| 1. |
- Ericson, Marten, et al.
(författare)
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Architecture landscape
- 2023
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Ingår i: Towards Sustainable and Trustworthy 6G: Challenges, Enablers, and Architectural Design. - 9781638282396 ; , s. 11-39
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The network architecture evolution journey will carry on in the years ahead, driving a large scale adoption of 5th Generation (5G) and 5G-Advanced use cases with significantly decreased deployment and operational costs, and enabling new and innovative use-case-driven solutions towards 6th Generation (6G) with higher economic and societal values. The goal of this chapter, thus, is to present the envisioned societal impact, use cases and the End-to-End (E2E) 6G architecture. The E2E 6G architecture includes summarization of the various technical enablers as well as the system and functional views of the architecture.
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| 2. |
- Ghoraishi, Mir, et al.
(författare)
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Towards versatile access networks (Chapter 3)
- 2023
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Ingår i: Towards Sustainable and Trustworthy 6G: Challenges, Enablers, and Architectural Design. - 9781638282396 ; , s. 40-120
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Compared to its previous generations, the 5th generation (5G) cellular network features an additional type of densification, i.e., a large number of active antennas per access point (AP) can be deployed. This technique is known as massive multipleinput multiple-output (mMIMO) [1]. Meanwhile, multiple-input multiple-output (MIMO) evolution, e.g., in channel state information (CSI) enhancement, and also on the study of a larger number of orthogonal demodulation reference signal (DMRS) ports for MU-MIMO, was one of the Release 18 of 3rd generation partnership project (3GPP Rel-18) work item. This release (3GPP Rel-18) package approval, in the fourth quarter of 2021, marked the start of the 5G Advanced evolution in 3GPP. The other items in 3GPP Rel-18 are to study and add functionality in the areas of network energy savings, coverage, mobility support, multicast broadcast services, and positioning
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| 3. |
- Haliloglu, Omer, et al.
(författare)
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Distributed MIMO Systems for 6G
- 2023
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Ingår i: 2023 Joint European Conference on Networks and Communications and 6G Summit, EuCNC/6G Summit 2023. ; , s. 156-161
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Konferensbidrag (refereegranskat)abstract
- This study focuses on Distributed MIMO (D-MIMO) systems and provides a discussion about their role in next generation networks. The paradigm shift to distributed networks offers great potential to address the 6G requirements, through macro diversity. As 6G scenarios and use cases continue to emerge, new challenges are likely to arise that may affect the widespread imp-lementation of D-MIMO. To address those, different deployment options have been proposed for roll-out considerations. They are composed of several sub-components that can be categorized as (i) wireless or wired fronthaul/backhaul, (ii) analog or digital signals, (iii) distributed or centralized processing, and (iv) coherent or non-coherent transmission. To facilitate standardization efforts, we provide 3GPP-aligned terminology for network nodes, multi-point transmission and reception schemes. In order to enable large-scale implementation of D-MIMO systems, it is important to determine the needed amount of distribution, develop practical solutions for high-frequency bands, and ways to convey data that meet the transport requirements. On this regard, we discuss key enablers and present simulation results for D-MIMO systems towards 6G. In particular, we present solutions for D-MIMO networks in dynamic scenarios related to channel estimation and layer-l mobility considering coherent and non-coherent joint transmission, and analog fronthaul implementation using analog-radio-over-fiber that are promising for high (upper mm-Wave and (sub-)THz) carrier frequencies, as well as integrated access and backhaul, network-controlled repeaters, and reconfigurable intelligent surfaces that are possible enablers for cost-efficient network densification at both low (cm-Wave, lower mm-Wave) and high carrier frequencies.
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| 4. |
- Interdonato, Giovanni, et al.
(författare)
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Ubiquitous cell-free Massive MIMO communications
- 2019
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Ingår i: EURASIP Journal on Wireless Communications and Networking. - : SPRINGEROPEN. - 1687-1472 .- 1687-1499.
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Forskningsöversikt (refereegranskat)abstract
- Since the first cellular networks were trialled in the 1970s, we have witnessed an incredible wireless revolution. From 1G to 4G, the massive traffic growth has been managed by a combination of wider bandwidths, refined radio interfaces, and network densification, namely increasing the number of antennas per site. Due its cost-efficiency, the latter has contributed the most. Massive MIMO (multiple-input multiple-output) is a key 5G technology that uses massive antenna arrays to provide a very high beamforming gain and spatially multiplexing of users and hence increases the spectral and energy efficiency (see references herein). It constitutes a centralized solution to densify a network, and its performance is limited by the inter-cell interference inherent in its cell-centric design. Conversely, ubiquitous cell-free Massive MIMO refers to a distributed Massive MIMO system implementing coherent user-centric transmission to overcome the inter-cell interference limitation in cellular networks and provide additional macro-diversity. These features, combined with the system scalability inherent in the Massive MIMO design, distinguish ubiquitous cell-free Massive MIMO from prior coordinated distributed wireless systems. In this article, we investigate the enormous potential of this promising technology while addressing practical deployment issues to deal with the increased back/front-hauling overhead deriving from the signal co-processing.
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| 5. |
- Larsson, Erik G, et al.
(författare)
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Reciprocity Calibration of Dual-Antenna Repeaters
- 2024
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Ingår i: IEEE Wireless Communications Letters. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2162-2337 .- 2162-2345. ; 13:6, s. 1606-1610
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Tidskriftsartikel (refereegranskat)abstract
- We present a reciprocity calibration method for dual-antenna repeaters in wireless networks. The method uses bi-directional measurements between two network nodes, A and B, where for each bi-directional measurement, the repeaters are configured in different states. The nodes A and B could be two access points in a distributed MIMO system, or they could be a base station and a mobile user terminal, for example. From the calibration measurements, the differences between the repeaters' forward and reverse gains are estimated. The repeaters are then (re-)configured to compensate for these differences such that the repeaters appear, transparently to the network, as reciprocal components of the propagation environment, enabling reciprocity-based beamforming in the network.
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| 6. |
- Tano, Richard, et al.
(författare)
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KPI impact on 5G NR deep sleep state adaption
- 2019
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Ingår i: 2019 Ieee 90Th Vehicular Technology Conference (Vtc2019-Fall). - : IEEE. - 9781728112206
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Konferensbidrag (refereegranskat)abstract
- In this paper we evaluate the performance impact of introducing the new deep sleep state features that may be deployed in 5G NR base stations. We evaluate the effects on traffic performance and energy efficiency by applying an updated power consumption model. Previously proposed power models may be too optimistic and thus the impact of a new more conservative power model has been investigated. A sensitivity analysis is also performed to understand the effects on the KPIs with various parameter settings of the power model. In the evaluations we show that the energy savings that is achievable by using a more conservative power model is still very high and that the impact on user performance can be small if the sleep states are applied in a thoughtful manner. Up to 80% energy savings is possible to achieve in a 5G hetnet scenario. The performance impact can be limited to a few percent extra delay on file transmissions. It is also found that even quite large modifications to the power model give similar results.
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| 7. |
- Wang Helmersson, Ke, 1960-, et al.
(författare)
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Uplink D-MIMO Processing and Combining Using Kalman Filter
- 2022
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Ingår i: Globecom 2022. - : IEEE. - 9781665435406 - 9781665435413 ; , s. 1703-1708
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Konferensbidrag (refereegranskat)abstract
- We propose a decentralized subset method for optimal processing and combining of uplink signals in a distributed MIMO (D-MIMO) network. We further propose the use of Kalman filters with the square-root implementation to estimate the received uplink signals. This square-root implementation is shown to be numerically stable when inverting the covariance matrix, as it always assures the covariance matrix to be symmetric and positive semi-definite. In the paper we also analyze the computational complexity and cost with different combining methods. We show that the Kalman filter implementation provides the same result as the MMSE method in terms of the spectral efficiencies and equivalent SINR. However, the Kalman filter implementation is shown to be very efficient as it provides the possibility to fully utilize parallel computing of distributed hardware processors. Moreover, the processing can be decentralized and the estimates can be aggregated from local estimates to as many access points (APs) as needed to reach the desired performance target. A Kalman filter implementation has the flexibility to aggregate signals in different ways, allowing the fronthaul architecture to support connectivity of individual APs in any combination of parallel or serial manners.
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