Md. Mijanur Rahman

Performance of PTS techniques with varied partition size in PAPR reduction of OFDM system

Orthogonal frequency division multiplexing (OFDM) is a promising modulation technique for transmitting large amounts of digital data through radio waves. One major drawback in OFDM communication is peak-to-average power ratio (PAPR). Mainly because of the nonlinearity of the high power amplifier, these results in high out-of-band radiation, inter-carrier interference, and bit error rate performance degradation. Partial transmit sequences (PTS), an attractive technique of PAPR reduction, provides significant PAPR reduction performance for (OFDM) signals. It essentially involves partitioning the OFDM data frame into disjoint sub-blocks. Adjacent partitioning (AP) scheme can be regarded as the best of the existing partitioning schemes when PAPR reduction performance and cost are considered together. In this paper, we study the impact of the size of PTS partitions on the performance through varying the size of the disjoint sub-blocks partition and comparing the PAPR reduction performance of three well known sub-block partitioning schemes namely Adjacent Partitioning (AP), Interleaved Partitioning (IP) and Pseudorandom Partitioning (PRP). Simulation results showed that performance of these PTS schemes largely depends on the chosen size of the partitions.

Event Driven Input Sequence T-Way Test Strategy Using Simulated Annealing

Exhaustive testing for event driven sequence input interaction is costly and not always practicable for all types of software testing. So, an alternative technique is crucial where optimum/near optimum test case generation is key concern. This paper presents a feasible test suite generation technique using Simulated Annealing (SA) algorithm for Event Driven Input Sequence Testing (EDIST)and called EDIST-SA T-way test strategy. The EDIST-SA technique focuses on a heuristic analysis for generating feasible and near optimum test suite(s), where a cost function carefully initiates acceptable test candidates and a fine-tuned cooling rate with temperature takes part as an iterative perspective. We corroborate on EDIST-SA algorithm by doing a large number of experiments to achieve optimum and/or near optimum test cases from a large number of test candidates. The experimental results are tested on a real application called Embedded Network Traffic Monitoring System (ENTM). Analysis on EDIST-SA strategy shows that the optimum test suite is found from some of the iterated solution and there is possibility to have more feasible accepted test suites.

PAPR Reduction in OFDM Signal by Incorporating Mu-Law Companding Approach into Enhanced PTS Scheme

Abstract Orthogonal Frequency Division Multiplexing (OFDM) is a potential transmission approach for high capacity communication systems. Despite the many advantages of OFDM, the major downside is the high peak-to-average power ratio (PAPR) which increases the system complexity, reduces the efficiency of the system, causes degradation in BER performance, and makes OFDM sensitive to nonlinear distortion in the transmission. Various methods have been proposed to deal with the PAPR problem, including the partial transmit sequence (PTS) that has attracted considerable attention. Hence, this paper presents a hybrid approach combining an enhanced PTS technique with Mu-Law companding. The PTS technique was enhanced through improving its sub-block partitioning scheme, where the enhanced partitioning scheme consolidated a conventional interleaved partitioning into an adjacent partitioning scheme. This incorporation of Mu-Law characteristic in time domain for PAPR reduction in OFDM essentially enhances the PAPR reduction performance, based on using numerical simulation results. Consequently, though the pseudorandom sub-block partition method obtains better PAPR reduction more than the other sub-block partition schemes (interleaved and adjacent) of ordinary PTS, it is quite difficult to be designed. The findings show that the enhanced PTS technique with Mu-Law companding, while maintaining low computational complexity, performs significantly better than the pseudorandom partitioning PTS on various types of modulation formats and subcarriers.

Test case generation for event driven systems using 4-way input test strategy

Since 1990s Combinatorial explosion is a crucial topic in software testing domain. In this domain the exhaustive input interaction test is not practical solution to test all software configurations for generating test cases. T-way test strategy provides a solution to overcome the problem. To date, most of the research on designing methods focus on combinations of input parameter values, where the T-way test strategy is applied to generate final test cases. However the methods are not applicable for event driven systems, where inputs are tested in the ordered form. In this paper a new method is proposed on T-way strategy to generate test cases using 4-way input interaction technique. The generated test cases are compared with the existing 4-way strategies. Result shows that in most cases the proposed method is able to generate efficient test cases compared with existing 4-way methods.

Variable length adjacent partitioning for PTS based PAPR reduction of OFDM signal

Peak-to-Average power ratio (PAPR) is a major drawback in OFDM communication. It leads the power amplifier into nonlinear region operation resulting into loss of data integrity. As such, there is a strong motivation to find techniques to reduce PAPR. Partial Transmit Sequence (PTS) is an attractive scheme for this purpose. Judicious partitioning the OFDM data frame into disjoint subsets is a pivotal component of any PTS scheme. Out of the existing partitioning techniques, adjacent partitioning is characterized by an attractive trade-off between cost and performance. With an aim of determining effects of length variability of adjacent partitions, we performed an investigation into the performances of a variable length adjacent partitioning (VL-AP) and fixed length adjacent partitioning in comparison with other partitioning schemes such as pseudorandom partitioning. Simulation results with different modulation and partitioning scenarios showed that fixed length adjacent partition had better performance compared to variable length adjacent partitioning. As expected, simulation results showed a slightly better performance of pseudorandom partitioning technique compared to fixed and variable adjacent partitioning schemes. However, as the pseudorandom technique incurs high computational complexities, adjacent partitioning schemes were still seen as favorable candidates for PAPR reduction.

Behavior of modified MVDR beamformer algorithm with realistic scenario

Smart antenna is a system based on the antenna elements which are distributed uniformly as array and on the beamformig (BF) algorithm. Each element in the array receives the wave plane signals individually, and then, the beamformer tries to produce the optimum weight for each element with respect to the reference element in the array. This technique is called beamforming. MVDR is one of the most important algorithms that provide optimum weight. The array elements are weighted to direct the main beam of the transmitted energy to the direction of the desired signal as well as direct null towards undesired signal. Mismatch may be occurs due to the location of reference element within the array. Mismatch in MVDR leads to suppress the desired signal and treats as interference. This paper presents a new technique to re-localize the selected reference element within the array. The reference element is chosen to be in the middle of the array instead of one end side of the array. The new location becomes more realistic with respect to received signals directions. Simulation results clarify that the modified MVDR overcomes the mismatch and self null phenomena in classical MVDR.

Effect of partition length variability on the performance of adjacent partitioing PTS in papr reduction of OFDM systems

Peak-to-Average Power Ratio (PAPR) reduction is an attractive research topic among the OFDM transmission research communities. Partial Transmit Sequence (PTS) has been a promising candidate out of the proposed PAPR reduction techniques without any distortion. In any PTS system, partitioning of the OFDM frame into disjoint sub-blocks is a crucial step. Adjacent partitioning (AP) is a rather simple partitioning scheme achieving attractive PAPR reduction performance. In this paper, we investigate effects of the length variability of disjoint sub-blocks on AP based PTS systems. In order to compare performance of variable length adjacent partitioning with the ordinary PTS scheme, we simulated other partitioning schemes, namely, interleaved, pseudorandom and fixed length adjacent partitioning for various types of modulation. Simulation results showed that the variable length adjacent partitioning is better than interleaved partitioning. However, it has worse PAPR reduction performance compared to the traditional adjacent and pseudorandom techniques.