| 1. |
- Almers, Peter, et al.
(författare)
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Effect of random walk phase noise on MIMO measurements
- 2005
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Ingår i: [Host publication title missing]. - 1550-2252. ; 61:1, s. 141-145
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Konferensbidrag (refereegranskat)abstract
- In this paper we study the influence of phase noise from free-running local oscillators on SAGE signal parameter estimation. Phase noise is here modeled as a random-walk process. We present phase noise estimates from our LUND RUSK MIMO channel sounder, and draw conclusions on requirements on local oscillators' phase noise in terms of the Allan variance. We investigate an error propagation effect in SAGE, and finally, we present random-walk phase noise effect on channel capacity.
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| 2. |
- Almers, Peter, et al.
(författare)
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Exercises
- 2005
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Ingår i: Wireless Communications. - 9780470848883 - 047084888X - 0470848871 ; , s. 561-593
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Czink, Nicolai, et al.
(författare)
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Tracking time-variant cluster parameters in MIMO channel measurements: algorithm and results
- 2007
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents a joint clustering-and-tracking framework to identify time-variant cluster parametersfor geometry-based stochastic MIMO channel models.The method uses a Kalman filter for tracking and predicting cluster positions, a novel consistentinitial guess procedure that accounts for predicted cluster centroids, and the well-known KPower-Means algorithm for cluster identification.We tested the framework by applying it to three entirely different sets of MIMO channel measurementdata obtained by different channel sounders: indoor measurements conducted at 2.55GHz, outdoor rural measurements at 300 MHz, and outdoor sub-urban measurements at 2.0 GHz.The time-variant cluster parameters of interest are: (i) cluster movement, (ii) change of clusterspreads, (iii) cluster lifetimes, and birth and death rates of cluster.We find that clusters show significant movement in parameter space depending on the environment.The spreads of individual clusters change rather randomly over their lifetime, with astandard deviation up to 150% of their mean spread. The cluster lifetime is approximately exponentiallydistributed, however additionally one has to account for long-living clusters coming fromthe line-of-sight path or from major reflectors.
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| 4. |
- Gustafson, Carl, et al.
(författare)
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Directional analysis of measured 60 GHz indoor radio channels using SAGE
- 2011
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Ingår i: [Host publication title missing]. - 1550-2252. - 9781424483327
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Konferensbidrag (refereegranskat)abstract
- Abstract in Undetermined Directional properties of the radio channel are of high importance for the development of reliable wireless systems operating in the 60 GHz frequency band. Using transfer functions measured from 61 to 65 GHz in a conference room we have extracted estimates of the multi-path component parameters using the SAGE algorithm. In the paper we compare results for line-of-sight (LOS) scenarios and the corresponding non-line-of-sight (NLOS) scenarios and present values of the direction spread at the Tx and the Rx.
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| 5. |
- Gustafson, Carl, et al.
(författare)
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On mm-Wave Multi-path Clustering and Channel Modeling
- 2014
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X. ; 62:3, s. 1445-1455
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Tidskriftsartikel (refereegranskat)abstract
- Efficient and realistic mm-wave channel models are of vital importance for the development of novel mm-wave wireless technologies. Though many of the current 60 GHz channel models are based on the useful concept of multi-path clusters, only a limited number of 60 GHz channel measurements have been reported in the literature for this purpose. Therefore, there is still a need for further measurement based analyses of multi-path clustering in the 60 GHz band. This paper presents clustering results for a double-directional 60 GHz MIMO channel model. Based on these results, we derive a model which is validated with measured data. Statistical cluster parameters are evaluated and compared with existing channel models. It is shown that the cluster angular characteristics are closely related to the room geometry and environment, making it infeasible to model the delay and angular domains independently. We also show that when using ray tracing to model the channel, it is insufficient to only consider walls, ceiling, floor and tables; finer structures such as ceiling lamps, chairs and bookshelves need to be taken into account as well.
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| 6. |
- Haneda, Katsuyuki, et al.
(författare)
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60 GHz Spatial Radio Transmission: Multiplexing or Beamforming?
- 2013
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X. ; 61:11, s. 5735-5743
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Tidskriftsartikel (refereegranskat)abstract
- This paper compares the capacity improvement capability of spatial multiplexing and beamforming techniques for 60 GHz spatial transmissions in a multi-carrier radio system such as orthogonal frequency division multiplexing. The term beamforming in this paper refers to the conventional gain focusing, for the strongest propagation path, by narrow antenna beams. Our channel capacity metric depends only on the multipath richness of the propagation channel and the antenna aperture size, but is otherwise independent of the realization of antenna elements on the aperture. Our analysis also reveals the spatial degrees-of-freedom (SDoF) of the radio channel, which is the maximum number of antenna elements on the aperture for efficient spatial multiplexing. We evaluate the capacity and SDoF of single-polarized 60 GHz radio channels measured in a conference room environment. Our results show that the radio channel offers multiple SDoFs both in line-of-sight (LOS) and non-LOS (NLOS) scenarios such that spatial multiplexing can improve the channel capacity, provided that the receive signal-to-noise ratio (SNR) is sufficiently high to utilize them. Under 10 dBm of the transmit power, the high receive SNR is guaranteed when the antenna aperture size is larger than 12 in LOS and 92 in NLOS scenarios, respectively.
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| 7. |
- Haneda, Katsuyuki, et al.
(författare)
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Feasibility study of a mm-wave impulse radio using measured radio channels
- 2011
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Ingår i: [Host publication title missing]. - 1550-2252. - 9781424483327
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Konferensbidrag (refereegranskat)abstract
- Abstract in UndeterminedA millimeter-wave (mm-wave) impulse radio is an attractive alternative to existing high-speed mm- wave radio systems because of the potential for a simpler transceiver architecture. This paper studies the feasibility of a mm-wave impulse radio system for home and office use by considering state-of-the- art transceivers and multiple-input multiple-output measured propagation channels as well as the IEEE 802.15.3c channel model. Our analysis reveals that reliable data transmission is infeasible even in line-of-sight (LOS) scenarios because of a low power level at the Rx if we do not use beamforming. However, introducing 7×7 beamforming at the Tx dramatically improves the coverage beyond 5 m distance in the LOS scenario and up to 5 m in a non- line-of-sight (NLOS) scenario, though the performance varies in the NLOS scenario, depending on the Tx and Rx locations. We propose an adaptive transmit signaling scheme that adjusts the pulse repetition frequency depending on the delay dispersion of the propagation channel in order to avoid intersymbol interference and keep the Rx structure simple. The proposed transmit signaling scheme leads to a pulse transmission rate of 250 Mpulses/s in all measured channels while the rate is lower when the 802.15.3c model is considered because of a more multipath-rich characteristics than our measured channels.
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| 8. |
- Haneda, Katsuyuki, et al.
(författare)
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Measurement of loop-back interference channels for outdoor-to-Indoor full-duplex radio relays
- 2010
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Ingår i: Proceedings of the Fourth European Conference on Antennas and Propagation. - 9788476534724 - 9781424464319
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Konferensbidrag (refereegranskat)abstract
- A full-duplex relay enhances the end-to-end spectral efficiency compared to a half-duplex relay, provided that the loop-back interference at relays is managed well. In order to study the feasibility of the full-duplex relay, it is crucial to measure and model the loop-back interference channels. This paper presents a measurement campaign of these channels for outdoor-to-indoor communications. A compact relay antenna was developed to serve as a signal repeater between outdoor base stations and indoor users, and was used for the loop-back interference channel measurement. Measurement results revealed that the mean interference level was -48 dB in the compact relay antenna, and it could be further reduced by placing the outdoor and indoor antennas in a different position referred to as a separate relay. Combined with an appropriate countermeasure to reduce the interference level, such as an interference canceller, the full-duplex operation of indoor compact relay terminal was found to be feasible.
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| 9. |
- Haneda, Katsuyuki, et al.
(författare)
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Spatial Degrees-of-Freedom of 60 GHz Multiple-Antenna Channels
- 2013
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Ingår i: [Host publication title missing]. - 1550-2252.
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Konferensbidrag (refereegranskat)abstract
- This paper studies the potential of spatial multiplexing for measured 60 GHz radio channels by estimating the number of eigenchannels. It is well-known that the number of available eigenchannels is dependent on a propagation channel condition as well as antenna array conguration. We evaluate a spatial degrees- of-freedom (SDoF) metric that depends on the propagation conditions and the antenna aperture size, but is otherwise independent of the realization of antenna elements on the aperture. The SDoF metric is a measure of the effective number of antenna elements for spatial multiplexing. We evaluate the SDoF for 60 GHz multiple-input multiple-output channels measured in a conference room environment under a line-of- sight (LOS) condition. Our analysis reveals that the SDoF is more than one for a transmit- receive antenna separation of more than 2 m, which indicates that spatial multiplexing can work in such LOS scenarios. Our results indicate that using only 10 antenna elements at each of the transmit and receive antenna aperture is sufficient for effective spatial multiplexing performance in the considered propagation scenario. Furthermore, by using just 5 antennas at each aperture, eigenchannels down to −15 dB relative magnitude can still be captured.
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| 10. |
- Khan, Waqas Nawaz, et al.
(författare)
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Performance Evaluation of Time-Reversal on Measured 60 GHz Wireless Channels
- 2013
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Ingår i: Wireless Personal Communications. - : Springer Science and Business Media LLC. - 1572-834X .- 0929-6212. ; 71:1, s. 707-717
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Tidskriftsartikel (refereegranskat)abstract
- Time-reversal (TR) signal processing has the potential to focus the transmitted signal at a desired receive (Rx) location in both space and time. At lower frequency bands, TR in conjunction with array antennas at transmit (Tx) or Rx has been shown to significantly improve its focusing performance relative to the case of single antennas at both link ends. This work for the first time investigates TR processing for multi-antenna systems in the 60 GHz band. We consider both multiple-input-single-output and single-input-multiple-output (SIMO) channels measured in the 60 GHz band in a conference room environment and investigate the effect of array size and its orientation on spatial and temporal compression properties of TR. It is observed that the root mean square (RMS) delay spread can be reduced significantly by the application of TR in the 60 GHz band and that the orientation of the Rx array significantly affects TR performance for SIMO systems.
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