proposed in the literature in order to quantify the energy savings are overviewed. The weaknesses of the current metrics in order to evaluate NLEE have been discussed in detail and more elaborate metric forms have been suggested. Then, a NLEE evaluation methodology is proposed to calculate the suggested indicator, and unlike GSMA method it is based on network segmentation, direct measuring in both network and terminal side, and prediction. We believe that network modularization and frequent observation are the only ways in order to understand the reasoning behind the obtained NLEE metric and propose solutions for the improvement. However, it comes with the increased complexity and challenges to be resolved. We present a summary of the most important difficulties, our suggestions and open questions in order to answer “How to accurately assess the NLEE in wireless access network”.

  • 43. Verenzuela, D.
    et al.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). Freelinguist.com, Sweden.
    Scalable D2D Communications for Frequency Reuse >> 1 in 5G2017In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 16, no 6, p. 3435-3447, article id 7891615Article in journal (Refereed)
    Abstract [en]

    Proximity-based applications are becoming fast growing markets suggesting that device-to-device (D2D) communications is becoming an essential part of the future mobile data networks. We propose scalable admission and power control methods for D2D communications underlay cellular networks to increase the reuse of frequency resources and thus network capacity while maintaining QoS to all users. In practice, as D2D communications will generate a new layer of interference, it is essential to take D2D interference into account in inter-cell interference coordination for multi-cell communications. The aim of the proposed methods is to maximize the number of D2D links under QoS constraints, therefore maximizing network frequency reuse in a practical 5G multi-cell environment. Different schemes are designed for applications that have different levels of complexity and availability of channel state information. Numerical results show that by using D2D and the proposed multi-cell interference coordination and low power transmission method, the network spectral efficiency can be increased by as much as ten times, while low outage probability can be assured to provide QoS for all users.

  • 44. Verenzuela, Daniel
    et al.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Scalable Device-to-Device Communications For Frequency Reuse>> 1Manuscript (preprint) (Other academic)
    Abstract [en]

    Proximity based applications are becoming fast growing markets suggesting that Device-to-Device (D2D) communications is becoming an essential part of future mobile data networks. We propose scalable admission and power control methods for D2D communications underlay cellular networks to increase the reuse of frequency resources and thus network capacity while maintaining QoS to all users. The aim of the proposed methods is to maximize the number of D2D links under QoS constraints, therefore maximizing network frequency reuse, while considering different levels of complexity an d available channel state information (CSI) in a multi-cell environment. Numerical results show that by using D2D and the proposed multi-cell interference coordination and low power transmission method, the network spectral efficiency can be increased by as much as ten times, while low outage probability can be assured to provided QoS for all users.

  • 45.
    Verenzuela, Daniel
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Scalable Interference Coordination for Device-to-Device Communications2015In: Computer Communications Workshops (INFOCOM WKSHPS), 2015 IEEE Conference on, IEEE conference proceedings, 2015, p. 348-353Conference paper (Refereed)
    Abstract [en]

    Proximity based applications are becoming fastgrowing markets suggesting that Device-to-Device (D2D) communicationsis going to be an essential part of future cellularnetworks, thus studying the scalability of the system is ofparamount importance. This paper focuses on the problem ofscalability defined as finding the maximum number of D2D linksthat can share the same resources with cellular user equipments(CUEs) while assuring quality-of-service (QoS) to all users incellular networks of any size. To solve this problem a carefuldesign of interference coordination schemes is needed, thus wepresent two solutions namely full channel state information(CSI) optimal (F-CSIOp) scheme and partial CSI distributed(P-CSID) scheme. The first solution is based on an optimizationproblem that uses full CSI to maximize the number of D2Dlinks while providing QoS to all users. However implementingthis solution in real systems is infeasible due to high complexityand signaling overhead, thus we present the later solution basedon a low complexity distributed algorithm that uses limitedCSI. The results show that the P-CSID scheme is able to offerhigh spectrum efficiency and good scalability while assuring lowoutage probability to provide QoS for all users.

  • 46.
    Wang, Y.
    et al.
    Xi'an Jiaotong University.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wang, X.
    Xi'an Jiaotong University.
    A Non-cooperative Scheme for SFR-Based Power Control in LTE Networks2014Conference paper (Refereed)
    Abstract [en]

    We propose a non-cooperative power allocation scheme for cellular systems using soft frequency reuse and in the power control, each user selfishly maximizes its utility.To find the tradeoff between QoS satisfaction and energy consumption, we design a utility function that considers both QoS requirements and the cost. We then show there exists a Nash equilibrium and provide conditions to assure its uniqueness. This scheme has limited signaling overhead and only pricing information needs to be exchanged among cells. Simulation results show that this scheme improves throughput and coverage performance compared with conventional SFR schemes.

  • 47. Wang, Y.
    et al.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wang, X.
    Joint Interference Mitigation and Power Allocation for Multi-Cell LTE Networks: A Non-Cooperative Game Approach2014In: 2014 IEEE 80th Vehicular Technology Conference (VTC Fall), IEEE , 2014, p. 6966031-Conference paper (Refereed)
    Abstract [en]

    We propose a non-cooperative game-theoretic power allocation (NGPA) scheme for interference mitigation in long term evolution (LTE) uplink in this paper. We first set up the interference model employing conventional soft frequency reuse (SFR) scheme for inter-cell interference coordination (ICIC) in a nineteen-cell LTE network. Since each user may selfishly maximize its own performance in power allocation, we design a utility function that considers both quality of service (QoS) satisfaction and energy consumption. We then investigate the existence of Nash equilibrium and derive a sufficient condition to assure its uniqueness. Simulation results show that the proposed scheme improves throughput and coverage performances compared with conventional SFR schemes. Moreover, this scheme only requires limited signaling overhead among cells, which can be readily implemented in a distributed manner for practical systems.

  • 48.
    Wang, Yuanshuang
    et al.
    KTH, School of Information and Communication Technology (ICT). China Elect Technol Grp Corp, Res Inst 28, Nanjing, Jiangsu, Peoples R China.;Roy.
    Liu, Junjun
    China Elect Technol Grp Corp, Res Inst 28, Nanjing, Jiangsu, Peoples R China..
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT).
    Decentralized Cross-Layer Optimization for Energy-Efficient Resource Allocation in HetNets2018In: 2018 INTERNATIONAL CONFERENCE ON CYBER-ENABLED DISTRIBUTED COMPUTING AND KNOWLEDGE DISCOVERY (CYBERC 2018), IEEE , 2018, p. 470-474Conference paper (Refereed)
    Abstract [en]

    In this paper, we develop a joint physical and medium access control (MAC) layer optimization (JPMO) scheme based on game theory for energy-efficient resource allocation and interference management in heterogeneous networks (HetNets). In HetNets, cross-tier interference and co-tier interference significantly limit the network performance. Moreover, when each user only has its own channel state information and chooses its transmission policy independently without any coordination mechanism, it will result in the network collapse or waste of channel resources. To maximize the network efficiency, we develop the JPMO scheme through pricing mechanism from the perspective of game theory. Then we transform this scheme into a two-stage Stackelberg game, in which macrocell determines the transmission policy in MAC layer first, and then SCs perform EE power allocation in physical layer. Simulation results validate the effectiveness of the proposed scheme.

  • 49.
    Wang, Yuanshuang
    et al.
    Xi'an Jiaotong University.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wang, Xia
    Xi'an Jiaotong University.
    An Energy-Efficient Non-Cooperative Game Approach for Channel-Aware Distributed Medium Access Control2014In: 2014 IEEE 80th Vehicular Technology Conference (VTC Fall), IEEE , 2014, p. 1-6Conference paper (Refereed)
    Abstract [en]

    In this paper, an energy-efficient non-cooperative game approach is proposed for channel-aware distributed medium access control (EN-CDMAC) in slotted-Aloha systems, where users act selfishly to improve their own utilities. To resolve the network contention in a distributed manner, the capture model is employed and a pricing-based non-cooperative game scheme is designed to enable selfish users effectively achieve multi-user diversity by adjusting their equilibrium thresholds while guaranteeing fairness by the pricing mechanism. Then the existence of Nash equilibrium is proved, and the necessary and sufficient condition is derived to ensure its uniqueness. Furthermore, the equilibrium stability is investigated with stochastic process theory. Simulation results show that the proposed approach significantly improves the network throughput and delay performance without sacrificing energy efficiency compared to the conventional slotted-Aloha scheme. In particular, the proposed approach is more applicable for high-load systems.

  • 50. Wang, Yuanshuang
    et al.
    Zhao, Ning
    Wang, Xia
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Energy-Efficient Resource Allocation for Different QoS Requirements in Heterogeneous Networks2016In: 2016 IEEE 83RD VEHICULAR TECHNOLOGY CONFERENCE (VTC SPRING), IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    In this paper, we study the energy-efficient resource allocation (EERA) for heterogeneous networks, where different quality of service (QoS) requirements, including minimum-rate guarantee services and best effort (BE) services are taken into consideration. We formulate EERA scheme as a mixed-integer non-convex optimization problem, in which the power and sub-carrier allocation are jointly optimized to maximize the network utility, mitigate the cross-tier interference, and guarantee the fairness between the two classes of services and the fairness among the BE services. After transforming the problem into a convex optimization problem by some mathematic manipulations, we design an efficient iterative algorithm to solve this problem by Lagrangian dual decomposition method and gradient-based method. Simulation results validate the convergence and effectiveness of the proposed scheme.

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