The Radar Resource Management problem in a multitarget joint tracking and classification scenario is considered. The problem is solved using a previously introduced dynamic budget-balancing algorithm that models the sensor tasks as Partially Observable Markov Decision Processes. It is shown that tracking and classification tasks can be considered as a single task type. Furthermore, it is shown how the task resource allocations can be jointly optimized using a carefully formulated cost function based on the task threat variance. Multiple two-dimensional radar scenarios demonstrate how sensor resources are allocated depending on the current knowledge of the target position and class. In contrast to previous approaches, the novelty of this paper lies in combining tracking and classification performance into asingle cost function, preventing heuristic trade-offs. ... Read more

The radar resource management problem in a multitarget tracking scenario is considered. The problem is solved using a dynamic budget balancing algorithm. It models the different sensor tasks as partially observable Markov decision processes and solves them by applying a combination of Lagrangian relaxation and policy rollout. The algorithm has a generic architecture and can be applied to different radar or sensor systems and cost functions.This is shown through simulations of two-dimensional tracking scenarios. Moreover, it is demonstrated how the algorithm allocates the sensor time budgets dynamically to a changing environment in a nonmyopic fashion. Its performance is compared with different resource allocation techniques and its computational load is investigated with respect to several input parameters. ... Read more

Radar Resource Management in a multi-sensor multi-target scenario is considered. A dynamic resource balancing algorithm is proposed which optimizes target task parameters assuming an underlying partially observable Markov decision process (POMDP). By applying stochastic optimization methods, such as policy rollout, the POMDP is solved non-myopically. The approximately optimal approach is formulated assuming a central processor. Subsequently, a distributed implementation is introduced that converges to the same results as given by the centralized implementation and requires less computational resources. The performance of the proposed approach for both centralized and distributed implementation is demonstrated through dynamic tracking scenarios. ... Read more

Recent advances in Multi-Function Radar (MFR) systems led to an increase in their degrees of freedom. As a result, modern MFR systems are capable of adjusting many parameters during runtime. An automatic adaptation of the radar system to changing situations, like weather conditions, interference, or target maneuvers, is often mentioned in the context of MFR and is usually called Radar Resource Management (RRM). This thesis aims at developing a generic framework and approximately optimal algorithmic solutions for solving RRM problems. This is achieved by formulating the sensor tasks as Partially Observable Markov Decision Processes (POMDPs). Although the focus is on MFR, the approach is not limited to such sensor systems and has broader applicability. In Chapter 2, a first step is taken by investigating Lagrangian Relaxation (LR) and the subgradient method for optimally distributing the sensor resources to the different tasks in a multi-target tracking scenario. A constrained optimization problem is formulated. Using LR, the constraints can be included in the cost function. In a time-invariant scenario, it is shown that the proposed Optimal Steady-State Budget Balancing (OSB) algorithm will lead to balanced budgets based on track parameters like maneuverability and measurement uncertainty. The time-invariant scenario is a special case of general tracking scenarios, and the presented solution can be seen as the optimal POMDP solution in that case. Since real-world applications quickly lead to time-varying scenarios, it is demonstrated how the approach can be extended to such cases. Finally, the proposed method is compared with other budget assignment strategies. Subsequently, the tracking tasks are explicitly formulated as POMDPs, and the novel Approximately Optimal Dynamic Budget Balancing (AODB) algorithm is proposed in Chapter 3. The algorithm applies a combination of LR and Policy Rollout (PR). PR is a Monte Carlo sampling method for POMDPs to find the expected future cost. Due to its generic architecture, the framework can be applied to different radar or sensor systems and cost functions. In a time-invariant scenario, the algorithm calculates a solution close to the optimal steady-state solution, as presented in Chapter 2. This is shown through simulations of a two-dimensional tracking scenario. Moreover, it is demonstrated how the algorithm dynamically allocates the sensor time budgets to the tasks in a changing environment using a non-myopic fashion. Finally, the algorithm's performance is compared with different resource allocation techniques. Based on the previous results, Chapter 4 conducts a detailed investigation of the computational load of the AODB algorithm. It is shown how the choice of several input parameters influences computational performance. Additionally, Model Predictive Control (MPC) is applied in the same framework as an alternative POMDP solution method. Compared to stochastic optimization methods such as PR, the computational load is dramatically reduced while the resource allocation results are similar. This is shown through simulations of dynamic multi-target tracking scenarios in which the cost and computational load of different approaches are compared. So far, this thesis has used tracking scenarios to demonstrate the validity of the proposed algorithms. Chapter 5 shows how to apply the proposed framework and algorithmic solution to a multi-target joint tracking and classification scenario. It is shown that tracking and classification can be considered in a single task type. Furthermore, it is shown how the task resource allocations can be jointly optimized using a single carefully formulated cost function based on the task threat variance. Multiple two-dimensional radar scenarios demonstrate how sensor resources are allocated depending on the current knowledge of the target position and class. Chapter 6 extends the single-sensor approach shown in the previous chapters to multiple sensors and demonstrates the usefulness of the proposed algorithm in two different multi-sensor multi-target tracking scenarios. The first scenario considers a generic surveillance situation. An approximately optimal approach based on the previously proposed algorithm is formulated assuming a central processor. Subsequently, a distributed implementation is introduced that converges to the same results as the centralized implementation and requires less computational resources. The performance of the proposed approach for both centralized and distributed implementation is demonstrated through dynamic tracking scenarios. The second scenario focuses explicitly on an automotive application. The proposed generic framework and algorithmic solution are used to allocate scarce resources across multiple mobile sensor nodes. A central system manages the nodes' transmission and shares sensing data with other sensor nodes if this improves the overall track accuracy. The proposed method allocates time and frequency resources. Through simulation of a typical traffic situation, the validity of the approach is demonstrated. This thesis shows that the application of the proposed novel generic framework and algorithmic solution increases the performance w.r.t. heuristic solutions. Furthermore, it is demonstrated that the proposed framework allows the user to exchange elements such as cost function or POMDP solution method to adjust it to specific needs. The proposed method can be applied in many different areas involving different types of sensors. Possible applications include automotive scenarios, such as autonomous driving or traffic monitoring, (maritime) surveillance, and air traffic control. ... Read more

The radar resource management problem in a multi-target tracking scenario is considered. Partially observable Markov decision processes (POMDPs) are used to describe each tracking task. Model predictive control is applied to solve the POMDPs in a non-myopic way. As a result, the computational complexity compared to stochastic optimization methods such as policy rollout is dramatically reduced while the resource allocation results maintain similar. This is shown through simulations of dynamic multi-target tracking scenarios in which the cost and computational complexity of different approaches are compared. ... Read more

The radar resource management problem in a multitarget tracking scenario for multi-function radar is considered. To solve it, an optimal balancing of the sensor budget by applying Lagrangian relaxation and the subgradient method is proposed. In a time-invariant scenario it is shown that the proposed method will lead to balanced budgets based on track parameters like maneuverability and measurement uncertainty. Moreover, since real world applications quickly lead to time-varying scenarios, it is demonstrated how the approach can be extended to such cases. Furthermore the proposed method is compared with other budget assignment strategies. This paper is the first step into exploring optimal non-myopic solutions using a POMDP framework for surveillance radar applications involving detection, tracking and classification. ... Read more

The sensor resource management problem in a multi-object tracking scenario is considered. In order to solve it, a dynamic budget balancing algorithm is proposed which models the different sensor tasks as partially observable Markov decision processes. Those are being solved by applying a combination of Lagrangian relaxation and policy rollout. The algorithm converges to a solution which is close to the optimal steady-state solution. This is shown through simulations of a two-dimensional tracking scenario. Moreover, it is demonstrated how the algorithm allocates the sensor time budgets dynamically to a changing environment and takes predictions of the future situation into account. ... Read more

In this paper, waveforms for MIMO phased array radar to enhance cross-range resolution are investigated. The problem of high sidelobes in range created by the use of Hybrid Codes with a single waveform and spatial coding is considered and a method to reduce these sidelobes by the use of Golay sequences as spatial codes is proposed. It is shown that the proposed method achieves the same range performance as a phased array radar with one waveform, despite creating additional sidelobes in Doppler. ... Read more