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  • 1.
    Abrahamsson, Lars
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Fast Estimation of Relations Between Aggregated Train Power System Data and Traffic Performance2011In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 60, no 1, p. 16-29Article in journal (Refereed)
    Abstract [en]

    Transports via rail are increasing, and major railway infrastructure investments are expected. An important part of this infrastructure is the railway power supply system (RPSS). Future railway power demands are not known. The more distant the uncertain future, the greater the number of scenarios that have to be considered. Large numbers of scenarios make time-demanding (some minutes, each) full simulations of electric railway power systems less attractive and simplifications more so. The aim, and main contribution, of this paper is to propose a fast approximator that uses aggregated traction system information as inputs and outputs. This approximator can be used as an investment planning constraint in the optimization. It considers that there is a limit on the intensity of the train traffic, depending on the strength of the power system. This approximator approach has not previously been encountered in the literature. In the numerical example of this paper, the approximator inputs are the power system configuration; the distance between a connection from contact line to the public grid, to another connection, or to the end of the contact line; the average values and the standard deviations of the inclinations of the railway; the average number of trains; and their average velocity for that distance. The output is the maximal attainable average velocity of an added train for the described railway power system section. The approximator facilitates studies of many future railway power system loading scenarios, combined with different power system configurations, for investment planning analysis. The approximator is based on neural networks. An additional value of the approximator is that it provides an understanding of the relations between power system configuration and train traffic performance.

  • 2.
    Ahmed, Furqan
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Alfredo Dowhuszko, Alexis
    Tirkkonen, Olav
    Self-Organizing Algorithms for Interference Coordination in Small Cell Networks2017In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 66, no 9, p. 8333-8346Article in journal (Refereed)
    Abstract [en]

    This paper discusses novel joint (intracell and intercell) resource allocation algorithms for self-organized interference coordination in multicarrier multiple-input multiple-output (MIMO) small cell networks. The proposed algorithms enable interference coordination autonomously, over multiple degrees of freedom, such as base station transmit powers, transmit precoders, and user scheduling weights. A generic a-fair utility maximization framework is considered to analyze performance-fairness tradeoff and to quantify the gains achievable in interference-limited networks. The proposed scheme involves limited inter-base station signaling in the form of two step (power and precoder) pricing. Based on this decentralized coordination, autonomous power and precoder update decision rules are considered, leading to algorithms with different characteristics in terms of user data rates, signaling load, and convergence speed. Simulation results in a practical setting show that the proposed pricing-based self-organization can achieve up to 100% improvement in cell-edge data rates when compared to baseline optimization strategies. Furthermore, the convergence of the proposed algorithms is also proved theoretically.

  • 3.
    Alabbasi, Abdulrahman
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
    Rezki, Zouheir
    Shihada, Basem
    Outage Analysis of Spectrum Sharing Over M-Block Fading With Sensing Information2017In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 66, no 4, p. 3071-3087Article in journal (Refereed)
    Abstract [en]

    Future wireless technologies, such as fifth-generation (5G), are expected to support real-time applications with high data throughput, e.g., holographic meetings. From a bandwidth perspective, cognitive radio (CR) is a promising technology to enhance the system's throughput via sharing the licensed spectrum. From a delay perspective, it is well known that increasing the number of decoding blocks will improve system robustness against errors while increasing delay. Therefore, optimally allocating the resources to determine the tradeoff of tuning the length of the decoding blocks while sharing the spectrum is a critical challenge for future wireless systems. In this paper, we minimize the targeted outage probability over the block-fading channels while utilizing the spectrum-sharing concept. The secondary user's outage region and the corresponding optimal power are derived, over two-block and M-block fading channels. We propose two suboptimal power strategies and derive the associated asymptotic lower and upper bounds on the outage probability with tractable expressions. These bounds allow us to derive the exact diversity order of the secondary user's outage probability. To further enhance the system's performance, we also investigate the impact of including the sensing information on the outage problem. The outage problem is then solved via proposing an alternating optimization algorithm, which utilizes the verified strict quasi-convex structure of the problem. Selected numerical results are presented to characterize the system's behavior and show the improvements of several sharing concepts.

  • 4.
    Bao, Jinchen
    et al.
    Southwest Jiaotong Univ, Prov Key Lab Informat Coding & Transmiss, Chengdu 611731, Sichuan, Peoples R China..
    Ma, Zheng
    Southwest Jiaotong Univ, Prov Key Lab Informat Coding & Transmiss, Chengdu 611731, Sichuan, Peoples R China..
    Xiao, Ming
    Royal Inst Technol, Dept Commun Theory, S-10044 Stockholm, Sweden..
    Ding, Zhiguo
    Univ Lancaster, Sch Comp & Commun, Lancaster LA1 4YW, England..
    Zhu, Zhongliang
    Southwest Jiaotong Univ, Prov Key Lab Informat Coding & Transmiss, Chengdu 611731, Sichuan, Peoples R China..
    Performance Analysis of Uplink SCMA With Receiver Diversity and Randomly Deployed Users2018In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, no 3, p. 2792-2797Article in journal (Refereed)
    Abstract [en]

    This paper considers the performance analysis of sparse code multiple access (SCMA) with receive diversity arrays and randomly deployed users in a cellular uplink scenario. The impact of path loss on the performance of SCMA is characterized, by assuming independent Rayleigh fading and joint maximum likelihood (ML) receivers. A tight upper bound on the probability of symbol detection error is derived, and the achievable diversity and coding gains are investigated. The analytical results are validated by using simulations, and show that a diversity order which is equal to the product of the number of receive antennas and the signal-space diversity can be achieved, and the large-scale path-loss decreases only the coding gain.

  • 5.
    Ben Slimane, Slimane
    KTH, Superseded Departments, Signals, Sensors and Systems.
    An Improved PSK Scheme for Fading Channels1998In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 47, no 2, p. 703-710Article in journal (Refereed)
    Abstract [en]

    The performance of uncoded phase-shift-keying (PSK) schemes over fading channels is only inversely proportional to the signal-to-noise ratio, which is not very reliable for digital communication applications. Improving their performance has been approached by means of coded modulation schemes, where code redundancy combined with interleaving introduces some degree of diversity that depends on the complexity of the code. This paper proposes an alternative way in improving the performance of PSK schemes over fading channels by looking at the reference scheme first. It is shown that by using interleaving combined with a proper signal constellations and still using symbol-by-symbol detection, a higher diversity is obtained and the performance of uncoded PSK schemes over fading channels is considerably improved. With this simple modification, the obtained performance is comparable to that of the best four-state trellis-coded-modulation (TCM) 8PSK schemes reported in the literature. By optimizing the reference scheme first, it is shown that this technique optimizes the performance of Ungerboeck's trellis-coded 8PSK schemes over fading channThe performance of uncoded phase-shift-keying (PSK) schemes over fading channels is only inversely proportional to the signal-to-noise ratio, which is not very reliable for digital communication applications. Improving their performance has been approached by means of coded modulation schemes, where code redundancy combined with interleaving introduces some degree of diversity that depends on the complexity of the code. This paper proposes an alternative way in improving the performance of PSK schemes over fading channels by looking at the reference scheme first. It is shown that by using interleaving combined with a proper signal constellations and still using symbol-by-symbol detection, a higher diversity is obtained and the performance of uncoded PSK schemes over fading channels is considerably improved. With this simple modification, the obtained performance is comparable to that of the best four-state trellis-coded-modulation (TCM) 8PSK schemes reported in the literature. By optimizing the reference scheme first, it is shown that this technique optimizes the performance of Ungerboeck's trellis-coded 8PSK schemes over fading channels. In fact, without altering their performance over the additive white Gaussian noise (AWGN) channel, significant coding gain over fading channels is achieved.els. In fact, without altering their performance over the additive white Gaussian noise (AWGN) channel, significant coding gain over fading channels is achieved

  • 6.
    Ben Slimane, Slimane
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Reducing the Peak-to-Average Power Ratio of OFDM Signals Through Precoding2007In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 56, no 2, p. 686-695Article in journal (Refereed)
    Abstract [en]

    Orthogonal-frequency-division-multiplexing (OFDM) techniques allow the transmission of high data rates over broadband radio channels subject to multipath fading without the need for powerful channel equalization. However, they are very sensitive to nonlinear effects due to the high peak-to-average power ratio (PAPR) owned by their transmitted signals. This paper proposes an efficient technique for reducing the PAPR of OFDM signals. The proposed technique is data-independent and, thus, does not require new processing and optimization for each transmitted OFDM block. The reduction in PAPR of the OFDM signal is obtained through a proper selection of a precoding scheme that distributes the power of each modulated symbol over the OFDM block. The obtained results show that this precoding scheme is an attractive solution to the PAPR problem of OFDM signals. It is shown, through computer simulations, that the PAPR of precoded OFDM signals approaches that of single-carrier signals. The good improvement in PAPR given by the present technique permits the reduction of the complexity and cost of the transmitter significantly. The precoding schemes also take advantage of the frequency variations of the communication channel and can provide considerable performance gain in fading-multipath channels.

  • 7.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Tight Bounds on the Error Probability of Coded Modulation Schemes in Rayleigh Fading Channels1995In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 44, no 1, p. 121-130Article in journal (Refereed)
  • 8.
    Brandt, Rasmus
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Bengtsson, Mats
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Distributed CSI Acquisition and Coordinated Precoding for TDD Multicell MIMO Systems2016In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 65, no 5, p. 2890-2906Article in journal (Refereed)
    Abstract [en]

    Several distributed coordinated precoding methods exist in the downlink multicell MIMO literature, many of which assume perfect knowledge of received signal covariance and local effective channels. In this work, we let the notion of channel state information (CSI) encompass this knowledge of covariances and effective channels. We analyze what local CSI is required in the WMMSE algorithm for distributed coordinated precoding, and study how this required CSI can be obtained in a distributed fashion. Based on pilot-assisted channel estimation, we propose three CSI acquisition methods with different tradeoffs between feedback and signaling, backhaul use, and computational complexity. One of the proposed methods is fully distributed, meaning that it only depends on over-the-air signaling but requires no backhaul, and results in a fully distributed joint system when coupled with the WMMSE algorithm. Naively applying the WMMSE algorithm together with the fully distributed CSI acquisition results in catastrophic performance however, and therefore we propose a robustified WMMSE algorithm based on the well known diagonal loading framework. By enforcing properties of the WMMSE solutions with perfect CSI onto the problem with imperfect CSI, the resulting diagonally loaded spatial filters are shown to perform significantly better than the naive filters. The proposed robust and distributed system is evaluated using numerical simulations, and shown to perform well compared with benchmarks. Under centralized CSI acquisition, the proposed algorithm performs on par with other existing centralized robust WMMSE algorithms. When evaluated in a large scale fading environment, the performance of the proposed system is promising.

  • 9.
    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.

  • 10. Choi, Okyoung
    et al.
    Kim, Seokhyun
    Jeong, Jaeseong
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Lee, Hyang-Won
    Chong, Song
    Delay-Optimal Data Forwarding in Vehicular Sensor Networks2016In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 65, no 8, p. 6389-6402Article in journal (Refereed)
    Abstract [en]

    The vehicular sensor network (VSN) is emerging as a new solution for monitoring urban environments such as intelligent transportation systems and air pollution. One of the crucial factors that determine the service quality of urban monitoring applications is the delivery delay of sensing data packets in the VSN. In this paper, we study the problem of routing data packets with minimum delay in the VSN by exploiting 1) vehicle traffic statistics, 2) anycast routing, and 3) knowledge of future trajectories of vehicles such as busses. We first introduce a novel road network graph model that incorporates the three factors into the routing metric. We then characterize the packet delay on each edge as a function of the vehicle density, speed, and the length of the edge. Based on the network model and delay function, we formulate the packet routing problem as a Markov decision process (MDP) and develop an optimal routing policy by solving the MDP. Evaluations using real vehicle traces in a city show that our routing policy significantly improves the delay performance compared with existing routing protocols. Specifically, optimal VSN data forwarding (OVDF) yields, on average, 96% better delivery ratio and 72% less delivery delay than existing algorithms in some areas distant from destinations.

  • 11.
    Cui, Yaping
    et al.
    Southwest Jiaotong Univ, Sch Informat Sci & Technol, Chengdu 610031, Sichuan, Peoples R China.;Chongqing Univ Posts & Telecommun, Sch Commun & Informat Engn, Chongqing 400065, Peoples R China..
    Fang, Xuming
    Southwest Jiaotong Univ, Sch Informat Sci & Technol, Chengdu 610031, Sichuan, Peoples R China..
    Fang, Yuguang
    Univ Florida, Dept Elect & Comp Engn, Gainesville, FL 32611 USA..
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Optimal Nonuniform Steady mmWave Beamforming for High-Speed Railway2018In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, no 5, p. 4350-4358Article in journal (Refereed)
    Abstract [en]

    Using higher frequency bands (e.g., millimeter waves) to provide higher data rate is an effective way to eliminate performance bottleneck for future wireless networks, particularly for cellular networks based high-speed railway (HSR) wireless communication systems. However, higher frequency bands suffer from significant path loss and narrow-beam coverage, which pose serious challenges in cellular networks, especially under the HSR scenario. Meanwhile, as one of the key performance indexes of ultrareliable and low-latency communications in 5G systems, network reliability should be guaranteed to provide steady reliable data transmission along the railway, especially when safety-critical railway signaling information is delivered. In this paper, we propose a novel beamforming scheme, namely, optimal nonuniform steady mmWave beamforming, to guarantee the network reliability under an interleaved redundant coverage architecture for future HSR wireless systems. Moreover, we develop a bisection-based beam boundary determination (BBBD) method to determine the service area of each predefined RF beam. Finally, we demonstrate that the proposed optimal nonuniform steady mmWave beamforming can provide steady reliable data transmissions along the railway, and the network reliability requirements can be guaranteed when the proposed BBBD method is used. We expect that our optimal nonuniform steady mmWave beamforming provides a promising solution for future HSR wireless systems.

  • 12.
    Devarakota, Pandu Ranga Rao
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Castillo-Franco, Marta
    IEE S. A., Luxembourg.
    Ginhoux, Romuald
    IEE S. A., Luxembourg.
    Mirbach, Bruno
    IEE S. A., Luxembourg.
    Kater, Serge
    IEE S. A., Luxembourg.
    Ottersten, Björn
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    3-D-Skeleton-Based Head Detection and Tracking Using Range Images2009In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 58, no 8, p. 4064-4077Article in journal (Refereed)
    Abstract [en]

    Vision-based 3-D head detection and tracking systems have been studied in several applications like video surveillance, face-detection systems, and occupant posture analysis. In this paper, we present the development of a topology-based framework using a 3-D skeletal model for the robust detection and tracking of a vehicle occupant's head position from low-resolution range image data for a passive safety system. Unlike previous approaches to head detection, the proposed approach explores the topology information of a scene to detect the position of the head. Among the different available topology representations, the Reeb graph technique is chosen and is adapted to low-resolution 3-D range images. Invariance of the graph under rotations is achieved by using a Morse radial distance function. To cope with the particular challenges such as the noise and the large variations in the density of the data, a voxel neighborhood connectivity notion is proposed. A multiple-hypothesis tracker (MHT) with nearest-neighbor data association and Kalman filter prediction is applied on the endpoints of the Reeb graph to select and filter the correct head candidate out of Reeb graph endpoints. A systematic evaluation of the head detection framework is carried out on full-scale experimental 3-D range images and compared with the ground truth. It is shown that the Reeb graph topology algorithm developed herein allows the correct detection of the head of the occupant with only two head candidates as input to the MHT. Results of the experiments demonstrate that the proposed framework is robust under the large variations of the scene. The processing requirements of the proposed approach are discussed. It is shown that the number of operations is rather low and that real-time processing requirements can be met with the proposed method.

  • 13.
    Devarakota, Pandu Ranga Rao
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Castillo-Franco, Marta
    IEE S.A., ZAE Weiergewan, 5326 Contern, Luxembourg.
    Ginhoux, Romuald
    IEE S.A., ZAE Weiergewan, 5326 Contern, Luxembourg.
    Mirbach, Bruno
    IEE S.A., ZAE Weiergewan, 5326 Contern, Luxembourg.
    Ottersten, Björn
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Occupant classification using range images2007In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 56, no 4, p. 1983-1993Article in journal (Refereed)
    Abstract [en]

    Static occupant classification is an important requirement in designing so-called smart airbags. Systems for this purpose can be either based on pressure sensors or vision sensors. Vision-based systems are advantageous over pressure-sensor-based systems as they can provide additional functionalities like dynamic occupant-position analysis or child-seat orientation detection. The focus of this paper is to evaluate and analyze static occupant classification using a low-resolution range sensor, which is based on the time-of-flight principle. This range sensor is advantageous, since it provides directly a dense range image that is independent of the ambient illumination conditions and object textures. Herein, the realization of an occupant-classification system, using a novel low-resolution range image sensor, is described, methods for extracting robust features from the range images are investigated, and different classification methods are evaluated for classifying occupants. Bayes quadratic classifier, Gaussian mixture-model classifier, and polynomial classifier are compared to a clustering-based linear-regression classifier using a polynomial kernel. The latter one shows improved results compared to the first-three classification methods. Full-scale tests have been conducted on a wide range of realistic situations with different adults and child seats in various postures and positions. The results prove the feasibility of low-resolution range images for the current application.

  • 14.
    Di Marco, Piergiuseppe
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Park, Pan Gun
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Analytical Modeling of Multi-hop IEEE 802.15.4 Networks2012In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 61, no 7, p. 3191-3208Article in journal (Refereed)
    Abstract [en]

    Many of existing analytical studies of the IEEE 802.15.4 medium access control (MAC) protocol are not adequate because they are often based on assumptions such as homogeneous traffic and ideal carrier sensing, which are far from reality for multi-hop networks, particularly in the presence of mobility. In this paper, a new generalized analysis of the unslotted IEEE 802.15.4 MAC is presented. The analysis considers the effects induced by heterogeneous traffic due to multi-hop routing and different traffic generation patterns among the nodes of the network and the hidden terminals due to reduced carrier-sensing capabilities. The complex relation between MAC and routing protocols is modeled, and novel results on this interaction are derived. For various network configurations, conditions under which routing decisions based on packet loss probability or delay lead to an unbalanced distribution of the traffic load across multi-hop paths are studied. It is shown that these routing decisions tend to direct traffic toward nodes with high packet generation rates, with potential catastrophic effects for the node's energy consumption. It is concluded that heterogeneous traffic and limited carrier-sensing range play an essential role on the performance and that routing should account for the presence of dominant nodes to balance the traffic distribution across the network.

  • 15. Du, Rong
    et al.
    Chen, Cailian
    Yang, Bo
    Lu, Ning
    Guan, Xinping
    Xuemin, Shen
    Effective Urban Traffic Monitoring by Vehicular Sensor Networks2015In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 64, no 1, p. 273-286Article in journal (Refereed)
    Abstract [en]

    Traffic monitoring in urban transportation systems can be carried out based on vehicular sensor networks. Probe vehicles (PVs), such as taxis and buses, and floating cars (FCs), such as patrol cars for surveillance, can act as mobile sensors for sensing the urban traffic and send the reports to a traffic-monitoring center (TMC) for traffic estimation. In the TMC, sensing reports are aggregated to form a traffic matrix, which is used to extract traffic information. Since the sensing vehicles cannot cover all the roads all the time, the TMC needs to estimate the unsampled data in the traffic matrix. As this matrix can be approximated to be of low rank, matrix completion (MC) is an effective method to estimate the unsampled data. However, our previous analysis on the real traces of taxis in Shanghai reveals that MC methods do not work well due to the uneven samples of PVs, which is common in urban traffic. To exploit the intrinsic relationship between the unevenness of samples and traffic estimation error, we study the temporal and spatial entropies of samples and successfully define the important criterion, i.e., average entropy of the sampling process. A new sampling rule based on this relationship is proposed to improve the performance of estimation and monitoring.With the sampling rule, two new patrol algorithms are introduced to plan the paths of controllable FCs to proactively participate in trafficmonitoring. By utilizing the patrol algorithms for real-data-set analysis, the estimation error reduces from 35% to about 10%, compared with the random patrol or interpolation method in traffic estimation. Both the validity of the exploited relationship and the effectiveness of the proposed patrol control algorithms are demonstrated.

  • 16. Dutta, Amit Kumar
    et al.
    Hari, K. V. S.
    KTH. Indian Institute of Science, India.
    Hanzo, Lajos
    Minimum-Error-Probability CFO Estimation for Multiuser MIMO-OFDM Systems2015In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 64, no 7, p. 2804-2818Article in journal (Refereed)
    Abstract [en]

    We consider carrier frequency offset (CFO) estimation in the context of multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems over noisy frequency-selective wireless channels with both single- and multiuser scenarios. We conceived a new approach for parameter estimation by discretizing the continuous-valued CFO parameter into a discrete set of bins and then invoked detection theory, analogous to the minimum-bit-error-ratio optimization framework for detecting the finite-alphabet received signal. Using this radical approach, we propose a novel CFO estimation method and study its performance using both analytical results and Monte Carlo simulations. We obtain expressions for the variance of the CFO estimation error and the resultant BER degradation with the single- user scenario. Our simulations demonstrate that the overall BER performance of a MIMO-OFDM system using the proposed method is substantially improved for all the modulation schemes considered, albeit this is achieved at increased complexity.

  • 17. Festag, A.
    et al.
    Papadimitratos, Panagiotis
    Tielert, T.
    Design and Performance of Secure Geocast for Vehicular Communication2010In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 59, no 5, p. 2456-2471Article in journal (Refereed)
    Abstract [en]

    The characteristics of vehicular communication environments and their networking and application requirements have led to the development of unique networking protocols. They enable vehicle-to-vehicle and vehicle-to-infrastructure communication based on the IEEE 802.11 technology, ad hoc principles, and wireless multihop techniques using geographical positions. These protocols, which are commonly referred to as Geocast, greatly support the vehicular communication and applications but necessitate a tailored security solution that provides the required security level with reasonable processing and protocol overhead, as well as reasonably priced onboard and road-side unit equipment. In this paper, we present the design of a security solution for Geocast, which is based on cryptographic protection, plausibility checks using secure neighbor discovery and mobility-related checks, trustworthy neighborhood assessment, and rate limitation. We analyze the achieved security level of the proposed scheme and assess its overhead and performance. Furthermore, we develop a software-based prototype implementation of a secure vehicular communication system. We find that the proposed security measures could result in a network performance bottleneck in realistic vehicular scenarios. Finally, we analyze the tradeoff between security overhead and protocol performance and determine the minimal processing overhead needed for acceptable performance.

  • 18.
    Frodigh, Magnus
    KTH, Superseded Departments, Teleinformatics.
    Performance  bounds for Power Control Supported DCA-algorithms in Highway Micro Cellular Radio Systems1995In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 44, no 2, p. 238-243Article in journal (Refereed)
    Abstract [en]

    To achieve a high spectrum efficiency in cellular radio systems, the radio resource allocation algorithms have to be adaptive to the actual traffic and interference situation. The focus of the paper is on performance bounds of a cellular radio system using dynamic channel assignment (DCA) combined with power control (PC). A trivial upper bound on the performance is identified. The bound is given by the performance of a hypothetical system which is able to use all channels simultaneously in all cells. A lower bound on the performance is derived from a theoretical PC supported DCA-algorithm. For a highway micro cellular system and a deterministic propagation model, numerical results show that the lower and upper bounds are tight. That is, the results indicate that it is possible to use all channels in all cells simultaneously and still provide an acceptable signal-to interference ratio in all assigned communication links.

  • 19.
    Gimenez, Jordi Joan
    et al.
    Univ Politecn Valencia, iTEAM Res Inst, E-46022 Valencia, Spain..
    Sung, Ki Won
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Gomez-Barquero, David
    Univ Politecn Valencia, iTEAM Res Inst, E-46022 Valencia, Spain..
    Semianalytical Approach to the PDF of SINR in HPHT and LPLT Single-Frequency Networks2018In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, no 5, p. 4173-4181Article in journal (Refereed)
    Abstract [en]

    Single-frequency networks (SFN) are widely adopted in terrestrial broadcast networks based on high-power high-tower (HPHT) deployments. The mobile broadcasting standard Evolved Multimedia Broadcast Multicast Service (eMBMS) has been enhanced in Release 14 to enable SFN operation with larger CP duration which may allow for the deployment of large area SFNs and even the combined operation between HPHT and low-power low-tower (LPLT) cellular stations. The knowledge of the signal-to-interference-plus-noise ratio (SINR) distribution over an SFN area may facilitate the selection of transmission parameters according to the network topology. This paper presents a semianalytical method for the calculation of the SINR distribution in SFNs with low computational complexity compared to Monte Carlo simulations. The method, which builds on previous work developed for cellular communications, is applied to HPHT+LPLT SFNs and evaluated against different transmission and network parameters.

  • 20.
    Giordano, Giuseppe
    et al.
    Chalmers Univ Technol, Dept Elect Engn, S-41296 Gothenburg, Sweden..
    Klass, Verena
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Behm, Mårten
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Sjöberg, Jonas
    Chalmers Univ Technol, Dept Elect Engn, S-41296 Gothenburg, Sweden..
    Model-Based Lithium-Ion Battery Resistance Estimation From Electric Vehicle Operating Data2018In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, no 5, p. 3720-3728Article in journal (Refereed)
    Abstract [en]

    State-of-health estimates of batteries are essential for onboard electric vehicles in order to provide safe, reliable, and cost-effective battery operation. This paper suggests a method to estimate the 10-s discharge resistance, which is an established battery figure of merit from laboratory testing, without performing the laboratory test. Instead, a state-of-health estimate of batteries is obtained using data directly from their operational use, e.g., onboard electric vehicles. It is shown that simple dynamical battery models, based on a current input and a voltage output, with model parameters dependent on temperature and state of charge, can be derived using AutoRegressive with eXogenous input models, whose order can be adjusted to describe the complex battery behavior. Then, the 10-s discharge resistance can be conveniently computed from the identified model parameters. Moreover, the uncertainty of the estimated resistance values is provided by the method. The suggested method is validated with usage data from emulated electric vehicle operation of an automotive lithium-ion battery cell. The resistance values are estimated accurately for a state-of-charge and temperature range spanning typical electric vehicle operating conditions. The identification of the model parameters and the resistance computation are very fast, rendering the method suitable for onboard application.

  • 21.
    Goubet, Olivier
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. THALES Communications and Security, Paris, France.
    Baudic, Gwilherm
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Institut Supérieur de l'Aéronautique et de l'Espace, Toulouse, France.
    Gabry, Frédéric
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Oechtering, Tobias J.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Low-Complexity Scalable Iterative Algorithms for IEEE 802.11p Receivers2015In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 64, no 9, p. 3944-3956Article in journal (Refereed)
    Abstract [en]

    In this paper, we investigate receivers for vehicle-to- vehicle (V2V) and vehicle-to-infrastructure (V2I) communications. Vehicular channels are characterized by multiple paths and time variations, which introduce challenges in the design of receivers. We propose an algorithm for IEEE 802.11p-compliant receivers, based on orthogonal frequency-division multiplexing (OFDM). We employ iterative structures in the receiver as a way to estimate the channel despite variations within a frame. The channel estimator is based on factor graphs (FGs), which allow the design of soft iterative receivers while keeping acceptable computational complexity. Throughout this paper, we focus on designing a receiver that offers a good complexity-performance tradeoff. Moreover, we propose a scalable algorithm to be able to tune the tradeoff, depending on the channel conditions. Our algorithm allows reliable communications while offering a considerable decrease in computational complexity. In particular, numerical results show the tradeoff between complexity and performance measured in computational time and bit error rate (BER), as well as frame error rate (FER) achieved by various interpolation lengths used by the estimator, which both outperform by decades the standard least squares (LS) solution. Furthermore, our adaptive algorithm shows a considerable improvement in terms of computational time and complexity against state-of-the-art and classical receptors while showing acceptable BER and FER performance.

  • 22.
    Grandhi, Sudheer A.
    et al.
    Wireless Inf. Network Lab., Rutgers University.
    Vijayan, Rajiv
    Wireless Inf. Network Lab., Rutgers University.
    Goodman, David J.
    Wireless Inf. Network Lab., Rutgers University.
    Zander, Jens
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Centralized Power Control in Cellular Radio Systems1993In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 42, no 4, p. 466-468Article in journal (Refereed)
    Abstract [en]

    This paper describes a centralized power control scheme for cellular mobile radio systems. The power for the mobiles in the proposed scheme is computed based on signal strength measurements. All the mobiles using the same channel in this scheme will attain a common carrier-to-interference ratio. The proposed scheme is analyzed and shown to have an optimal solution.

  • 23.
    Gross, James
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Punyal, Oscar
    RWTH Aachen University.
    Pereira, Carlos
    University of Porto.
    Aguiar, Ana
    University of Porto.
    Experimental Characterization and Modeling of RF Jamming Attacks on VANETs2015In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 64, no 2, p. 524-540Article in journal (Refereed)
    Abstract [en]

    In this work, we evaluate the performance of 802.11p-based vehicular communications in the presence of RF jamming attacks. Specifically, we characterize the transmission success rate of a car-to-car link subject to constant, periodic, and reactive RF jamming. First, we conduct extensive measurements in an anechoic chamber, where we study the benefits of built-in techniques for interference mitigation. In addition, we identify that the periodic transmission of preamblelike jamming signals can hinder successful communication despite being up to five orders of magnitude weaker than the signal of interest. We further provide the rationale behind this remarkably high jammer eectiveness. Additionally, we quantify the impact of reaction delay and interference signal length on the eectiveness of the reactive jammer. Next, by means of outdoor measurements, we evaluate the suitability of the indoor measurements for being used as a model to characterize the performance of car-to-car communications in the presence of RF jamming. Finally, we conduct outdoor measurements emulating a vehicular platoon and study the threats that RF jamming poses to this VANET application. We observe that constant, periodic, but also reactive jammer can hinder communication over large propagation areas, which would threaten road safety.

  • 24.
    Guimaraes, Francisco R. V.
    et al.
    Univ Fed Ceara, Wireless Telecom Res Grp GTEL, CP 6005, BR-60440970 Fortaleza, Ceara, Brazil..
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control. Ericsson Res, S-16483 Stockholm, Sweden.
    Freitas, Walter C., Jr.
    Univ Fed Ceara, Wireless Telecom Res Grp GTEL, CP 6005, BR-60440970 Fortaleza, Ceara, Brazil..
    Silva, Yuri C. B.
    Univ Fed Ceara, Wireless Telecom Res Grp GTEL, CP 6005, BR-60440970 Fortaleza, Ceara, Brazil..
    Pricing-Based Distributed Beamforming for Dynamic Time Division Duplexing Systems2018In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, no 4, p. 3145-3157Article in journal (Refereed)
    Abstract [en]

    Multicell dynamic time division duplexing (TDD) systems make it possible to adapt the number of uplink and downlink time slots in each cell to the prevailing cell-wide traffic demand. Although dynamic TDD systems can be advantageously deployed in scenarios in which the uplink and downlink traffic demands are asymmetric and time varying, dynamic TDD systems give rise to base station to base station (BS-to-BS) interference and user equipment to user equipment (UE-to-UE) interference that negatively impact the system performance. In this paper, we propose employing a distributed beamforming scheme to mitigate the BS-to-BS interference and thereby to improve the uplink performance. Specifically, the proposed scheme uses interference pricing to find the appropriate precoder vectors at the BSs, which also improves the signal-to-interference-plus-noise ratio (SINR) performance in the downlink. We compare the performance of the pricing-based (PB) beamforming scheme with that of zero-forcing beamforming in an outdoor picocell environment specified by the 3rd Generation Partnership Project using a realistic system simulator. We find that the proposed PB scheme boosts the SINR in the uplink at the expense of a small degradation of the downlink SINR compared with the zero-forcing scheme. On the other hand, the PB beamforming approach can significantly reduce the downlink transmit power levels and thereby improve the overall energy efficiency of the system.

  • 25.
    Hamid, Mohamed
    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.
    Björsell, Niclas
    Academy for Natural Science and Built Environment, University of Gävle.
    Slimane, Ben Slimane
    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 and Eigenvalue-Based Combined Fully-Blind Self-Adapted Spectrum Sensing Algorithm2015In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 65, no 2, p. 630-642Article in journal (Refereed)
    Abstract [en]

    In this paper, a comparison between energy and maximum-minimum eigenvalue detectors is performed. The comparison has been made concerning the sensing complexity and the sensing accuracy in terms of the receiver operating characteristics curves. The impact of the signal bandwidth compared to the observation bandwidth is studied for each detector. For the energy detector, the probability of detection increases monotonically with the increase of the signal bandwidth. For the maximum-minimum eigenvalue detector, an optimal value of the ratio between the signal bandwidth and the observation bandwidth is found to be $0.5$ when reasonable values of the system dimensionality are used. Based on the comparison findings, a combined two-stage detector is proposed. The combined detector performance is evaluated based on simulations and measurements. The combined detector achieves better sensing accuracy than the two individual detectors with a complexity lies in between the two individual complexities. The combined detector is fully-blind and self-adapted as the maximum-minimum eigenvalue detector estimates the noise and feeds it back to the energy detector. The performance of the noise estimation process is evaluated in terms of the normalized mean square error.

  • 26. 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.

  • 27.
    Hong, Yi
    et al.
    University of South Australia.
    Rasmussen, Lars Kildehöj
    University of South Australia.
    Iterative switched decoding for interleave-division multiple-access systems2008In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 57, no 3, p. 1939-1944Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider an interleave-division multiple-access (IDMA) system with multiple users transmitting over a shared additive white Gaussian noise channel. In an IDMA system, the information sequence of each user is encoded by a low-rate serially concatenated code consisting of a convolutional code and a repetition code. To reduce decoding complexity, it has been proposed to only decode the inner repetition code for the first few iterations before including the full concatenated code constraints into the decoding process. Here, we characterize this concept of switched decoding as the parallel decoding of two complementary punctured codes and propose a systematic design procedure based on the extrinsic information transfer chart and trajectory analyses, leading to the best decoding convergence-complexity tradeoffs.

  • 28.
    Hossain, M. M. Aftab
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Cavdar, Cicek
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Bjornson, Emil
    Linkoping Univ, Dept Elect Engn, S-58183 Linkoping, Sweden..
    Jantti, Riku
    Aalto Univ, Sch Elect Engn, Espoo 02150, Finland..
    Energy Saving Game for Massive MIMO: Coping With Daily Load Variation2018In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, no 3, p. 2301-2313Article in journal (Refereed)
    Abstract [en]

    Massive MIMO (MM) is one of the leading technologies that can cater for very high capacity demand. However, energy consumption of MM systems needs to be load adaptive in order to cope with the significant temporal load variations (TLV) over a day. In this paper, we propose a game-theoretic model for studying load adaptive multicell massive MIMO system where each base station (BS) adapts the number of antennas to the TLV in order to maximize the downlink energy efficiency (EE). The utility function considered here is defined as the number of bits transferred per Joule of energy. In order to incorporate the TLV, the load at each BS is modeled as an M/G/m/m state dependent queue under the assumption that the network is dimensioned to serve a maximum number of users at the peak load. The EE maximization problem is formulated in a game theoretic framework where the number of antennas to be used by a BS is determined through the best response iteration. This load adaptive system achieves around 24% higher EE and saves around 40% energy compared to a baseline system where the BSs always run with the fixed number of antennas that is most energy efficient at the peak load and that can be switched OFF when there is no traffic.

  • 29.
    Hu, Yulin
    et al.
    RWTH Aachen University.
    Gross, James
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Schmeink, Anke
    RWTH Aachen University.
    On the Capacity of Relaying with Finite Blocklength2015In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, no 99Article in journal (Refereed)
    Abstract [en]

    In this paper, the relaying performance is studied under the finite blocklength regime. The overall error probability of relaying is derived. Moreover, we investigate the Blocklength- Limited capacity (BL-capacity) of relaying. We prove that the BL-capacity of relaying is quasiconcave in the overall error probability. Therefore, the BL-capacity has a global maximum value which can be achieved by choosing an appropriate error probability. Through numerical investigations, we validate our analytical model and compare the performance of relaying under the finite blocklength regime versus the Shannon capacity regime.

  • 30.
    Hu, Yulin
    et al.
    RWTH Aachen University.
    Gross, James
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Schmeink, Anke
    RWTH Aachen University.
    QoS-Constrained Energy Efficiency of Cooperative ARQ in Multiple DF Relay Systems2015In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, p. 848-859Article in journal (Refereed)
    Abstract [en]

    In this paper, we study the higher-layer performance as well as the "throughput, delay, energy consumption" tradeoff problem for multi-relay assisted cooperative automatic repeat request (C-ARQ) protocols. We study a practical scenario where only the average channel state information is available at the source and relays. We consider four multi-relay C-ARQ protocols, and derive closed-form expressions for the transmission delay distribution, the energy consumption and the higherlayer queuing performance. Furthermore, we analyze the QoSconstrained energy efficiency performances of the protocols. Our analysis is validated by simulations. In addition, we evaluate the system performance under these C-ARQ protocols and for different topologies. We conclude several guidelines for the design of efficient C-ARQ protocols. Finally, a simple extension of the studied C-ARQ protocols is proposed, which improves the QoSconstrained energy efficiency by 4%.

  • 31.
    Hu, Yulin
    et al.
    Rhein Westfal TH Aachen, Inst Theoret Informat Technol, D-52062 Aachen, Germany..
    Schmeink, Anke
    Rhein Westfal TH Aachen, Inst Theoret Informat Technol, D-52062 Aachen, Germany..
    Gross, James
    KTH, School of Electrical Engineering (EES).
    Optimal Scheduling of Reliability-Constrained Relaying System Under Outdated CSI in the Finite Blocklength Regime2018In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, no 7, p. 6146-6155Article in journal (Refereed)
    Abstract [en]

    Under the assumption of outdated channel state information at the source, we maximize the finite blocklength throughput of a two-hop relaying system while guaranteeing a reliability constraint. We investigate the tradeoff between the choice of so-called scheduling weights to avoid transmission errors and the resulting coding rate. We show that the corresponding maximization of the throughput can be solved efficiently by iterative algorithms that require a recomputation of the scheduling weights prior to each transmission. Thus, we also study heuristics relying on choosing the scheduling weights only once. Through numerical analysis, we first provide insights to the structure of the throughput under different scheduling weights and channel correlation coefficients. We then turn to the comparison of the optimal scheduling with the heuristic and show that the performance gap between them is only significant for relaying systems with high average signal-to-noise ratios on the backhaul and relaying link. In particular, the optimal scheduling scheme provides most value in case that the data transmission is subject to strict reliability constraints, justifying the significant additional computational burden.

  • 32.
    Hu, Yulin
    et al.
    Rhein Westfal TH Aachen, ISEK Lab, D-52074 Aachen, Germany..
    Serror, Martin
    Rhein Westfal TH Aachen, Chair Commun & Distributed Syst, D-52074 Aachen, Germany..
    Wehrle, Klaus
    Rhein Westfal TH Aachen, Chair Commun & Distributed Syst, D-52074 Aachen, Germany..
    Gross, James
    KTH, School of Electrical Engineering (EES). KTH Royal Inst Technol, Sch Elect Engn, S-10044 Stockholm, Uppland, Sweden..
    Finite Blocklength Performance of Cooperative Multi-Terminal Wireless Industrial Networks2018In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, no 7, p. 5778-5792Article in journal (Refereed)
    Abstract [en]

    Cooperative diversity is one of the candidate solutions for enabling ultrareliable low-latency wireless communications (URLLC) for industrial applications. Even if only a moderate density of terminals is present, it allows in typical scenarios the realization of a high diversity degree. It is furthermore only based on a reorganization of the transmission streams, making it achievable even with relatively simple transceiver structures. On the downside, it relies crucially on the distribution of accurate channel state information while cooperative transmissions naturally consume time. With the current goal of providing latencies in the range of 1 ms and below, it is, thus, open if cooperative systems can scale in terms of the number of terminals and the overhead. In this paper, we study these issues with respect to a finite blocklength error model that accounts for decoding errors arising from "above-average" noise occurrences even when communicating below the Shannon capacity. We show analytically that the overall error performance of cooperative wireless systems is convex in the decoding error probability of finite blocklength error models. We then turn to numerical evaluations, where several design characteristics of low-latency systems are identified: First, the major performance improvement is associated with two-hop transmissions in comparison to direct transmissions. The additional improvement due to more hops is only marginal. Second, with an increasing system load, cooperative systems feature a higher diversity gain, which leads to a significant performance improvement despite the increased overhead and a fixed overall frame duration. Third, when considering a realistic propagation environment for industrial deployments, cooperative systems can be shown to generally achieve URLLC requirements.

  • 33.
    Huang, Jinliang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Communication Systems, CoS.
    Signell, Svante
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Communication Systems, CoS.
    On Performance of Adaptive Modulation in MIMO Systems Using Orthogonal Space-Time Block Codes2009In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 58, no 8, p. 4238-4247Article in journal (Refereed)
    Abstract [en]

    We provide a systematic study of adaptive modulation schemes in multiple-input multiple-output (MIMO)orthogonal space-time block codes (OSTBC) systems. Closed-form expressions are obtained to evaluate systemperformance, e.g., average spectral efficiency, bit-error-ratio (BER), and outage probability. Provided the closedformexpressions, the optimal SNR thresholds that yield the maximal average spectral efficiency can be solved. Inorder to reduce complexity of the optimal algorithm, an original method which can achieve approximately the sameperformance as the optimal one is proposed. Furthermore, we apply these methods in a more practical situation,where channel estimation is imperfect, and examine how the performance is affected due to channel estimationerrors.

  • 34.
    Janssen, Gerard J. M.
    et al.
    Telecommunication and Traffic-Control Systems Group, Department of Information Technology and Systems, Delft University of Technology, 2600 GA Delft, The Netherlands.
    Ben Slimane, Slimane
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Antenna Diversity for a Narrow-band successive-Cancellation Multiuser Detector2004In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 53, no 5, p. 1303-1315Article in journal (Refereed)
    Abstract [en]

    The performance of a successive-cancellation multiuser detector (SC-MUD) for narrow-band signals operating in the Rayleigh-fading channel is shown to deteriorate severely unless very large power margins at the receiver are maintained. To mitigate this deterioration, antenna diversity is applied and adapted to the SC-MUD. In each detection stage, the best signal for detection and the corresponding combining weights are determined jointly. Two criteria for selecting the best signal based on maximizing the signal-to-noise-plus-interference ratio and maximizing the minimum distance-to-noise ratio, respectively, are proposed and evaluated. For signal combining, zero forcing and minimum mean square error (mmse) combining are considered. The obtained results show that the SC-MUD with mmse combining performs close to maximum likelihood joint detection while keeping a much lower computational complexity when the number of users is less than the number of receive antennas. The effect of channel-estimation errors is investigated for orthogonal training sequences and shown to result in a minor degradation compared to perfect estimation.

  • 35.
    Khormuji, Majid Nasiri
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Larsson, Erik G.
    Finite-SNR Analysis and Optimization of Decode-and-Forward Relaying Over Slow-Fading Channels2009In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 58, no 8, p. 4292-4305Article in journal (Refereed)
    Abstract [en]

    We provide analytical results on the finite signal-to-noise ratio (SNR) outage performance of packet-based decode-and-forward relaying over a quasi-static fading channel, with different types of transmitter channel state information (CSI). At the relay, we consider repetition coding (RC) and parallel coding (PC). At the destination, we consider receivers based on selection combining (SC), code combining (CC), and maximum-ratio combining (MRC) (the latter only for the case of RC at the relay). Based on available CSI, we optimize the number of channel uses consumed by the source and by the relay for each packet. In doing so, we consider three different protocols that make use of different combinations of long-term CSI, 1-bit CSI, and complete CSI, respectively, at the source node. Several interesting observations emerge. For example, we show that for high SNRs, SC and CC provide the same outage probabilities when the source has perfect CSI.

  • 36.
    Kim, Su Min
    et al.
    Korea Advanced Institute of Science and Technology, Daejeon, Korea.
    Jung, Bang Chul
    Choi, Wan
    Sung, Dan Keun
    Effects of Heterogenous Mobility on Rate Adaptation and User Scheduling in Cellular Networks With HARQ2013In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 62, no 6, p. 2735-2748Article in journal (Refereed)
    Abstract [en]

    In this paper, we investigate the effects of heterogeneous mobility on rate adaptation and user scheduling in cellular networks with hybrid automatic repeat request (HARQ). To this end, we first show the performance tradeoff between two extreme scheduling criteria: retransmission-oriented scheduling (ROS) and mixed scheduling (MS) criteria over time-correlated Rayleigh fading channels. Then, we propose an ROS-based joint rate adaptation and user scheduling (JRAUS) policy for cellular networks and compare it with the conventional and reference JRAUS policies. We also evaluate the system-level performance of the proposed ROS-based JRAUS policy in various user distribution and mobility scenarios. In particular, in an asymmetric user distribution and heterogeneous mobility scenario, which is the most general one in practice, the proposed JRUAS policy yields a throughput gain of 49% and a fairness gain of 155% over the conventional JRAUS policies. In this paper, we find that the rate adaptation is significant not only in a single point-to-point link but in multiuser systems with heterogeneous mobility as well.

  • 37.
    Kim, Sumin
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Jung, Bang Chul
    Ericsson Res, Sweden.
    Sung, Dan Keun
    Joint Link Adaptation and User Scheduling With HARQ in Multicell Environments2016In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 65, no 3, p. 1292-1302Article in journal (Refereed)
    Abstract [en]

    Intercell interference (ICI) is one of the most critical factors affecting performance of cellular networks. In this paper, we investigate a joint link adaptation and user scheduling problem for a multicell downlink employing hybrid automatic repeat request (HARQ) techniques, where the ICI exists among cells. We first propose an approximation method on aggregated ICI for analyzing an effective signal-to-interference-and-noise ratio (SINR) with the HARQ technique at users, which is known as identical path-loss approximation (IPLA). Based on the proposed IPLA, we propose a transmission rate selection algorithm maximizing an expected throughput at each user. We also propose a simple but effective cross-layer framework jointly combining transmission rate adaptation and user scheduling techniques, considering both HARQ and ICI. It is shown that the statistical distribution of the effective SINR at users based on the IPLA agrees well with the empirical distribution, while the conventional Gaussian approximation (GA) does not work well in the case that dominant ICIs exist. Thus, IPLA enables base stations (BSs) to choose more accurate transmission rates. Furthermore, the proposed IPLA-based cross-layer policy outperforms existing policies in terms of both system throughput and user fairness.

  • 38.
    Larsson, Erik G
    et al.
    KTH, School of Engineering Sciences (SCI).
    Selen, Y
    Stoica, P
    Adaptive equalization for frequency-selective channels of unknown length2005In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 54, no 2, p. 568-579Article in journal (Refereed)
    Abstract [en]

    This paper studies adaptive equalization for time-dispersive communication channels whose impulse responses have unknown lengths. This problem is important, because an adaptive equalizer designed for an incorrect channel length is suboptimal; it often estimates an unnecessarily large number of parameters. Some solutions to this problem exist (e.g., attempting to estimate the "channel length" and then switching between different equalizers); however, these are suboptimal owing to the difficulty of correctly identifying the channel length and the risk associated with an incorrect estimation of this length. Indeed, to determine the channel length is effectively a model order selection problem, for which no optimal solution is known. We propose a novel systematic approach to the problem under study, which circumvents the estimation of the channel length. The key idea is to model the channel impulse response via a mixture Gaussian model, which has one component for each possible channel length. The parameters of the mixture model are estimated from a received pilot sequence. We derive the optimal receiver associated with this mixture model, along with some computationally efficient approximations of it. We also devise a receiver, consisting of a bank of soft-output Viterbi algorithms, which can deliver soft decisions. Via numerical simulations, we show that our new method can outperform conventional adaptive Viterbi equalizers that use a fixed or an estimated channel length.

  • 39. Li, J.
    et al.
    Chen, W.
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Shu, F.
    Liu, X.
    Efficient video pricing and caching in heterogeneous networks2015In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. PP, no 99, article id 7365479Article in journal (Refereed)
    Abstract [en]

    Evidence indicates that downloading on-demand videos accounts for a dramatic increase in data traffic over cellular networks. Caching popular videos in the storage of small-cell base stations (SBS), namely, small-cell caching, is an efficient technology for mitigating redundant data transmissions over backhaul channels in heterogeneous networks (HetNet). In this paper, we consider a commercialized small-cell caching system consisting of a video retailer (VR), multiple network service providers (NSP) and mobile users (MU). The VR leases its popular videos to the NSPs for the purpose of making profits, and the NSPs, after placing these videos to their SBSs, can efficiently reduce the repetitive video transmissions over their backhaul channels. We study such a system within the framework of Stackelberg game. We first model the MUs and SBSs as two independent Poisson point processes, and develop the probability of the event that an MU can obtain the demanded video directly from the memory of an SBS. Then, based on the derived probability, we formulate a Stackelberg game to jointly maximize the average profit of the VR and the NSPs. Also, we investigate the Stackelberg equilibrium via solving an optimization problem. Numerical results are provided for verifying the proposed framework by showing its effectiveness on pricing and resource allocation.

  • 40. Li, Jun
    et al.
    Yuan, Jinhong
    Malaney, Robert
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Chen, Wen
    Full-Diversity Binary Frame-Wise Network Coding for Multiple-Source Multiple-Relay Networks Over Slow-Fading Channels2012In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 61, no 3, p. 1346-1360Article in journal (Refereed)
    Abstract [en]

    We study the design of network codes for M-source N-relay (M - N - 1) wireless networks over slow-fading channels. Binary frame-wise network coding (BFNC) based on cyclic-shifting matrices is developed to achieve full diversity and good coding gain. We develop a criterion in the context of BFNC that if satisfied guarantees to achieve full diversity gain. Based on this criterion, we propose an algorithm to design low-complexity encoders for a BFNC scheme by exploiting quasi-cyclic low-density parity-check (LDPC) code structures. We also design practical decoders based on the belief propagation decoding principle with a focus on large block lengths. Numerical results demonstrate that our BFNC schemes have substantial benefits over previous complex field and Galois field network coding schemes in the sense that our BFNC schemes can achieve full diversity gain and high coding gain for arbitrary block lengths with low encoding/decoding complexity.

  • 41.
    Li, Nan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Rasmussen, Lars Kildehöj
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Performance Analysis of Cognitive User Cooperation Using Binary Network Coding2018In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, no 8, p. 7355-7369Article in journal (Refereed)
    Abstract [en]

    We consider a cognitive radio network where a primary and a secondary transmitter, respectively, communicate a message to their primary and secondary receivers over a packet-based wireless link, using a joint automatic-repeat-request (ARQ) error control scheme. The secondary transmitter assists in the retransmission of the primary message, which improves the primary performance, and as a reward it is granted limited access to the transmission resources. Conventional ARQ, as well as two network-coding schemes are investigated for applications in the retransmission phase; namely the static network-coding scheme and the adaptive network-coding scheme. For each scheme we analyze the transmission process by investigating the distribution of the number of transmission attempts. We divide every frame into three transmission sessions and in each session we discover that the number of transmission attempts follows a certain negative binomial distribution, in which case can be further approximated by a normal distribution. Considering both the cases of an adaptive frame size and a truncated frame size, we derive analytical results on system performances and discuss the comparison of three schemes. Besides, the approximation method greatly reduces the complexity of transmission analysis, especially in the truncated frame-size case. Numerical results show that our analysis are valid and closely match the simulations.

  • 42. Maitra, Madhubanti
    et al.
    Saha, Debashis
    Bhattacharjee, Partha Sarathi
    Mukherjee, Amitava
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    An intelligent paging strategy using rule-based AI technique for locating mobile terminals in cellular wireless networks2008In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 57, no 3, p. 1834-1845Article in journal (Refereed)
    Abstract [en]

    This paper proposes an efficient rule-based paging strategy (RBPS) using a well-known concept of artificial intelligence, namely, rule base. The novelty of the scheme lies in devising "rules" that offer a potential mapping from seemingly disparate input data items (yet having some statistical relations) to an almost exact position of mobile terminals (MTs). Considering the conventional models of call arrival, cell residence, and mobility, we have developed a stochastic model to analyze the performance of the scheme. Interestingly, RBPS requires no additional processing at NITS and involves a nominal overhead at mobile switching centers. Simulation results reveal that RBPS significantly outperforms the blanket paging scheme adopted in Global System for Mobile (GSM) communications. In addition, results are very much encouraging when compared with the popular shortest-distance-first scheme. Finally, RBPS is generic enough to be potentially used in next-generation wireless networks, irrespective of any standards, with only minor adaptations to conform to the respective standards.

  • 43.
    Manssour, Jawad
    et al.
    Ericsson AB.
    Osseiran, Afif
    Ericsson AB.
    Ben Slimane, Slimane
    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.
    A Unicast Retransmission Scheme Based on Network Coding2012In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 61, no 2, p. 871-876Article in journal (Refereed)
    Abstract [en]

    A novel scheme for data retransmission for wireless unicast communication is presented. The scheme is based on a transmitter and receiver structure and bit-level data processing using a combination of channel coding and network coding that allows retransmissions to contain the previously incorrectly received information and new information, both destined to the same receiver. Results show that, for the chosen forward error codes, up to 68.75% retransmission throughput gains are achieved compared to HARQ with Chase combining.

  • 44.
    Martin, Cristoff
    et al.
    Luxembourg International Advanced Studies in Information Technologies, 1471 Luxembourg, Luxembourg.
    Geurtz, Alexander
    SES GLOBAL S.A., 6815 Betzdorf, Luxembourg.
    Ottersten, Björn
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Statistical analysis and optimal design for efficient mobile satellite broadcast with diversity2008In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 57, no 2, p. 986-1000Article in journal (Refereed)
    Abstract [en]

    The design of mobile satellite broadcast architectures requires complex tradeoffs involving technical, economical, and regulatory aspects. A satisfactory quality of service in terms of the number of receivers successfully receiving the broadcasted cervices can be ensured using space, terrestrial, and time diversity techniques. The amount of applied diversity affects the system's spectral efficiency and performance. In addition, dedicated satellite and terrestrial networks represent significant investments, and regulatory limitations on terrestrial deployment may further complicate the system design. Herein, we provide insights into the technical aspects of the aforementioned tradeoffs by deriving an efficient method to estimate what system resources in terms of spectrum and delay are required to provide a satisfactory number of end users with mobile broadcast services using space, terrestrial, and time diversity techniques. The presented results are based on statistical models of the mobile satellite channel for which efficient analytical design and error rate estimation methods are derived. To provide a coded space and time diversity, a generalized approach is taken that includes most transmission schemes in use, or considered for use, for mobile satellite broadcast as special cases. As a side result, it is shown that for optimal error rate performance, the provided time diversity should be designed by taking into account channel statistics. An efficient yet simple method of enumerating time-varying Markov chains is also included. The proposed techniques and results are illustrated with numerical examples using temporal Ku-band channel statistics. The examples include a wide range of possible transmission schemes in system configurations with and without space and terrestrial diversity and, thus, demonstrate how different transmission schemes and infrastructure configurations can be compared.

  • 45.
    Ping, He
    et al.
    National University of Singapore.
    Tjhung, T T
    National University of Singapore.
    Rasmussen, Lars Kildehöj
    National University of Singapore.
    Decision-feedback blind adaptive multiuser detector for synchronous CDMA system2000In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 49, no 1, p. 159-166Article in journal (Refereed)
  • 46.
    Rasmussen, Lars Kildehöj
    et al.
    Georgia Institute of Technology.
    Wicker, Stephen B.
    Georgia Institute of Technology.
    A COMPARISON OF 2 COMBINING TECHNIQUES FOR EQUAL GAIN, TRELLIS-CODED DIVERSITY RECEIVERS1995In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 44, no 2, p. 291-295Article in journal (Refereed)
  • 47. Rasti, Mehdi
    et al.
    Sharafat, Ahmad R.
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    A Distributed Dynamic Target-SIR-Tracking Power Control Algorithm for Wireless Cellular Networks2010In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 59, no 2, p. 906-916Article in journal (Refereed)
    Abstract [en]

    The well-known fixed-target-signal-to-interference-ratio (SIR)-tracking power control (TPC) algorithm provides all users with their given feasible fixed target SIRs but cannot improve the system throughput, even if additional resources are available. The opportunistic power control (OPC) algorithm significantly improves the system throughput but cannot guarantee the minimum acceptable SIR for all users (unfairness). To optimize the system throughput subject to a given lower bound for the users' SIRs, we present a distributed dynamic target-SIR tracking power control algorithm (DTPC) for wireless cellular networks by using TPC and OPC in a selective manner. In the proposed DTPC, when the effective interference (the ratio of the received interference to the path gain) is less than a given threshold for a given user, that user opportunistically sets its target SIR (which is a decreasing function of the effective interference) to a value higher than its minimum acceptable target SIR; otherwise, it keeps its target SIR fixed at its minimum acceptable level. We show that the proposed algorithm converges to a unique fixed point starting from any initial transmit power level in both synchronous and asynchronous power-updating cases. We also show that our proposed algorithm not only guarantees the (feasible) minimum acceptable target SIRs for all users (in contrast to the OPC) but also significantly improves the system throughput, compared with the TPC. Furthermore, we demonstrate that DTPC, along with TPC and OPC, can be utilized to apply different priorities of transmission and service requirements among users. Finally, when users are selfish, we provide a game-theoretic analysis of our DTPC algorithm via a noncooperative power control game with a new pricing function.

  • 48. Sharma, S. K.
    et al.
    Chatzinotas, S.
    Ottersten, Björn
    Interdisciplinary Centre for Security, Reliability, and Trust, University of Luxembourg, 2721 Luxembourg City, Luxembourg.
    Eigenvalue-based sensing and SNR estimation for cognitive radio in presence of noise correlation2013In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 62, no 8, p. 3671-3684Article in journal (Refereed)
    Abstract [en]

    Herein, we present a detailed analysis of an eigenvalue-based sensing technique in the presence of correlated noise in the context of a cognitive radio (CR). We use standard-condition-number (SCN)-based decision statistics based on asymptotic random matrix theory (RMT) for the decision process. First, the effect of noise correlation on eigenvalue-based spectrum sensing (SS) is analytically studied under both the noise-only and signal-plus-noise hypotheses. Second, new bounds for the SCN are proposed to achieve improved sensing in correlated noise scenarios. Third, the performance of fractional-sampling (FS)-based SS is studied, and a method to determine the operating point for the FS rate in terms of sensing performance and complexity is suggested. Finally, a signal-to-noise ratio (SNR) estimation technique based on the maximum eigenvalue of the covariance matrix of the received signal is proposed. It is shown that the proposed SCN-based threshold improves sensing performance in correlated noise scenarios, and SNRs up to 0 dB can be reliably estimated with a normalized mean square error (MSE) of less than 1% in the presence of correlated noise without the knowledge of noise variance.

  • 49. Song, Kang
    et al.
    Ji, Baofeng
    Huang, Yongming
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Yang, Luxi
    Performance Analysis of Heterogeneous Networks With Interference Cancellation2017In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 66, no 8, p. 6969-6981Article in journal (Refereed)
    Abstract [en]

    The performance of heterogeneous networks (HetNets) is investigated with both direct and relay-aided transmission strategies in a macrocell. We first propose an interference cancelation scheme at the macro base station on the basis of canceling cross-tier interferences from the macro base station to small-cell users. Then, expressions of the probability density function (PDF) and cumulative distribution function (CDF) of all receivers in both macro and small cells are derived, and the closed-form overall outage probability, average bit error rate (BER), and spectral efficiency of the network are obtained. Based on the derivations, we propose two adaptive relay-aided transmission schemes with instantaneous and statistical channel state information (CSI) to further improve the spectral efficiency. We show that the SNR boost at the small-cell mobile station comes from the cancelation of the cross-layer interference by the macro base station. Therefore, the performance of the small cell is improved greatly with interference cancelation, while the overall performance of the HetNet is also ameliorated. The numerical results finally show the validity of our analysis.

  • 50.
    Timus, Bogdan
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Soldati, Pablo
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Kim, Dongwoo
    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.
    Cross-Layer Resource Allocation Model for Cellular-Relaying Network Performance Evaluation2011In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 60, no 6, p. 2765-2776Article in journal (Refereed)
    Abstract [en]

    The enhancement of cellular networks with relaying technologies is expected to bring significant technoeconomic benefits at the expense of more complex resource allocation. Suitable models for solving network dimensioning problems in cellular-relaying networks must handle radio resource allocation among hundreds of links and tackle interactions between networking layers. For this purpose, we propose a novel cross-layer resource allocation model based on average interference and ideal rate adaptation for the physical layer (PHY), time shares for the medium access layer, and fluid flows for the transport and network layers. We formulate a centralized social welfare maximization problem. When the routes are selected with an a priori algorithm, we show that the resource allocation problem admits an equivalent convex formulation. We show a numerical example for how to use the proposed framework for configuring the backhaul link in a practical relaying network. The overall problem of selecting routes and allocating time shares and link rates is nonconvex. We propose an iterative suboptimal algorithm to solve the problem based on a novel approximation of PHY. We state and prove several convergence properties of the algorithm and show that it typically outperforms routing based on signal-to-noise ratio only.

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