| 1. |
- Vlastaras, Dimitrios, et al.
(author)
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Vehicle Detection through Wireless Vehicular Communication
- 2014
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In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; 2014:1, s. 146-153
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Journal article (peer-reviewed)abstract
- Vehicles in the future are anticipated to have the ability to communicate and exchange useful information in order to avoid collisions. However, for this cooperation to be possible, all vehicles will have to be equipped with compatible wireless modules, based on, e.g. IEEE 802.11p (used in ITS-G5 or WAVE), which implements intelligent transport systems operating in the 5 GHz frequency band. During the implementation phase of the system, there will be many older vehicles without such equipment that can cause hazard as information about them will not be available to vehicles equipped with IEEE 802.11p modules. In this paper, we present a system to be used as a roadside unit (RSU), developed explicitly for infrastructure-to-vehicle (I2V) communication that can solve the aforementioned traffic safety problems. The system consists of a universal medium-range radar (UMRR) and an IEEE 802.11p modem integrated together to detect vehicles, with or without communication capabilities, and forward their position and speed vectors to vehicles, with IEEE 802.11p modules installed, for collision avoidance. Tests have been performed by using our system in parallel with vehicles in which IEEE 802.11p modules are installed and comparing the content in the Cooperative Awareness Messages obtained from both systems. Accuracy tests have been performed in order to verify the system, and Kalman filtering is applied on the radar data to improve the accuracy of the system further.
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| 2. |
- Hammarberg, Peter, et al.
(author)
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Iterative receivers with channel estimation for multi-user MIMO-OFDM: complexity and performance
- 2012
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In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; , s. 1-17
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Journal article (peer-reviewed)abstract
- Abstract in UndeterminedA family of iterative receivers is evaluated in terms of complexity and performance for the case of an uplink multi-user (MU) multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system. The transmission over block fading channels is considered. The analyzed class of receivers is performing channel estimation inside the iterative detection loop, which has been shown to improve estimation performance. As part of our results we illustrate the ability of this type of receiver to reduce the required amount of pilot symbols. A remaining question to ask is which combinations of estimation and detection algorithms that provide the best trade-off between performance and complexity. We address this issue by considering MU detectors and channel estimators, with varying algorithm complexity. For MU detection, two algorithms based on parallel interference cancellation (PIC) are considered and compared with the optimal symbol-wise maximum a-posteriori probability (MAP) detector. For channel estimation, an algorithm performing joint minimum-mean-square-error (MMSE) estimation is considered along with a low complexity replica making use of a Krylov subspace method. An estimator based on the space alternating generalized expectation-maximization (SAGE) algorithm is also considered. Our results show that low-complexity algorithms provide the best tradeoff, even though more receiver iterations are needed to reach a desired performance.
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| 3. |
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| 4. |
- Apelfröjd, Rikke, et al.
(author)
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Design and measurement based evaluations of coherent JT CoMP : a study of precoding, user grouping and resource allocation using predicted CSI
- 2014
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In: EURASIP Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; , s. 100-
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Journal article (peer-reviewed)abstract
- Coordinated multipoint (CoMP) transmission provides high theoretic gains in spectral efficiency with coherent joint transmission (JT) to multiple users. However, this requires accurate channel state information at the transmitter (CSIT) and also user groups with spatially compatible users. The aim of this paper is to use measured channels to investigate if significant CoMP gains can still be obtained with channel estimation errors. This turns out to be the case, but requires the combination of several techniques. We here focus on coherent downlink JT CoMP to multiple users within a cluster of cooperating base stations. The use of Kalman predictors is investigated to estimate the complex channel gains at the moment of transmission. It is shown that this can provide sufficient CSIT quality for JT CoMP even for long (> 20 ms) system delays at 2.66 GHz at pedestrian velocities or, for lower delays, at 500 MHz, at vehicular velocities. A user grouping and resource allocation scheme that provides appropriate groups for CoMP is also suggested. It provides performance close to that obtained by exhaustive search at very low complexity, low feedback cost and very low backhaul cost. Finally, a robust linear precoder that takes channel uncertainties into account when designing the precoding matrix is considered. We show that, in challenging scenarios, this provides large gains compared with zero-forcing precoding. Evaluations of these design elements are based on measured channels with realistic noise and intercluster interference assumptions. These show that high JT CoMP gains can be expected, on average over large sets of user positions, when the above techniques are combined - especially in severely intracluster interference limited scenarios.
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| 5. |
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| 6. |
- Chatzinotas, Symeon, et al.
(author)
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Interference mitigation techniques for clustered multicell joint decoding systems
- 2011
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In: EURASIP Journal on Wireless Communications and Networking. - Springer : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; 132:1
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Journal article (peer-reviewed)abstract
- Multicell joint processing has originated from information-theoretic principles as a means of reaching the fundamental capacity limits of cellular networks. However, global multicell joint decoding is highly complex and in practice clusters of cooperating Base Stations constitute a more realistic scenario. In this direction, the mitigation of intercluster interference rises as a critical factor towards achieving the promised throughput gains. In this paper, two intercluster interference mitigation techniques are investigated and compared, namely interference alignment and resource division multiple access. The cases of global multicell joint processing and cochannel interference allowance are also considered as an upper and lower bound to the interference alignment scheme, respectively. Each case is modelled and analyzed using the per-cell ergodic sum-rate throughput as a figure of merit. In this process, the asymptotic eigenvalue distribution of the channel covariance matrices is analytically derived based on free-probabilistic arguments in order to quantify the sum-rate throughput. Using numerical results, it is established that resource division multiple access is preferable for dense cellular systems, while cochannel interference allowance is advantageous for highly sparse cellular systems. Interference alignment provides superior performance for average to sparse cellular systems on the expense of higher complexity.
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| 7. |
- Chen, Lei, 1981-, et al.
(author)
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Generalizing and Optimizing Fractional Frequency Reuse in Broadband Cellular Radio Access Networks
- 2012
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In: EURASIP Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; 230
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Journal article (peer-reviewed)abstract
- For broadband cellular access based on orthogonal frequency divisionmultiple access (OFDMA), fractional frequency reuse (FFR) is one ofthe key concepts for mitigating inter-cell interference and therebyoptimizing cell-edge performance. In standard FFR, the number of OFDMAsub-bands and the reuse factor are both fixed. Whereas this works wellfor an idealized cell pattern, it is neither directly applicable noradequate for real-life networks with very irregular cell layouts. Inthis paper, we generalize the standard FFR to allow for flexibilities inthe total number of sub-bands as well as the number of sub-bands ineach cell-edge zone, enabling network-adaptive FFR. Two powerassignment strategies that use fixed power per sub-band prior tosub-band allocation and apply cell-specific power derived from thenumber of sub-bands allocated to each cell-edge zone, respectively,are investigated. Optimization algorithms based on local search aredeveloped for sub-band allocation to maximize the cell-edgethroughput. Evaluations using networks with realistic radiopropagation conditions demonstrate the applicability of the generalizedand optimized FFR in performance engineering of OFDMA networks.
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| 8. |
- Christopoulos, Dimitrios, et al.
(author)
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Linear and nonlinear techniques for multibeam joint processing in satellite communications
- 2012
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In: EURASIP Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; , s. 162-
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Journal article (peer-reviewed)abstract
- Existing satellite communication standards such as DVB-S2, operate under highly-efficient adaptive coding and modulation schemes thus making significant progress in improving the spectral efficiencies of digital satellite broadcast systems. However, the constantly increasing demand for broadband and interactive satellite links emanates the need to apply novel interference mitigation techniques, striving towards Terabit throughput. In this direction, the objective of the present contribution is to investigate joint multiuser processing techniques for multibeam satellite systems. In the forward link, the performance of linear precoding is investigated with optimal nonlinear precoding (i.e., dirty article coding) acting as the upper performance limit. To this end, the resulting power and precoder design problems are approached through optimization methods. Similarly, in the return link the concept of linear filtering (i.e., linear minimum mean square error) is studied with the optimal successive interference cancelation acting as the performance limit. The derived capacity curves for both scenarios are compared to conventional satellite systems where beams are processed independently and interbeam interference is mitigated through a four color frequency reuse scheme, in order to quantify the potential gain of the proposed techniques.
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| 9. |
- Dely, Peter, 1982-, et al.
(author)
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Optimization of WLAN associations considering handover costs
- 2012
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In: EURASIP Journal on Wireless Communications and Networking. - : Springer. - 1687-1472 .- 1687-1499. ; 255
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Journal article (peer-reviewed)abstract
- In Wireless Local Area Network (WLAN) hotspots the coverage areas of Access Points (APs) often overlap considerably. Current state of the art optimization models find the optimal AP for each user station by balancing the load across the network. Recent studies have shown that in typical commercial WLAN hotspots the median connection duration is short. In such dynamic network settings the mentioned optimization models might cause many handovers between APs to accommodate for user arrivals or mobility. We introduce a new mixed integer linear optimization problem that allows to optimize handovers but takes into account the costs of handovers such as signaling and communication interruption. Using our model and extensive numeric simulations we show that disregarding the handover costs leads to low performance. Based on this insight we design a new optimization scheme that uses estimates of future station arrivals and mobility patterns. We show that our scheme outperforms current optimization mechanisms and is robust against estimation errors
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| 10. |
- Gholami, Mohammad Reza, 1976, et al.
(author)
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Wireless network positioning as a convex feasibility problem
- 2011
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In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1499 .- 1687-1472. ; 2011:1
-
Journal article (peer-reviewed)abstract
- In this semi-tutorial paper, the positioning problem is formulated as a convexfeasibility problem (CFP). To solve the CFP for non-cooperative networks, we con-sider the well-known projection onto convex sets (POCS) technique, and study itsproperties for positioning. We also study outer-approximation (OA) methods tosolve CFP problems. We then show how the POCS estimate can be upper boundedby solving a non-convex optimization problem. Moreover, we introduce two tech-niques based on OA and POCS to solve the CFP for cooperative networks andobtain two new distributed algorithms. Simulation results show that the proposedalgorithms are robust against non-line-of-sight conditions.
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| 11. |
- Gustafsson, Fredrik, 1964-, et al.
(author)
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Sensor models and localization algorithms for sensor networks based on received signal strength
- 2012
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In: EURASIP Journal on Wireless Communications and Networking. - : Springer. - 1687-1472 .- 1687-1499. ; 1:16
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Journal article (peer-reviewed)abstract
- Received signal strength (RSS) can be used in sensor networks as a ranging measurement for positioning and localization applications. This contribution studies the realistic situation where neither the emitted power nor the power law decay exponent be assumed to be known. The application in mind is a rapidly deployed network consisting of a number of sensor nodes with low-bandwidth communication, each node measuring RSS of signals traveled through air (microphones) and ground (geophones). The first contribution concerns validation of a model in logarithmic scale, that is, linear in the unknown nuisance parameters (emitted power and power loss constant). The parameter variation is studied over time and space. The second contribution is a localization algorithm based on this model, where the separable least squares principle is applied to the non-linear least squares (NLS) cost function, after which a cost function of only the unknown position is obtained. Results from field trials are presented to illustrate the method, together with fundamental performance bounds. The ambition is to pave the way for sensor configuration design and more thorough performance evaluations as well as filtering and target tracking aspects.
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| 12. |
- Hasani, Bilal, et al.
(author)
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Collaborative routing and data delivery architecture for commercial wireless sensor networks
- 2013
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In: EURASIP Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; :1, s. 54-
-
Journal article (peer-reviewed)abstract
- Lately, wireless sensor network applications have emerged for provision of commercial services to end users. This results in commercial deployment of sensor networks which is as an important research area due to a number of design and quality of service challenges. An important technical challenge for sensor service provision to end users is managing dynamic network conditions such as unreliability of sensor nodes and network links which results in frequent service outages. This research is aimed at addressing this challenge. It presents a novel architecture which utilizes the availability of multiple sensor networks under different administrative domains, deployed in an area such that maximum network connectivity and high service availability are ensured. The architecture incorporates modifications and enhancements at the medium access control and the routing layers of sensor nodes for the collaborative operation of sensor networks. The design is based on IEEE 802.15.4 standard and ad hoc on demand distance vector routing protocol. The proposed architecture is mathematically analyzed with regards to overheads associated with the design such as routing and communication, and techniques to minimize these overheads are recommended. Through simulations using OMNET++, we show that the proposed architecture effectively provides connectivity for disconnected nodes achieving an overall increase in throughput for all the cooperating networks.
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| 13. |
- Jacobsson, Martin, et al.
(author)
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Comparing wireless flooding protocols using trace-based simulations
- 2013
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In: EURASIP Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; , s. 169:1-15
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Journal article (peer-reviewed)abstract
- Most wireless multi-hop networks, such as ad hoc networks and wireless sensor networks, need network-wide broadcasting, which is best done with a flooding protocol. In this article, we use packet trace information from a real test-bed network to define a simulator for flooding protocol performance studies. Five protocols are compared using the simulator. Trace-based simulations promise to have the benefits of the simulator, such as reducing required work effort and repeatability but still produce results close to the real test-bed or deployment. We propose and evaluate different approaches on how to use collected trace data and how to tune the parameters to achieve the best possible accuracy in comparison with actual test-bed measurements. We study the resulting accuracy of the model so that performance studies know with what confidence a certain conclusion can be made. Using the new trace-based model and knowing its accuracy, we compare the five flooding protocols to gain additional insights into their performance. Finally, by modifying the trace data, we study how real-world effects, such as links with in-between qualities and asymmetric links, influence the different flooding protocols.
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| 14. |
- Katselis, Dimitrios, et al.
(author)
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Training sequence design for MIMO channels: an application-oriented approach
- 2013
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; 2013, s. 245-
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Journal article (peer-reviewed)abstract
- In this paper, the problem of training optimization for estimating a multiple-input multiple-output (MIMO) flat fading channel in the presence of spatially and temporally correlated Gaussian noise is studied in an application-oriented setup. So far, the problem of MIMO channel estimation has mostly been treated within the context of minimizing the mean square error (MSE) of the channel estimate subject to various constraints, such as an upper bound on the available training energy. We introduce a more general framework for the task of training sequence design in MIMO systems, which can treat not only the minimization of channel estimator's MSE but also the optimization of a final performance metric of interest related to the use of the channel estimate in the communication system. First, we show that the proposed framework can be used to minimize the training energy budget subject to a quality constraint on the MSE of the channel estimator. A deterministic version of the 'dual' problem is also provided. We then focus on four specific applications, where the training sequence can be optimized with respect to the classical channel estimation MSE, a weighted channel estimation MSE and the MSE of the equalization error due to the use of an equalizer at the receiver or an appropriate linear precoder at the transmitter. In this way, the intended use of the channel estimate is explicitly accounted for. The superiority of the proposed designs over existing methods is demonstrated via numerical simulations.
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| 15. |
- Khattak, Rabiullah, et al.
(author)
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Jointly optimized rate-compatible UEP-LDPC codes for half-duplex co-operative relay networks
- 2014
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In: EURASIP Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; 2014
-
Journal article (peer-reviewed)abstract
- This paper addresses the design of low-density parity-check (LDPC) codes for half-duplex co-operative relay networks. Structured rate-compatible codes with unequal error protection (UEP) are designed through joint optimization of the codes for the channels between source and relay and source and destination. The proposed codes clearly outperform simpler LDPC codes which are not optimized for relay channels and puncturing-based rate-compatible LDPC codes, and they show a significant performance improvement over the direct link communication depending on the position of relay. The optimization algorithm for the proposed codes is based on density evolution using the Gaussian approximation and optimal variable node degree distributions are found through iterative linear programming. Interestingly, they anyhow show performance which is almost comparable to the performance of codes optimized through a more complex non-linear optimization algorithm. We analyze the performance of our proposed codes with short, medium and long block lengths, and with low and high rates under realistic assumptions, i.e., imperfect decoding of the codeword at relay and variant signal-to-noise ratio within a single codeword.
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| 16. |
- Kuiper, Erik, et al.
(author)
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A framework for performance analysis of geographic delay-tolerant routing
- 2012
-
In: EURASIP Journal on Wireless Communications and Networking. - : Hindawi Publishing Corporation / SpringerOpen / Springer Verlag (Germany). - 1687-1472 .- 1687-1499. ; :184
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Journal article (peer-reviewed)abstract
- A major tool used for evaluating routing protocols in ad hoc and delay-tolerant networks is simulation. Whereas the results from simulations give good insights, they are limited to the specific scenario set-up that is used. If the scenario changes, new and often time-consuming simulations have to be run. Moreover, the simulation time in packet-level simulators with fairly realistic physical layer implementation, such as ns-2, generally grows rapidly in the number of nodes. This practically limits the number of nodes in a simulation, even if the limit can be extended by the use of simulation federations. Larger scenarios can also be facilitated by the use of more abstraction in the physical layer; abstractions that may impact the validity of the results. In this article, we present the forward-wait framework--a mathematical model describing the packet movements for opportunistic geographic delay-tolerant routing protocols. By describing packet movements as a sequence of alternating forwarding and waiting phases, the framework can accurately predict the routing performance. Key input parameters to the framework are random variables describing the forwarding and waiting phases. We show how the properties of the random variables can be derived, both via abstract modeling and small scale ns-2 simulation data. The model is then used to demonstrate the prediction capabilities of the framework in providing results that are close to the (much slower) packet-level simulations.
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| 17. |
- Lakshmana, Tilak Rajesh, 1980, et al.
(author)
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Partial joint processing with efficient backhauling using particle swarm optimization
- 2012
-
In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1499 .- 1687-1472. ; 2012
-
Journal article (peer-reviewed)abstract
- In cellular communication systems with frequency reuse factor of one, user terminals(UT) at the cell-edge are prone to intercell interference. Joint processing is one of the coordinated multipoint transmission techniques proposed to mitigate this interference. In the case of centralized joint processing, the channel state information fed back by the users need to be available at the central coordination node for precoding. The precoding weights (with the user data) need to be available at the corresponding base stations to serve the UTs. These increase the backhaul traffic. In this article, partial joint processing (PJP) is considered as a general framework that allows reducing the amount of required feedback. However, it is difficult to achieve a corresponding reduction on the backhaul related to the precoding weights, when a linear zero forcing beamforming technique is used. In this work, particle swarm optimization is proposed as a tool to design the precoding weights under feedback and backhaul constraints related to PJP.The precoder obtained with the objective of weighted interference minimization allows some multiuser interference in the system, and it is shown to improve the sum rate by 66% compared to a conventional zero forcing approach, for those users experiencing low signal to interference plus noise ratio.
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| 18. |
- Li, Jingya, 1986, et al.
(author)
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Resource allocation for clustered network MIMO OFDMA systems
- 2012
-
In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1499 .- 1687-1472. ; 2012
-
Journal article (peer-reviewed)abstract
- In this paper, we address the resource allocation problem for the downlink of a large network MIMO OFDMA system with 3-sector base stations (BSs). The system is statically divided into a number of disjoint clusters of sectors. A two-step resource allocation scheme is proposed involving the inter-cluster and the intra-cluster levels. As a first step or inter-cluster level, two cooperative frequency reuse approaches are designed to mitigate the inter-cluster interference. A user partition method is proposed to divide the users of each cluster into cluster-edge and cluster-center users. To balance the cell-edge and the cell-average performance, a fairness jug function is introduced to determine the frequency partition of the cooperative frequency reuse approaches. Then, as a second step or intra-cluster level, a utility-based joint scheduling and power allocation algorithm is proposed for each cluster, to maximize the sum utility of all users in the cluster under per-sector power constraints. Zero-forcing joint transmission is used across multiple sectors within the same cluster. Simulation results show that the proposed scheme can efficiently reduce the inter-cluster interference and provide considerable performance improvement in terms of both the cell-edge and cell-average user data rate. The proposed two-step resource allocation scheme can be implemented independently in each cluster without inter-cluster information exchange, which is an attractive property for practical systems, since it reduces both the network signaling overhead and the computational complexity.
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| 19. |
- Limmanee, A, et al.
(author)
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Optimal power policies and throughput scaling analyses in fading cognitive broadcast channels with primary outage probability constraint
- 2014
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; , s. 35-
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Journal article (peer-reviewed)abstract
- This paper focuses on a spectrum-sharing-based fading cognitive radio broadcast channel (BC) with a single-antenna secondary base station (SBS) and M single-antenna secondary receivers (SRs) utilizing the same spectrum band with a delay-sensitive primary user (PU). The service-quality requirement for the primary user is set by an outage probability constraint (POC). We address the optimal power allocation problem for the SBS ergodic sum capacity (ESC) maximization in the secondary BC network subject to POC and a transmit power constraint at SBS specified by either a long-term or a short-term power constraint. The optimality conditions reveal that in each joint channel state, the SBS allocates transmission power to the only one selected SR with the highest value of a certain metric consisting of the ratio of the SR's direct channel power gain and the sum of interference power and noise power at the SR. Then, the secondary network throughput scaling analysis as the number of SRs becomes large, is also investigated, showing that if PU applies a truncated channel inversion (TCI) power policy, the SBS ESC scales like epsilon(p) log(log M) where epsilon(p) is the PU outage probability threshold. To reduce the amount of channel side information (CSI) transferred between the two networks, we propose a suboptimal transmission scheme which requires only 1-bit feedback from the delay-sensitive PR (partial CSI). We show that the new power control policy is asymptotically optimal, i.e. the SBS ESC under this reduced feedback scheme still scales like epsilon(p) log(log M).
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| 20. |
- Makki, Behrooz, 1980, et al.
(author)
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Fairness, power allocation, and CSI quantization in block fading multiuser systems
- 2013
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In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1499 .- 1687-1472. ; 2013:249
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Journal article (peer-reviewed)abstract
- This paper studies the fairness, power allocation and channel state information (CSI) quantization in multiuser systems utilizing multiple feedback bits per user. For a given set of schedulers, we obtain the system throughput with different power allocation strategies and any combination of different fading distributions. Moreover, the system performance under users different outage probability constraints is investigated. Assuming homogenous users, as a special case, the throughput is determined for fixed and random request networks. Considering nonidentical fading channels between the transmitter and receivers, the throughput is found under the K-significant average feedback bit allocation technique and two suboptimal fairness schemes are investigated which satisfy different quality-of-service requirements. The results show that, using optimal power allocation, the first quantization region (QR) of each user is the only QR for which no power may be allocated. The system outage probability vanishes as the number of users goes to infinity. Users hard outage probabilityconstraints can be satisfied at the cost of one more QR in the channel quantizer. Finally, the proposed fairness schemes are more flexible than the standard proportional fair (PF) scheduling in dealing with the throughput-fairness tradeoff. However, their superiority over PF scheduling depends on the fairness constraint.
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| 21. |
- Makki, Behrooz, 1980, et al.
(author)
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Multiuser Diversity in Correlated Rayleigh-fading Channels
- 2012
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In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1499 .- 1687-1472. ; 2012
-
Journal article (peer-reviewed)abstract
- This article studies the effect of scheduling and multiuser diversity on the performance of correlated Rayleigh-fading channels. More specifically, the power-limited channel average rate is obtained for quasi-static correlated fading channels. The results are obtained in the cases where there is perfect or imperfect channel state information available at the transmitter. Simulation results show that the average rate reduction due to channels dependencies is ignorable in low correlation conditions. However, the effect of scheduling and multiuser diversity on the average rate reduces substantially as the fading channels dependency increases. Also, for different channels correlation conditions, considerable performance improvement is achieved via very limited number of feedback bits.
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| 22. |
- Makki, Behrooz, 1980, et al.
(author)
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On an HARQ-based Coordinated Multi-point Network using Dynamic Point Selection
- 2013
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In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1499 .- 1687-1472. ; 209:1
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Journal article (peer-reviewed)abstract
- This paper investigates the performance of coordinated multi-point (CoMP) networks in the presence of hybrid automatic repeat request (HARQ) feedback. With an information theoretic point of view, the throughput and the outage probability of different HARQ protocols are studied for slow-fading channels. The results are compared with the ones obtained in the presence of repetition codes and basic HARQ, or when there is no channel state information available at the base stations. The analytical and numerical results demonstrate the efficiency of the CoMP-HARQ techniques in different conditions.
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| 23. |
- Makki, Behrooz, 1980, et al.
(author)
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On the Capacity of Rayleigh-Fading Correlated Spectrum Sharing Networks
- 2011
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In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1499 .- 1687-1472. ; 2011:1
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Journal article (peer-reviewed)abstract
- Recently, substantial attention has been paid to improve the spectral efficiency of communication setups using different spectrum sharing techniques. This paper aims to studythe capacity of Rayleigh-fading spectrum sharing channels inthe case where there is correlation between the fading channels. Assuming perfect channel state information (CSI), the channel capacity is obtained under different unlicensed user power adaptation capabilities and the licensed user outage probability and received interference power constraints. Theoretical and simulation results show that there is considerable potential for data transmission of unlicensed users with limited degradation of the licensed users data transmission efficiency.
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| 24. |
- Mayer, Zoltán, et al.
(author)
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On the Impact of Control Channel Reliability on Coordinated Multi-Point Transmission
- 2014
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In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1499 .- 1687-1472. ; 28
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Journal article (peer-reviewed)abstract
- In the heterogeneous networks (HetNets), co-channel interference is a serious problem. Coordinated multi-point (CoMP) transmission has emerged as a powerful technique to mitigate co-channel interference. However, all CoMP techniques rely on information exchange through reliable control channels, which are unlikely to be available in HetNets. In this paper, we study the effect of unreliable control channels, consisting of the access links and backhaul links, on the performance of CoMP. A control channel model is introduced by assigning link failure probability (LFP) to backhaul and access links for the cooperative clusters. Three CoMP architectures, namely the centralized, semi-distributed and fully distributed are analyzed. We investigate the probability of deficient control channels reducing quality of service, and impeding transmission. General closed-form expressions are derived for the probability of a cooperative transmission node staying silent in a resource slot due to unreliable control links. By evaluating the average sum rate of users within a CoMP cluster, we show that the performance gains offered by CoMP quickly diminish, as the unreliability of the control links grows.
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| 25. |
- Nicoli, M., et al.
(author)
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Localization in mobile wireless and sensor networks
- 2011
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In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1499 .- 1687-1472. ; 2011
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Journal article (other academic/artistic)
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| 26. |
- Ochandiano, Pello, et al.
(author)
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Factor graph based detection approach for high-mobility OFDM systems with large FFT modes
- 2012
-
In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1499 .- 1687-1472. ; 2012:331, s. 1-12
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Journal article (peer-reviewed)abstract
- In this article, a novel detector design is proposed for orthogonal frequency division multiplexing (OFDM) systems over frequency selective and time varying channels. Namely, we focus on systems with large OFDM symbol lengths where design and complexity constraints have to be taken into account and many of the existing ICI reduction techniques can not be applied. We propose a factor graph (FG) based approach for maximum a posteriori (MAP) symbol detection which exploits the frequency diversity introduced by the ICI in the OFDM symbol. The proposed algorithm provides high diversity orders allowing to outperform the free-ICI performance in high-mobility scenarios with an inherent parallel structure suitable for large OFDM block sizes. The performance of the mentioned near-optimal detection strategy is analyzed over a general bit-interleaved coded modulation (BICM) system applying low-density parity-check (LDPC) codes. The inclusion of pilot symbols is also considered in order to analyze how they assist the detection process.
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| 27. |
- Phan, Hoc, et al.
(author)
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Adaptive transmission in MIMO AF relay networks with orthogonal space-time block codes over Nakagami-m fading
- 2012
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer. - 1687-1472 .- 1687-1499. ; :11
-
Journal article (peer-reviewed)abstract
- In this article, we apply different adaptive transmission techniques to dual-hop multiple-input multiple-output amplify-and-forward relay networks using orthogonal space-time block coding over independent Nakagami-m fading channels. The adaptive techniques investigated are optimal simultaneous power and rate (OSPR), optimal rate with constant power (ORCP), and truncated channel inversion with fixed rate (TCIFR). The expressions for the channel capacity of OSPR, ORCP, and TCIFR, and the outage probability of OSPR, and TCIFR are derived based on the characteristic function of the reciprocal of the instantaneous signal-to-noise ratio (SNR) at the destination. For sufficiently high SNR, the channel capacity of ORCP asymptotically converges to OSPR while OSPR and ORCP achieve higher channel capacity compared to TCIFR. Although TCIFR suffers from an increase in the outage probability relative to OSPR, it provides the lowest implementation complexity among the considered schemes. Along with analytical results, we further adopt Monte Carlo simulations to validate the theoretical analysis.
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| 28. |
- Reider, Norbert, et al.
(author)
-
A distributed power control and mode selection algorithm for D2D communications
- 2012
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; , s. 266-
-
Journal article (peer-reviewed)abstract
- Device-to-device (D2D) communications underlaying a cellular infrastructure has recently been proposed as a means of increasing the resource utilization, improving the user throughput and extending the battery lifetime of user equipments. In this article we propose a new distributed power control algorithm that iteratively determines the signal-to-noise-and-interference-ratio (SINR) targets in a mixed cellular and D2D environment and allocates transmit powers such that the overall power consumption is minimized subject to a sum-rate constraint. The performance of the distributed power control algorithm is benchmarked with respect to the optimal SINR target setting that we obtain using the Augmented Lagrangian Penalty Function method. The proposed scheme shows consistently near optimum performance both in a single-input-multiple-output and a multiple-input-multiple-output setting. We also propose a joint power control and mode selection algorithm that requires single cell information only and clearly outperforms the classical cellular mode operation.
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| 29. |
- Sharma, Shree Krishna, et al.
(author)
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Interference alignment for spectral coexistence of heterogeneous networks
- 2013
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; :1, s. 46-
-
Journal article (peer-reviewed)abstract
- The coexistence of heterogeneous networks within the same spectrum for enhancing the spectrum efficiency has attracted large interest lately in the research community. Furthermore, the research interest towards the deployment of small cells and multibeam satellites is increasing due to high capacity, easier deployment and higher energy efficiency. However, due to the scarcity of available spectrum and the requirement of additional spectrum for these systems, small cells need to coexist with macrocells and multibeam satellites need to coexist with monobeam satellites within the same spectrum. In this context, this contribution investigates an underlay spectral coexistence mechanism which exploits an interference alignment (IA) technique in order to mitigate the interference of cognitive transmitters towards the primary receivers in a normal uplink mode. More specifically, three types of IA techniques, namely static, uncoordinated and coordinated are investigated. The performance of the IA technique is evaluated and compared with primary only, resource division and no-mitigation techniques in terms of sum-rate capacity, primary to secondary rate ratio and primary rate protection ratio. It is shown that the coordinated IA technique perfectly protects the primary rate in both terrestrial and satellite coexistence scenarios.
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| 30. |
- Tran, Hung, et al.
(author)
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Delay performance of cognitive radio networks for point-to-point and point-to-multipoint communications
- 2012
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer. - 1687-1472 .- 1687-1499. ; :9
-
Journal article (peer-reviewed)abstract
- In this article, we analyze the packet transmission time in spectrum sharing systems where a secondary user (SU) simultaneously accesses the spectrum licensed to primary users (PUs). In particular, under the assumption of an independent identical distributed Rayleigh block fading channel, we investigate the effect of the peak interference power constraint imposed by multiple PUs on the packet transmission time of the SU. Utilizing the concept of timeout, exact closed-form expressions of outage probability and average packet transmission time of the SU are derived. In addition, employing the characteristics of the M/G/1 queuing model, the impact of the number of PUs and their peak interference power constraint on the stable transmission condition and the average waiting time of packets at the SU are examined. Moreover, we then extend the analysis for point-to-point to point-to-multipoint communications allowing for multiple SUs and derive the related closed-form expressions for outage probability and successful transmission probability for the best channel condition. Numerical results are provided to corroborate our theoretical results and to illustrate applications of the derived closed-form expressions for performance evaluation of cognitive radio networks.
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| 31. |
- Yajnanarayana, Vijaya, et al.
(author)
-
Spectral efficient IR-UWB communication design for low complexity transceivers
- 2014
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer. - 1687-1472 .- 1687-1499. ; 2014:158
-
Journal article (peer-reviewed)abstract
- Ultra wideband (UWB) radio for communication has several challenges. From the physical layer perspective, asignaling technique should be optimally designed to work in synergy with the underneath hardware to achievemaximum performance. In this paper, we propose a variant of pulse position modulation (PPM) for physical layersignaling, which can achieve raw bitrate in excess of 150 Mbps on a low complexity in-house developed impulseradio UWB platform. The signaling system is optimized to maximize bitrate under practical constraints of lowcomplexity hardware and regulatory bodies. We propose a detector and derive its theoretical performance boundsand compare the performance in simulation in terms of symbol error rates (SER). Modifications to the signaling, whichcan increase the range by 4 times with a slight increase in hardware complexity, is proposed. Detectors for thismodification and a comparative study of the performance of the proposed UWB physical layer signaling schemes interms of symbol error rates are discussed.
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| 32. |
- Åkerberg, Johan, et al.
(author)
-
Efficient integration of secure and safety critical industrial wireless sensor networks
- 2011
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer. - 1687-1472 .- 1687-1499. ; :1
-
Journal article (peer-reviewed)abstract
- Wireless communication has gained more interest in industrial automation due to flexibility, mobility, and cost reduction. Wireless systems, in general, require additional and different engineering and maintenance tasks, for example cryptographic key management. This is an important aspect that needs to be addressed before wireless systems can be deployed and maintained efficiently in the industry. In this paper, we take an holistic approach that addresses safety and security regardless of the underlying media. In our proposed framework we introduce security modules which can be retrofitted to provide end-to-end integrity and authentication measures by utilizing the black channel concept. With the proposed approach, we can extend and provide end-to-end security as well as functional safety using existing automation equipment and standards, such as Profisafe, Profinet IO, and WirelessHART. Furthermore, we improve the WirelessHART standard with periodic and deterministic downlink transmissions to enable efficient usage of wireless actuators, as well as improving the performance of functional safety protocols.
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| 33. |
- Savic, Vladimir, et al.
(author)
-
Indoor Positioning Using Nonparametric Belief Propagation Based on Spanning Trees
- 2010
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; , s. 1-12
-
Journal article (peer-reviewed)abstract
- Nonparametric belief propagation (NBP) is one of the best-known methods for cooperative localization in sensor networks. It is capable of providing information about location estimation with appropriate uncertainty and to accommodate non-Gaussian distance measurement errors. However, the accuracy of NBP is questionable in loopy networks. Therefore, in this paper, we propose a novel approach, NBP based on spanning trees (NBP-ST) created by breadth first search (BFS) method. In addition, we propose a reliable indoor model based on obtained measurements in our lab. According to our simulation results, NBP-ST performs better than NBP in terms of accuracy and communication cost in the networks with high connectivity (i.e., highly loopy networks). Furthermore, the computational and communication costs are nearly constant with respect to the transmission radius. However, the drawbacks of proposed method are a little bit higher computational cost and poor performance in low-connected networks.
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| 34. |
- Al-Saadeh, Osama, et al.
(author)
-
A performance comparison of in-band full duplex and dynamic TDD for 5G indoor wireless networks
- 2017
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer. - 1687-1472 .- 1687-1499.
-
Journal article (peer-reviewed)abstract
- In-band full duplex has emerged as a solution for high data rate and low access delay for 5G wireless networks after its feasibility has been demonstrated. However, the impact of the in-band full duplex on the system-level performance of multi-cell wireless networks has not been investigated thoroughly. In this paper, we conduct an extensive simulation study to investigate the performance of in-band full duplex for indoor 5G small cell wireless networks. Particularly, we compare the in-band full duplex with static and dynamic time division duplexing schemes which require much less hardware complexity. We examine the effects of beamforming and interference cancellation under various traffic demands and asymmetry situations in the performance comparison. Our objective is to identify under which condition and with which technology support the in-band full duplex becomes advantageous over the simpler duplexing schemes. Numerical results indicate that for highly utilized wireless networks, in-band full duplex should be combined with interference cancellation and beamforming in order to achieve a performance gain over traditional duplexing schemes. Only then in-band full duplex is considered to be advantageous at any number of active mobile stations in the network and any downlink to uplink traffic proportion. Our results also suggest that in order to achieve a performance gain with the in-band full duplex in both links, the transmit power of the access points and the mobile stations should be comparable.
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| 35. |
- Alexandropoulos, G. C., et al.
(author)
-
RIS-enabled smart wireless environments: deployment scenarios, network architecture, bandwidth and area of influence
- 2023
-
In: Eurasip Journal on Wireless Communications and Networking. - 1687-1499 .- 1687-1472. ; 2023:1
-
Research review (peer-reviewed)abstract
- Reconfigurable intelligent surfaces (RISs) constitute the key enabler for programmable electromagnetic propagation environments and are lately being considered as a candidate physical-layer technology for the demanding connectivity, reliability, localisation, and sustainability requirements of next-generation wireless networks. In this paper, we first present the deployment scenarios for RIS-enabled smart wireless environments that have been recently designed within the ongoing European Union Horizon 2020 RISE-6G project, as well as a network architecture integrating RISs with existing standardised interfaces. We identify various RIS deployment strategies and sketch the core architectural requirements in terms of RIS control and signalling, depending on the RIS hardware architectures and respective capabilities. Furthermore, we introduce and discuss, with the aid of simulations and reflect array measurements, two novel metrics that emerge in the context of RIS-empowered wireless systems: the RIS bandwidth of influence and the RIS area of influence. Their extensive investigation corroborates the need for careful deployment and planning of the RIS technology in future wireless networks.
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| 36. |
- Almers, Peter, et al.
(author)
-
Survey of channel and radio propagation models for wireless MIMO systems
- 2007
-
In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; 2007
-
Journal article (peer-reviewed)abstract
- This paper provides an overview of the state-of- the-art radio propagation and channel models for wireless multiple-input multiple-output (MIMO) systems. We distinguish between physical models and analytical models and discuss popular examples from both model types. Physical models focus on the double-directional propagation mechanisms between the location of transmitter and receiver without taking the antenna configuration into account. Analytical models capture physical wave propagation and antenna configuration simultaneously by describing the impulse response (equivalently, the transfer function) between the antenna arrays at both link ends. We also review some MIMO models that are included in current standardization activities for the purpose of reproducible and comparable MIMO system evaluations. Finally, we describe a couple of key features of channels and radio propagation which are not sufficiently included in current MIMO models. Copyright c 2007 P. Almers et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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| 37. |
- Arvanitaki, Antonia, et al.
(author)
-
Performance analysis of congestion-aware secure broadcast channels
- 2021
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer. - 1687-1472 .- 1687-1499. ; 2021:1
-
Journal article (peer-reviewed)abstract
- Congestion-aware scheduling in case of downlink cellular communication has ignored the distribution of diverse content to different clients with heterogeneous secrecy requirements. Other possible application areas that encounter the preceding issue are secure offloading in mobile-edge computing, and vehicular communication. In this paper, we extend the work in Arvanitaki et al. (SN Comput Sci 1(1):53, 2019) by taking into consideration congestion and random access. Specifically, we study a two-user congestion-aware broadcast channel with heterogeneous traffic and different security requirements. We consider two randomized policies for selecting which packets to transmit, one is congestion-aware by taking into consideration the queue size, whereas the other one is congestion-agnostic. We analyse the throughput and the delay performance under two decoding schemes at the receivers, and provide insights into their relative security performance and into how congestion control at the queue holding confidential information can help decrease the average delay per packet. We show that the congestion-aware policy provides better delay, throughput, and secrecy performance for large arrival packet probabilities at the queue holding the confidential information. The derived results also take account of the self-interference caused at the receiver for whom confidential data is intended due to its full-duplex operation while jamming the communication at the other user. Finally, for two decoding schemes, we formulate our problems in terms of multi-objective optimization, which allows for finding a trade-off between the average packet delay for packets intended for the legitimate user and the throughput for the other user under congestion-aware policy.
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| 38. |
- Aslam, Mohammed Zahid, et al.
(author)
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Performance of a dense urban massive MIMO network from a simulated ray-based channel
- 2019
-
In: EURASIP Journal on Wireless Communications and Networking. - : SPRINGEROPEN. - 1687-1472 .- 1687-1499.
-
Journal article (peer-reviewed)abstract
- Massive MIMO network deployments are expected to be a key feature of the upcoming 5G communication systems. Such networks are able to achieve a high level of channel quality and can simultaneously serve multiple users with the same resources. In this paper, realistic massive MIMO channels are evaluated both in single and multi-cell environments. The favorable propagation property is evaluated in the single-cell scenario and provides perspectives on the minimal criteria required to achieve such conditions. The dense multi-cell urban scenario provides a comparison between linear, planar, circular, and cylindrical arrays to evaluate a large-scale multi-cell massive MIMO network. The system-level performance is predicted using two different kinds of channel models. First, a ray-based deterministic tool is utilized in a real North American city environment. Second, an independent and identically distributed (i.i.d.) Rayleigh fading channel model is considered, as often used in previously published massive MIMO studies. The analysis is conducted in a 16-macro-cell network with both randomly distributed outdoor and indoor users. It is shown that the physical array properties like the shape and configuration have a large impact on the throughput statistics. Although the system-level performance with i.i.d. Rayleigh fading can be close to the deterministic prediction in some situations (e.g., with large linear arrays), significant differences are noticed when considering other types of arrays. The differences in the performance of the various arrays utilizing the exact same network parameters and the same number of total antenna elements provide insights into the selection of these physical parameters for upcoming 5G networks.
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| 39. |
- Avgouleas, Ioannis, et al.
(author)
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A wireless caching helper system with heterogeneous traffic and random availability
- 2021
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer. - 1687-1472 .- 1687-1499. ; 2021:1
-
Journal article (peer-reviewed)abstract
- Multimedia content streaming from Internet-based sources emerges as one of the most demanded services by wireless users. In order to alleviate excessive traffic due to multimedia content transmission, many architectures (e.g., small cells, femtocells, etc.) have been proposed to offload such traffic to the nearest (or strongest) access point also called "helper". However, the deployment of more helpers is not necessarily beneficial due to their potential of increasing interference. In this work, we evaluate a wireless system which can serve both cacheable and non-cacheable traffic. More specifically, we consider a general system in which a wireless user with limited cache storage requests cacheable content from a data center that can be directly accessed through a base station. The user can be assisted by a pair of wireless helpers that exchange non-cacheable content as well. Files not available from the helpers are transmitted by the base station. We analyze the system throughput and the delay experienced by the cached user and show how these performance metrics are affected by the packet arrival rate at the source helper, the availability of caching helpers, the caches parameters, and the users request rate by means of numerical results.
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| 40. |
- Aziz, Imran, et al.
(author)
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60 GHz RF module with beam-steering optimization algorithm for high data rate access and backhaul communications
- 2022
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer Nature. - 1687-1472 .- 1687-1499. ; 2022:1
-
Journal article (peer-reviewed)abstract
- This paper presents an 802.11ad-based radio frequency module for high data rate fixed wireless access and backhaul communications. The transceiver chip is manufactured in SiGe BiCMOS technology covering 57-71 GHz, providing 16 RX and 16 TX paths with combined output power of more than 20 dBm. The chip is packaged using embedded wafer-level BGA technology of the size 12.6 x 12.6 x 0.8 mm (3) and employs advanced dielectric materials with 2 metallic redistribution layers. The package integrates the transceiver chip with RX and TX high gain PCB antenna arrays, allowing effective isotropic radiated power (EIRP) of more than 40 dBm. Beam steering is achieved in +/- 50(o) by the transceiver through providing appropriate weights to the antenna arrays. The paper presents generation of beamforming lookup table along with optimization of the power distribution to the array. This optimization results in flattening of the EIRP over the whole beam-steering range and frequency bandwidth. The module allows for data rates up to 10 Gbps by employing full- channel 128 QAM and half-channel 256 QAM single-carrier modulation.
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| 41. |
- Bassoo, Vandana, et al.
(author)
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A potential transmitter architecture for future generation green wireless base station
- 2009
-
In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; :doi:10.1155/2009/821846
-
Journal article (peer-reviewed)abstract
- Current radio frequency power amplifiers in 3G base stations have very high power consumption leading to a hefty cost and negative environmental impact. In this paper, we propose a potential architecture design for future wireless base station. Issues associated with components of the architecture are investigated. The all-digital transmitter architecture uses a combination of envelope elimination and restoration (EER) and pulse width modulation(PWM)/ pulse position modulation (PPM). The performance of this architecture is predicted from the measured output power and efficiency curves of a GaN amplifier. 57% efficiency is obtained for an OFDM signal limited to 8dB peak to average power ratio. The PWM/PPM drive signal is generated using the improved Cartesian sigma delta techniques. It is shown that an RF oversampling by a factor of four meets the WLAN spectral mask and WCDMA specification is met by an RF oversampling of sixteen.
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| 42. |
- Bilstrup, Katrin, et al.
(author)
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On the ability of the 802.11p MAC method and STDMA to support real-time vehicle-to-vehicle communications
- 2009
-
In: EURASIP Journal on Wireless Communications and Networking. - New York : Hindawi Publishing Corporation. - 1687-1472 .- 1687-1499. ; 2009:902414, s. 1-14
-
Journal article (peer-reviewed)abstract
- Traffic safety applications using vehicle-to-vehicle (V2V) communication is an emerging and promising area within the intelligent transportation systems (ITS) sphere. Many of these new applications require real-time communication with high reliability, meaning that packets must be successfully delivered before a certain deadline. Applications with early deadlines are expected to require direct V2V communications, and the only standard currently supporting this is the upcoming IEEE 802.11p, included in the wireless access in vehicular environment (WAVE) stack. To meet a real-time deadline, timely and predictable access to the channel is paramount. However, the medium access method used in 802.11p, carrier sense multiple access with collision avoidance (CSMA/CA), does not guarantee channel access before a finite deadline. In this paper, we analyze the communication requirements introduced by traffic safety applications, namely, low delay, reliable, real-time communications.We show by simulation of a simple, but realistic, highway scenario, that vehicles using CSMA/CA can experience unacceptable channel access delays and, therefore, 802.11p does not support real-time communications. In addition, we present a potential remedy for this problem, namely, the use of self-organizing time division multiple access (STDMA). The real-time properties of STDMA are investigated by means of the same highway simulation scenario, with promising results.
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| 43. |
- Bodin, Ulf, et al.
(author)
-
Proportional throughput differentiationwith cognitive load-control on WSN channels
- 2015
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; :1
-
Journal article (peer-reviewed)abstract
- Wireless sensor networks are nowadays used in various applications to facilitate monitoring and actuation tasks, e.g., for smart grids and industrial automation. Some of these applications require guarantees or at least assurances on reliability. Such applications expect predictable throughput and delay, which are hard to maintain in environments with changing radio conditions. QoS-aware MAC protocols capable of handling such environments are well explored. They require however protocol changes and are therefore difficult to deploy. This paper presents an application layer forwarding service that offers proportional differentiation while limiting network load to preserve high utilization and predictability. Demands for capacity are expressed as fractions of the overall channel throughput. We show that this service can be implemented with a cognitive load controller (CLC) based on fuzzy logic and quality assessed with utility functions for application layer packet loss and throughput. We evaluate the CLC for 802.15.4 with CSMA/CA through NS-3 simulations showing that it offers the intended service while adjusting load for high overall throughput and low delay
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| 44. |
- Cavalcanti de Castro, Marcel, 1978-, et al.
(author)
-
Opportunistic P2P Communications in Delay Tolerant Rural Scenarios
- 2011
-
In: EURASIP Journal on Wireless Communications and Networking. - New York : Hindawi. - 1687-1472 .- 1687-1499. ; Januari
-
Journal article (peer-reviewed)abstract
- Opportunistic networking represents a promising paradigm for support of communications, specifically in infrastructure-less scenarios such as remote areas communications. In principle in opportunistic environments, we would like to make available all the applications thought for traditional wired and wireless networks like file sharing and content distribution. In this paper we present a delay tolerant scenario for file sharing applications in rural areas where an opportunistic approach is exploited. In order to support communications, we compare two peer-to-peer (P2P) schemes initially conceived for wireless networks and prove their applicability and usefulness to a DTN scenario where replication of resources can be used to improve the lookup performance and the network can be occasionally connected by mean of a data mule. Simulation results show the suitability of the schemes and allow to derive interesting design guidelines on the convenience and applicability of such approaches
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| 45. |
- Chong, Z., et al.
(author)
-
Pricing in Noncooperative Interference Channels for Improved Energy Efficiency
- 2010
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer. - 1687-1472 .- 1687-1499. ; 2010
-
Journal article (peer-reviewed)abstract
- We consider noncooperative energy-efficient resource allocation in the interference channel. Energy efficiency is achieved when each system pays a price proportional to its allocated transmit power. In noncooperative game-theoretic notation, the power allocation chosen by the systems corresponds to the Nash equilibrium. We study the existence and characterize the uniqueness of this equilibrium. Afterwards, pricing to achieve energy-efficiency is examined. We introduce an arbitrator who determines the prices that satisfy minimum QoS requirements and minimize total power consumption. This energy-efficient assignment problem is formulated and solved. We compare our setting to that without pricing with regard to energy-efficiency by simulation. It is observed that pricing in this distributed setting achieves higher energy-efficiency indifferent interference regimes.
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| 46. |
- Chu, Thi My Chinh, et al.
(author)
-
Hybrid spectrum access with relay assisting both primary and secondary networks under imperfect spectrum sensing
- 2016
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer. - 1687-1472 .- 1687-1499.
-
Journal article (peer-reviewed)abstract
- This paper proposes a novel hybrid interweave-underlay spectrum access for a cognitive amplify-and-forward relay network where the relay forwards the signals of both the primary and secondary networks. In particular, the secondary network (SN) opportunistically operates in interweave spectrum access mode when the primary network (PN) is sensed to be inactive and switches to underlay spectrum access mode if the SN detects that the PN is active. A continuous-time Markov chain approach is utilized to model the state transitions of the system. This enables us to obtain the probability of each state in the Markov chain. Based on these probabilities and taking into account the impact of imperfect spectrum sensing of the SN, the probability of each operation mode of the hybrid scheme is obtained. To assess the performance of the PN and SN, we derive analytical expressions for the outage probability, outage capacity, and symbol error rate over Nakagami-m fading channels. Furthermore, we present comparisons between the performance of underlay cognitive cooperative radio networks (CCRNs) and the performance of the considered hybrid interweave-underlay CCRN in order to reveal the advantages of the proposed hybrid spectrum access scheme. Eventually, with the assistance of the secondary relay, performance improvements for the PN are illustrated by means of selected numerical results.
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| 47. |
- Conchon, Emmanuel, et al.
(author)
-
W-NINE : A Two-stage Emulation Platform for Mobile and Wireless Systems
- 2010
-
In: EURASIP Journal on Wireless Communications and Networking. - : Hindawi Publishing Corporation. - 1687-1472 .- 1687-1499. ; 2010, s. 1-20
-
Journal article (peer-reviewed)abstract
- More and more applications and protocols are now running on wireless networks. Testing the implementation of such applications and protocols is a real challenge as the position of the mobile terminals and environmental effects strongly affect the overall performance. Network emulation is often perceived as a good trade-off between experiments on operational wireless networks and discrete-event simulations on Opnet or ns-2. However, ensuring repeatability and realism in network emulation while taking into account mobility in a wireless environment is very difficult. This paper proposes a network emulation platform, called W-NINE, based on off-line computations preceding online pattern-based traffic shaping. The underlying concepts of repeatability, dynamicity, accuracy, and realism are defined in the emulation context. Two different simple case studies illustrate the validity of our approach with respect to these concepts.
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| 48. |
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| 49. |
- Diallo, A., et al.
(author)
-
Diversity characterization of optimized two-antenna systems for UMTS handsets
- 2007
-
In: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1499 .- 1687-1472. ; 2007, s. 9-
-
Journal article (peer-reviewed)abstract
- This paper presents the evaluation of the diversity performance of several two-antenna systems for UMTS terminals. All the measurements are done in a reverberation chamber and in a Wheeler cap setup. First, a two-antenna system having poor isolation between its radiators is measured. Then, the performance of this structure is compared with two optimized structures having high isolation and high total effciency, thanks to the implementation of a neutralization technique between the radiating elements. The key diversity parameters of all these systems are discussed, that is, the total effciency of the antenna, the envelope correlation coefficient, the diversity gains, the mean effective gain (MEG), and the MEG ratio. The comparison of all these results is especially showing the benefit brought back by the neutralization technique. Copyright (c) 2007.
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| 50. |
- Do, Tan Tai, et al.
(author)
-
Waveform domain framework for capacity analysis of uplink WCDMA systems
- 2015
-
In: EURASIP Journal on Wireless Communications and Networking. - : Springer. - 1687-1472 .- 1687-1499.
-
Journal article (peer-reviewed)abstract
- This paper investigates the capacity limit of an uplink WCDMA system considering a continuous-time waveform signal. Various realistic assumptions are incorporated into the problem, which make the study valuable for performance assessment of real cellular networks to identify potentials for performance improvements in practical receiver designs. An equivalent discrete-time channel model is derived based on sufficient statistics for optimal decoding of the transmitted messages. The capacity regions are then characterized using the equivalent channel considering both finite constellation and Gaussian distributed input signals. The capacity with sampling at the receiver is also provided to exemplify the performance loss due to a typical post-processing at the receiver. Moreover, we analyze the asymptotic capacity when the signal-to-noise ratio goes to infinity. The conditions to simultaneously achieve the individual capacities are derived, which reveal the impacts of signature waveform space, channel frequency selectivity and signal constellation on the system performance.
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