| 1. |
- Kakkavas, Anastasios, et al.
(författare)
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5G downlink multi-beam signal design for LOS positioning
- 2019
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Ingår i: 2019 IEEE Global Communications Conference, GLOBECOM 2019 - Proceedings.
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Konferensbidrag (refereegranskat)abstract
- In this work, we study optimal transmit strategies for minimizing the positioning error bound in a line-of-sight scenario, under different levels of prior knowledge of the channel parameters. For the case of perfect prior knowledge, we prove that two beams are optimal, and determine their beam directions and optimal power allocation. For the imperfect prior knowledge case, we compute the optimal power allocation among the beams of a codebook for two different robustness-related objectives, namely average or maximum squared position error bound minimization. Our numerical results show that our low-complexity approach can outperform existing methods that entail higher signaling and computational overhead.
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| 2. |
- Kakkavas, Anastasios, et al.
(författare)
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Position Information from Reflecting Surfaces
- 2021
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Ingår i: IEEE Wireless Communications Letters. - 2162-2345 .- 2162-2337. ; 10:6, s. 1300-1304
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Tidskriftsartikel (refereegranskat)abstract
- In the context of positioning an agent with a single-anchor, this contribution focuses on the Fisher information about the position, orientation and clock offset of the agent provided by single-bounce reflections. The availability of prior knowledge of the agent’s environment is taken into account via a prior distribution of the position of virtual anchors, and the rank, intensity and direction of provided information is studied. We show that when no prior knowledge is available, single-bounce reflections offer position information in the direction parallel to the reflecting surface, irrespective of the agent’s and anchor’s locations. We provide a geometrically intuitive explanation of the results and present numerical examples demonstrating their potential implications.
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| 3. |
- Kakkavas, Anastasios, et al.
(författare)
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Power Allocation and Parameter Estimation for Multipath-based 5G Positioning
- 2021
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Ingår i: IEEE Transactions on Wireless Communications. - 1558-2248 .- 1536-1276. ; 20:11, s. 7302-7316
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Tidskriftsartikel (refereegranskat)abstract
- We consider a single-anchor multiple-input multiple-output orthogonal frequency-division multiplexing system with imperfectly synchronized transmitter (Tx) and receiver (Rx) clocks, where the Rx estimates its position based on the received reference signals. The Tx, having (imperfect) prior knowledge about the Rx location and the surrounding geometry, transmits reference signals based on a set of fixed beams. We develop strategies for the power allocation among the beams aiming to minimize the expected Cramér-Rao lower bound for Rx positioning. Additional constraints on the design are included to make the optimized power allocation robust to uncertainty on the line-of-sight (LOS) path direction. Furthermore, the effect of clock asynchronism on the proposed allocation strategies is studied. Our evaluation results show that, for non-negligible synchronization error, it is optimal to allocate a large fraction of the available power for the illumination of the non-LOS (NLOS) paths, which help resolve the clock offset. In addition, the complexity reduction achieved by our proposed suboptimal approach incurs only a small performance degradation. We also propose an off-grid compressed sensing-based position estimation algorithm, which exploits the information on the clock offset provided by NLOS paths, and show that it is asymptotically efficient.
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| 4. |
- Wu, Yibo, 1996, et al.
(författare)
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Cooperative localization with angular measurements and posterior linearization
- 2020
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Ingår i: 2020 IEEE International Conference on Communications Workshops, ICC Workshops 2020 - Proceedings.
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Konferensbidrag (refereegranskat)abstract
- The application of cooperative localization in vehicular networks is attractive to improve accuracy and coverage of the positioning. Conventional distance measurements between vehicles are limited by the need for synchronization and provide no heading information of the vehicle. To address this, we present a cooperative localization algorithm using posterior linearization belief propagation (PLBP) utilizing angle-of-arrival (AoA)-only measurements. Simulation results show that both directional and positional root mean squared error (RMSE) of vehicles can be decreased significantly and converge to a low value in a few iterations. Furthermore, the influence of parameters for the vehicular network, such as vehicle density, communication radius, prior uncertainty, and AoA measurements noise, is analyzed.
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| 5. |
- Zaidi, Ali, et al.
(författare)
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Evaluation of Waveforms for Mobile Radio Communications Above 6 GHz
- 2016
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Ingår i: 2016 IEEE Globecom Workshops (GC Wkshps), 4-8 Dec. 2016. - 2166-0069.
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Konferensbidrag (refereegranskat)abstract
- This paper provides a high level comparison of several multi-carrier and single-carrier waveforms based on the evaluations performed in mmMAGIC project. The waveforms are assessed for the performance indicators that are relevant to mobile radio communication above 6 GHz, specially the millimeter wave frequencies. The evaluations are performed in mmMAGIC waveform simulators under common assumptions on carrier frequencies, waveform parameters, channel and impairment models. The evaluation results reveal that OFDM is suitable for above 6 GHz communication. For above ↑30 GHz communication, OFDM with PAPR reduction and DFTS-OFDM are both promising options. Moreover, some potential enhancements to OFDM (use of window/pulse shape, subband filters, unique word, zero tailing), parametrization of FBMC, and constrained envelop continuous phase modulation for above 6 GHz communication have been discussed.
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