Temat: MIMO-OFDM - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Improvement of LTE Downlink Channel Estimation Performance by Using an Adaptive Pilot Pattern
Autorzy:: Youssefi, M. A.
Abbadi, J. E.
Powiązania:: https://bibliotekanauki.pl/articles/307570.pdf
Data publikacji:: 2015
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: channel estimation
LTE
MIMO
OFDM
pilot pattern
Opis:: This paper proposes an adaptive pilot pattern to improve channel estimation performance for LTE downlink system with high mobility. The downlink pilot positions are predefined in the time and frequency domain with fixed pilot pattern in LTE standard. However, that pilot structure is not efficient in a fast time varying channel, and leads to a decrease of channel estimation performance. The authors propose and evaluate the performance of LTE downlink channel estimation using an adaptive pilot scheme to optimally use pilot tones over time varying channels. It is shown that only seven bits of additional wide-band feedback per frame and per user are required to optimally support adaptive pilot pattern. Simulation results show that the proposed method allows high performance in terms of throughput and channel estimation error. This analysis shows that LTE downlink throughput could be increased over 4%.
Źródło:: Journal of Telecommunications and Information Technology; 2015, 2; 59-63
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: New OSTBC for Blind Channel Estimation and Tracking in MIMO-OFDM Systems
Autorzy:: Tami, Abdelkader
Keche, Mokhtar
Bouazza, Boubaker S.
Powiązania:: https://bibliotekanauki.pl/articles/958059.pdf
Data publikacji:: 2019
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: MIMO
OFDM
blind channel estimation
OSTBC
SS-KCE
Opis:: Applying orthogonal space time block coding (OSTBC) to multiple-input multiple-output (MIMO) systems helps reduce receiver complexity. However, this approach has been applied only to ﬂat fading channels, as when the channel is a frequency selective fading MIMO channel, OSTBC cannot be used directly since its orthogonal propriety may be lost. Furthermore, the MIMO channel is not always known. To deal with this problem, many techniques were proposed to estimate the channel using a training sequence. Unfortunately, these techniques reduce the useful spectral bandwidth. This paper proposes OSTBC for blind channel estimation and data detection in the case of a MIMO frequency selective channel. The aim of this new OSTBC is twofold: to solve the ambiguity of channel estimation and to reduce the complexity of the detector. By exploiting the well-known technique of orthogonal frequency division multiplexing (OFDM), the frequency selective fading MIMO channel is split into a set of ﬂat fading subchannels. Moreover, to accommodate the fact that a MIMO channel can be time varying, the steady state Kalman channel estimator (SS-KCE) is extended to track the channel’s fast variations. The performance of the proposed blind algorithm is related by the adequate choice of the number of subcarriers and it is compared with other existing approaches by means of Monte Carlo simulations.
Źródło:: Journal of Telecommunications and Information Technology; 2019, 3; 49-57
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Performance Improvement for Vehicular Communications Using Alamouti Scheme with High Mobility
Autorzy:: Yousseﬁ, My Abdelkader
Mouhsen, Ahmed
Powiązania:: https://bibliotekanauki.pl/articles/308551.pdf
Data publikacji:: 2020
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: IEEE 802.11p
MIMO
MISO
OFDM
SFBC
STBC
vehicular channel
Opis:: The IEEE 802.11p standard is the basic protocol for wireless access in a vehicular environment (WAVE), providing high throughput for multimedia and high quality for vehicular transmissions. However, IEEE 802.11p fails to offer any multi-antenna approaches. In this paper, a multipleinput single-output (MISO) implementation with orthogonal frequency division multiplexing (OFDM), aiming to improve the performance of IEEE 802.11p, is proposed. The authors investigate the impact of time-varying channel on the performance of Alamouti space-time block codes (STBC) in OFDM systems. The Alamouti STBC approach shows good performance in slow time-varying environments, while its Alamouti space frequency block codes (SFBC) counterpart performs better over fast time-varying environments. An adaptive switching scheme is proposed to select appropriate spaceblock coding (STBC or SFBC) in vehicular channels with high mobility levels. It is shown that the proposed adaptive scheme provides better performance compared with traditional spaceblock codes.
Źródło:: Journal of Telecommunications and Information Technology; 2020, 3; 47-56
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Investigation of Vehicular S-LSTM NOMA Over Time Selective Nakagami-m Fading with Imperfect CSI
Autorzy:: Shankar, Ravi
Chaudhary, Bhanu Pratap
Mishra, Ritesh Kumar
Powiązania:: https://bibliotekanauki.pl/articles/2174454.pdf
Data publikacji:: 2022
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: inter-symbol interference
MIMO
NOMA
orthogonal frequency division multiplexing
OFDM
S-LSTM
zero-mean circularly symmetric complex Gaussian
ZM-CSCG
Opis:: In this paper, the performance of a deep learningbased multiple-input multiple-output (MIMO) non-orthogonal multiple access (NOMA) system is investigated for 5G radio communication networks. We consider independent and identically distributed (i.i.d.) Nakagami-m fading links to prove that when using MIMO with the NOMA system, the outage probability (OP) and end-to-end symbol error rate (SER) improve, even in the presence of imperfect channel state information (CSI) and successive interference cancellation (SIC) errors. Furthermore, the stacked long short-term memory (S-LSTM) algorithm is employed to improve the system’s performance, even under time-selective channel conditions and in the presence of terminal’s mobility. For vehicular NOMA networks, OP, SER, and ergodic sum rate have been formulated. Simulations show that an S-LSTM-based DL-NOMA receiver outperforms least square (LS) and minimum mean square error (MMSE) receivers. Furthermore, it has been discovered that the performance of the end-to-end system degrades with the growing amount of node mobility, or if CSI knowledge remains poor. Simulated curves are in close agreement with the analytical results.
Źródło:: Journal of Telecommunications and Information Technology; 2022, 4; 47--59
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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