Given the nature of broadcasting systems having limited feedback to the transmitter, impairments induced during transmission need to be coped with at the receiver. In this paper, we focus on digital multimedia broadcasting (DMB) which is deployed in South Korea. An extensive measurement campaign conducted in a live DMB system resulted in a set of videos containing a wide range of syntax, freeze, and texture impairments. Subjective tests were conducted with participants from East Asia which rated the quality of DMB video clips with syntax, freeze, and texture impairments and the related repaired clips. The analysis of the obtained quality ratings has revealed the potential of quality of experience (QoE) improvement of each of the three impairment types. The results support the conjecture that syntax repair offers the largest QoE improvement followed by freeze repair and texture repair. This finding can assist system developers of digital broadcasting systems in deciding about the range of repair techniques to be engaged subject to, e.g., QoE, complexity, and latency constraints.

The advancements of high resolution display technologies support applications ranging from mobile multimedia streaming to automotive cockpits and infotainment systems. Given the limited transmission and processing resources in a mobile communication context, a large number of upscaling methods for restoring high-resolution visual content from low-resolution representations have been proposed and assessed from a theoretical point of view. This paper, therefore, deals with the practical implementation of state-of-the-art upscaling methods on development boards. The proposed tool chain and solutions may be applied as a general framework for the implementation of current and future upscaling methods on resource limited devices.

This paper studies a header syntax repair approach for quality enhancement of digital video broadcasting (DMB) videos. A sensitivity analysis of the impact of transmission errors in different parts of the header of the underlying MPEG-2 transport stream packets on DMB video quality is provided. On this basis, a header syntax repair approach is presented using header masks and bounded minimum distance decoding of the headers of the received DMB packets. Objective and subjective quality assessment show a tremendous improvement in the quality of the header syntax repaired DMB video clips. The concepts of the header syntax repair approach proposed for packets of DMB video streams may also be adapted to the syntax of packet formats of other digital video standards.

Modern optimization problems in economics, medicine, and engineering are becoming more complicated and have a convoluted search space with multiple minima. These problems are multimodal with objective functions exhibiting multiple peaks, valleys, and hyperplanes of varying heights. Furthermore, they are nonlinear, non-smooth, non-quadratic, and can have multiple satisfactory solutions. In order to select a best solution among several possible solutions that can meet the problem objectives, it is desirable to find many such solutions. For these problems, the gradient information is either not available or not computable within reasonable time. Therefore, solving such problems is a challenging task. Recent years have seen a plethora of activities to solve such multimodal problems using non-traditional methods. These methods are nature inspired and are becoming popular due to their general applicability and effective search strategies. In this chapter, we assess the ability of an improved bat algorithm (IBA) to solve multimodal problems in noise-free and additive white Gaussian noise (AWGN) environments. Numerical results are presented to show that the IBA can successfully locate multiple solutions in both noise-free and AWGN environments with a relatively high degree of accuracy.

In real-world engineering problems, several conflicting objective functions have often to be optimized simultaneously. Typically, the objective functions of these problems are too complex to solve using derivative-based optimization methods. Integration of navigation and radar functionality with communication applications is such a problem. Designing sequences for these systems is a difficult task. This task is further complicated by the following factors: (i) conflicting requirements on autocorrelation and crosscorrelation characteristics; (ii) the associated cost functions might be irregular and may have several local minima. Traditional or gradient based optimization methods may face challenges or are unsuitable to solve such a complex problem. In this paper, we pose simultaneous optimization of autocorrelation and crosscorrelation characteristics of Oppermann sequences as a multiobjective problem. We compare the performance of prominent state-of-the-art multiobjective evolutionary meta-heuristic algorithms to design Oppermann sequences for integrated radar and communication systems.

Performance of polyphase sequences in radar applications can be evaluated using measures including autocorrelation function, integrated sidelobe ratio (ISLR), and peak-to-sidelobe ratio (PSLR). In this paper, we adopt particle swarm optimization to find optimal parameters of Oppermann sequences such that sequences with optimal ISLR and PSLR are generated. This class of sequences has been chosen as it allows to design for a wide range of correlation characteristics by essentially controlling three parameters. A sequence design example is provided in order to illustrate that particle swarm optimization is indeed well-suited to produce optimal sequence designs with respect to the considered performance measures.

The cross-ambiguity function (CAF) relates to the correlation processing of signals in radar, sonar, and communication systems in the presence of delays and Doppler shifts. It is a commonly used tool in the analysis of signals in these systems when both delay and Doppler shifts are present. In this chapter, we aim to tackle the CAF synthesization problem such that the synthesized CAF approximates a desired CAF. A CAF synthesization problem is addressed by jointly designing a pair of waveforms using a metaheuristic approach based on the echolocation of bats. Through four examples, it is shown that such an approach can be used as an effective tool in synthesizing different types of CAFs.

Modern engineering and scientific optimisation problems are becoming complicated. In order to cope with the increasing level of difficulty of these problems, optimisation methods are required to find more than one solution to these problems. The aim of this paper is to gain an insight into the ability of cuckoo search to locate more than one solution for multimodal problems. We also study the performance of this algorithm in the additive white Gaussian noise. Numerical results are presented to show that the cuckoo search algorithm can successfully locate multiple solutions in both non-noise and additive white Gaussian noise with relatively high degree of accuracy.

Test functions are important to validate and compare the performance of various optimization algorithms. In previous years, there have been many test or benchmark functions reported in the literature. However, there is no standard list or set of benchmark functions with diverse properties that algorithms may be tested upon. On the other hand, any new optimization algorithm should be tested by a diverse range of test or benchmark functions so as to see if it can solve certain types of problems or not. For this purpose, we compile here 140 benchmark functions for unconstrained optimization problems.

Test functions are important to validate and compare the performance of optimization algorithms. There have been many test or benchmark functions reported in the literature; however, there is no standard list or set of benchmark functions. Ideally, test functions should have diverse properties so that can be truly useful to test new algorithms in an unbiased way. For this purpose, we have reviewed and compiled a rich set of 175 benchmark functions for unconstrained optimization problems with diverse properties in terms of modality, separability, and valley landscape. This is by far the most complete set of functions so far in the literature, and tt can be expected this complete set of functions can be used for validation of new optimization in the future.

The cross-ambiguity function (CAF) is commonly used to analyze the delay-Doppler characteristics of signals in radar, sonar, and communication systems. Accordingly, a CAF relates to the correlation processing of signals in the presence of delays and Doppler shifts. In this paper, we use a metaheuristic approach to address the CAF synthesis problem by jointly designing a pair of waveforms. The CAF of waveforms designed in this way, approximates a desired pre-defined CAF. It turns out that the waveforms designed by this approach have the benefit of low peak-to-average power ratios. Numerical examples are presented to show that nature-inspired metaheuristic algorithms can be used as an effective tool to synthesize different types of CAFs.

Random walks play an important and central role in metaheuristic and stochastic optimization algorithms. The two key components of the search process in metaheuristic algorithms (MAs) are intensification and diversification. The overall efficiency of a metaheuristic optimization algorithm depends on a sound balance between these two components. In MAs, exploration is achieved by randomization in combination with a deterministic procedure. In this way, the newly generated solutions are distributed as diversely as possible in the problem search space. In most of the MAs, randomization is realized using a uniform or Gaussian distribution. However, this is not the only way to achieve randomization. In recent years, the use of Lévy distribution has emerged as an alternative to uniform or Gaussian distributions. In view of these details, this chapter focuses on using Lévy flights (LFs) in the context of global optimization. A survey of the most important MAs using LFs to achieve intensification and diversification for solving global optimization problems is presented. The different components and concepts of Lévy-flight-based MAs are discussed and their similarities and differences are analyzed.

Integration of multiple functions such as navigation and radar tasks with communication applications has attracted substantial interest in recent years. In this chapter, we therefore focus on the waveform optimization for such integrated systems based on Oppermann sequences. These sequences are defined by a number of parameters that can be chosen to design sequence sets for a wide range of performance characteristics. It will be shown that meta-heuristic algorithms are wellsuited to find the optimal parameters for these sequences. The motivation behind the use of biologically inspired heuristic and/or meta-heuristic algorithms is due to their ability to solve large, complex, and dynamic problems

The design of integrated radar and communication systems may be based on sets of polyphase sequences such as Oppermann sequences. In this paper, we derive an analytical expression for the cross-ambiguity function of weighted pulse trains with Oppermann sequences. Further, the auto-ambiguity function is deduced from this as a special case. Numerical examples are provided to illustrate the relationship between sequence parameters and performance characteristics.

The performance of conventional polyphase pulse compression codes such as the Frank, Frank-Zadoff-Chu (FZC), P1, P2, P3, P4, and Px codes will be compared with Oppermann codes. While the majority of the former code classes focus on radar applications, Oppermann codes have been discussed only within the context of code-division multiple-access (CDMA) systems. We therefore consolidate findings on the conventional codes and extend the performance assessment to Oppermann codes by accounting for Doppler shifts as needed in radar applications. It is shown that Oppermann codes can conceptually support integrated radar and communication systems as compared to the P1, P2, P3, P4, and Px codes where this is not readily feasible. The numerical results given here illustrate that Oppermann codes outperform Px codes in the presence of Doppler shifts as supported by the ambiguity function.

In this paper, we consider the design of integrated radar and communication systems that utilize weighted pulse trains with the elements of Oppermann sequences serving as complex-valued weights. An analytical expression of the ambiguity function for weighted pulse trains with Oppermann sequences is derived. Given a family of Oppermann sequences, it is shown that the related ambiguity function depends only on one sequence parameter. This property simplifies the design of the associated weighted pulse trains as it constrains the degrees of freedom. In contrast to the single polyphase pulse compression sequences that are typically deployed in radar applications, the families considered in this paper form sets of sequences. As such, they readily facilitate also multiple-access in communication systems. Numerical examples are provided that show the wide range of options offered by Oppermann sequences in the design of integrated radar and communication systems.

This paper describes the comparison between constant envelope root-of-unity (CE-RU) and Nyquist filtered quadriphase sequences for code division multiple access (CDMA) applications. The salient feature of CE-RU filtering is the constant envelope property of the filtered sequences. The preservation of constant envelope of the sequences is desirable in fading environments. It is shown that the correlation properties of CE-RU filtered 4-phase sequences are better than those of Nyquist filtered 4-phase sequences. Preliminary results on bit error rate (BER) performance of CE-RU versus the Nyquist filtered 4-phase sequences on the additive white Gaussian noise (AWGN) channel are also presented.

This paper studies the construction and effects of filtering on the correlation properties of 4-phase sequences that are suitable for the use in spread spectrum multiple access communications. An introduction on the construction methods of these sequences from the set of binary sequences is presented. The effects of filtering on the correlation properties by using Nyquist and constant envelope root-of-unity (CE-LI-RU) filtering technique are also investigated. It is shown that it is possible to achieve better correlation properties by using the latter filtering method while maintaining the perfect constant envelope, which is not possible with Nyquist filtering

Due to the availability of potentially large sets of sequences with good correlation characteristics, the interest in the implementation of complex spreading sequences (CSS) in code division multiple access (CDMA) systems, has increased dramatically. In this paper, the simulated bit error rate (BER) performance of a synchronous balanced quadrature phase shift keying (QPSK) CDMA system, employing different classes of CSS, is presented for Gaussian and multipath fading channel conditions.