Wyniki wyszukiwania - BazTech

1

Studying and Modeling the Performance of the TCM-STBC Systems in the Rayleigh Channel

Bendelhoum Mohammed Sofiane, Lahcene Mohamed Rida, Menezla Fayssal, Elarbi Abderraouf

Journal of Telecommunications and Information Technology

|

2021

|

nr 1

1--7

EN

Multiple-input multiple-output (MIMO) systems will play an important role in future generations of wireless networks. Space-time block code (STBC) and space-time trellis code (STTC) are two techniques that may be used in multi-antenna radio systems. This paper aims, most importantly, to study the performance of STBC systems at different values of such parameters as spectral efficiency, matrix codes and constellations. A performance comparison between STBC and STTC schemes is performed. In order to show the efficiency of the system’s ability to communicate with uncoded and coded transmission structures over AWGN and Rayleigh channels, the trellis-coded modulation (TCM) is introduced. The results obtained show that the proposed TCM-STBC system model, using one and two receiving antennas, improves the performance of Rayleigh channel communication systems at 9.5 dB and 11.5 dB for a BER of 10−5.

2

Performance Improvement for Vehicular Communications Using Alamouti Scheme with High Mobility

Yousseﬁ My Abdelkader, Mouhsen Ahmed

Journal of Telecommunications and Information Technology

|

2020

|

nr 3

47--56

EN

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.

3

A Soft-Output STBC Decoder for Aeronautical Telemetry

Louёt Yves, Othman Rami, Skrzypczak Alexandre

Journal of Telecommunications and Information Technology

|

2020

|

nr 1

13--20

EN

Alamouti encoding is a well-known space time block encoding technique used to improve the received signal quality in Rayleigh fading channels. In aeronautical telemetry, this encoding technique is applied to shaped oﬀset quadrature phase shift keying tier generation (SOQPSK-TG) modulation in order to handle the two-antenna issue. It is provided for in telemetry-related IRIG standards. In this paper, we propose a unique decoding architecture for Alamouti-encoded SOQPSK-TG signals, taking advantage of pulse amplitude modulation decomposition with soft and hard outputs. We exploit this result to obtain a Viterbi algorithm (VA) for hard decoding and a soft output Viterbi algorithm (SOVA) for soft and hard decoding, with a twofold beneﬁt: operation using one trellis structure, unlike decoders that are based on the 8-waveforms cross-correlated trellis-coded quadrature modulation (XTCQM) approximation, and very attractive bit error rate performance, as well as a complexity trade-oﬀ.

4

Ocena efektywności wieloantenowej techniki MIMO w zróżnicowanych warunkach transmisji sygnału

Michalak J., Uljasz B., Ziółkowski C.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

|

2012

|

nr 2-3

77-80

PL

Przedstawiono wyniki symulacji komputerowej systemu wieloantenowego MIMO 2x2 (Mu/f/p/e Input Multiple Output) z koderem STBC (Space Time Block Coding) Alamoutiego w porównaniu do systemu SISO (Single Input Single Output). Celem badania było określenie stopnia efektywności układu MIMO zależnie od prędkości i kierunku ruchu korespondenta, warunków propagacji oraz konfiguracji anten. Zależnie od założeń symulacyjnych uzyskano wyniki potwierdzające przewagę MIMO nad SISO w zakresie od kilku do kilkunastu dB.

EN

Results of computer simulation tests of the STBC Alamouti MIMO 2x2 system in comparison to SISO were presented in this article. The aim was to assess of effectiveness of MIMO versus SISO in assumed propagation conditions. Depending on subscriber motion, propagation conditions as well as antenna system configuration different results were received. But each time MIMO system was not worse than SISO and many times it is significantly better than SISO with gain from a few to a dozen or so dB.

5

MIMO versus SISO : simulation results

Michalak J., Ziółkowski C., Uljasz B.

Biuletyn Wojskowej Akademii Technicznej

|

2012

|

Vol. 61, nr 1

223-239

EN

Results of computer simulation tests of the STBC Alamouti MIMO 2×2 system in comparison to SISO were presented in this paper. The aim was to assess effectiveness of MIMO versus SISO in assumed propagation conditions. Depending on subscriber motion, propagation conditions as well as antenna system configuration, different results were received. In each configuration, MIMO system was not worse than SISO and many times it is significantly better than SISO with gain from a few to a dozen or so dB.

PL

W artykule zaprezentowano wyniki symulacji komputerowej systemu wieloantenowego MIMO 2×2 (ang. Multiple Input Multiple Output) z koderem STBC (ang. Space Time Block Coding) Alamoutiego w porównaniu do systemu SISO (ang. Single Input Single Output). Celem badania było określenie stopnia efektywności układu MIMO zależnie od prędkości i kierunku ruchu korespondenta, warunków propagacji oraz konfiguracji anten. Zależnie od założeń symulacyjnych uzyskano wyniki potwierdzające przewagę MIMO nad SISO w zakresie od kilku do kilkunastu dB.