In this thesis, we study channel estimation in time-varying cooperative network. Since channels vary with time, we insert training blocks periodically to trace channel variation. In this work, we adopt Kalman filter to trace channel variation due to its low complexity. By storing previous channel estimate, Kalman filter simply requires to process next received vectors to update current channel estimate. We use all past observations to estimate current channel state to avoid wasting information. In content of cooperation, we directly estimate effective channel from source through relay to the destination. The reason is that, we separately estimate the source-relay and relay-destination links, relays need extra efforts to estimate the channel and feedback estimates to the destination. It will increase the computational loading on relays, and the feedback channel may suffer channel fading, resulting in more distortion of estimates. Therefore, the destination directly estimate effective channel, using Kalman filter to trace variation. Furthermore, we design pre-coding scheme on relays for forwarding training symbols in order to reduce channel estimation errors and obtain more accurate channel information. To detect data symbols, we need to channel state information over each data block as well. Therefore, estimates over previous training blocks are interpolated to estimate channel over data blocks based on LMMSE criterion. Since estimates over training blocks are obtained from Kalman filter, it consequently improves estimation quality of the channel over the data blocks. The main contributions of the thesis are optimal training design to reduce the estimation error, the estimation based on Kalman filter, and linearly combing the estimates to provide more accurate estimates of the channels over data blocks.

After the 1990s, Japan has been deeply influenced by international trends as well as its own political and economic development. With the traditional Tenno system, Japan confronted the rapid rise and impact of the civilians' social consciousness. The change can be observed and traced back to the period after the Great Hanshin earthquake in 1995, when a volunteering civic engagement started automatically and later spread up the realization and implementation of the Non-Profit Organizations (NPO) Act. Based on my observations regarding legal regulations and institutional changes , this dissertation constructs a society-centered theory to explore and to analyze the relationship between the Japanese government and NPOs during the new period. This dissertation also seeks to explain how civic social ideologies developed and promoted the NPO Act and the establishment of the new JICA. In order to be more precise on the topic, I examine the change and the development by dividing the progress into ¡§traditional period¡¨ and ¡§new period¡¨ with after the cold war in the 1990s. On reviewing the changes of patterns and features of the development, I study the new interactive modes between state and society. The emphasis of this study is to show how Japan accelerated the NPO and ODA legal regulation and institutional changes. Furthermore, the study discusses how, the unique and new type of intermediate organizations, that support NPOs, developed after the execution of the NPO Act, and how those agencies provided local governments with NPOs cooperative partnership. In addition, this dissertation uses the platform of NPO Center of Chiba Prefecture as a case study, to analyze how to effectively combine members to spread the idea of ¡§NPO Prefecture,¡¨ and how to reorganize the system of new JICA in order to adopt outward environment and inward NPO participation. In other words, by demonstrating this new mode of cooperative partnership, the study expects to provide scholars with a reference of relative subjects and hopes to support the development of civil society in the developing countries.

This thesis investigates cooperative communication under the framework of cognitive radio network, which consists of primary and secondary users(PU & SU). The cooperative and cognitive radio network (CCR) adopts overlay dynamic spectrum access, That is, the SU simultaneously assists PU¡¦s transmission and transmits its own message using spectrum shared by primary user. The secondary user adopts decode-and-forward (DF) relaying to assist the primary user in transmitting message. With secondary user¡¦s assistance, the cooperative system can be treat as an equivalent multiple input single output (MISO) system to attain the spatial diversity of the primary user. The virtual MISO system can reduce the outage probability and enhance the transmission reliability. Under the requirement on primary user's transmission quality, secondary user transmits both user¡¦s signals simultaneously, so that the secondary acquires authority to access spectrum. Based on limited feedback regarding SNR of link between primary transmitter and receiver, secondary user allocates transmission power of primary signal and secondary signal to increase throughput and spectrum efficiency of SU subject to satisfying PU¡¦s outage constraint.

In this paper, we explore a cooperative code-division-multiple-access(CDMA) network. Users cooperate by forwarding each other¡¦s messages toward the destination. For simplicity, we assume that signal reception at the destination is well-synchronized. Due to practical design issues of CDMA systems, spreading waveforms allocated to users are not perfectly orthogonal in general. This results in multiple-access interference(MAI) at relays and destination. In CDMA uplink networks one common approach is to adopt decorrelating multi-user detection, but it will lead to noise amplification[16,17]. Therefore, we employ relay-assisted decorrelating multiuser detector(RAD-MUD) to mitigate MAI[1] by performing half of decorrelation at the relay and destination respectively. Based on the availability of CSI at relays, we can further adopt cooperative strategies to improve performance, e.g., transmit beamforming and selective relaying. The destination side will use minimum mean-square error(MMSE) detector to demodulate source symbols. In the existing literatures, channel state information(CSI) is assumed to be perfectly known at relay and destination. Actually, CSI is obtained from channel estimation, which usually contains estimation errors. In order to alleviate effects of channel estimation, one goal of this thesis is to design a robust system. Using estimated CSI and statistical property channel estimation errors, we design robust precoder and detector for the relay and destination. It shows that, even with distortion on channel estimations, the system still achieve excellent transmission efficiency. From the simulation results, it shows that the robust design is better than the system without consider channel estimation errors. Finally, we can see that the stable robust design can effectively mitigate effects of imperfect CSI.

In this thesis, we consider cognitive radio networks (CRN) combined with cooperative transmission, and investigate relay selection and power allocation strategies to maximize network lifetime (NLT). Cognitive radio network enhances spectrum efficiency resource by exploiting capabilities of cognition, learning and coordination against insufficient spectrum resource. In underlay cognitive radio network, however, transmitted energy of secondary user is constrained by interference level observed at primary user (PU). Though cooperation among secondary users (SU), multiple relays from virtual antenna array to improve transmission rate and reliability by exploiting spatial diversity. Most existing works assume that cooperative secondary users are plugged and with infinite energy device. In this thesis, we consider secondary cooperative systems where relays are battery-powered and with finite energy. We will investigate relay-selection schemes to reduce energy consumption of secondary relays and prolong network lifetime under the premises that secondary user¡¦s transmission rate is guaranteed and interference constraint of primary user is met. Our major difference between this work and previous works is the definition of network lifetime, which is defined by the maximum duration that the probability of secondary user¡¦s achievable rate below the guaranteed value, i.e. outage probability, is lower than a predetermined threshold. We proposed four relay-selection methods which take channel state information (CSI) and residual energy information (REI) into considerations to prolong network lifetime. Since the selection metrics of the proposed strategies requires CSI and REI of each individual relay, so the relay-selection can be accomplished in distributed manner through opportunistic sensing. No additional overhead is demanded for information exchange.

This dissertation addresses the design and stability analysis of decentralized, cooperative control laws for multivehicle systems. Advances in communication, navigation, and surveillance systems have enabled greater autonomy in multivehicle systems, and there is a shift toward decentralized, cooperative systems for computational efficiency and robustness. In a decentralized control scheme, control inputs are determined onboard each vehicle; therefore, decentralized controllers are more efficient for large numbers of vehicles, and the system is more robust to communication failures and reconfiguration. The design of decentralized, cooperative control laws is explored for a nonlinear vehicle model that can be represented in a double-integrator form. Cooperative controllers are functions of spacing errors with respect to other vehicles in the system, where the communication structure defines the information that is available to each vehicle. Control inputs are selected to achieve internal stability, or zero steady-state spacing errors, between vehicles in the system. Closed-loop equations of motion for the cooperative system can be written in a structural form, where damping and stiffness matrices contain control gains acting on the velocity and positions of the vehicles, respectively. The form of the stiffness matrix is determined by the communication structure, where different communication structures yield different control forms. Communication structures are compared using two structural analysis tools: modal cost and frequency-response functions, which evaluate the response of the multivehicle systems to disturbances. The frequency-response information is shown to reveal the string stability of different cooperative control forms. The effects of time delays in the feedback states of the cooperative control laws on system stability are also investigated. Closed-loop equations of motion are modeled as delay differential equations, and two stability notions are presented: delay-independent and delay-dependent stability. Lastly, two additional cooperative control forms are investigated. The first control form spaces vehicles along an arbitrary path, where distances between vehicles are constant for a given spacing parameter. This control form shows advantages over spacing vehicles using control laws designed in an inertial frame. The second control form employs a time-based spacing scheme, which spaces vehicles at constant-time intervals at a desired endpoint. The stability of these control forms is presented.

Pursuit and evasion games have garnered much research attention since the class of problems was first posed over a half century ago. With wide applicability to both civilian and military problems, the study of pursuit and evasion games showed much early promise. Early work generally focused on analytical solutions to games involving a single pursuer and a single evader. These solutions generally assumed simple system dynamics to facilitate convergence to a solution. More recently, numerical techniques have been utilized to solve more difficult problems. While many sophisticated numerical tools exist for standard optimization and optimal control problems, developing a more complete set of numerical tools for pursuit and evasion games is still a developing topic of research. This thesis extends the current body of numeric solution tools in two ways. First, an existing approach that modifies sophisticated optimization tools to solve two player pursuer and evasion games is extended to incorporate a class of state inequality constraints. Several classical problems are solved to illustrate the e±cacy of the new approach. Second, a new cooperation metric is introduced into the system objective function for multi-player pursuit and evasion games. This new cooperation metric encourages multiple pursuers to surround and then proceed to capture an evader. Several examples are provided to demonstrate this new cooperation metric.

Cooperative effect in the radiation process has been studied in for more than half a century. It is important in the sense of both basic physics and applied science. In this work, we study the dynamics of the cooperative spontaneous emission from an ensemble of N atoms which is uniformly excited by absorbing a single photon. We reveal that there are two different regimes in which the system exhibits totally different behaviors. One of them is the superradiance type of behavior: the system decays much quicker than single atom decay, with a decay rate proportional to N(λ/R)2, where N is the atom numbers, R is the size of the atom cloud, and λ is the wavelength. We call it Markovian regime because the sytem does not persist memory effect. The other regime is called non-Markovian regime and the system oscillates with effective Rabi oscillation frequency while slowly decaying with a rate proportional to the photon escaping rate. The effective Rabi oscillation is a new type of dynamics which analogs well known Cavity QED behavior. Particularly in the Markovian regime, we study the system dynamics as a manybody eigenfunction and eigenvalue problem. For a dense cloud, we find analytical solutions for the eigenstates and corresponding eigenvalues, which can help to generally describe the system dynamics for any initial conditions in this regime. One of the applications is in atom microscopy. We propose a scheme to measure the distance between two atoms/molecules beyond diffraction limit. It covers the whole range from half the wavelength to sub-nanometers, utilizing both the atom localization technique and the collective frequency shift effect due to the cooperative effect in the radiation of the two atoms. Another application that we propose is to generate Coherent XUV radiation using Raman-type superradaince. We prove that intense short pulses of XUV radiation can be produced by Raman type superradiance from an ensemble of atoms/ions driven by visible or IR laser pulses.

This thesis suggests a new framework for cooperative modeling which supports concurrency design protocol with a design history tracking function. The proposed framework allows designers to work together while eliminating design conflicts and redundancies, and preventing infeasible designs. This framework provides methods to track optimal design path and redundant design history in the overall design process. This cooperative modeling architecture consists of a modeling server and voxel-based multi-client design tool. Design change among server and multiple clients are executed using the proposed concurrency design protocol. The design steps are tracked and analyzed using Design Tracking Graph and Design Tracking Matrix (DTM), which provide a design data exchange algorithm allowing seamless integration of design modifications between participating designers. This framework can be used for effective cooperative modeling, and helps identify and eliminate conflicts and minimize delay. The proposed algorithm supports effective cooperative design functions. First, it provides a method to obtain the optimal design path which can be stored in a design library and utilized in the future design. Second, it helps capture modeling pattern which can be used for analyzing designer's performance. Finally, obtained redundancies can be used to evaluate designer?s design efficiency.

Cooperative learning is a major teaching method which is used by many instructors as their teaching framework. It has been proven better than individual and competitive teaching methods by raising higher group achievements and individual achievements with more diverse reasoning and logic thinking, and more creative ideas. Many researchers make their efforts in promoting the outcomes of cooperative learning from different viewpoints. One of them is Zone of Proximal Development (ZPD), which emphasizes that teachers and learners with higher capability can support other learners to develop their ZPD through proper scaffolding. Prior Knowledge plays an important role in scaffolding. In order to maximize the effect of scaffolding, learners supported by scaffolding must possess enough prior knowledge. At the same time, teachers must consider the whole teaching progress and it is difficult to be aware of every individual learner¡¦s learning progress and offer adaptive assistance to each of them. Thus, we propose two mechanisms: knowledge diagnostic and learning material developed by using IT techniques to promote learners¡¦ prior knowledge in a specific domain. Students were given different mechanisms and divided into twenty groups to resolve their cooperative tasks. Their cooperative learning outcomes were measured by tasks achievement and perceived of cooperation process that is composed of perceived of cooperation extent, perceived of task conflict and perceived of emotional conflict. The result shows that the combination of knowledge diagnostic and learning material can promote students¡¦ prior knowledge in the domain we selected. The result of cooperative learning outcomes shows that there is a positive relationship between prior knowledge and task achievement, and a positive relationship between prior knowledge and perceived of task conflict, but there is no significant relationship between prior knowledge and perceived of cooperation extent and nor between prior knowledge and perceived of emotional conflict.