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| 2. |
- Erkip, Elza, et al.
(författare)
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Editorial Issue on 'Information Theoretic Foundations of Future Communication Systems'
- 2022
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Ingår i: IEEE Journal on Selected Areas in Information Theory. - 2641-8770. ; 3:1, s. 2-4
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Information theory, starting with Shannon’s groundbreaking work, has fundamentally shaped the way communication systems are designed and operated. Information theoretic principles form the underpinnings of modern communication networks. This issue explores how new advances in information theory can impact future communication systems. Several papers address issues at the heart of next generation wireless and wired networks: Multiple access, including access by a massive number of devices, multi-hop, large antenna arrays, communication security, and timeliness of information. Others consider new applications such as joint communication and sensing, communication for learning and inference, wireless imaging, and new storage mediums such as DNA, thereby providing the information theoretic foundations of modalities beyond human-to-human communications.
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| 3. |
- Seifi, Nima, 1981, et al.
(författare)
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Adaptive Multicell 3-D Beamforming in Multiantenna Cellular Networks
- 2016
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Ingår i: IEEE Transactions on Vehicular Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9545 .- 1939-9359. ; 65:8, s. 6217-6231
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Tidskriftsartikel (refereegranskat)abstract
- We consider a cellular network with multiantenna base stations (BSs) and single-antenna users, multicell cooperation, imperfect channel state information (CSI), and directional antennas, each with a vertically adjustable beam. We investigate the impact of the elevation angle of the BS antenna pattern, which is denoted as tilt, on the performance of the considered network when employing either a traditional single-cell transmission or a fully cooperative multicell transmission. Using the results of this investigation, we propose a novel hybrid multicell cooperation technique in which the intercell interference is controlled via either cooperative beamforming in the horizontal plane or coordinated beamforming in the vertical plane of the wireless channel, which is denoted as adaptive multicell 3-D beamforming. The main idea is to divide the coverage area into two disjoint vertical regions and adapt the multicell cooperation strategy at the BSs when serving each region. A fair scheduler is used to share the time slots between the vertical regions. It is shown that the proposed technique can achieve performance comparable with that of a fully cooperative transmission but with significantly lower complexity and signaling requirements. To facilitate computationally efficient simulation and design space exploration, accurate approximations of the user ergodic rate are proposed for different transmission strategies under imperfect CSI.
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| 4. |
- Seifi, Nima, 1981, et al.
(författare)
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Coordinated 3D Beamforming for Interference Management in Cellular Networks
- 2014
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Ingår i: IEEE Transactions on Wireless Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-2248 .- 1536-1276. ; 13:10, s. 5396-5410
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Tidskriftsartikel (refereegranskat)abstract
- We consider downlink transmission in a cellular network consisting of multi-antenna base stations (BSs), single-antenna mobile users, directional antennas each with a vertically adjustable beam, and control signaling delays in feedback and backhaul links. We propose a novel transmission technique in which intercell interference management is performed via coordinating the beamforming jointly in the horizontal and vertical planes of the wireless channel, denoted as coordinated 3D beamforming. In the horizontal plane, we focus on intercell interference cancelation (ICIC) and investigate its performance when the provided channel state information (CSI) is impaired due to delay/mobility. It is demonstrated that the superiority of ICIC over conventional intracell maximum ratio transmission is highly dependent on the CSI accuracy. In the vertical plane, we consider intercell interference control via coordinatively adapting the elevation angle of the BS antenna pattern, denoted as tilt, to the locations of the scheduled users. It is shown that with perfect CSI interference management should be performed in the horizontal plane using ICIC, while at high delay/mobility it should be done in the vertical plane via coordinated tilt adaptation. For intermediate values of delay/mobility, joint interference management in both planes is required.
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| 5. |
- Seifi, Nima, 1981, et al.
(författare)
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Coordinated Single-Cell vs Multi-Cell Transmission with Limited-Capacity Backhaul
- 2010
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Ingår i: IEEE Asilomar Conf. on Signals, Systems, and Computers, Pacific Grove, CA, Nov. 2010. - 1058-6393. - 9781424497218 ; , s. 1217-1221
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Konferensbidrag (refereegranskat)abstract
- Base station coordination is an efficient techniqueto transcend the limits on spectral efficiency imposed by intercellinterference. In this paper, we compare the performance ofdifferent coordination strategies with different amount of channelstate information (CSI) and data sharing among the coordinatingbase stations. We focus on the effect of limited backhaul capacityin a two-cell network. Contrary to the common belief, we showthat coordination strategies with no data and only limited CSIsharing is preferred to those with full data and CSI sharing whenthe backhaul capacity is relatively low and the edge SNR is high.
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| 6. |
- Seifi, Nima, 1981, et al.
(författare)
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Joint transmission mode and tilt adaptation in coordinated small-cell networks
- 2014
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Ingår i: 2014 IEEE International Conference on Communications Workshops, ICC 2014. - 9781479946402 ; , s. 598-603
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Konferensbidrag (refereegranskat)abstract
- We study downlink transmission in a wireless network consisting of small-sized cells, denoted as a small-cell network (SCN). We consider multi-antenna base stations (BSs) and single-antenna users, BS coordination, 3D antenna patterns, and fair scheduling. We investigate the impact of the elevation angle of the BS antenna pattern, denoted as tilt, on the performance of the considered SCN when employing either a conventional uncoordinated transmission mode or a fully coordinated transmission mode. Using the results of this investigation, we propose a novel hybrid-mode transmission technique that can achieve a performance comparable to that of a fully coordinated transmission but with a significantly lower complexity and signaling requirement. The main idea is to divide the coverage area into two so-called vertical regions and jointly adapt the transmission mode and the tilt at the BSs when serving each region. A fair scheduler is used to share the time-slots between the vertical regions and among the users in each region.
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| 7. |
- Seifi, Nima, 1981, et al.
(författare)
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Multimode Transmission in Network MIMO Downlink with Incomplete CSI
- 2011
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Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180. ; 2011, s. Art. no. 743916-
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Tidskriftsartikel (refereegranskat)abstract
- We consider a cooperative multi-cell MIMO (a.k.a network MIMO) downlink system with multiantennabase stations (BSs), which are connected to a central unit and communicate with multi-antennausers. In such a network, obtaining perfect channel state information (CSI) of all users at the central unitto exploit opportunistic scheduling requires a substantial amount of feedback and backhaul signaling.In this paper, we propose a scheduling algorithm based only on the knowledge of the average receivedSNR at each user from all the cooperating BSs, denoted as incomplete CSI. Multi-mode transmission isapplied that is able to adaptively adjust the number of data streams transmitted to each user. Utilizingthe results of random matrix theory, an analytical framework is proposed to approximate the ergodicrate of each user with different number of data streams. Using these approximate ergodic rates, a jointuser and mode selection algorithm is proposed, where only the scheduled users need to feed backinstantaneous CSI. Simulation results demonstrate that the developed analytical framework providesa good approximation for a practical number of antennas. While substantially reducing the feedbackoverhead, it is shown that the proposed scheduling algorithm performs closely to the opportunisticscheduling algorithm that requires instantaneous CSI feedback from all users.
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