• Design and study of a circular polarised conical-disc-backed spiral antenna for X-Band applications

      Ur-Rehman, Masood; Safdar, Ghazanfar Ali; Yang, Xiaodong; Chen, Xiaodong; University of Bedfordshire; Xidian University; Queen Mary University of London (IEEE, 2017-10-02)
      Design of a conical-disc-backed circular-polarized Archimedean single-arm spiral antenna is presented in this paper. The antenna operation covers the X -band frequencies ranging from 8 to 12 GHz. The antenna makes use of a very simple structure having the single-arm spiral backed by a cone-shaped metallic disc to achieve high gain, circular polarization, and unidirectional symmetric radiation near the boresight. The diameter of the antenna only measures to 40 mm. The simulated and measured results show that the antenna has a very good impedance matching (better than −10 dB), good right-hand circular polarization (with an axial ratio of ≤3 dB) throughout the frequency range of interest, and offers a maximum peak gain of 11.4 dBiC. The presented S11 response and radiation pattern results also show that the antenna offers excellent performance in the X -band with no need of a balun. Antenna usefulness is also established through a detailed parametric study and comparison with a traditional flat disc structure. Compact size, simple design, wide range, and high gain make the proposed antenna design a good choice for radar, terrestrial communications, and satellite/aerospace communications applications.
    • Energy management in LTE networks

      Kanwal, Kapil; Safdar, Ghazanfar Ali; Ur-Rehman, Masood; Yang, Xiaodong; University of Bedfordshire (IEEE, 2017-03-28)
      Wireless cellular networks have seen dramatic growth in number of mobile users. As a result, data requirements, and hence the base-station power consumption has increased significantly. It in turn adds to the operational expenditures and also causes global warming. The base station power consumption in long-term evolution (LTE) has, therefore, become a major challenge for vendors to stay green and profitable in competitive cellular industry. It necessitates novel methods to devise energy efficient communication in LTE. Importance of the topic has attracted huge research interestsworldwide. Energy saving (ES) approaches proposed in the literature can be broadly classied in categories of energy efcient resource allocation, load balancing, carrier aggregation, and bandwidth expansion. Each of these methods has its own pros and cons leading to a tradeoff between ES and other performance metrics resulting into open research questions. This paper discusses various ES techniques for the LTE systems and critically analyses their usability through a comprehensive comparative study.
    • Interference mitigation in D2D communication underlaying LTE-A network

      Safdar, Ghazanfar Ali; Ur-Rehman, Masood; Muhammed, Mujahid; Imran, Muhammad Ali; Tafazolli, Rahim; University of Bedfordshire; Birmingham City University; University of Glasgow; University of Surrey (IEEE, 2016-10-25)
      The mobile data traffic has risen exponentially in recent days due to the emergence of data intensive applications, such as online gaming and video sharing. It is driving the telecommunication industry as well as the research community to come up with new paradigms that will support such high data rate requirements within the existing wireless access network, in an efficient and effective manner. To respond to this challenge, device-to-device (D2D) communication in cellular networks is viewed as a promising solution, which is expected to operate, either within the coverage area of the existing eNB and under the same cellular spectrum (in-band) or separate spectrum (out-band). D2D provides the opportunity for users located in close proximity of each other to communicate directly, without traversing data traffic through the eNB. It results in several transmission gains, such as improved throughput, energy gain, hop gain, and reuse gain. However, integration of D2D communication in cellular systems at the same time introduces new technical challenges that need to be addressed. Containment of the interference among D2D nodes and cellular users is one of the major problems. D2D transmission radiates in all directions, generating undesirable interference to primary cellular users and other D2D users sharing the same radio resources resulting in severe performance degradation. Efficient interference mitigation schemes are a principal requirement in order to optimize the system performance. This paper presents a comprehensive review of the existing interference mitigation schemes present in the open literature. Based on the subjective and objective analysis of the work available to date, it is also envisaged that adopting a multi-antenna beamforming mechanism with power control, such that the transmit power is maximized toward the direction of the intended D2D receiver node and limited in all other directions will minimize the interference in the network. This could maximize the sum throughput and hence, guarantees the reliability of both the D2D and cellular connections.
    • Review of machine learning based fault detection for centrifugal pump induction motors

      Sunal, Cem Ekin; Dyo, Vladimir; Velisavljevic, Vladan; ; University of Bedfordshire (IEEE, 2022-07-01)
      Centrifugal pumps are an integral part of many industrial processes and are used extensively in water supply, sewage, heating and cooling systems. While there are several review papers on machine learning-based fault diagnosis on induction motors, its application to centrifugal pumps has received relatively little attention. This work attempts to summarize and review recent research and development in machine learning-based pump condition monitoring and fault diagnosis. The paper starts with a brief explanation of pump operation including common pump faults and the main principles of the motor current signature analysis (MCSA) method. This is followed by a detailed explanation of various machine learning-based methods including the types of detected faults, experimental details and reported accuracies. The performances of different approaches are then presented systematically in a unified table. Finally, the authors discuss practical aspects and challenges related to data collection, storage and real-world implementation.