Orthogonal Frequency Division Multiplexing/Modulation (OFDM) is widely used for symbol level modulationdemodulation in communication systems for a high data rate low distance range applications. OFDM refers to both multiplexing and modulation technique to transmit parallel data using orthogonal carriers in the same or different frequency bands. In this work, DWT-OFDM is modeled which aims to se...

Presently in communication areas Digital Video Broad casting in terrestrial (DVB-T) is playing an important role for the transmission of digital video worldwide. Orthogonal frequency division multiplexing (OFDM) is becoming a popular modulation scheme for wireless communication systems to achieve high throughput, high data capacity, spectral efficiency and resilience to multipath. In OFDM the d...

Visible Light Communication (VLC) using light emitting diodes (LEDs) has been gaining increasing attention in recent years as it is appealing for a wide range of applications such as indoor positioning. Orthogonal frequency division multiplexing (OFDM) has been applied to indoor wireless optical communications in order to mitigate the effect of multipath distortion of the optical channel as wel...

The previous link adaptation algorithms on ofdm based systems use equal modulation order for all sub carrier index within a block. For multimedia transmission using ofdm as the modulation technique, unequal constellation is used within one ofdm subcarrier block, a set of subcarriers for audio and another set for video transmissions. A generic model has been shown for such a transmission and lin...

This paper deals with the MIMO-OFDM technique that candidate with the fourth generation (4G) of the wireless communication systems, this technique can provide high data rate transmission without increasing transmit power and expanding bandwidth, also it can efficiently use space resources and has a bright future. This paper presents the channel coding assisted STBC-OFDM systems, and employs the...

The fundamental block of WiMAX (Worldwide Interoperability for Microwave Access) PHY layer is Orthogonal Frequency Division Multiplexing (OFDM). The main issue raised in OFDM is high Peak to Average Power Ratio (PAPR) due to multicarrier signal. This paper proposes architecture for PAPR reduction to improve network performance of WiMAX in urban areas where typically Non-Line of sight communicat...

The impact of the fiber Kerr effect on error statistics in the nonlinear (high power) transmission of the OFDM 16-QAM signal over a 2000 km EDFA-based link is examined. We observed and quantified the difference in the error statistics for constellation points located at three power-defined rings. Theoretical analysis of a trade-off between redundancy and error rate reduction using probabilistic...

High Peak – to – average power ratio (PAPR) of transmitted signals is a major shortcoming for multicarrier modulation system such as orthogonal frequency division multiplexing (OFDM) and wavelet packet modulation (WPM). This paper introduces a novel OFDM system base on dual – tree complex wavelet transform (DT-CWT). In the proposed scheme, DTCWT is used in the place of fast Fourier transform (F...

To meet the strong demand for broadband multimedia services by both nomadic and mobile users, it is important to increase the bit rate of future mobile communications systems. To enhance system capacity, novel technologies or new concepts for improving bandwidth efficiency are indispensable. In this paper, an adaptive downlink modulation using OFDM and MC-CDMA is presented for maximizing the sy...

In direct-detection OFDM systems, the nonlinear effects caused by optical modulation and fiber transmission can degrade system performance severely. this study, we propose a new companding transform to improve of direct detection systems. The demonstration is realized Monte-Carlo simulation intensity DCO-OFDM at 40 Gbps over 80 km standard single mode link. influence parameters on in different ...