| 1. |
- Björnson, Emil, Professor, 1983-, et al.
(författare)
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MASSIVE MIMO IN SUB-6 GHZ AND MMWAVE : PHYSICAL, PRACTICAL, AND USE-CASE DIFFERENCES
- 2019
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Ingår i: IEEE wireless communications. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1536-1284 .- 1558-0687. ; 26:2, s. 100-108
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Tidskriftsartikel (refereegranskat)abstract
- The use of base stations (BSs) and access points (APs) with a large number of antennas, called Massive MIMO (multiple-input multiple-output), is a key technology for increasing the capacity of 5G networks and beyond. While originally conceived for conventional sub-6 GHz frequencies, Massive MIMO (mMIMO) is also ideal for frequency bands in the range 30-300 GHz, known as millimeter wave (mmWave). Despite conceptual similarities, the way in which mMIMO can be exploited in these bands is radically different, due to their specific propagation behaviors and hardware characteristics. This article reviews these differences and their implications, while dispelling common misunderstandings. Building on this foundation, we suggest appropriate signal processing schemes and use cases to efficiently exploit mMIMO in both frequency bands.
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| 2. |
- Bourdoux, Andre, et al.
(författare)
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D1.2 MaMi Channel Characteristics: Measurement Results
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This deliverable presents channel measurement results for the scenariosOpen exhibition and Crowded auditiorium. The measurement procedureand equipment are described. Massive MIMO (MaMi) channel characteristicsand key parameters are extracted and used in an extended COST 2100channel model for MaMi. The initial validation performed shows that themodel is capable of reproducing the statistics in terms of temporal behaviorof the user separability, singular value spread, capacity and sum-rate anddirectional characteristics. The model can be used for system and link levelMaMi simulations.
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| 3. |
- Callebaut, Gilles, et al.
(författare)
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6G Radio Testbeds: Requirements, Trends, and Approaches
- 2024
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Ingår i: IEEE Microwave Magazine. - 1527-3342 .- 1557-9581. ; 25:4, s. 14-31
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Tidskriftsartikel (refereegranskat)abstract
- The proof of the pudding lies in eating, and that is why 6G testbeds are essential in the progress toward the next generation of wireless networks. Theoretical research toward 6G wireless networks proposes advanced technologies to serve new applications and drastically improve energy performance. Testbeds are indispensable to validate these new technologies under more realistic conditions. This article clarifies the requirements for 6G radio testbeds, reveals trends, and introduces approaches toward their development.
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| 4. |
- Callebaut, Gilles, et al.
(författare)
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An Open Dataset Storage Standard for 6G Testbeds
- 2023
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Ingår i: 2023 IEEE Conference on Antenna Measurements and Applications (CAMA). - 9798350323047 ; , s. 347-352
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Konferensbidrag (refereegranskat)abstract
- The emergence of sixth-generation (6G) networks has spurred the development of novel testbeds, including sub-THz networks, cell-free systems, and 6G simulators. To maximize the benefits of these systems, it is crucial to make the generated data publicly available and easily reusable by others. Although data sharing has become a common practice, a lack of standardization hinders data accessibility and interoperability. In this study, we propose the Dataset Storage Standard (DSS) to address these challenges by facilitating data exchange and enabling convenient processing script creation in a testbed-agnostic manner. DSS supports both experimental and simulated data, allowing researchers to employ the same processing scripts and tools across different datasets. Unlike existing standardization efforts such as SigMF and NI RF Data Recording API, DSS provides a broader scope by accommodating a common definition file for testbeds and is not limited to RF data storage. The dataset format utilizes a hierarchical structure, with a tensor representation for specific experiment scenarios. In summary, DSS offers a comprehensive and flexible framework for enhancing the FAIR principles (Findability, Accessibility, Interoperability, and Reusability) in 6G testbeds, promoting open and efficient data sharing in the research community.
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| 5. |
- Callebaut, Gilles, et al.
(författare)
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Dynamic Federations for 6G Cell-Free Networking: Concepts and Terminology
- 2022
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Ingår i: 23rd International Workshop on Signal Processing Advances in Wireless Communication (SPAWC). - 9781665494564 - 9781665494557
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Konferensbidrag (refereegranskat)abstract
- Cell-Free networking is one of the prime candidatesfor 6G networks. Despite being capable of providing the 6Gneeds, practical limitations and considerations are often neglectedin current research. In this work, we introduce the conceptof federations to dynamically scale and select the best set ofresources, e.g., antennas, computing and data resources, to servea given application. Next to communication, 6G systems are expected to provide also wireless powering, positioning and sensing,further increasing the complexity of such systems. Therefore,each federation is self-managing and is distributed over thearea in a cell-free manner. Next to the dynamic federations,new accompanying terminology is proposed to design cell-freesystems taking into account practical limitations such as timesynchronization and distributed processing. We conclude withan illustration with four federations, serving distinct applications,and introduce two new testbeds to study these architectures andconcepts.
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| 6. |
- Callebaut, Gilles, et al.
(författare)
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Experimental Exploration of Unlicensed Sub-GHz Massive MIMO for Massive Internet-of-Things
- 2021
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Ingår i: IEEE Open Journal of the Communications Society. - 2644-125X. ; 2, s. 2195-2204
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Tidskriftsartikel (refereegranskat)abstract
- IoT networks are getting overcrowded following the vast increase in number of Internet-of-Things (IoT) devices and connections. Networks can be extended with more gateways, increasing the number of supported devices. However, as investigated in this work, massive MIMO has the potential to increase the number of simultaneous connections and moreover lower the energy expenditure of these devices. We present a study of the channel characteristics of massive MIMO in the narrowband unlicensed sub-GHz band. The goal is to support IoT applications with strict requirements in terms of number of devices, power consumption, and reliability. The assessment is based on experimental measurements using both a uniform linear and a rectangular array. Our study demonstrates and validates the advantages of deploying massive MIMO gateways to serve IoT nodes. While the results are general, here we specifically focus on static nodes. The array gain and channel hardening effect yield opportunities to lower the transmit power of IoT nodes while also increasing reliability. The exploration confirms that exploiting large arrays brings great opportunities to connect a massive number of IoT devices by separating the nodes in the spatial domain. In addition, we give an outlook on how static IoT nodes could be scheduled based on partial channel state information.
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| 7. |
- Callebaut, Gilles, et al.
(författare)
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Grant-Free Random Access of IoT devices in Massive MIMO with Partial CSI
- 2023
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Ingår i: 2023 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE, WCNC. - : IEEE. - 9781665491228 - 9781665491235
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Konferensbidrag (refereegranskat)abstract
- The number of wireless devices is drastically increasing, resulting in many devices contending for radio resources. In this work, we present an algorithm to detect active devices for unsourced random access, i.e., the devices are uncoordinated. The devices use a unique, but non-orthogonal preamble, known to the network, prior to sending the payload data. They do not employ any carrier sensing technique and blindly transmit the preamble and data. To detect the active users, we exploit partial channel state information (CSI), which could have been obtained through a previous channel estimate. For static devices, e.g., Internet of Things nodes, it is shown that CSI is less time-variant than assumed in many theoretical works. The presented iterative algorithm uses a maximum likelihood approach to estimate both the activity and a potential phase offset of each known device. The convergence of the proposed algorithm is evaluated. The performance in terms of probability of miss detection and false alarm is assessed for different qualities of partial CSI and different signal-to-noise ratio.
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| 8. |
- Callebaut, Gilles, et al.
(författare)
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Massive MIMO goes Sub-GHz : Implementation and Experimental Exploration for LPWANs
- 2020
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Ingår i: Conference Record of the 54th Asilomar Conference on Signals, Systems and Computers, ACSSC 2020. - 1058-6393. - 9780738131269 ; 2020-November, s. 1101-1105
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Konferensbidrag (refereegranskat)abstract
- Low-Power Wide-Area Networks operating in the unlicensed bands are being deployed to connect a rapidly growing number of Internet-of-Things devices. While the unlicensed sub-GHz band offers favorable propagation for long-range connections, measurements show that the energy consumption of the nodes is still mostly dominated by the wireless transmission affecting their autonomy. We investigate the potential benefits of deploying massive MIMO technology to increase system reliability and at the same time support low-energy devices with good coverage at sub-GHz frequencies. The impact of different antenna configurations and propagation conditions is analyzed. Both actual average experienced array gain and channel hardening are examined. The assessment demonstrates the effect of channel hardening as well as the potential benefits of the experienced array gain. These measurements serve as a first assessment of the channel conditions of massive MIMO at sub-GHz frequencies and are, to the best of our knowledge, the first of its kind.
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| 9. |
- Cosmas, John, et al.
(författare)
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Towards joint communication and sensing (Chapter 4)
- 2023
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Ingår i: Towards Sustainable and Trustworthy 6G: Challenges, Enablers, and Architectural Design. - 9781638282396 ; , s. 121-158
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Localization of user equipment (UE) in mobile communication networks has been supported from the early stages of 3rd generation partnership project (3GPP). With 5th Generation (5G) and its target use cases, localization is increasingly gaining importance. Integrated sensing and localization in 6th Generation (6G) networks promise the introduction of more efficient networks and compelling applications to be developed.
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| 10. |
- Diaz, Isael, et al.
(författare)
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A New Digital Front-End for Flexible Reception in Software Defined Radio
- 2015
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Ingår i: Microprocessors and Microsystems. - : Elsevier BV. - 0141-9331. ; 39:8, s. 889-900
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Tidskriftsartikel (refereegranskat)abstract
- Future mobile terminals are expected to support an ever increasing number of Radio Access Technologies (RAT) concurrently. This imposes a challenge to terminal designers already today. Software Defined Radio (SDR) solutions are a compelling alternative to address this issue in the digital baseband, given its high flexibility and low Non-Recurring Engineering (NRE) cost. However, the challenge still remains in the Digital Front-End (DFE), where many operations are too complex or energy hungry to be implemented as software instructions. Thus, new architectures are needed to feed the SDR digital baseband while keeping complexity and energy consumption at bay. In this article the architecture of a Digital Front-End Receiver (DFE-Rx) for the next-generation mobile terminals is presented. The flexibility needed for multi-standard support is demonstrated by detecting, synchronizing and reporting carrier-frequency offset, of multiple concurrent radio standards. Moreover, the proposed architecture has been fabricated in a 65 nm CMOS low power high-VT cell technology in a die size of 5 mm2. The core module of the DFE-Rx, the synchronization engine, has been measured at 1.2 V and reports an average power consumption of 1.9 mW during Wireless Local Area Network (WLAN) reception and 1.6 mW during configuration, while running at 10 MHz.
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