User Interface and RF-Front End Design for Radio Direction Finding-Miniature Unmanned Air Vehicles (RDF-MUAV)

Radio direction finding perform better at high altitude due to greater line of sight coverage. In this paper, the radio direction finding-miniature unmanned air vehicles (RDF-MUAVs) platform able to localize the beacon by accessing the direction of signal and report it back to the ground station immediately, improving search and rescue operations. RDF-MUAV system divided into four major part; RF front end design; RF software design; ground station design; and user interface (UI). This paper focuses on two out of the four major parts, which designing a good UI and RF front end to be integrated into the system. The UI is designed using Linux, Apache, MySQL, PHP (LAMP) architecture in Raspberry Pi platform that can display accurate data obtained from RDF-MUAVs. The UI is based on HTML which is lightweight, modifiable and can be accessed through smartphone, tablets, or personal computer. In the antenna design, phase direction finder method is chosen. The rotation of antenna can be done by moving the UAV to obtain the bearing to the source signal. Proposed type of antenna is Yagi-Uda antenna due to its high gain and relatively small size. The folded dipole is chosen as the driven element of the antenna due to its bandwidth characteristics and directivity. Result shows the function-al bandwidth is 200MHz which can accept electromagnetic waves from 500MHz to 600MHz and 900MHz to 1000MHz. Overall, the design implementations provide a feasible system in search and rescue operation

User clustering and resource allocation in downlinkCoMP with NOMA

In coordinated multipoint (CoMP) system, the cell-edge performance is improved by minimizing inter-cell interference (ICI) through coordination of resources. Additionally, the non-orthogonal multiple access (NOMA) has been introduced as a promising candidate to further enhance the throughput of next generation wireless communication systems. NOMA allows multiple users to access the wireless channel in the same bandwidth simultaneously, however at different transmit power. In joint transmission NOMA in CoMP (JT-NOMA-CoMP), multiple cells jointly transmit data to users using the same time-frequency resources, which significantly improves the system performance. In this paper, we present a low-complexity user clustering and resource allocation strategy in downlink JP-NOMA-CoMP system with multiple antenna. Based on computer simulation, we show that the proposed approach outperforms the conventional JP-OMA-CoMP and single antenna JP-NOMA-CoMP in terms of achievable sum rate

A hybrid predictive technique for lossless image compression

Compression of images is of great interest in applications where efficiency with respect to data storage or transmission bandwidth is sought.The rapid growth of social media and digital networks have given rise to huge amount of image data being accessed and exchanged daily. However, the larger the image size, the longer it takes to transmit and archive. In other words, high quality images require huge amount of transmission bandwidth and storage space. Suitable image compression can help in reducing the image size and improving transmission speed. Lossless image compression is especially crucial in fields such as remote sensing healthcare network, security and military applications as the quality of images needs to be maintained to avoid any errors during analysis or diagnosis. In this paper, a hybrid prediction lossless image compression algorithm is proposed to address these issues. The algorithm is achieved by combining predictive Differential Pulse Code Modulation (DPCM) and Integer Wavelet Transform (IWT). Entropy and compression ratio calculation are used to analyze the performance of the designed coding. The analysis shows that the best hybrid predictive algorithm is the sequence of DPCM-IWT-Huffman which has bits sizes reduced by 36%, 48%, 34% and 13% for tested images of Lena, Cameraman, Pepper and Baboon, respectively

Negative refraction metamaterial with low loss property at millimeter wave spectrum

The design of the millimetre-wave (MMW) metamaterials (MMs) unit cell operates at 28 GHz is presented and numerically investigated. The proposed structure composed of a modified split ring resonator (MSRR) printed on both sides of the substrate layer. Popular MM structures such as S-shape, G-shape, and Ω-shape are adjusted to operate at the 28 GHz for comparison purpose. MSRR achieves a wide bandwidth of 1.1 GHz in comparison with its counterparts at the resonance frequency. Moreover, the proposed structure presents very low losses by providing the highest transmission coefficient, S21, at the corresponding frequency region. The radiation loss is substantially suppressed and the negativity of the constitutive parameters of the proposed MM structure is maintained. By applying the principle of the electromagnetically induced transparency (EIT) phenomenon, the MSRR unit cell induces opposite currents on both sides of the substrate which leads to cancelling out the scattering fields and suppresses the radiation loss. The constitutive parameters of the MM structures are retrieved using well-known retrieval algorithm. The proposed structure can be used to enhance the performance of fifth-generation (5G) antenna such as the gain and bandwidth

Resource allocation for downlink coordinated multipoint (CoMP) in LTE-advanced

Coordinated multipoint (CoMP) in LTE-Advanced is considered as a promising way to enhance spectrum efficiency in interference-limited wireless network through base station (BS) cooperation. However, resource allocation is one of the key challenges faced by CoMP network because resource allocation strategy of one cell affects the other cells' performance. Moreover, due to the scarcity of wireless network resources such as bandwidth and power, efficient resource allocation strategy is always desirable. In this paper, a low-complexity resource allocation strategy in CoMP that aims to achieve high network throughput is presented. The resource allocation strategy consists of three modules which are performed sequentially; user allocation module, subcarrier allocation module and power allocation module. Our simulation study shows that the proposed strategy gives significant performance gain in CoMP LTE-Advanced network

Liquid properties inspired non-cooperative resource allocation for femtocell networks

This paper addressed the problem of decentralized and non-cooperative resource allocation among resource sharing base stations in multi-channel wireless access networks. Inspired by cohesion and adhesion properties of liquid form of matter, we propose a sophisticated yet elegant technique in ensuring nearoptimal individual and overall utility of the resource shared base stations. While using game theoretic framework to represent non-cooperative nature of the decision-makers, this scheme will induce cooperation-like behaviour to self-interested players resulting in significant increase of utility and faster convergence as compared to generic distributed resource allocation technique

Inter-cell interference mitigation and coordination in comp systems

Coordinated Multi-Point (CoMP) transmission and reception is seen as a promising technology to achieve higher spectral efficiency in LTE-Advanced systems. Base stations cooperation can be one of the most important enabling technologies beneficial in scenarios with high inter-cell interference (ICI). In this paper, interference mitigation and coordination schemes in CoMP are being discussed. Simulation study to show the significant effect of ICI to cell-edge performance is presented. In this work, we proposed an interference cancellation scheme with minimal backhaul requirements in addition to existing inter-cell interference coordination (ICIC) schemes

Communications in computer and information science: techniques on relaying for LTE-advanced network

Relay-assisted cellular network is a major concern in research studies around the world as it can aid the cell to achieve coverage extension and capacity enhancement. Long Term Evolution-Advanced (LTE-A), a candidate from Third Generation Partnership Project (3GPP) has include relaying as one of its key technologies to meet International Mobile Telecommunications (IMT) Advanced requirements. This article focuses on relay architectures from LTE-A and the types of relay defined in the standard. Pros and cons of developed relaying strategies, transmission schemes together with relay selection pairing scheme are also reviewed. This article also provides simulation results comparing performance between transmission with and without the usage of relay. In addition, recent studies extending the relaying concept such as cognitive and cooperative relaying as a hot research topic are also discussed