| 51. |
- Luan, Fengyu, et al.
(författare)
-
Geometrical Cluster-Based Scatterer Detection Method with the Movement of Mobile Terminal
- 2015
-
Ingår i: IEEE 81st Vehicular Technology Conference (VTC Spring), 2015.
-
Konferensbidrag (refereegranskat)abstract
- When a mobile station moves along a trajectory, it will see different parts of the same scatterers or scatterer groups during its movement. In this paper, we present a new method to identify such physical clusters of scatterers, and the corresponding groups of multipath components (MPCs) interacting with those clusters, from measurements of channel impulse responses. The method is based on identifying MPCs that have similar long-term properties - in the sense that they ``effectively interact with'' the same physical clusters, The method consists of four steps: (1) estimate the delays, the DOAs and the amplitudes of the MPCs in each time snapshot; (2) track the MPCs in the time-delay domain; (3) localize all the scattering points in a 2-D Cartesian coordinate system and cluster them on a map with a traditional Kmeans clustering algorithm; (4) merge the scattering points of different MPCs into physical clusters. The method is evaluated using both synthetic data and real measurement data from a suburban area. In the latter case, the locations and the sizes of the interacting objects identified from the measurements show excellent agreement with the location of physical objects in the environment such as pillars and buildings.
|
|
| 52. |
- Mahler, Kim, et al.
(författare)
-
Measurement-Based Wideband Analysis of Dynamic Multipath Propagation in Vehicular Communication Scenarios
- 2017
-
Ingår i: IEEE Transactions on Vehicular Technology. - 1939-9359. ; 66:6, s. 4657-4667
-
Tidskriftsartikel (refereegranskat)abstract
- Realistic propagation modeling requires a detailed understanding and characterization of the radio channel properties. This paper is based on channel sounder measurements with 1 GHz bandwidth at a carrier frequency of 5.7 GHz and particular tracking methods. We present statistical models for the number of, birth rate, lifetime, excess delay and relative Doppler frequency of individual multipath components (MPCs). Our findings are concluded from 72 measurement runs in eight relevant vehicular communication scenarios and reveal wide insights into the dynamic propagation process in vehicular communication scenarios.
|
|
| 53. |
- Mahler, Kim, et al.
(författare)
-
Propagation channel in a rural overtaking scenario with large obstructing vehicles
- 2016
-
Ingår i: IEEE Vehicular Technology Conference. - 9781509016983
-
Konferensbidrag (refereegranskat)abstract
- Reliable connectivity between vehicles is a requirement for efficient overtaking warning systems. We investigate the 6 GHz propagation channel between oncoming vehicles with five different types of large obstructing vehicles in a poor scattering environment. The presented channel gains emphasize the advantages of different antenna positions and the difference between a straight road and curved road. We conclude that connectivity ranges on a straight road are close to the minimum distance required by a warning system. We furthermore conclude that the channel gain of antennas mounted inside the vehicle can be higher compared to antennas mounted on the roof, which can increase the connectivity range significantly.
|
|
| 54. |
- Mahler, Kim, et al.
(författare)
-
Propagation of multipath components at an urban intersection
- 2016
-
Ingår i: 2015 IEEE 82nd Vehicular Technology Conference, VTC Fall 2015 - Proceedings. - 9781479980918
-
Konferensbidrag (refereegranskat)abstract
- Urban intersections constitute an important safety-critical scenario for vehicle-to-vehicle communication. Based on measurements, this paper presents detailed investigations of the radio wave propagation processes in a typical urban intersection. We focus on one time instance of the propagation process and set up hypothesis for locations of the scattering objects. Multipath components (MPCs) are identified and an MPC tracking algorithm is applied. The number of MPCs and the lifetime of MPCs for this communication scenario are analyzed. It is concluded that the lifetime of an MPC is heavily dependent on its relative power, with typical values in the range 0.05-0.3 s corresponding to 0.5-3 m travel distance of the vehicles.
|
|
| 55. |
- Mahler, Kim, et al.
(författare)
-
Tracking of Wideband Multipath Components in a Vehicular Communication Scenario
- 2017
-
Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545. ; 66:1, s. 15-25
-
Tidskriftsartikel (refereegranskat)abstract
- A detailed understanding of the dynamic processes of vehicular radio channels is crucial for its realistic modeling. In this paper, we present multipath components (MPCs) tracking results from a channel sounder measurement with 1-GHz bandwidth at a carrier frequency of 5.7 GHz. We describe in detail the applied algorithms and perform a tracking performance evaluation based on artificial channels and on measurement data from a tunnel scenario. The tracking performance of the proposed algorithm is comparable to the tracking performance of the state-of-the-art Gaussian mixture probability hypothesis density filter but with a significantly lower complexity. The fluctuation of the measured channel gain is followed very well by the proposed tracking algorithm, with a power loss of only 2.5 dB. We present statistical distributions for the number of MPCs and the birth/death rate. The applied algorithms and tracking results can be used to enhance the development of geometry-based channel models.
|
|
| 56. |
- Malkowsky, Steffen, et al.
(författare)
-
Implementation of Low-latency Signal Processing and Data Shuffling for TDD massive MIMO Systems
- 2017
-
Ingår i: ; , s. 260-265
-
Konferensbidrag (refereegranskat)abstract
- Low latency signal processing and high throughput implementations are required in order to realize real-time TDD massive MIMO communications, especially in high mobility scenarios. One of the main challenges is that the up-link and down-link turnaround time has to be within the coherence time of the wireless channel to enable efficient use of reciprocity. This paper presents a hardware architecture and implementation of this critical signal processing path, including channel estimation, QRD-based MMSE decoder/precoder and distributed reciprocity calibration. Furthermore, we detail a switch-based router implementation to tackle the stringent throughput and latency requirements on the data shuffling network. The proposed architecture was verified on the LuMaMi testbed, based on the NI SDR platform. The implementation supports real-time TDD transmission in a 128x12 massive MIMO setup using 20 MHz channel bandwidth. The processing latency in the critical path is less than 0.15 ms, enabling reciprocity-based TDD massive MIMO for high-mobility scenarios.
|
|
| 57. |
- Malkowsky, Steffen, et al.
(författare)
-
The World's First Real-Time Testbed for Massive MIMO: Design, Implementation, and Validation
- 2017
-
Ingår i: IEEE Access. - 2169-3536. ; , s. 9073-9088
-
Tidskriftsartikel (refereegranskat)abstract
- This paper sets up a framework for designing a massive multiple-input multiple-output (MIMO) testbed by investigating hardware and system-level requirements such as processing complexity, duplexing mode and frame structure. Taking these into account, a generic system and processing partitioning is proposed which allows flexible scaling and processing distribution onto a multitude of physically separated devices. Based on the given hardware constraints such as maximum number of links and maximum throughput for peer-to-peer interconnections combined with processing capabilities, the framework allows to evaluate available off-the-shelf hardware components. To verify our design approach, we present the Lund University Massive MIMO (LuMaMi) testbed which constitutes the first reconfigurable real-time hardware platform for prototyping massive MIMO. Utilizing up to 100 base station antennas and more than 50 field-programmable gate arrays (FPGAs), up to 12 user equipments are served on the same time/frequency resource using an LTE-like OFDM TDD-based transmission scheme. Field trials with this system show that massive MIMO can spatially separate a multitude of users in a static indoor and static/dynamic outdoor environment.
|
|
| 58. |
- Mannesson, Anders, et al.
(författare)
-
Tightly Coupled Positioning and Multipath Radio Channel Tracking
- 2016
-
Ingår i: IEEE Transactions on Aerospace and Electronic Systems. - 0018-9251. ; , s. 1522-1535
-
Tidskriftsartikel (refereegranskat)abstract
- Radio based localization is an active research topic with a wide range of applications. In this paper, we focus on localization of a radio receiver equipped with an inertial measurement unit. The localization is performed while simultaneously constructing a map of the small scale fading pattern in the local radio environment. The map in our case is a ray-trace-based multipath channel model. This solution is enabled by sensor fusion of information from the channel estimation data and the inertial sensors, and it does not assume any knowledge of, e.g., transmitter locations. The sensor data is fused in a recursive state space model that combines the kinematic motion model with the ray-based radio channel model, and the state vector is estimated using a particle filter. The choice of the particle filter is justified by the multimodal characteristics of the posterior likelihood distributions that follows from the nonlinearities of the problem. The work is assuming a single receiver antenna but the approach can also be transferred to multiple antenna systems. We study the performance of the approach under realistic assumptions, based on the performance of today’s low-cost inertial sensors and radio systems, including accelerometer and gyroscope noise, and also radio receiver frequency error and noise. Simulations show a significant improvement in long-term positioning performance, evaluated against dead reckoning. The work is concluded with experiments which serve as a proof of concept for the proposed technique, using no extra equipment compared to what can be found in a modern cellular phone.
|
|
| 59. |
- Marinho, Marco A. M., 1986-, et al.
(författare)
-
Performance Assessment for Distributed Broadband Radio Localization
- 2018
-
Ingår i: 2018 52nd Asilomar Conference on Signals, Systems, and Computers. - Washington, DC : IEEE. - 9781538692189 - 9781538692165 - 9781538692172 - 9781538692196 ; , s. 20-23
-
Konferensbidrag (refereegranskat)abstract
- Various emerging technologies, such as autonomous vehicles and fully autonomous flying, require precision positioning. This work presents a localization and tracking method based on joint direction of arrival (DOA), time delay, and range estimation using the SAGE algorithm. The proposed method does not rely on external sources of information such as global navigation satellite systems (GNSS). The method is opportunistic and does not require any location-based data exchange. A set of numerical simulations is presented to assess the performance of the proposed method.
|
|
| 60. |
- Neij, Lena, et al.
(författare)
-
Lunds kommuns klimatpolitiska råd: Rapport 2019
- 2019
-
Rapport (populärvet., debatt m.m.)abstract
- Lunds kommuns klimatpolitiska råd bildades hösten 2018 med uppdrag attutvärdera hur Lunds kommuns samlade politik är förenlig med de klimatmålsom antagits av kommunfullmäktige. Rådet som är det första lokala klimatpolitiska rådet i Sverige är en unik satsning för främjandet av ett aktivt och framåtsyftande lokalt klimatarbete.Sveriges kommuner har en viktig roll att fylla i klimatarbetet – för såväl minskad klimatpåverkan som anpassning till ett förändrat klimat. Lunds kommun har genom åren visat på handlingskraft inom miljö- och klimatområdet och har antagit ambitiösa klimatmål. I bildandet av ett klimatpolitiskt råd befäster kommunen sin ambition om att bedriva ett kunskapsbaserat klimatarbete. Kommunens vision ”Lund skapar framtiden – med kunskap, innovation och öppenhet” inspirerar även till handling och engagemang i det lokala klimatarbetet. Samarbetet mellan Lunds kommun och akademin har sedan länge stimulerat utvecklingen i Lund och utgör en viktig källa till nytänkande och problemlösning. Rådet ser fram emot uppgiften att utvärdera kommunens klimatarbete men uttrycker samtidigt en ödmjukhet inför komplexiteten i detta arbete. Rådets ambition är att bidra konstruktivt och lösningsorienterat till utvecklingen av det lokala klimatarbetet.Lunds kommuns klimatpolitiska råd kommer årligen att presentera en rapport i vilken rådet granskar Lunds kommuns samlade klimatpolitik. Detta är rådets första rapport och granskningen utgår från de mål som presenteras i LundaEko II under rubrikerna ”Minsta möjliga klimatpåverkan” och ”Klimatanpassning”. I rapporten utvärderar rådet i vilken utsträckning kommunens arbete är tillräckligt för att nå etappmålen för 2020 samt identifierar utmaningar och rekommendationer för arbetet med att nå de övergripande målen för 2030 och 2050. Rådet påbörjade sitt uppdrag först hösten 2018 och har behövt ägna tid åt att lära känna kommunens lokala klimatarbete. Granskningen i rådets första rapport är därför av övergripande karaktär.Ett framgångsrikt klimatarbete förutsätter en bred kunskapsbas. Lunds kommuns klimatpolitiska råd består av forskare med bred tvär- och mångvetenskaplig kompetens från Lunds universitet (LU) och SLU Alnarp. Ett lyckat klimatarbete kräver även ett bredare engagemang, vilket rådet avser bidra till genom god kommunikation och inkluderande dialog.
|
|
