| 171. |
- Khan, Muhammad Gufran, et al.
(författare)
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Non-coherent detection of impulse radio UWB signals based on fourth order statistics
- 2011
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Ingår i: Wireless Personal Communications. - : Springer Science and Business Media LLC. - 1572-834X .- 0929-6212.
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Tidskriftsartikel (refereegranskat)abstract
- Low-complex and low power non-coherent energy detector (ED) is interesting for low data rate impulse radio (IR) ultra wideband (UWB) systems but, compared to coherent receivers, it suffers from a loss in performance due to low signal-to-noise ratio (SNR) at the detector. In addition, the performance of an ED strongly depends on the integration interval (window size) of the integrator and the window position. A non-coherent kurtosis detector (KD) and a fourth-order detector (FD), which can discriminate between Gaussian noise signals and non-Gaussian IR-UWB signals by directly estimating the fourth-order moment of the received signal, are presented. The performance of the detectors is evaluated using real channels measured in a corridor, an office and a laboratory environment. The results show that bit-error-rate (BER) performance of the proposed KD receiver is better than the ED receiver only under certain conditions, while the FD receiver is slightly better than the ED in low SNR region and its performance improves as the SNR increases. In addition, the performance of the FD receiver is less sensitive to overestimation of the integration interval making it relatively robust to variations of the channel delay spread. Finally, a criteria for the selection of integration time of the proposed detector is suggested.
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| 172. |
- Khan, Muhammad Gufran, et al.
(författare)
-
Non-Coherent Fourth-Order Detector for Impulse Radio Ultra Wideband Systems : Empirical Evaluation Using Channel Measurements
- 2013
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Ingår i: Wireless personal communications. - : Springer. - 0929-6212 .- 1572-834X. ; 68:1, s. 27-46
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Tidskriftsartikel (refereegranskat)abstract
- Low-complex and low-power non-coherent energy detectors (EDs) are interesting for low data rate impulse radio (IR) ultra wideband (UWB) systems, but suffer from a loss in performance compared to coherent receivers. The performance of an ED also strongly depends on the integration interval (window size) of the integrator and the window position. This paper presents a non-coherent fourth-order detector (FD) which can discriminate between Gaussian noise signals and non-Gaussian IR-UWB signals by directly estimating the fourth-order moment of the received signal. The performance of the detectors is evaluated using realistic channels measured in a corridor, an office and a laboratory environment. The results show that bit-error-rate (BER) performance of the proposed FD receiver is slightly better than the ED in low signal-to-noise ratio (SNR) region and its performance improves as the SNR increases. In addition, BER of the FD receiver is less sensitive to overestimation of the integration interval making it relatively robust to variations of the channel delay spread. Finally, a criteria for the selection of integration time of the proposed detector is suggested.
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| 173. |
- 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
-
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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| 174. |
- Khosravi, Hedieh, et al.
(författare)
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Experimental Analysis of Physical Interacting Objects of a Building at mmWave Frequencies
- 2024
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Ingår i: 18th European Conference on Antennas and Propagation, EuCAP 2024.
-
Konferensbidrag (refereegranskat)abstract
- Understanding the evolution of multipath components (MPCs) in real radio channels is crucial to enhancing channel modeling and multipath-assisted positioning. This paper provides an experimental analysis of the behavior of MPCs originating from a standard building facade at millimeter wave (mmWave) frequencies. Utilizing a high-resolution channel parameter estimation method alongside a joint clustering and tracking technique, we identify physical interacting objects and analyze their lifetimes and quantities. The building wall under study is shown to have many distributed distinct backscattering points and reflection contributions due to the windows. Our findings shed light on the reflection and scattering patterns from standard building elements, highlighting the importance of including them in channel models, positioning methods, and ray tracing simulations.
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| 175. |
- Kihl, Maria, et al.
(författare)
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Simulation modelling and analysis of a realistic radio channel model for V2V communications
- 2010
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Ingår i: Proceedings of ICUMT - International Congress on Ultra Modern Telecommunications and Control Systems. - 2157-0221. - 9781424472857 ; , s. 981-988
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Konferensbidrag (refereegranskat)abstract
- Realistic radio channel models are crucial for the success of vehicle-to-vehicle (V2V) system investigations. In this paper, we summarize the important parameters for V2V channel models and describe relevant measurement campaigns. Also, we develop and evaluate an ns-3 simulation model of a realistic V2V channel model that is based on measurements in Sweden. The channel model incorporates the effects of obstacles between the transmitter and receiver. We show that the resulting pathloss is very different compared with available models.
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| 176. |
- Koivunen, Jukka, et al.
(författare)
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Dynamic multi-link indoor MIMO measurements at 5.3 GHz.
- 2007
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Ingår i: Proc 2nd European Conference on Antennas and Propagation (EuCAP 2007).
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Konferensbidrag (refereegranskat)abstract
- A dynamic multi-link MIMO channel indoor measurement campaign at 5.3 GHz is presented in this paper. The system setup is described and capacity with interference (with and without power control) results based on the dynamic multilink MIMO measurements are shown, and we experience a strong correlation between the relative capacity and SIR. Furthermore, an interference suppression metric is introduced and pathloss exponents and delay spreads are also presented, when moving from a typical office corridor to a large entrance hall at the premises of Lund University, Sweden.
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| 177. |
- Kolmonen, Veli-Matti, et al.
(författare)
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A dual-link capacity analysis of measured time-variant radio indoor channels
- 2010
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Ingår i: 2010 IEEE 71st Vehicular Technology Conference. - 9781424425181
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Konferensbidrag (refereegranskat)abstract
- There has been extensive research about single link multiple-input multiple-output (MIMO) channels, both simulated and measured, but only few studies have targeted multilink analysis with measured channel data. Hence, in this paper, we analyze the influence of spatial separation of user terminals and the human shadowing effect on the MIMO capacity and to the signal to interference ratio (SIR) in a time-variant dual-link scenario. The paper analyses the dual-link channel capacity based on simulations as well as measurements conducted using dynamic dual-link dual-polarized wideband MIMO channel sounder in an indoor office environment, and compare the results to the singlelink capacity. Here the analysis is restricted to 4 x 4 MIMO links. The following conclusions have been obtained from the analyses: 1) Compared to the single link case, the dual-link channel capacity is more affected by the SIR than the spatial separation of the users. 2) The human shadowing introduced variations of SIR up to ±10 dB, causing large fluctuations in the dual-link capacity.
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| 178. |
- Kolmonen, Veli-Matti, et al.
(författare)
-
A dynamic dual-link wideband MIMO channel sounder for 5.3 GHz
- 2010
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456. ; 59:4, s. 873-883
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedIn this paper, we present and evaluate the performance of a dynamic dual-link wideband multiple-input-multiple-output ( MIMO) channel sounder. The channel sounder can simultaneously measure two wideband dual-polarized links, each with a MIMO matrix size of 30 x 30 and 30 x 32. Multi-link MIMO systems, including multiuser and cooperative MIMO, are essential parts of future high-throughput wireless local area networks and fourth-generation cellular systems. To fully understand such systems, the dynamic characteristics of multilink MIMO channels have to be measured. In this paper, we present a channel sounder that enables such measurements, including double-directional parameter estimation possibility for both links. The presented dual-link MIMO channel sounder does not suffer from the deficiencies of previous "virtual multiuser" measurement systems. Furthermore, system analysis and sample results from a measurement campaign with this channel sounder at 5.3 GHz in an indoor office environment are presented.
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| 179. |
- Kolmonen, V. -M., et al.
(författare)
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Dual-link capacity analysis of measured time-variant indoor radio channels
- 2010
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 46:8, s. 72-592
-
Tidskriftsartikel (refereegranskat)abstract
- There has been extensive research about single link multiple-input multiple-output (MIMO) channels, both simulated and measured, but only a few studies have targeted multilink analysis with measured channel data. Hence, in this presented report, the authors analyse the influence of spatial separation of user terminals and the human shadowing effect on the MIMO capacity and on the signal-to-interference ratio in indoor radio channels.
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| 180. |
- Kolmonen, Veli-Matti, et al.
(författare)
-
Measurement-based evaluation of interlink correlation for indoor multi-user MIMO Channels
- 2010
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 9, s. 311-314
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedThe properties of the single-link multiple-input-multiple- output (MIMO) propagation channels have been analyzed in many studies based on extensive propagation measurements. In this letter, we extend the measurement-based analysis to dual-link MIMO propagation channels. Here, we examine interlink correlation by evaluating the correlation of eigenvectors obtained from multiple MIMO links. We also investigated how the physical propagation phenomena produced the interlink correlation. Results indicate that interlink correlation may exist. Sometimes it is found to be very high also for far separated receive units, depending on similarity of dominant propagation mechanisms between multiple MIMO links and also on antenna array properties.
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