in this paper the problem of minimizing the total transmitting power subject to a fixedtotal bit rate in ofdm systems is considered. upper bounds on transmitting power and bit rate ofeach subcarrier can also be taken into account. in practice, the number of bits of each subcarriershould be integer and nonnegative. in this paper an analytical optimal solution is derived for thecase of assuming t...

orthogonal frequency division multiplexing (ofdm) has become a promising method for many wireless communication applications. however, one main drawback of ofdm systems is the high peak-to-average power ratio (papr). selected mapping (slm) is a well-known technique to decrease the problem of high papr in ofdm systems. in this method, transmitter is obliged to send some bits named side informati...

This paper proposes an analytical model for evaluating the performance of dense wavelength division multiplexing (DWDM) for all optical orthogonal frequency division multiplexing (AO-OFDM) optical wireless channel. The investigated performance for proposed system is evaluated for the parameters  bit error rate (BER) and Q factor .The constellation diagrams, and bit error rate (BER) of the recei...

The high Peak to Average Power Ratio (PAPR) of Orthogonal Frequency Division Multiplexing (OFDM) and MIMO-OFDM systems reduces the system efficiency. In this paper, an extension of Tone Reservation (TR) method is introduced for PAPR reduction in Space Frequency Block Coded OFDM (SFBC-OFDM) systems. The proposed algorithm is based on a time domain kernel which is added to the signal of the anten...

In this work various channel estimation algorithms of the Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM) are studied. The result of Linear Minimum Mean Square Error (LMMSE) channel estimation algorithm was compared with the Least Squares (LS) and Minimum Mean Square Error (MMSE) for both OFDM and MIMO-O...

Orthogonal frequency division multiplexing (OFDM) has become a promising method for many wireless communication applications. However, one main drawback of OFDM systems is the high peak-to-average power ratio (PAPR). Selected mapping (SLM) is a well-known technique to decrease the problem of high PAPR in OFDM systems. In this method, transmitter is obliged to send some bits named side informati...

one of the limitations of orthogonal frequency division multiplexing (ofdm) in many applications is its sensitivity to frequency shifts, errors normally referred to as carrier frequency offset (cfo). although, this small offset is negligible in conventional single carrier communication systems, it is a severe problem in the ofdm systems. because, the carriers in ofdm are inherently closely spac...

A carrier frequency synchronization scheme is proposed for orthogonal frequency-division multiplexing (OFDM) systems in the presence of phase noise (PHN). In the proposed scheme, carrier frequency synchronization is performed based on the maximum-likelihood (ML) algorithm using an OFDM preamble symbol. The proposed scheme is compared with conventional methods. Simulation results are presented t...

Tone Reservation (TR) is one of the well-known methods for PAPR reduction of Orthogonal Frequency Division Multiplexing (OFDM) systems. In this method some sub-carriers are reserved for PAPR reduction and the symbols in these sub-carriers are selected such that the PAPR of the OFDM frame is minimized. In this paper, the iterative algorithm introduced earlier for TR method in single antenna OFDM...

Orthogonal Frequency Division Multiplexing (OFDM) is a well known technique for the broadband wireless communication system. However, a main problem in OFDM is its vulnerability to frequency offset errors due to which the orthogonality is destroyed that result in Inter carrier Interference (ICI). ICI causes power leakage among subcarriers thus degrading the system performance. This paper studie...