Radar Signal Processing for Interference Mitigation

It is necessary for radars to suppress interferences to near the noise level to achieve the best performance in target detection and measurements. In this dissertation work, innovative signal processing approaches are proposed to effectively mitigate two of the most common types of interferences: jammers and clutter. Two types of radar systems are considered for developing new signal processing algorithms: phased-array radar and multiple-input multiple-output (MIMO) radar. For phased-array radar, an innovative target-clutter feature-based recognition approach termed as Beam-Doppler Image Feature Recognition (BDIFR) is proposed to detect moving targets in inhomogeneous clutter. Moreover, a new ground moving target detection algorithm is proposed for airborne radar. The essence of this algorithm is to compensate for the ground clutter Doppler shift caused by the moving platform and then to cancel the Doppler-compensated clutter using MTI filters that are commonly used in ground-based radar systems. Without the need of clutter estimation, the new algorithms outperform the conventional Space-Time Adaptive Processing (STAP) algorithm in ground moving target detection in inhomogeneous clutter. For MIMO radar, a time-efficient reduced-dimensional clutter suppression algorithm termed as Reduced-dimension Space-time Adaptive Processing (RSTAP) is proposed to minimize the number of the training samples required for clutter estimation. To deal with highly heterogeneous clutter more effectively, we also proposed a robust deterministic STAP algorithm operating on snapshot-to-snapshot basis. For cancelling jammers in the radar mainlobe direction, an innovative jamming elimination approach is proposed based on coherent MIMO radar adaptive beamforming. When combined with mutual information (MI) based cognitive radar transmit waveform design, this new approach can be used to enable spectrum sharing effectively between radar and wireless communication systems. The proposed interference mitigation approaches are validated by carrying out simulations for typical radar operation scenarios. The advantages of the proposed interference mitigation methods over the existing signal processing techniques are demonstrated both analytically and empirically

Mobile and Wireless Communications

Mobile and Wireless Communications have been one of the major revolutions of the late twentieth century. We are witnessing a very fast growth in these technologies where mobile and wireless communications have become so ubiquitous in our society and indispensable for our daily lives. The relentless demand for higher data rates with better quality of services to comply with state-of-the art applications has revolutionized the wireless communication field and led to the emergence of new technologies such as Bluetooth, WiFi, Wimax, Ultra wideband, OFDMA. Moreover, the market tendency confirms that this revolution is not ready to stop in the foreseen future. Mobile and wireless communications applications cover diverse areas including entertainment, industrialist, biomedical, medicine, safety and security, and others, which definitely are improving our daily life. Wireless communication network is a multidisciplinary field addressing different aspects raging from theoretical analysis, system architecture design, and hardware and software implementations. While different new applications are requiring higher data rates and better quality of service and prolonging the mobile battery life, new development and advanced research studies and systems and circuits designs are necessary to keep pace with the market requirements. This book covers the most advanced research and development topics in mobile and wireless communication networks. It is divided into two parts with a total of thirty-four stand-alone chapters covering various areas of wireless communications of special topics including: physical layer and network layer, access methods and scheduling, techniques and technologies, antenna and amplifier design, integrated circuit design, applications and systems. These chapters present advanced novel and cutting-edge results and development related to wireless communication offering the readers the opportunity to enrich their knowledge in specific topics as well as to explore the whole field of rapidly emerging mobile and wireless networks. We hope that this book will be useful for students, researchers and practitioners in their research studies

Secure protocols for wireless availability

Since wireless networks share a communication medium, multiple transmissions on the same channel cause interference to each other and degrade the channel quality, much as multiple people talking at the same time make for inefficient meetings. To avoid transmission collision, the network divides the medium into multiple orthogonal channels (by interleaving the channel access in frequency or time) and often uses medium access control (MAC) to coordinate channel use. Alternatively (e.g., when the wireless users use the same physical channel), the network users can emulate such orthogonal channel access in processing by spreading and coding the signal. Building on such orthogonal access technology, this dissertation studies protocols that support the coexistence of wireless users and ensure wireless availability. In contrast to other studies focusing on improving the overall e fficiency of the network, I aim to achieve reliability at all times. Thus, to study the worst-case misbehavior, I pose the problem within a security framework and introduce an adversary who compromised the network and has insider access. In this dissertation, I propose three schemes for wireless availability: SimpleMAC, Ignore-False-Reservation MAC (IFR-MAC), and Redundancy O ffset Narrow Spectrum (RONS). SimpleMAC and IFR-MAC build on MAC protocols that utilize explicit channel coordination in control communication. SimpleMAC counters MAC-aware adversary that uses the information being exchanged at the MAC layer to perform a more power e fficient jamming attack. IFR-MAC nulli ffies the proactive attack of denial-of-service injection of false reservation control messages. Both SimpleMAC and IFR-MAC quickly outperform the Nash equilibrium of disabling MAC and converge to the capacity-optimal performance in worst-case failures. When the MAC fails to coordinate channel use for orthogonal access or in a single-channel setting (both cases of which, the attacker knows the exact frequency and time location of the victim's channel access), RONS introduces a physical-layer, processing-based technique for interference mitigation. RONS is a narrow spectrum technology that bypasses the spreading cost and eff ectively counters the attacker's information-theoretically optimal strategy of correlated jamming