Efficient time reversal strategy for MISO-OFDM systems

Abstract

In this work, we are interested in implementing, developing, and evaluating a time reversal strategy for a multiple-input single-output orthogonal frequency division multiplexing system. This strategy enjoys a good trade-off between the computational complexity and performance in terms of bit error rate where it offers a good coding gain by forming a beam in the direction of the destination at a price of channel state information available at the transmitter. In time reversal technique, a higher coding and diversity gain can be achieved by increasing the number of transmitting antennas, which focuses the formed beam to the direction of the destination antenna. By achieving this, the received signal-to-noise ratio can be maximized which makes time reversal a good candidate for multiple-input single-output systems while keeping a low complexity. The performance of the proposed system is evaluated in terms of bit error rate where our simulations show that the proposed strategy enjoys the full diversity gain, which is equal to the number of transmitting antennas. Moreover, a robust channel estimation technique is proposed to improve the overall system in terms of bit error rate.

Girth aware normalized min sum decoding algorithm for shorter length low density parity check codes

“…In Figure 6, the decoding algorithms of LDPC codes GA-NMS, NMS, and the standard MS are studied and evaluated in terms of convergence behaviors throughout the iterations when decoding messages coded by WRAN code at non-noisy region SNR= [3,4,5,6] dB. The GA-NMS converges faster than the NMS at higher SNR values SNR= [4,5,6] dB, by comparing the efficiency of the GA-NMS algorithm for the both WRAN and WIMAX codes already evaluated in [20]. It is seen that the results obtained by WIMAX code are better than those obtained by WRAN code, resulting from the difference of size a difference of cyclic structure for both codes and others parameters.…”

“…We are living in an era of advanced technology, the need for wireless access for voice and multimedia has increased enormously. This need has created a wide range of technical challenges like cost, high speed, throughput, low complexity, low power and low latency as in [1]- [4]. Low density parity check (LDPC) codes [5] of shorter length (i.e., codes with dimension k in the range of 50 to 1000 bits) are considered as they offer advantages in terms of latency and complexity, at the cost of performance degradation due to the increased number of short cycles in the tanner graph (TG) [6], contrary to the LDPC code with the large block length as we can see in the study presented in [7] or [8].…”

A Beamforming Technique Using Rotman Lens Antenna for Wireless Relay燦etworks

“…In the recent years, several techniques have been proposed in the field of wireless communications to enhance the error performance of the whole system and its achievable throughput [1][2][3][4][5][6]. A group of these techniques works by increasing or optimizing the transmitted power, while another group is applying powerful forward error detection and correction techniques to increase the achievable gain.…”

“…Later on, several schemes are suggested to improve both diversity order and coding gain by combining diversity techniques with coding algorithms including but not limited to space-frequency coding (SFC) schemes and spacetime coding (STC) schemes [10,[13][14][15]. Furthermore, special diversity techniques using beamforming schemes [11][12][17][18][19] are used to steer the transmitting antenna beams towards the destination terminal to enhance the BER performance and the throughput by maximizing the received signal to noise ratio (SNR), given that the BER performance of the multi-antenna systems suffer from the multiuser interference and channel impairments [1][2][3][4][5][6][7][8][9]. In addition, it is very well known that it is difficult to deploy several antennas at the same mobile station due to several limitations.…”