| 1. |
- Azimi-Abarghouyi, Seyed Mohammad, et al.
(författare)
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Coverage analysis of finite cellular networks: A stochastic geometry approach
- 2018
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Ingår i: IWCIT 2018 - Iran Workshop on Communication and Information Theory. - 9781538641491 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- This paper develops a tractable modeling and analysis framework for finite cellular wireless networks using stochastic geometry. Defining finite homogeneous Poisson point processes to model the number and locations of access points in a confined region, we study the coverage probability for an arbitrarily-located reference user that is served by the closest access point. The distance distribution and the Laplace transform (LT) of the interference are derived. We also derive a closed-form lower bound on the LT of the interference. Our analyses reveal that a higher path loss exponent improves the coverage probability and that there is a location where the coverage probability is maximized.
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| 2. |
- Azimi-Abarghouyi, Seyed Mohammad, et al.
(författare)
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Decentralized Compute-and-Forward for Ad Hoc Networks
- 2016
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Ingår i: IEEE Wireless Communications Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 2162-2345 .- 2162-2337. ; 5:6, s. 652-655
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, we introduce a decentralized compute-and-forward (DCMF) protocol to solve the rank failure problem in compute-and-forward (CMF) ad hoc multi-user multi-relay networks without a central coordinator. In sufficiently strong inter-relay links, we show that the DCMF scheme can reach the same achievable rate as in the successive centralized CMF (SCCMF), which is a modified version of the previously introduced centralized CMF in using our proposed successive method for a fair comparison. We evaluate the outage probability and rate of the proposed strategy, and compare the results with those of the conventional CMF and decode-and-forward, and the SCCMF.
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| 3. |
- Azimi-Abarghouyi, Seyed Mohammad, et al.
(författare)
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Integer-Forcing Message Recovering in Interference Channels
- 2018
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Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 67:5, s. 4124-4135
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose a scheme referred to as integer-forcing message recovering (IFMR) to enable receivers to recover their desirable messages in interference channels. Compared to the state-of-the-art integer-forcing linear receiver (IFLR), our proposed IFMR approach needs to decode considerably less number of messages. In our method, each receiver recovers independent linear integer combinations of the desirable messages each from two independent equations. We propose an efficient polynomial-time algorithm to sequentially find the equations and integer combinations with maximum rates and analyze its complexity. We evaluate the performance of our scheme and compare the results with the minimum mean-square error linear receiver (MMSELR) and lattice-reduction-aided successive interference cancellation with signal-to-interference-plus-noise ratio maximizing preprocessing (LaR-aided SIC with SINR-Max), as well as the IFLR schemes. The results indicate that our IFMR scheme outperforms the MMSELR and LaR-aided SIC with SINR-Max schemes, in terms of achievable rate, considerably. Also, compared to the IFLR, the IFMR scheme achieves slightly less rates in moderate signal-to-noise ratios, with significantly less overall implementation complexity.
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| 4. |
- Azimi-Abarghouyi, Seyed Mohammad, et al.
(författare)
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Stochastic Geometry Modeling and Analysis of Finite Millimeter Wave Wireless Networks
- 2019
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Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 68:2, s. 1378-1393
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Tidskriftsartikel (refereegranskat)abstract
- This paper develops a stochastic geometry-based approach for the modeling and analysis of finite millimeter wave (mm Wave) wireless networks where a random number of transmitters and receivers are randomly located inside a finite region. We consider a selection strategy to serve a reference receiver by the transmitter providing the maximum average received power among all transmitters. In our system model, we employ the unique features of mm Wave communications such as directional transmit and receive beamforming and different channels for line-of-sight (LOS) and non-line-of-sight (NLOS) links. Accordingly, deploying a blockage process suitable for mm Wave networks, we study the coverage probability and the ergodic rate for the reference receiver that can be located everywhere inside the network region. As key steps for the analyses, the distribution of the distance from the reference receiver to its serving LOS or NLOS transmitter and LOS and NLOS association probabilities are derived. We also derive the Laplace transform of the interferences from LOS and NLOS transmitters. Finally, we propose upper and lower bounds on the coverage probability that can be evaluated easier than the exact results, and investigate the impact of different parameters including the receiver location, the beamwidth, and the blockage process exponent on the system performance.
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| 5. |
- Azimi-Abarghouyi, Seyed Mohammad, et al.
(författare)
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Stochastic geometry modeling and analysis of single- and multi-cluster wireless networks
- 2018
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Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 66:10, s. 4981-4996
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Tidskriftsartikel (refereegranskat)abstract
- This paper develops a stochastic geometry-based approach for the modeling and analysis of single- and multi-cluster wireless networks. We first define finite homogeneous Poisson point processes to model the number and locations of the transmitters in a confined region as a single-cluster wireless network. We study the coverage probability for a reference receiver for two strategies; closest-selection, where the receiver is served by the closest transmitter among all transmitters, and uniform-selection, where the serving transmitter is selected randomly with uniform distribution. Second, using Matern cluster processes, we extend our model and analysis to multi-cluster wireless networks. Here, two types of receivers are modeled, namely, closed- and open-access receivers. Closed-access receivers are distributed around the cluster centers of the transmitters according to a symmetric normal distribution and can be served only by the transmitters of their corresponding clusters. Open-access receivers, on the other hand, are placed independently of the transmitters and can be served by all transmitters. In all cases, the link distance distribution and the Laplace transform (LT) of the interference are derived. We also derive closed-form lower bounds on the LT of the interference for single-cluster wireless networks. The impact of different parameters on the performance is also investigated.
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| 6. |
- Bai, Bo, et al.
(författare)
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Caching based socially-aware D2D communications in wireless content delivery networks: a hypergraph framework
- 2016
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Ingår i: IEEE Wireless Communications. - 1536-1284 .- 1558-0687. ; 23:4, s. 74-81
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Tidskriftsartikel (refereegranskat)abstract
- The emergence of the D2D communications paradigm has transformed the way in which cellular networks are operated. Previous work in D2D communications, however, mainly focused on interference management and capacity maximization of both D2D links and cellular links. Recent literature has observed that the QoE can be greatly enhanced by caching contents in mobile devices, with a carefully designed caching strategy. In this article, we propose a novel hypergraph framework that designs the caching based D2D communication scheme by taking social ties among users and common interests into consideration. We first present the considered features of the D2D transmission scheme, social characteristics consideration, and interest similarity impact. The key concepts of hypergraph and related techniques, such as hypergraph coloring and multidimensional matching, are explained. Then some design issues with simulation results in the proposed framework are discussed in detail, which show the potential of the proposed approach. By jointly considering social ties, common interests, and the D2D transmission scheme, we believe the proposed framework explores new opportunities and future directions in caching based socially-aware D2D communications.
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| 7. |
- Baianifar, Mahdi, et al.
(författare)
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Effect of users height distribution on the coverage of mmwave cellular networks with 3d beamforming
- 2019
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Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 7, s. 68091-68105
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we study the effect of users' height distribution on the coverage probability of millimeter-wave (mmWave) cellular networks that utilize three-dimensional beamforming (3DBF). The users and base stations (BSs) are equipped with multiple antennas and both line-of-sight (LOS) and non-LOS links exist in the channel which are, respectively, modeled by the Nakagami-m and Rayleigh distribution. In this setup, we investigate the tilt angle optimization of the BS antenna arrays for maximizing the coverage probability under two regimes of noise limited and interference limitedd. In both cases, by adopting a stochastic geometry approach, we analytically derive the coverage probability, and then, find the optimal tilt angle that maximizes this probability. In addition, in the noise limited regime, we show that the optimal tilt angle depends on the average distance between each user and its serving BS and also their effective height. In the interference-limited regime, we further consider different rules for associating users to the BSs. Meanwhile, since in this regime, the tilt angle optimization is very complex, we propose a low complexity approach to find the optimal tilt angle that has a performance close to the optimal solution. We further study the asymptotic behavior when the density of the BSs or signal-To-interference ratio tends to infinity or zero. Finally, through the numerical simulations, we show that using the 3DBF and also incorporating the users' height distribution in the tilt angle optimization lead to a substantial improvement in the coverage probability of the mmWave cellular networks.
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| 8. |
- Baianifar, Mahdi, et al.
(författare)
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Impact of User Height on the Coverage of 3D Beamforming-Enabled Massive MIMO Systems
- 2017
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Ingår i: 2017 IEEE 28TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE RADIO COMMUNICATIONS (PIMRC). - 9781538635315 ; 2017-October, s. 1-5
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Konferensbidrag (refereegranskat)abstract
- In this paper, we perform a coverage analysis of a cellular massive multiple-input multiple-output (MaMIMO) network which adopts 3D beamforming. In contrast to the previous works on 3D beamforming which assume that all users are placed on the ground (i.e., in a 2D environment), we consider a more practical scenario where the users of the network are dropped in a 3D environment with different heights. In this scenario, by adopting a stochastic geometry framework, first we calculate the coverage probability of the network as a function of the users height. Then considering this coverage probability as the objective function, the optimum tilt angle of the base stations antenna pattern is found and the effect of users' heights on this tilt angle is investigated. Our numerical results show that by taking the users' heights into account and using the proposed method, a considerable improvement is achieved in the performance of the network compared to other similar 3D beamforming methods that ignore the users' height distribution.
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| 9. |
- Bockelmann, C., et al.
(författare)
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Massive Machine-Type Communications in 5G: Physical and MAC-Layer Solutions
- 2016
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Ingår i: IEEE Communications Magazine. - 0163-6804 .- 1558-1896. ; 54:9, s. 59-65
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Tidskriftsartikel (refereegranskat)abstract
- MTC are expected to play an essential role within future 5G systems. In the FP7 project METIS, MTC has been further classified into mMTC and uMTC. While mMTC is about wireless connectivity to tens of billions of machine-type terminals, uMTC is about availability, low latency, and high reliability. The main challenge in mMTC is scalable and efficient connectivity for a massive number of devices sending very short packets, which is not done adequately in cellular systems designed for human-type communications. Furthermore, mMTC solutions need to enable wide area coverage and deep indoor penetration while having low cost and being energy-efficient. In this article, we introduce the PHY and MAC layer solutions developed within METIS to address this challenge.
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| 10. |
- Chen, X., et al.
(författare)
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Beamforming MIMO-OFDM Systems in the Presence of Phase Noises at Millimeter-Wave Frequencies
- 2017
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Ingår i: 2017 IEEE Wireless Communications and Networking Conference Workshops, WCNCW 2017.
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Konferensbidrag (refereegranskat)abstract
- In this paper, the effects of oscillator phase noises on multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems are studied. It is shown that phase noises of common oscillators at the transmitter and at the receiver have the same influence on the performance of (single-stream) beamforming MIMO-OFDM systems. When each antenna is equipped with an independent oscillator, the phase noises at the transmitter and at the receiver can have different influences depending on the numbers of transmit and receive antennas. Specially, the phase noise effect at the transmitter (receiver) can be alleviated by having more transmit (receive) antennas for the case of independent oscillators. It is found that the independent oscillator case outperforms the common oscillator case without phase noise compensation or with only common phase error (CPE) correction in terms of error vector magnitude (EVM). Nevertheless, unlike the independent oscillator case, the intercarrier interference (ICI) caused by the common oscillator can be effectively compensated by advanced phase noise mitigation schemes, resulting in better EVM performance than for the independent oscillator case.
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