| 1. |
- Björnson, Emil, Professor, 1983-, et al.
(författare)
-
MASSIVE MIMO IN SUB-6 GHZ AND MMWAVE : PHYSICAL, PRACTICAL, AND USE-CASE DIFFERENCES
- 2019
-
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
-
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
-
Ingår i: 2023 IEEE Conference on Antenna Measurements and Applications (CAMA). - 9798350323047 ; , s. 347-352
-
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
-
Ingår i: 23rd International Workshop on Signal Processing Advances in Wireless Communication (SPAWC). - 9781665494557 - 9781665494564
-
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)
-
Experimental Exploration of Unlicensed Sub-GHz Massive MIMO for Massive Internet-of-Things
- 2021
-
Ingår i: IEEE Open Journal of the Communications Society. - 2644-125X. ; 2, s. 2195-2204
-
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
-
Ingår i: Conference Record of the 54th Asilomar Conference on Signals, Systems and Computers, ACSSC 2020. - 1058-6393. - 9780738131269 ; 2020-November, s. 1101-1105
-
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
-
Ingår i: Towards Sustainable and Trustworthy 6G: Challenges, Enablers, and Architectural Design. - 9781638282396 ; , s. 121-158
-
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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| 11. |
- Diaz, Isael, et al.
(författare)
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Next Generation Digital Front-End for Multi-Standard Concurrent Reception
- 2013
-
Ingår i: [Host publication title missing].
-
Konferensbidrag (refereegranskat)abstract
- This article presents an architecture of a Digital Front-End Receiver (DFE-Rx) for the next-generation mobile terminals. A main focus is placed in flexibility, scalability and concurrency. The architecture is capable of detecting, synchronizing and reporting carrier-frequency offset, of multiple concurrent radio standards. The proposed receiver is fabricated in a 65nm CMOS low power high-VT cell technology in a die size of 5mm2. The synchronization engine has been measured at 1.2V and reports an average power consumption of 1.9mW during IEEE 802.11 reception and 1.6mW during configuration, while running at 10MHz.
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| 12. |
- Diaz, Isael, et al.
(författare)
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Selective Channelization on an SDR Platform for LTE-A Carrier Aggregation.
- 2012
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Ingår i: 19th IEEE International Conference on Electronics, Circuits and Systems (ICECS), 2012. - 9781467312615 ; , s. 316-319
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Konferensbidrag (refereegranskat)abstract
- The total transmission bandwidth and component carrier aggregation proposed by LTE-Advanced, sets a new challenge to the design of terminals. This article presents a way to assure terminals cope with the large bandwidth in an efficient manner. Various filtering methods are explored showing that an SDR architecture, such as ADRES (Architecture for Dynamically Reconfigurable Embedded Systems), is suitable for dynamic adaptation of filtering methods as function of the aggregation scheme and the individual bandwidth assigned to each terminal. This method is able to reduce the processing load by 70% for LTE-A with legacy support and possibly higher reduction when LTE legacy is not supported. Simulations conclude that the performance loss derived from the proposed method is marginal with no negative repercussion on the posterior baseband stages.
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| 13. |
- Fitzgerald, Emma, et al.
(författare)
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A Light Signaling Approach to Node Grouping for Massive MIMO IoT Networks
- 2022
-
Ingår i: Computers. - : MDPI AG. - 2073-431X. ; 11:6
-
Tidskriftsartikel (refereegranskat)abstract
- Massive MIMO is one of the leading technologies for connecting very large numbers of energy-constrained nodes, as it offers both extensive spatial multiplexing and large array gain. A challenge resides in partitioning the many nodes into groups that can communicate simultaneously such that the mutual interference is minimized. Here we propose node partitioning strategies that do not require full channel state information, but rather are based on nodes’ respective directional channel properties. In our considered scenarios, these typically have a time constant that is far larger than the coherence time of the channel. We developed both an optimal and an approximation algorithm to partition users based on directional channel properties, and evaluated them numerically. Our results show that both algorithms, despite using only these directional channel properties, achieve similar performance in terms of the minimum signal-to-interference-plus-noise ratio for any user, compared with a reference method using full channel knowledge. In particular, we demonstrate that grouping nodes with related directional properties is to be avoided. We hence realize a simple partitioning method, requiring minimal information to be collected from the nodes, and in which this information typically remains stable over the long term, thus promoting the system’s autonomy and energy efficiency.
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| 14. |
- Gunnarsson, Sara, et al.
(författare)
-
Channel Hardening in Massive MIMO-A Measurement Based Analysis
- 2018
-
Ingår i: 2018 IEEE 19th International Workshop on Signal Processing Advances in Wireless Communications, SPAWC 2018. - 9781538635124 ; 2018-June
-
Konferensbidrag (refereegranskat)abstract
- Wireless-controlled robots, cars and other critical applications are in need of technologies that offer high reliability and low latency. Massive MIMO, Multiple-Input Multiple-Output, is a key technology for the upcoming 5G systems and is one part of the solution to increase the reliability of wireless systems. More specifically, when increasing the number of base station antennas in a massive MIMO systems the channel variations decrease and the so-called channel hardening effect appears. This means that the variations of the channel gain in time and frequency decrease. In this paper, channel hardening in massive MIMO systems is assessed based on analysis of measurement data. For an indoor scenario, the channels are measured with a 128-port cylindrical array for nine single-antenna users. The analysis shows that in a real scenario a channel hardening of 3.2-4.6 dB, measured as a reduction of the standard deviation of the channel gain, can be expected depending on the amount of user interaction. Also, some practical implications and insights are presented.
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| 15. |
- Gunnarsson, Sara, et al.
(författare)
-
Channel hardening in massive mimo : Model parameters and experimental assessment
- 2020
-
Ingår i: IEEE Open Journal of the Communications Society. - 2644-125X. ; 1, s. 501-512
-
Tidskriftsartikel (refereegranskat)abstract
- Reliability is becoming increasingly important for many applications envisioned for future wireless systems. A technology that could improve reliability in these systems is massive MIMO (Multiple- Input Multiple-Output). One reason for this is a phenomenon called channel hardening, which means that as the number of antennas in the system increases, the variations of channel gain decrease in both the time- and frequency domain. Our analysis of channel hardening is based on a joint comparison of theory, measurements and simulations. Data from measurement campaigns including both indoor and outdoor scenarios, as well as cylindrical and planar base station arrays, are analyzed. The simulation analysis includes a comparison with the COST 2100 channel model with its massive MIMO extension. The conclusion is that the COST 2100 model is well suited to represent real scenarios, and provides a reasonable match to actual measurements up to the uncertainty of antenna patterns and user interaction. Also, the channel hardening effect in practical massive MIMO channels is less pronounced than in complex independent and identically distributed (i.i.d.) Gaussian channels, which are often considered in theoretical work.
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| 16. |
- Gunnarsson, Sara, et al.
(författare)
-
Lousy processing increases energy efficiency in massive MIMO systems
- 2017
-
Ingår i: 2017 European Conference on Networks and Communications (EuCNC). - 9781538638736
-
Konferensbidrag (refereegranskat)abstract
- Massive MIMO (MaMIMO) is a key technology for 5G wireless communication, enabling large increase in both spectral and energy efficiency at the same time. Before it can be deployed, it is important to find efficient implementation strategies. Because of the many antennas, an essential part of decreasing complexity, and further improving energy efficiency, is optimization of the digital signal processing (DSP) in the per-antenna functions. Assuming an orthogonal frequency-division multiplexing (OFDM) based MaMIMO system, this paper explores coarse quantization in the per-antenna digital transmit filters and inverse fast Fourier transforms (IFFTs) and evaluates it in terms of performance and complexity savings. Results show that DSP complexity can be greatly reduced per-antenna, and therefore significant power savings can be achieved, with limited performance degradation. More specifically, when going towards MaMIMO and therefore increasing the number of antennas from 8 to 64, it is possible to reduce the complexity in each transmit filter by 55%. Also, when using 6 bits to represent the input signal and 6 bits for the filter coefficients, this results in an SNR degradation of less than 0.5 dB compared to floating-point performance. Consequently, we conclude that the overall system energy greatly benefits from lousy per-antenna processing.
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| 17. |
- Larsson, Erik G., 1974-, et al.
(författare)
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Out-of-Band Radiation From Antenna Arrays Clarified
- 2018
-
Ingår i: IEEE Wireless Communications Letters. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2162-2337 .- 2162-2345. ; 7:4, s. 610-613
-
Tidskriftsartikel (refereegranskat)abstract
- Non-linearities in radio-frequency transceiver hardware, particularly in power amplifiers, cause distortion in-band and out-of-band. Contrary to claims made in recent literature, in a multiple-antenna system this distortion is correlated across the antennas in the array. A significant implication of this fact is that out-of-band emissions caused by non-linearities are beamformed, in some cases into the same direction as the useful signal.
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| 18. |
- Marinsek, Alexander, et al.
(författare)
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Channel Performance Metrics and Evaluation for XR Head-Mounted Displays with mmWave Arrays
- 2024
-
Ingår i: IEEE Transactions on Communications. - 0090-6778. ; , s. 1-1
-
Tidskriftsartikel (refereegranskat)abstract
- Millimeter-wave (mmWave) technology holds the potential to revolutionize head-mounted displays (HMDs) by enabling high-speed wireless communication with nearby processing nodes, where complex video rendering can take place. However, the sparse angular profile of mmWave channels, coupled with the narrow field of view (FoV) of patch-antenna arrays and frequent HMD rotation, can lead to poor performance. We introduce six channel performance metrics to evaluate the performance of an HMD equipped with mmWave arrays. We analyze the metrics using analytical models, discuss their impact for the application, and apply them to 28 GHz channel sounding data, collected in a conference room using eight HMD patch-antenna arrays, offset by 45° from each other in azimuth. Our findings confirm that a single array performs poorly due to the narrow FoV, and featuring multiple arrays along the HMD’s azimuth is required. Namely, the broader FoV stabilizes channel gain during HMD rotation, lessens the attenuation caused by line of sight (LoS) obstruction, and increases the channel’s spatial multiplexing capability. In light of our findings, we conclude that it is imperative to either equip the HMD with multiple arrays or, as an alternative approach, incorporate macroscopic diversity by leveraging distributed access point (AP) infrastructure.
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| 19. |
- Marinsek, Alexander, et al.
(författare)
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Impact of Array Configuration on Head-Mounted Display Performance at mm Wave Bands
- 2023
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Ingår i: 2023 Joint European Conference on Networks and Communications and 6G Summit, EuCNC/6G Summit 2023. - 9798350311020 ; , s. 192-197
-
Konferensbidrag (refereegranskat)abstract
- Immersing a user in life-like extended reality (XR) scenery using a head-mounted display (HMD) with a constrained form factor and hardware complexity requires remote rendering on a nearby edge server or computer. Millimeter-wave (mmWave) communication technology can provide sufficient data rate for wireless XR content transmission. However, mmWave channels exhibit severe sparsity in the angular domain. This means that distributed antenna arrays are required to cover a larger angular area and to combat outage during HMD rotation. At the same time, one would prefer fewer antenna elements/arrays for a lower complexity system. Therefore, it is important to evaluate the trade-off between the number of antenna arrays and the achievable performance to find a proper practical solution. This work presents indoor 28 GHz mmWave channel measurement data, collected during HMD mobility, and studies the dominant eigenmode (DE) gain. DE gain is a significant factor in under-standing system performance since mm Wave channel sparsity and eigenmode imbalance often results in provisioning the majority of the available power to the DE. Moreover, it provides the upper performance bounds for widely-adopted analog beamformers. We propose 3 performance metrics - gain trade-off, gain volatility, and minimum service trade-off - for evaluating the performance of a multi-array HMD and apply the metrics to indoor 28 GHz channel measurement data. Evaluation results indicate, that 3 arrays provide stable temporal channel gain. Adding a 4th array further increases channel capacity, while any additional arrays do not significantly increase physical layer performance.
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| 20. |
- Muneer, Sidra, et al.
(författare)
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System Design and Performance for Antenna Reservation in Massive MIMO
- 2022
-
Ingår i: 2022 IEEE 96th Vehicular Technology Conference, VTC 2022-Fall 2022 - Proceedings. - 1550-2252. - 9781665454681 ; 2022-September
-
Konferensbidrag (refereegranskat)abstract
- Peak to average power (PAPR) reduction of OFDM signals is critical in order to improve power amplifier (PA) efficiency in base stations. For massive MIMO, the complexity of these methods can become a real bottleneck in implementing low power digital signal processing chains. In this work, we consider an antenna reservation technique, which uses a low complexity clipping method to reduce signal peaks and leverages the benefit of massive antennas, by reserving a subset of antennas in order to compensate for the clipping distortion. Reserving antennas on the other hand reduces the potential array gain in the massive MIMO system, complicating the application of antenna reservation. This work explores various design space parameters in antenna reservation such as number of reserved antennas, amount of peak reduction and clipping methods. We investigate the impact of these parameters on the error vector magnitude at the user and on the adjacent channel power ratio at both transmitter and user positions. Our results enable a deeper understanding of antenna reservation as a low complexity PAPR reduction method in massive MIMO systems.
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| 21. |
- Tärneberg, William, et al.
(författare)
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Towards Practical Cell-Free 6G Network Deployments: An Open-Source End-to-End Ray Tracing Simulator
- 2023
-
Ingår i: 2023 57th Asilomar Conference on Signals, Systems, and Computers.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The advent of 6G wireless communication marks a transformative era in technological connectivity, bringing forth challenges and opportunities alike. This paper unveils an innovative, open-source simulator, meticulously crafted for cell-free 6G wireless networks. This simulator is not just a tool but a gateway to the future, blending cutting-edge channel models with the simulation of both physical propagation effects and intricate system-level protocols. It stands at the forefront of technological advancement by integrating LIS and MIMO technologies, harnessing the power of the Unity game engine for efficient ray-tracing and GPU-accelerated computations. The unparalleled flexibility in scenario configuration, coupled with its unique ability to dynamically simulate interactions across network layers, establishes this simulator as an indispensable asset in pioneering &G systems' research and development.
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| 22. |
- Van Der Perre, Liesbet, et al.
(författare)
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Efficient DSP and Circuit Architectures for Massive MIMO : State of the Art and Future Directions
- 2018
-
Ingår i: IEEE Transactions on Signal Processing. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1053-587X .- 1941-0476. ; 66:18, s. 4717-4736
-
Tidskriftsartikel (refereegranskat)abstract
- Massive MIMO is a compelling wireless access concept that relies on the use of an excess number of base-station antennas, relative to the number of active terminals. This technology is a main component of 5G New Radio and addresses all important requirements of future wireless standards: a great capacity increase, the support of many simultaneous users, and improvement in energy efficiency. Massive MIMO requires the simultaneous processing of signals from many antenna chains, and computational operations on large matrices. The complexity of the digital processing has been viewed as a fundamental obstacle to the feasibility of Massive MIMO in the past. Recent advances on system-algorithm-hardware co-design have led to extremely energy-efficient implementations. These exploit opportunities in deeply-scaled silicon technologies and perform partly distributed processing to cope with the bottlenecks encountered in the interconnection of many signals. For example, prototype ASIC implementations have demonstrated zero-forcing precoding in real time at a 55 mW power consumption (20 MHz bandwidth, 128 antennas, and multiplexing of 8 terminals). Coarse and even error-prone digital processing in the antenna paths permits a reduction of consumption with a factor of 2 to 5. This article summarizes the fundamental technical contributions to efficient digital signal processing for Massive MIMO. The opportunities and constraints on operating on low-complexity RF and analog hardware chains are clarified. It illustrates how terminals can benefit from improved energy efficiency. The status of technology and real-life prototypes discussed. Open challenges and directions for future research are suggested.
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| 23. |
- Van Der Perre, Liesbet, et al.
(författare)
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RadioWeaves for efficient connectivity : analysis and impact of constraints in actual deployments
- 2019
-
Ingår i: Conference record of the Fifty-Third Asilomar Conference on Signals, Systems & Computers. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781728143002 - 9781728143019 ; , s. 15-22
-
Konferensbidrag (refereegranskat)abstract
- We present a new type of wireless access infrastructure consisting of a fabric of dispersed electronic circuits and antennas that collectively function as a massive, distributed antenna array. We have chosen to name this new wireless infrastructure "RadioWeaves" and anticipate they can be integrated into indoor and outdoor walls, furniture, and other objects, rendering them a natural part of the environment. Technologically, RadioWeaves will deploy distributed arrays to create both favorable propagation and antenna array interaction. The technology leverages on the ideas of large-scale intelligent surfaces and cell-free wireless access. Offering close to the service connectivity and computing, new grades in energy efficiency, reliability, and low latency can be reached. The new concept moreover can be scaled up easily to offer a very high capacity in specific areas demanding so. In this paper we anticipate how two different demanding use cases can be served well by a dedicated RadioWeaves deployment: a crowd scenario and a highly reflective factory environment. A practical approach towards a RadioWeaves prototype, integrating dispersed electronics invisibly in a room environment, is introduced. We outline the many and diverse R&D challenges that need to be addressed to realize the great potential of the RadioWeaves technology.
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| 24. |
- Willhammar, Sara, et al.
(författare)
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Fading in Reflective and Heavily Shadowed Industrial Environments With Large Antenna Arrays
-
Ingår i: IEEE Open Journal of Antennas and Propagation. - 2637-6431.
-
Tidskriftsartikel (refereegranskat)abstract
- One of the required communication solutions to support novel use cases, e.g. in industrial environments, for 5G systems and beyond is ultra-reliability low-latency communication (URLLC). An enabling technology for URLLC is massive multiple-input multiple-output (MIMO), which with its large antenna arrays can increase reliability due to improved user separation, array gain and the channel hardening effect. Measurements have been performed in an operating factory environment at 3.7 GHz with a co-located massive MIMO array and a unique randomly distributed array. Channel hardening can appear when the number of antennas is increased such that the variations of channel gain (small-scale fading) is decreased and it is here quantified. The cumulative distribution function (CDF) of the channel gains then becomes steeper and its tail is reduced. This CDF is modeled and the required fading margins are quantified. By deploying a distributed array, the large-scale power variations can also be reduced, further improving reliability. The large array in this rich scattering environment, creates a more reliable channel as it approaches an independent identically distributed (i.i.d.) complex Gaussian channel, indicating that one can rethink the system design in terms of e.g. channel coding and re-transmission strategies, in order to reduce latency. To conclude, massive MIMO is a highly interesting technology for reliable connectivity in reflective and heavily shadowed industrial environments.
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