This paper presents the bit error rate performance of the low density parity check (LDPC) with the concatenation of convolutional channel coding based orthogonal frequency-division-multiplexing (OFDM) using space time block coded (STBC). The OFDM wireless communication system incorporates 3/4-rated convolutional encoder under various digital modulations (BPSK, QPSK and QAM) over an additative white gaussian noise (AWGN) and fading (Raleigh and Rician) channels. At the receiving section of the simulated system, Maximum Ratio combining (MRC) channel equalization technique has been implemented to extract transmitted symbols without enhancing noise power. Keyword:

In this paper, we study the performance of Low density Parity Check (LDPC) coded orthogonal frequency-division multiplexing (COFDM) systems  when they are applied on the short data block of a narrowband (NB) power line communications (PLC) channel. In the modelled system simulations have been performed using different code lengths. It is assumed that the channel has a multipath propagation with two different noise scenarios: AWGN background noise with and without the presence of impulsive noise. Performances of Various soft and hard decision LDPC decoder schemes such as belief propagation (BP), weighted bit flipping (WBF), improved weighted bit flipping (IWBF) and implementation-efficient reliability ratio based weighted bit flipping (IRRWBF) decoders were investigated. It has been shown for all simulations performed in PLC channel model showed that remarkable performance improvement can be achieved by using short-length LDPC codes. Especially, the improvements are striking when the BP decoding algorithms are employed on the receiver side.

No abstract

Power line communication (PLC) technology is actually among the most renowned technologies for home environments due to their low-cost installation opportunities. In this study, the bit error rate (BER) performances of binary low-density parity check (LDPC) coded orthogonal frequencydivision multiplexing (OFDM) systems have been considered over indoor PLC channels. Performances comparison of diverse soft and hard decision LDPC decoder schemes such as Min-Sum (MS), weighted bit flipping (WBF), gradient descent bit-flip (GDBF), noisy gradient descent bit-flip (NGDBF) and its few variants including the single-bit NGDBF (S-NGDBF), multi-bit NGDBF (M-NGDBF) and smoothed-multi-bit NGDBF (SM-NGDBF) decoders were examined in the modeled network. To evaluate the BER performance analyses three different PLC channel scenarios were generated by using new and more realistic PLC channel model proposal were also employed. All of the simulations performed in Canete's PLC channel model showed that remarkable performance improvement can be achieved by using short-length LDPC codes. Especially, the improvements are striking when the MS or SM-NGDBF decoding algorithms are employed on the receiver side.

No abstract