Research on LDPC in an OFDM System

In this paper, LDPC codes and OFDM technologies are studied, and combines LDPC and OFDM to simulate and verify the performance. The encoding of LDPC and logarithmic domain BP decoding algorithm and the principle of OFDM are introduced. Through MATLAB, the simulation of OFDM-LDPC system in different channel, different code length, different iteration times, LDPC and OFDM-LDPC in the same conditions are compared. Through simulation analysis, we can know that the performance of OFDM-LDPC system will improve with the increase of the code length. When the SNR is small, the number of iterations has little effect on the performance of OFDM-LDPC system. When the SNR is large, the performance of the system will be improved with the increase of the number of iterations. The performance of OFDM-LDPC codes is better than that of LDPC codes. The performance of OFDM-LDPC code is better than LDPC code in multipath Rayleigh fading channel.

Analysis of the energy harvesting non-orthogonal multiple access technique for defense applications over Rayleigh fading channel conditions

The energy harvesting (EH) technique has ignited a rising research interest due to its ability to enhance the battery power of user equipment by harvesting energy by using a simple radio frequency circuit. In this paper, the simultaneous wireless information and power transfer non-orthogonal multiple access (NOMA) technique is investigated over Rayleigh fading channel conditions. EH NOMA improves the power efficiency, and it results in better throughput as compared to conventional NOMA techniques. In this paper, we investigate the achievable data rate and the outage probability performance of the near user, also called the relay user (RU), and the far user (FU). It can clearly be shown that the RU data rate is saturated and at 1 bits/s/Hz will become constant, while the FU data rate increases with an increase in transmitted power. It is seen by analysis that the RU data rate would saturate due to EH. It is further shown that with a transmitted power of 18 dBm, the net output of the FUs is readily shown to be based around a value of 2.80 bits/s/Hz. In comparison, it is shown that the FU’s instantaneous information rate dropped below the target data rate.