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The DCM scheme is exploited as the modulation scheme for high-data rate transmission in the MB-OFDM system. However, since the DCM modulated symbols are repeatedly fed into the IFFT block, the MB-OFDM system has a high PAPR problem. In this paper, improved DCM is proposed for PAPR reduction in the MB-OFDM systems. The proposed scheme uses a circular shifting operation of the gray coded 16-QAM constellation...
The dual carrier modulation (DCM) has been proposed for use in the multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB). The DCM has a significant diversity improvement in multi-path fading channel, but it suffers from a high peak-to-average power ratio (PAPR). Many PAPR reduction schemes have been introduced for solving the PAPR problem. However, general PAPR reduction...
A high peak-to-average power ratio (PAPR) is one of the serious disadvantages of an orthogonal frequency-division multiplexing (OFDM) system. Therefore, many PAPR reduction methods have been introduced. Especially, the signal scrambling methods such as selective mapping (SLM), partial transmit sequences (PTS), and polyphase interleaving and inversion (PII) are the attractive methods for obtaining...
Orthogonal Frequency Division Multiple Access (OFDMA) allows multiuser to make use of the same bandwidth as the single user OFDM for data transmission. This paper considers resource allocation algorithm which supports the user Quality of Service (QoS) with Multiuser OFDM cellular system. In this paper, we discuss how to achieve QoS without wasting subcarriers after subcarrier allocation. A proposed...
Orthogonal frequency division multiplexing (OFDM) is an attractive and effective technique for wireless communications. However, an OFDM signal has a large peak-to-average power ratio (PAPR), which will cause serious nonlinear distortion especially when the signal passes through a nonlinear system. Adaptive symbol selection scheme (ASSS) is used to reduce the unwanted PAPR by selecting the adaptive...
In an orthogonal frequency division multiplexing (OFDM) system, in-phase and quadrature (I/Q) imbalances generated in the analog front-end introduce inter-channel interference (ICI) and, consequently, error performance degradation. In this paper, a general and exact expression involving the two-dimensional (2-D) Gaussian Q-function for symbol error probability of MPSK-OFDM signal with I/Q imbalances...
Orthogonal frequency division multiple access (OFDMA) allows multi-user to make use of the same bandwidth as the single-user OFDM for data transmission. This paper considers resource allocation algorithm which supports the user throughput fairness and quality of service (QoS) in the fixed relay based cellular system with TDD-OFDMA. By measuring the current level of user requirement and allocating...
Orthogonal frequency division multiplexing (OFDM) is a special form of multi-carrier modulation which is robust against the multipath effect and inter symbol interference (ISI). However, it is very sensitive to nonlinear effects due to the high peak-to- average power ratio (PAPR) owned by the transmitted signals. To reduce PAPR and improve the error performances of the OFDM signals over fading channels,...
One of the main disadvantages of orthogonal frequency division multiplexing (OFDM) is peak to average power ratio (PAPR) problem. The adaptive symbol selection scheme (ASSS) can be used to reduce the PAPR for OFDM signals. However, ASSS requires sending side information with data information that decreases the transmitted data rate or increases the complexity of the system. In this paper, we propose...
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