| 1. |
- Gomes, P. R. B., et al.
(författare)
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Tensor-Based Modeling and Processing for Channel Estimation in Two-Hop V2X MIMO Systems
- 2019
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Ingår i: 2019 IEEE Conference on Standards for Communications and Networking, CSCN 2019. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781728108643
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Konferensbidrag (refereegranskat)abstract
- Efficient vehicle-to-everything (V2X) communications improve traffic safety, enable autonomous driving and help to reduce environmental impacts. To achieve these objectives, accurate channel estimation in highly mobile scenarios becomes necessary. In this paper, we propose a tensor modeling-based approach for channel estimation and receiver design in a two-hop multiple-input multiple-output V2X communication system. Specifically, by exploiting a Tucker-2 modeling of the received signals, and relying on the joint estimation of the two-hop link, we formulate simple tensor-based closed-form and iterative semi-blind receivers. Furthermore, motivated by the parallel factor analysis (PARAFAC) structure of the time-varying multipath channel, we develop an iterative algorithm for estimating key parameters of the two-hop channel - including angles of departure, angles of arrival and path gains - from the factor matrices of the estimated channel tensors. Simulation results illustrate the performance of the proposed channel estimation and receiver algorithms in selected V2X communications scenarios.
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| 2. |
- Guimaraes, F. R. V., et al.
(författare)
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A Multi-Stream Pricing-Based Precoding and Power Control Algorithm for Dynamic TDD Networks
- 2019
-
Ingår i: 2019 IEEE Conference on Standards for Communications and Networking, CSCN 2019. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781728108643
-
Konferensbidrag (refereegranskat)abstract
- Dynamic time division duplexing (DTDD) cellular networks enable to adapt the number of uplink and downlink time slots to the prevailing traffic demands in each cell at the expense of base station (BS)-to-BS and user equipment (UE)-to-UE interference. Recognizing the importance of mitigating the effect of these additional interference types, previous works proposed multicell coordinated beamforming to realize the full potential of DTDD systems that employ multiple antennas at the BSs. Unfortunately, the previously proposed mechanisms suffer from slow convergence, which renders such schemes impractical in fast fading and highly mobile environments. In this paper, we formulate the multicell multi-stream DTDD beamforming problem as an optimization task, and propose a near-optimal pricing-based algorithm to determine the beam directions and transmit power levels for each stream at the BSs. The proposed distributed precoding and power control algorithm not only improves the downlink performance, but it also substantially mitigates the BS-to-BS interference levels, and thereby improves the uplink performance as well. Simulation results indicate that the proposed algorithm exhibits faster convergence than previously proposed near-optimal schemes at the expense of some small performance degradation in terms of the achieved signal-to-interference-plus-noise-ratio (SINR).
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| 3. |
- Paiva, A. R. L., et al.
(författare)
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Kalman-Filter-Based Tracking of Millimeter-Wave Channel Parameters for V2X Applications
- 2019
-
Ingår i: 2019 IEEE Conference on Standards for Communications and Networking, CSCN 2019. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728108643
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Konferensbidrag (refereegranskat)abstract
- The spectrum of millimeter waves, when properly exploited, represents an important asset for achieving the high data rates and low latencies required by applications in vehicular communications. However, vehicle scenarios are characterized by high mobility, which results in frequent misalignment of beams. Therefore, in these types of scenarios, beam tracking algorithms are important because they can keep the beams aligned with a low training overhead. Kalman filters are strong candidates for the implementation of such algorithms, because they ensure high channel tracking performance over a wide range of signal-to-noise-ratios (SNR) and are easy to implement. This work evaluates the performance of channel tracking methods based on Kalman filters for high mobility. Our numerical results show that the proposed Kalman filter-based channel tracking method has high performance at low SNR regimes compared to least square-based methods, and improve the robustness when using planar instead of linear arrays. Moreover, the proposed channel tracking method is shown to perform well in multipath fading scenarios, while achieving high performance in the presence of strong line-of-sight components.
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