optimal threat evaluation and weapon assignment algorithm for 

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multi-target air-borne threats. The algorithm provides a near optimal solution to the defense resource allocation problem while maintaining constraint satisfaction. The model used is kept flexible to compute the most optimal value for all classes of parameters. 

Figure 2: Graphical representation of TEWA along with two critical concerns found in multi-target scenarios Proposed solution tends to improve the optimality of the solution and assigns the most suitable values to critical parameters sued in TEWA decision making at the expense of extra computation. Section 2 of this paper presents literature survey. Section 3 covers our approach to TEWA along with parameter classification. The performance of proposed model is compared with an alternative greedy algorithm and the strengths and weaknesses of proposed algorithm are briefly discussed in section 4. Section 5 finally concludes this report.

## Ii. Literature Survey

TEWA is a complex system, having maximal or near maximal utilization of constrained resources as one of extreme important external factor. Main purpose of TEWA is to address two critical concerns related to multi-target scenarios i.e. deciding the order in which threats should be neutralized and deciding which WS to be used to neutralize a particular target. First concern relates to TE while weapon selection decision is the task of WA process. The subsequent part of this section discusses these two processes in detail. Figure 3 shows general classification of TE and WA models along with proposed hybrid solution and an outline of pre-processing phase. 

Tin G. and P. Cutler classified parameters related to TEWA 
into critical and sorting parameters, in [4]. We have amended this classification a little and divided the main parameters used in TEWA processing into three overlapping categories i.e. 

- **Triggering Parameters:** This class of parameters represents different thresholds used in TEWA system, to initiate a certain function. For example initial threat index is used to trigger TEWA process, status of a Defended Asset (DA) and Weapon System (WS) to be allotted (like Free to Fire, On Hold and Tight). 

- **Sorting Parameters:** Parameters belonging to this category are used to rank the threats, DAs and WSs. 

Main parameters include threat priority - that sorts the targets from the most threatening to the least threatening, Opportunity Index - a value indicating intent and capability of a target to inflict injury to a DA, calculated using Intent parameters and Capability parameters mentioned in section 2, kill capability (K.C) of a DA (a probability assigned to each DA 
based on the capability of a DA to destroy a particular type of threat) , lethality Index, condition (Up, Down, Destroyed) and status of a WS, time to DA, time to WS. 

- **Scheduling Parameters:** This class refers to the parameters that are used to assign a target either to a DA or to a WS. For example, weight of DA-Target pair (parametric equation using K.C in combination with Time to DA and load on DA), Weight of WSTarget pair (Time to WS in combination with Required elevation, Maximum elevation of a WS, Lethality Index, Stabilization time and Rate of Fire (ROF) of a WS 

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## A. Threat Evaluation (Te)

TE relates to threat ranking from the most threatening to the least threatening to decide the order in which threats should be neutralized. It consists of multiple systematic and operational activities designed to identify, evaluate, and manage anything that might pose a threat to identifiable targets [5]. TE is highly dependent on established situational picture i.e. target's current state estimates along with available contextual information (location of the defended assets (DAs) and attributes of Weapon Systems (WSs)) [6]. It can be seen as an ongoing two step process, where in first step, we determine if an entity intends to inflict damage to the defending forces and its interests, and in second stage we rank targets according to the level of threat they pose [7]. Typically threat evaluation has been seen from two perspectives: 