Mohd Azri Mohd Izhar

Utilization of 2-D Markov source correlation using block turbo codes

This paper proposes a joint source-channel coding technique using high rate block turbo codes where two-dimensional (2-D) source correlation of binary Markov source is well exploited. A modified Bahl-Cocke-Jelinek-Raviv (BCJR) algorithm is used in both horizontal and vertical decoders to exploit the 2-D source correlation. Based on extrinsic information transfer (EXIT) chart analysis and trajectory evaluation, we found out that the log-likelihood ratio (LLR) correlation for the block turbo codes increases as the source correlation becomes stronger and this prevents iterative decoding from convergence. A memory-1 accumulator with random interleaver is added to the design to minimise the LLR correlation and to achieve better performance when the source correlation is very strong. Further improvement can be achieved by replacing the memory-1 accumulator with a longer memory code to further reduce the statistical dependency of the LLR. It is shown that the proposed technique can achieve significant improvement over the standard system where the source correlation is not exploited.

Exploitation of 2D binary source correlation using turbo block codes with fine-tuning

This article proposes a joint source-channel coding technique for two-dimensional (2D) binary Markov sources by using concatenated turbo block codes composed of two Bose, Chaudhuri, Hocquenghem (BCH) codes, of which output is followed by a rate-1 recursive systematic convolutional code. The source correlation of all rows and columns of the 2D source is well exploited by using a modified Bahl–Cocke–Jelinek–Raviv (BCJR) algorithm for the decoding of the BCH codes. Simulation results show that the proposed technique outperforms in terms of bit error rate the codes that exploits one-dimensional (1D) source correlation using the modified BCJR algorithm, and obviously the conventional system without source correlation exploitation. In order to further improve the performance, this article aims to make fine-tuning of the code parameters, given the source correlation property, that can achieve performance even closer to the theoretical limit than without the fine-tuning. Finally, results of image transmission simulations using two images, one having strong and the other weak 2D correlation, are presented to demonstrate the effectiveness of our proposed technique.

PAPR Reduction Techniques in Generalized Inverse Discrete Fourier Transform Non-Orthogonal Frequency Division Multiplexing System

With the rapid growth of communications via the Internet, the need for an effective firewall system which has not badly affect the overall network performances has been increased. In this paper, a Field Programmable Gate Array (FPGA) -based firewall system with high performance has been implemented using Network FPGA (NetFPGA) with Xilinx Kintex-7 XC7K325T FPGA. Based on NetFPGA reference router project, a NetFPGA-based firewall system was implemented. The hardware module performs rule matching operation using content addressable memory (CAM) for higher speed data processing. To evaluate system performance, throughput, latency, and memory utilization were measured for different cases using different tools, also the number of rules that an incoming packet is subjected to was varied to get more readings using both software and hardware features. The results showed that the designed firewall system provides better performance than traditional firewalls. System throughput was doubled times of the one with Linux-Iptables firewalls.

Unary-Coded Dimming Control Improves ON-OFF Keying Visible Light Communication

An ideal visible light communication (VLC) system should facilitate reliable data transmission at high throughputs, while also providing flicker-free illumination at the user-defined dimming level. In this spirit, we conceive a unary code aided dimming scheme for ON-OFF keying (OOK) modulated VLC systems. The proposed unary-coded scheme facilitates joint dimming and throughput control, while relying on iterative decoding. It is demonstrated that the proposed unary-coded dimming scheme provides attractive throughput gains over its contemporaries and it is also capable of approaching the theoretical throughput limit. Furthermore, we design novel joint dimming-forward error correction coding schemes, which significantly outperform their compensation time dimming-based counterparts in terms of the attainable bit error rate performance as well as the throughput. Finally, in the quest for approaching the capacity, we also optimize our system using EXTRINSIC information transfer charts and demonstrate an SNR-gain of upto 6 dB over the compensation time dimming-based classic benchmarker.

Low complexity technique exploiting 2D source correlation using single parity check codes

This paper proposes a low complexity joint source-channel coding (JSCC) technique that can well exploit two-dimensional (2D) source correlation using turbo single parity check (SPC) codes. Based on similar structure of the product accumulate code, a rate-1 inner code is serially concatenated to the turbo SPC code structure in order to overcome the high error floor issue of turbo SPC codes. The 2D source correlation, horizontal and vertical directions of the source are exploited during the decoding process. In order to exploit the source statistics (i.e. transition probabilities), a decoding algorithm based on modified check operation is proposed. This modified check operation has significantly lower computational complexity than the previous technique that based on modified Bahl-Cocke-Jelinek-Raviv (BCJR) algorithm. Simulation results reveal that the proposed technique that based on modified check operation achieves about 4.5 times lower computational complexity than the technique that based on modified BCJR algorithm. In addition to the lower computational complexity, the proposed JSCC technique can achieve optimal performance, similar with the technique that based on modified BCJR algorithm. The interesting features of low computational complexity and high performance of the proposed technique is important in designing JSCC system exploiting higher dimensional source correlation.

Distributed turbo block codes in wireless relay networks

This paper proposes distributed turbo block codes (DTBC) for wireless relay networks by using extended Bose, Chaudhuri, Hocquenghem (eBCH) codes as the constituent codes. The proposed technique assumes all channels are orthogonal and requires two phases to complete the transmission. In the first phase, the source broadcasts its information together with the parity bit sequence from the first code. The relay received the data from the source and process the data by using decode and forward protocol. The decoded systematic data at relay is interleaved and encoded by the second encoder. For the second phase, the parity sequence generated by the second encoder at relay is forwarded to the destination. In order to retrieve the original information bits, the signals received at destination from the source and relay are processed by using turbo iterative decoding technique, and for that purpose, soft-input soft-output Chase-Phyndiah (CP) algorithm is used for the decoding. We have conducted a series of simulations to study the effect of different iteration numbers at destination, different numbers of test pattern for Chase algorithm at destination and different locations of relay in a line network model. From our results, we showed that the proposed cooperative scheme outperforms the non-cooperative system as long as the relay is not too far away from the source. Finally, we presented the results of the proposed system by using different constituent codes with different minimum Hamming distances.