Orthogonal frequency division multiplexing

Nghiên cứu "Ước lượng kênh truyền trong hệ thống đa robot sử dụng SDR" tập trung xây dựng một hệ thống thực nghiệm ước lượng kênh truyền phục vụ truyền thông trong hệ thống đa robot di động sử dụng các thiết bị vô tuyến định nghĩa bằng phần mềm (SDR - Software Define Radio). Hệ thống gồm 2 robot di động được lập trình cho 2 tình huống robot đứng yên và robot di động theo quỹ đạo cho trước. Hệ thống truyền thông được thực hiện thông qua điều chế đa sóng mang trực giao OFDM (Orthogonal Frequency Division Multiplexing) nhằm làm giảm ảnh hưởng của môi trường đa đường trong nhà.

6p phocuuvan0201 02-02-2024 7 5   Download

Bài viết "Giải pháp dạng sóng nhằm nâng cao hiệu suất thu hoạch năng lượng sóng RF" đề xuất một mạch thu hoạch năng lượng từ RF (radio frequency) và đánh giá ảnh hưởng của sóng RF được điều chế OFDM (Orthogonal Frequency-Division Multiplexing) cũng như sóng hình sine ở tần số 5.8 GHz lên hiệu suất của mạch chỉnh lưu. Hoạt động của mạch chỉnh lưu với dải công suất sóng từ -20 dBm đến 20 dBm cho hiệu suất chuyển đổi cao nhất lên tới 50%. Mời các bạn cùng tham khảo!

6p phocuuvan0201 02-02-2024 1 0   Download

Part 2 book "Principles of modern wireless communication systems - Theory and practice" includes content: Multiple input multiple output wireless communications; orthogonal frequency division multiplexing; wireless system planning.

132p muasambanhan06 03-02-2024 6 3   Download

In this paper, we propose a method that uses the non-uniform Fast Fourier Transform (FFT) to compensate for Doppler frequency shifts in orthogonal frequency division multiplexing (OFDM) based underwater acoustic (UWA) communication systems. To estimate the Doppler frequency shift, the paper proposes using a pilot carrier frequency (PCF) that is identified by transmitting with greater power in the frequency domain compared to other subcarriers.

7p vijeff 30-11-2023 3 3   Download

Part 1 book "MIMO-OFDM wireless communications with Matlab R" includes content: The wireless channel - Propagation and fading, SISO channel models, MIMO channel models, introduction to OFDM, synchronization for OFDM, channel estimation.

226p oursky02 07-08-2023 7 5   Download

Part 2 book "MIMO-OFDM wireless communications with Matlab R" includes content: PAPR reduction, inter cell interference mitigation techniques, MIMO - channel capacity, antenna diversity and space time coding techniques, signal detection for spatially multiplexed MIMO systems, exploiting channel state information at the transmitter side, multi user MIMO.

231p oursky02 07-08-2023 7 5   Download

In this paper, the authors propose alternative filters to improve the spectral properties of the filtered orthogonal frequency division multiplexing (filtered-OFDM) candidate waveform for new wireless systems (fifth generation (5G) and next generation).

11p viwarmachine 01-07-2023 4 4   Download

Bài viết Giải pháp thực nghiệm nâng cao chất lượng truyền dẫn tín hiệu internet trên mạng truyền hình cáp HFC (Hybrid Fiber Coaxial) trình bày phương pháp thực nghiệm xử lý và nâng cao chất lượng truyền dẫn tín hiệu Internet trên mạng truyền hình cáp HFC (Hybrid Fiber Coaxial) sử dụng kỹ thuật OFDM (Orthogonal Frequency-Division Multiplexing).

5p vijaguar 16-11-2022 9 3   Download

In this paper, the authors introduce a new signal used to efficiently jam the remote control and video transmission channels of unmanned aerial vehicles/drones (UAV/Dr) that using orthogonal frequency division multiplexing (OFDM) to protect targets from their threats.

10p vimclaren 20-10-2022 7 4   Download

Bài viết Kết hợp ước lượng nhiễu pha và kênh truyền biến đổi theo thời gian cho hệ thống OFDM tiến hành phân tích sự ảnh hưởng, mô hình hóa hệ thống và từ đó ước lượng sự thay đổi của đáp ứng kênh, nhiễu pha trong hệ thống OFDM (Orthogonal Frequency Division Multiplexing).

5p vilexus 30-09-2022 13 4   Download

This paper introduces the expectation maximization (EM)-based channel estimation for the high power amplifier (HPA)-incurred nonlinear orthogonal frequency division multiplexing (OFDM) systems based on the linearization using extended Bussgang decomposition

13p vibentley 08-09-2022 16 4   Download

Wireless networks - Lecture 42: IEEE 802.16. The main topics covered in this chapter include: IEEE 802.16 overview; WiMAX forum; characteristics of 802.16 frequency ranges; provide high-speed mobile data and telecommunications services; orthogonal frequency division multiplexing (OFDM);...

20p haoasakura 30-05-2022 13 3   Download

In this paper, we investigate the nonlinear and dispersion compensation efficiency in OFDM-WDM system using an advanced optical back propagation (OBP) approach based on split-step Fourier method.

7p viaespa2711 31-07-2021 28 5   Download

In recent years, optical orthogonal frequency division multiplexing (OOFDM) has emerged as a dominant research and development area in the field of high-speed optical communications. OFDM is a potential candidate as the most promising next-generation optical networks such as passive optical networks and optical transport networks, due to their simple configuration based on low cost, high speed data rates, high spectral efficiency, high quality of service and robustness against narrow band interference, frequency selective fading, and chromatic dispersion.

99p nguathienthan12 18-05-2021 17 6   Download

This paper investigates the impacts of InterChannel Interference (ICI) effects on a shallow underwater acoustic (UWA) orthogonal frequency-division multiplexing (OFDM) communication system. Considering both the turbulence of the water surface and the roughness of the bottom, a stochastic geometry-based channel model utilized for a wideband transmission scenario has been exploited to derive a simulation model. Since the system bandwidth and the subcarrier spacing is very limited in the range of a few kHz, the channel capacity of a UWA system is severely suffered by the ICI effect.

8p nguaconbaynhay11 16-04-2021 17 4   Download

This paper presents an implementation of NC under a two-way relay model and extends it to two non-straightforward scenarios: (i) multimedia transmission with layered coding and multiple-description coding, and (ii) cognitive radio with Vandermonde frequency division multiplexing (VFDM). The implementation is in real time and based on software-defined radio (SDR).

13p nguaconbaynhay11 07-04-2021 17 2   Download

In this work, one of the methods deploying encryption to cipher data is represented. The primary object of this project is applying Advanced Encryption Standard (AES) in communications based Orthogonal Frequency Division Multiplexing (OFDM). This article discusses the security of the method encrypting directly QAM symbols instead of input bit-stream.

8p tamynhan6 14-09-2020 33 3   Download

In this paper, we propose a fine time synchronization for a Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) system. The proposed algorithm uses one more IFFT to find the timing offset, then correct it. The simulations show that comparing to the conventional algorithm using cross-correlation method, the proposed algorithm has a higher timing detection probability.

5p 12120609 01-06-2020 24 1   Download

Orthogonal frequency division multiplexing (OFDM) has become a prevalent and widespread technique for the broadcast and transmission of signals over wireless channels and has been adopted in many wireless standards. OFDM may be united with antenna arrays at the transmitter and receiver side to improve the diversity gain and to improve the system competence on time-variant along with the frequency-selective channels, resulting in a multiple-input multiple-output (MIMO) composition.

4p son248 24-03-2020 30 1   Download

In this paper, an area-efficient low power Fast Fourier Transform (FFT) processor is proposed for Multi Input Multi Output—Orthogonal Frequency Division Multiplexing (MIMO-OFDM) that consists of a modified architecture of radix-2 algorithm which is described as Radix-2 multipath delay commutation (R2MDC). Orthogonal frequencydivision multiplexing is a popular method for high-data-rate wireless transmission.

8p son248 24-03-2020 26 1   Download