The Front End of Innovation in Defense: A Comprehensive Literature Review

Abstract

Innovation management, a multifaceted organizational process encompassing opportunities and ideas from inception to implementation, demands a systematic approach, particularly in the critical initial phase known as the Front End of Innovation (FEI). This pivotal phase significantly influences the entire innovation management chain. Despite its recognized importance, FEI in the defense sector has yet to be systematically addressed in the academic literature. Recognizing the vital role of FEI in the defense sector, this study addresses this deficiency through a systematic review, scrutinizing 24 documents from the scientific literature (Scopus and Web of Science databases) and gray literature (government defense documents). This research systematically maps key activities identified in seminal FEI models. These activities include the identification and analysis of opportunities; generation, enrichment, and screening of ideas; product concept definition; and consideration of influencing factors. Concurrently, this work aligns defense practices with established innovation models and provides valuable insights for optimizing the management dynamics of the military innovation process. Through this systematic inquiry, this study contributes to a nuanced understanding of the FEI in the defense sector, offering practical implications for enhancing defense innovation development.

1. Introduction

Innovation management, a complex and broad organizational process covering the entire spectrum, from identifying new opportunities and ideas to their practical implementation, poses significant challenges for managers across all organizational levels [1].

Notably, innovation seldom fails due to a lack of creativity; instead, it is the absence of discipline that plays a pivotal role in innovation failures [2]. From this perspective, Boeddrich [3] contends that systematic and structured procedures in the early phase, known as the Front End of Innovation (FEI), are imperative to avert adverse effects throughout the innovation management chain.

Multiple researchers emphasize that enhancing FEI activities contributes positively to organizational outcomes, bolstering the likelihood of successful innovation development [3, 4, 5, 6, 7, 8, 9]. Yet, the successful adoption of a FEI model requires considering some factors like organizational size and culture, as well as decision-making styles [10, 11].

Despite the increasing attention to FEI as a complex and multidisciplinary field [12], the defense context of FEI has not been sufficiently addressed in the academic literature, a gap this study endeavors to address. Therefore, this research aims to unravel the dynamics of FEI in the military sector through a systematic literature review, focusing on the research question: How can the current literature on the early phase of the innovation process in defense be mapped within seminal FEI models?

This question is pertinent given the Armed Forces’ distinct organizational culture, demanding innovation to sustain high-tech operational capabilities and mainly requiring innovations capable of inducing technological surprise in the theater of operations. Aligning defense practices with established models in innovation literature can furnish invaluable insights for improving the management dynamics of the military’s initial innovation phase. Moreover, by reviewing approaches used by different countries, the study recognizes that the suitability and significance of FEI management practices can differ across national defense contexts. It emphasizes how cultural and procedural nuances impact the development and adoption of new technologies in military settings.

Structured around the research question, this paper is organized as follows: Section 2 provides a theoretical foundation on FEI, seminal FEI models, and defense peculiarities. Section 3 outlines the research methodology. Section 4 delineates the mapping of the FEI in the defense sector within seminal FEI models. Section 5 discusses salient aspects identified throughout the study. Finally, Section 6 highlights the concluding remarks, outlining directions for future research.

2. Theoretical foundation

Before exploring the current literature on the early stage of the innovation process in defense, it is essential to understand the foundational topics involved: the FEI concept, the seminal FEI models, and the unique aspects of the military sector.

2.1 Front end of innovation (FEI)

The Fuzzy Front End (FFE) refers to the earliest stage in the New Product Development (NPD) process. This term was popularized by Smith and Reinertsen [13], as pointed out by Khurana and Rosenthal [10].

In 2002, Koen et al. [14] proposed the term Front End of Innovation (FEI), considering that the adjective “fuzzy” is “mysterious, lacks accountability, and cannot be critically evaluated” ([14], p. 30). The new term dissociated the idea that the initial phase of the innovation process was nebulous and uncontrollable. In this approach, the FEI is described as “those activities that come before the formal and well-structured NPD process” ([14], p. 30).

Figure 1 illustrates the breakdown of the product innovation management process into three phases: FEI, NPD, and implementation (the commercialization of the product in the market). The circular shape of the FEI suggests that ideas should flow and iterate until the formal definition of products is developed. In contrast, the NPD phase is depicted as a series of sequential, well-structured, and chronologically ordered steps [14, 15].

Figure 1.

Breakdown of the product innovation management process. Source: Adapted from Koen et al. [14, 15].

The FEI emerges as a crucial driver of positive outcomes for new products and, consequently, the overall success of the business [16]. Markham [6] underscores the profound impact of early-phase activities on product performance, emphasizing that the success of the front end stands as the strongest independent predictor of all NPD performance variables.

Selecting an appropriate FEI model requires careful consideration of various factors, including organizational size and culture, as well as decision-making style [10, 11]. As a response to these diverse organizational needs, numerous FEI models have been developed over time, offering distinct approaches to navigate their complexities, as detailed in the next section.

2.2 Seminal FEI models

In an integrative literature review, Pereira et al. [12] found that 26% of articles related to FEI contributed in terms of frameworks, models, processes, tools, and methodologies, exemplifying endeavors to structure the early phase of the innovation process in specific contexts.

While recent contributions are significant, seminal works have produced models that served as reference points for structuring the FEI. Table 1 provides an overview of the four seminal models identified by Pereira et al. [12, 20].

References	Model	Overview
Cooper [17, 18]	Stage-Gate	Proposes a system with well-defined stages to launch new products into the market. The early stages represent the front end of innovation and make use of control gates.
Khurana and Rosenthal [10, 11]	Three Phase Front End	Presents an approach that connects business and product strategy with specific product-related decisions.
Koen et al. [14, 15]	New Concept Development	Provides methods, tools, and techniques suitable for managing the front end of innovation. Moreover, the authors seek a common vision and terminology for the FEI.
Reid and De Brentani [19]	The Fuzzy Front End of New Product Development for Discontinuous Innovations	Details an approach focusing on disruptive innovation, proposing a structure based on a reverse flow of information (from the outside world into the organization).

Table 1.

Seminal FEI models.

Source: Adapted from Pereira et al. [12, 20].

After providing an overview of the seminal FEI models, it is essential to delve into the main elements of their structures. The stage-gate model, proposed by Cooper [17, 18], offers a systematic approach to the FEI through its first three stages/gates, as depicted in Figure 2. The process unfolds in distinct phases as follows:

• Stage 0 (Discovery): In this inaugural stage, the organization actively generates ideas for new products.

• Gate 1 (Idea screen): Ideas undergo a concise evaluation based on strategic, feasibility, and market criteria. Financial considerations are deferred at this point. Accepted ideas proceed to the next phase.

• Stage 1 (Scoping): The accepted idea transitions into a project, initiating a dual evaluation process:

  • Market evaluation: Involves research, user contact, and conceptual testing to determine market size and acceptance.

  • Technical evaluation: Encompasses feasibility, costs, and development timelines.

• Gate 2 (Second screen): Comprehensive information from market and technical evaluations prompts a reassessment of the project’s viability. If approved, the project advances to the next stage.

• Stage 2 (Build business case): Positioned just before product development, this stage involves:

  • Assessing the project’s attractiveness.

  • Defining clear objectives.

  • Conducting market, technical, operational, and financial evaluations.

• Gate 3 (Development): A pivotal decision point where the organization determines resource allocation for project development [17, 18].

Figure 2.

The FEI within the stage-gate model. Source: Adapted from Cooper [17].

The Three Phase Front End model, proposed by Khurana and Rosenthal [10, 11], organizes the FEI into three distinct phases, as depicted in Figure 3.

• Pre-Phase Zero: This initial phase concentrates on the continuous identification of opportunities within the organization. It involves generating ideas and conducting technological and market analyzes. When a promising opportunity is identified, it triggers the transition to Phase Zero. The authors emphasize that this phase should occur continuously within the organization.

• Phase Zero: This phase is initiated when Pre-Phase Zero identifies a promising opportunity. Its primary objective is to define the concept of a new product.

• Phase One: Following the conceptualization of the new product, Phase One focuses on analyzing feasibility and planning the project to initiate the NPD process formally. It is crucial to maintain a constant interface with the organization’s product and portfolio strategy throughout the entire process.

Figure 3.

Three Phase Front End model. Source: Khurana and Rosenthal [11].

The New Concept Development (NCD) model, proposed by Koen et al. [14, 15], is a theoretical construction composed of the three fundamental concepts: controllable activities, “engine” and influencing factors. Controllable activities represent the elements that the organization can control. The “engine” encompasses the controllable aspects of the organization that are responsible for driving the activities of the FEI. Finally, the influencing factors are variables that have an impact on the FEI and are relatively outside of the organization’s control [14, 15]. Table 2 details the structure of the NCD model. In the structure of the NCD model, organizational capabilities are classified as an influencing factor because they usually change very slowly and are therefore uncontrollable. Alternatively, organizational capabilities can be incorporated into the “engine” to the extent that the organization can modify and control them [14].

Concepts	Elements
Controllable activities	Opportunity identification; Opportunity Analysis; Idea generation; Idea enrichment; Idea selection; Concept definition
“The engine”	Culture; Leadership; Business strategy
Influencing factors	Organizational capabilities; The outside world; Customer and competitor influences; Enabling sciences and technology

Table 2.

Structure of the NCD model.

Source: Koen et al. [14].

The model proposed by Reid and De Brentani [19] provides a unique focus on disruptive innovations, highlighting their distinct entry into the organization compared to incremental innovations. According to this model, disruptive innovations typically originate from the external environment. Figure 4 illustrates how the front end of the innovation process initiates its flow based on information from the external environment, involving the identification of unstructured problems and the recognition of opportunities. This model emphasizes that disruptive innovations follow a distinctive path, with the FEI process being strongly influenced by external inputs. The opportunities identified undergo thorough analyzes and decisions at various organizational levels before being formally integrated into an NPD project [19].

Figure 4.

The Fuzzy Front End of new product development for discontinuous innovations. Source: Reid and De Brentani [19].

The seminal models presented – Cooper’s Stage-Gate Model, Khurana, and Rosenthal’s Three Phase Front End Model, Koen et al.’s New Concept Development (NCD) Model, and Reid and De Brentani’s Model for Discontinuous Innovations – vary in focus, approach, depth, and structuring of activities. Despite these differences, a common thread emerges as they collectively address the FEI through key activities: identification and analysis of opportunities, generation, enrichment, and screening of ideas, product concept definition, and consideration of influencing factors (encompassing the outside world, market and technology information, scenario planning, competitive analysis, and organizational issues such as culture, leadership, strategy, portfolio, and capabilities).

The ultimate objective of these FEI activities is to formulate a well-defined product concept before entering the formal NPD stage. Table 3 establishes the correspondence between FEI activities and the structures of the seminal models.

Activities	Structure of the seminal models
Identification and analysis of opportunities	Discovery [17] Pre-Phase Zero [11] Identification and analysis of opportunities [14] Boundary interface [19]
Generation, enrichment, and screening of ideas	Discovery and idea screening [17] Pre-Phase Zero [11] Generation, enrichment, and selection of ideas [14] Gatekeeping interface [19]
Product concept definition	Scoping and build business case [17] Phase Zero and Phase One [11] Concept definition [14] Project interface [19]
Consideration of influencing factors; The outside world, market and technology information, scenario planning, competitive analysis, and organizational issues (culture, leadership, strategy, portfolio, and capabilities)	Strategic, feasibility, market, technical, operational, and financial criteria [17] Technological and market analysis, and product & portfolio strategy [11] Organizational capabilities, the outside world, customer and competitor influences, enabling sciences and technology, and “the engine” – culture, leadership, and business strategy [14] Environmental information, and scenario analysis at the corporate and project levels [19]

Table 3.

FEI activities and their relationship with the seminal models.

To mitigate potential ambiguities in the interpretation of certain terms related to the FEI, Table 4 provides standardized reference definitions. This table serves as a reference guide, providing clear and standardized definitions for key terms associated with the FEI, enhancing clarity and consistency in their interpretation.

Term	Definition
Opportunity	“A business or technology gap, that a company or individual realizes, that exists between the current situation and an envisioned future in order to capture competitive advantage, respond to a threat, solve a problem, or ameliorate a difficulty” ([14], p. 7).
Ideia	“The most embryonic form of a new product or service. It often consists of a high-level view of the solution envisioned for the problem identified by the opportunity” ([14], p. 7).
Product concept	“A well-defined form, including both a written and visual description, that includes its primary features and customer benefits combined with a broad understanding of the technology needed” ([14], p. 7).
The outside world	“Distribution channels, law, government policy, customers, competitors, and political and economic climate” ([14], p. 8).
Organizational culture	“A pattern of shared basic assumptions that was learned by a group as it solved its problems of external adaptation and internal integration, that has worked well enough to be considered valid and, therefore, to be taught to new members as the correct way to perceive, think, and feel in relation to those problems” ([21], p. 17).
Organizational leadership	“It is originally the source of the beliefs and values that get a group moving in dealing with its internal and external problems” ([21], p. 36). “Leadership is needed to help the group identify the issues and deal with them” ([21], p. 407).
Organizational strategy	“A shared understanding of core mission, primary task, and manifest and latent functions” ([21], p. 88).
Organizational portfolio	“Collection of projects, programs, and other activities that are grouped together to meet strategic business objectives. The practice of portfolio management is integral to the implementation of an organization’s overall strategic plan” [22].
Organizational capacity	In the context of dynamic capabilities theory, it is defined as “the firm’s ability to integrate, build, and reconfigure internal and external competences to address rapidly changing environments” ([23], p. 516).

Table 4.

Definitions for terms related to the FEI.

2.3 Defense sector

The defense sector holds strategic importance for nations, embodying a comprehensive “set of attitudes, measures, and actions undertaken by the State, with an emphasis on the military expression of the power, to safeguard national territory, sovereignty, and national interests against predominantly external threats, whether potential or manifest” ([24], p. 77). Characterized by complexity, the defense sector exhibits key features:

• High technological level: The defense industry requires substantial investments in research, development, and innovation to create sophisticated products such as aircraft, ships, weapons, and systems. These must operate safely and reliably under severe conditions [25], often characterized as Complex Products and Systems (CoPS). CoPS involve customization, production in small quantities by a few companies, integration of diverse knowledge areas, and a lifecycle spanning decades [26].

• Technological duality: Innovations developed for military purposes may have civilian applications (spin-off) and vice versa (spin-in) [27, 28]. Dual-use technologies, like GPS and the Internet, initially developed for defense, now find widespread civilian applications.

• Governmental dependence: The defense market is highly regulated and relies on government contracts, resulting in a strong dependence on public resources. From a demand perspective, the defense market operates as a monopsony, with the State being the primary purchaser of goods and services [29, 30, 31].

• High market concentration: Global defense market dominance by a few companies leads to limited competition and protectionist practices. Oligopolies in the defense market can collude, manipulate prices, limit competition, or engage in practices like dumping [32] to control strategic interests [31, 33].

• Vulnerability to geopolitical issues: The demand for defense equipment is influenced by geopolitical conflicts and international relations, resulting in a volatile market subject to sudden changes. Companies may exploit geopolitical issues for financial or strategic reasons, impacting commitments during times of national crisis [31, 34].

In summary, the defense sector is characterized by its strategic importance, technological advancement, dual-use nature, governmental dependence, market concentration, and vulnerability to geopolitical issues. This situation is a combination of a monopoly/oligopoly, where a few major global players dominate the supply, and a monopsony, where the State centralizes the demand. Recognizing these peculiarities highlights the need for a comprehensive exploration of FEI dynamics within the defense sector.

3. Methodology

In conducting this literature review, a comprehensive search strategy was employed, encompassing both academic and gray literature, as recommended by Thomé et al. [35]. The initial approach involved the following strategies for searching academic literature:

• Databases: Scopus and Web of Science (WoS), aligning with the methodology outlined by Ferreira et al. [36].

• Search string: The search string was crafted by combining key terms related to the FEI and the defense sector. The FEI-related terms were derived from a frequency analysis of authors’ keywords, following the methodology of Ferreira et al. [36]. To capture the comprehensive scope of the defense sector, terms related to aerospace were also incorporated, acknowledging that certain countries treat both topics as a unified strategic theme. For instance, the United States has the U.S. Space Force under its Department of Defense [37]. The search was conducted on September 21, 2023, focusing on terms found in the title, abstract, and keywords:

  • Scopus database: TITLE-ABS-KEY((“front end of innovation” OR “front-end of innovation” OR “front end innovation” OR “front-end innovation” OR “fuzzy front end” OR “fuzzy front-end”) AND (“military” OR “defense” OR “defense” OR “navy” OR “army” OR “air force” OR “aerospace” OR “aeronautic*” OR “astronautic*” OR “avionics”)).

  • WoS database: TS = ((“front end of innovation” OR “front-end of innovation” OR “front end innovation” OR “front-end innovation” OR “fuzzy front end” OR “fuzzy front-end”) AND (“military” OR “defense” OR “defense” OR “navy” OR “army” OR “air force” OR “aerospace” OR “aeronautic*” OR “astronautic*” OR “avionics”)).

• Inclusion criteria: publications in English, Portuguese, or Spanish were considered, and the accessibility of the entire document was taken into account. Additionally, the publication had to address explicitly the FEI in the defense context.

The academic literature search yielded five documents from the Scopus database and two from WoS. Upon analysis, one redundancy was identified, resulting in six unique documents. Subsequently, it was observed that two articles did not meet the inclusion criteria, leaving four documents within the review scope. Following this initial search, the snowball technique was applied to identify relevant documents citing or cited by the selected publications. Additional efforts were made to explore works authored by the selected publications’ authors, uncovering three more documents.

In parallel with the academic literature search, the exploration of government defense management agencies’ websites led to the identification of 17 more documents. Therefore, while the academic literature contributed documents presenting general aspects of FEI in the defense sector, the gray literature addressed defense management in specific nations, ensuring representation across continents and encompassing both developed and developing countries. The nations (or alliances) covered included Australia, Brazil, China, India, NATO (North Atlantic Treaty Organization), the United Kingdom, the United States, and South Africa.

Thus, a total of 24 documents were selected for review. It is noteworthy that, during the research, no review works similar to this article were found. The steps of the review are represented in summary in Figure 5, using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) diagram, a tool for presenting the flow of information through the different phases of a systematic literature review [38].

Figure 5.

Stages of the systematic literature review. Source: Adapted from Page et al. [38].

4. Front end of innovation in the defense sector

The investigation of FEI in the defense sector is structured based on content mapping of the selected review documents, focusing on key FEI activities outlined in Section 2.2. These activities include the identification and analysis of opportunities; generation, enrichment, and screening of ideas; product concept definition; and consideration of influencing factors.

4.1 Identification and analysis of opportunities

The identification and analysis of opportunities serve as the primary catalyst for the FEI process. It occurs when an organization recognizes a gap, whether related to business or technology issues. This gap represents the difference between the current state and a desired future state, presenting an opportunity that can be exploited to gain a competitive advantage, address a threat, solve a problem, or enhance a situation [14]. As stressed by Khurana and Rosenthal [11], the phase of identifying and analyzing opportunities should be an ongoing and continuous process within an organization.

In the defense sector, the identification and analysis of opportunities are intricately tied to Capability-Based Planning (CBP), a central process in strategic defense management [39, 40]. This strategic planning paradigm, initially utilized in the United States Nuclear Program during the 1960s, saw broader adoption by the U.S. Department of Defense in 2001, becoming a reference for armed forces worldwide [41]. From this standpoint, Table 5 provides a mapping of the phase of identification and analysis of opportunities within the documents reviewed.

Documents	Approaches	National context
United States [42]	CBP is implemented through the Joint Capabilities Integration and Development System (JCIDS). The strategic approach begins by identifying scenarios for the U.S. Armed Forces’ operations. Then, the necessary capabilities for each scenario are determined. Finally, existing capabilities are evaluated, and gaps are identified (a process called Capabilities-Based Assessment – CBA). The assessment of capabilities follows the acronym DOTmLPF-P, which incorporates the following elements: Doctrine, Organization, Training, Materiel, Leadership and education, Personnel, Facilities, and Policy.	USA
NATO [43]	CBP is implemented following the acronym DOTMLPF-I, which incorporates the following elements: Doctrine, Organization, Training, Materiel, Leadership, Personnel, Facilities, and Interoperability. Notably, the interoperability element is included in the approach, considering NATO comprises 32 member countries, listed alphabetically as follows: Albania, Belgium, Bulgaria, Canada, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Lithuania, Luxembourg, Montenegro, North Macedonia, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Turkey, the Netherlands, the United Kingdom, and the United States.	NATO
United Kingdom [44]	Implements CBP following the DLOD concept, referring to Defense Lines of Development. DLOD encompasses Training, Equipment, Personnel, Information, Doctrine & Concepts, Organization, Infrastructure, Logistics, and Interoperability. The latter is only sometimes listed as a separate line of development but is essential for combined operations with allies.	United Kingdom
Australia [45]	Implements CBP following the FIC concept, which stands for Fundamental Inputs to Capability. FICs include Organization, Command and management, Personnel, Collective training, Major systems, Facilities and training areas, Supplies, Support, and Industry.	Australia
Barton [46]	Implements CBP similarly to the U.S. DOTmLPF-P approach.	China
India [47] and South Africa [48]	They highlight the capability-based approach without defining specific analysis elements.	India and South Africa
Brasil [49, 50]	CBP is implemented following the acronym DOAMEPI, which includes the following elements: Doctrine, Organization (and/or processes), Training, Materiel, Education, Personnel, and Facilities. It is worth noting that Brazil maintains a capabilities catalog to support its CBP.	Brazil
Helfat and Peteraf [51], Salvato and Rerup [52], and Wallin et al. [53]	They emphasize the importance of the capability-based approach in supporting planning for the development of new technological products.	Generic (academic literature)

Table 5.

Approaches to identification and analysis of opportunities within the review documents.

4.2 Generation, enrichment, and screening of ideas

According to Koen et al. [14], the generation and enrichment of ideas follow the identification and analysis of opportunities. An idea, as conceptualized by the authors, represents the most preliminary form of a new product or service, typically outlining a high-level vision for the planned solution related to the identified opportunity [14]. Cooper [17], in the stage-gate model, underscores that ideas for new products must undergo initial screening, known as gate 1, before being integrated into an organization’s project [17]. Reid and De Brentani [19] also stress the importance of a formal analysis of opportunities/ideas at the corporate level before progressing to the project level [19].

In the defense sector, as outlined in Table 6, the identification of the need for a new product occurs when a capability gap analysis indicates the necessity for a new materiel solution. This triggers the formal process of acquiring a defense product. Table 6 provides a mapping of the phase of generation, enrichment, and screening of ideas within the reviewed documents.

Documents	Approaches	National context
United States [42, 54]	The American approach prioritizes non-materiel solutions when addressing capability gaps, incorporating adjustments in Doctrine, Organization, Training, Leadership and education, Personnel, Facilities, and/or Policy (DOTmLPF-P). The lowercase “m” in the acronym signifies this approach. If a materiel solution is deemed necessary, an Initial Capabilities Document (ICD) is drafted, justifying the need for a new acquisition process. The ICD outlines the identified capability gap, the concept of operations (CONOPS) detailing the expected operational context of the materiel solution, and associated risks. A validated ICD is mandatory for a Materiel Development Decision (MDD), initiating the life cycle of the new product.	USA
United Kingdom [44]	Following a model similar to that of the USA, the identification of the need for a materiel solution and the elaboration/approval of the concept of operations initiate the life cycle of a new product.	United Kingdom
Australia [45]		Australia
India [47]		India
South Africa [48]		South Africa
Brasil [55]		Brazil

Table 6.

Approaches to idea generation, enrichment, and screening within the review documents.

4.3 Product concept definition

According to Koen et al. [14], a well-defined product concept should entail a comprehensive configuration, offering both written and visual descriptions that encapsulate the primary features, customer benefits, and a broad understanding of the required technologies. This stage in product development represents the final step preceding the formal NPD process [14]. The models proposed by Khurana and Rosenthal [11], Reid and De Brentani [19], and Cooper [17] also emphasize the significance of product concept development, feasibility analysis, project planning, and decision-making as crucial prerequisites before formally entering the NPD phase.

In the defense sector, the Armed Forces commonly adopt the systems engineering lifecycle concept to structure their acquisition processes [56]. Within this framework, the product concept undergoes development through a top-down approach, comprising two distinct phases: logical description (problem domain) and physical description (solution domain). The logical or functional description essentially outlines the intended functionalities of the new product from the user’s perspective, providing an operational view. Building upon the logical description, the physical description then defines the high-level architecture of the product elements, encompassing systems, subsystems, assemblies, and/or components, from a technical perspective [57, 58, 59]. Table 7 provides a mapping of the product concept definition phase within the reviewed documents.

Documents	Approaches	National context
United States [42, 54]	The US approach divides the life cycle of a defense product into six phases: Materiel Solution Analysis (MSA), Technology Maturation & Risk Reduction (TMRR), Engineering & Manufacturing Development (EMD), Production & Deployment (PD), Operations & Support (OS), and Disposal. The FEI phases (before NPD), MSA and TMRR, involve significant requirements engineering effort. MSA uses the CONOPS to define operational requirements, establishing operational performance parameters and attributes – Key Performance Parameters (KPPs) and Key System Attributes (KSAs). The physical description is preliminary, analyzing technical alternatives for product acquisition. MSA concludes with the approval of the Capability Development Document (CDD) Draft. The CDD Draft evolves during the TMRR phase, refining technical product requirements into the Request For Proposals (RFP), inviting companies to submit development proposals. TMRR concludes with the approval of the Preliminary Design Review (PDR), ensuring technological risks are mitigated and the product concept is ready to advance to the formal NPD stage.	USA
Innovations [60] and United Kingdom [44]	Divide the product life cycle into six phases: concept, assessment, demonstration, manufacture, in-service, and disposal. The FEI phases are concept and assessment. The concept phase develops the logical and physical descriptions of the product. The subsequent phase refines these descriptions through evaluations for risk reduction before entering NPD. Risk reduction is exemplified by technology competitions promoted by the UK Ministry of Defense to mature/identify alternatives for technological components of the product before its development/integration.	United Kingdom
Australia [45]	Divides the product life cycle into five phases: Strategy and Concepts, Risk Mitigation and Requirement Setting, Acquisition, In-Service, and Disposal. The FEI phases are Strategy & Concepts and Risk Mitigation & Requirement Setting. These phases define the logical and physical descriptions of the product and conduct risk reduction activities before entering NPD.	Australia
India [47]	Adopts distinct workflows depending on the acquisition modality: Buy, Buy and Make, Leasing, Make, Design and Development, and Strategic Partnership Model. In all cases, logical and physical descriptions are developed, in greater or lesser detail, to support the acquisition of a defense product.	India
South Africa [48]	Divides the life cycle of a defense product into four phases: Design, Development, Operation & Maintenance, and Disposal. The phase belonging to the FEI is the Design phase, where the product concept is developed before entering NPD.	South Africa
Brasil [55]	Divides the life cycle of a defense product into five phases: conception, acquisition, production, operation and support, and disposal. The phase belonging to the FEI is conception. The most important step of the conception phase is integrated design, which establishes the logical description (doctrinal/operational constraints and operational requirements) and the physical definition (technical requirements, conceptual design, technology map, integrated logistics support plan, and test and evaluation plan) of the product before entering NPD.	Brazil
Clegg et al. [61], Larsson et al. [62] and Johansson et al. [63]	In the aerospace and defense context, they present simulators or methodologies to support collaborative product concept development before entering NPD.	Generic (academic literature)

Table 7.

Approaches to product concept definition within the review documents.

4.4 Consideration of influencing factors

According to Koen et al. [14], influencing factors are variables that impact FEI and are relatively outside the organization’s control. Table 8 maps the influencing factors considered in the review documents.

Documents	Influencing factors	National context
United States [42, 54, 64, 65]	National guidelines (notably the National Security Strategy – NSS), budget management (PPBE process – Planning, Programming, Budgeting, and Execution), scenario planning, and the strategic portfolio of programs/projects/capabilities. Emphasis on analyzes of alternatives, feasibility, technological criticality (list of critical and emerging technologies), and technological maturity (TRL - Technology Readiness Levels of 6 or higher as reference value before entering NPD). Selection and continuity of leadership (military and/or civilian) in NPD project planning.	USA
NATO [43]	Emphasizes interoperability as a relevant factor, considering it integrates 32 member countries.	NATO
United Kingdom [44, 66]	Technological criticality (critical technological areas guided by the “Integrated Force Plan 2030”) and technological maturity (TRL 7 and SRL – System Readiness Level – 4 as reference values before entering NPD). Continuity management in NPD project planning.	United Kingdom
Australia [67, 68]	Government Office for Critical Technologies Policy Coordination periodically publishes a list of technologies to be prioritized in national technological projects, especially in the defense area. Action plan for the development of technological products to ensure mastery of critical technological areas.	Australia
IEDI [69]	Defines “frontier” technologies to reduce dependence on foreign components and supply chains in these areas. Emphasis on dual-use technologies, especially in basic research phases, where it is possible to circumvent international embargoes and undertake research in critical areas with developed countries.	China
India [47]	Emphasizes critical technological areas following “Make” or “Buy and Make” strategies. The Indigenous Content (IC) factor specifies the percentage that defense technological capability acquisition contracts should allocate to national investments.	India
South Africa [48]	Defines key areas to be prioritized in the development of the defense industrial base to reduce technological dependency.	South Africa
Brasil [55, 70]	Technological criticality (priority areas defined in the strategic plan) and technological maturity (product development must have critical component technologies with a TRL of 6 or higher). The concept of technological duality gains importance for extra-budgetary resources and the integration of military and civilian sectors.	Brazil

Table 8.

Influencing factors within the review documents.

5. Discussion

After presenting the review results, it is essential to delve deeper into key findings and considerations identified throughout the study.

5.1 Synthetic diagnosis of the results

Table 9 provides a condensed overview, offering a synthetic diagnosis of the results derived from the review. It succinctly outlines FEI activities in the defense sector and establishes connections with the influencing factors under consideration.

Activity	Description	Influencing factors
Identification and analysis of opportunities	Identification of capability gap within CBP. The analysis considers the following elements: doctrine, organization, training, materiel, leadership and education, personnel, facilities, logistics, interoperability, and policy.	National guidelines, public budget, scenario planning, geopolitical issues, and strategic portfolio.
Generation, enrichment, and screening of ideas	When analyzing a capability gap, if a materiel solution is the only way to fill it, it is necessary to justify and develop the concept of operations for that solution (what is expected from the materiel solution in the operational context). The approval of the concept of operations initiates the life cycle of the new product.
Product concept definition	The product concept is developed in a top-down approach divided into two stages: logical description (problem domain) and physical description (solution domain). The logical or functional description essentially defines what the new product should be able to do from the user’s perspective. It usually relies on the concept of operations to elicit the product’s operational requirements, establishing parameters and attributes of operational performance. Based on the logical description, the physical description defines the high-level architecture of the product elements (systems, subsystems, assemblies, and/or components) from a technical perspective. The physical description is generally represented by the product’s technical requirements. The physical description underpins the mapping of component technologies; the decision on the acquisition model (purchase and/or research and development); the signing of supply, development, and/or integration contracts; and the planning of the acquisition project. The approval of the product concept initiates the formal NPD stage.	Analyzes of alternatives, feasibility, technological criticality, technological maturity, and possible use of the concept of technological duality for capturing extra-budgetary resources and integrating military and civilian sectors. Planning of the NPD project (scope, cost, time, life cycle, and leadership continuity).

Table 9.

FEI activities in the defense sector.

5.2 Peculiarities of FEI in the defense sector

After systematically mapping the FEI in defense sector against established FEI models, several distinct aspects specific to the military context have emerged, as shown in Table 10.

Aspect	Military FEI	Seminal FEI models
Systems engineering approach	Government documents highlight the prevalent use of systems engineering activities, particularly in requirements engineering and systems lifecycle management, during the early phases of military innovation.	Often, they overlook the systems engineering approach, emphasizing the need for innovation models tailored to the defense sector.
National strategic focus	The optimization of FEI primarily serves the common good, development, and survival of the State, differing from the profit-driven motives of commercial entities.; Consideration of geopolitical aspects and alignment with high-level national guidelines becomes crucial in this context.	Generally designed for technology product manufacturing companies, lacking emphasis on the broader national scope inherent in defense innovation.
Technological duality	The defense sector incorporates the concept of technological duality, where innovations or technologies intended for military use may find civilian applications (spin-off), and vice versa (spin-in). This dual-use perspective is essential in the defense sector, influencing decisions on resource allocation and fostering collaboration between military and civilian technological advancements.	The emphasis is typically on generating ideas and concepts within a specific industry or market to meet customer needs or address market gaps. The models may not explicitly consider the dual-use potential or the transferability of technologies between military and civilian domains.
Technological criticality	FEI in the military context is closely tied to the concept of technological criticality. Investments in defense prioritize mapping critical technological areas to promote strategic sectors in the national industrial base.	The strategic mapping of critical technologies for national development, as seen in the defense sector, is a specific consideration that goes beyond the scope of traditional FEI models.
Technological maturity	Defense innovation involves assessing the maturity of critical technologies to mitigate risks before entering the formal NPD stage. The TRL scale is commonly used for this assessment. The TRL scale, and in some cases, the SRL, plays a crucial role in gauging the readiness of critical technologies, ensuring they meet the required standards before advancing to NPD.	While traditional FEI models may indirectly touch upon aspects of technology readiness, they typically do not incorporate a formalized assessment process like the TRL scale. The emphasis in traditional FEI models is often on customer-centric aspects, market dynamics, and the development of innovative solutions.
Organizational capabilities as the “engine”	FEI, in defense, places organizational capabilities at the core, considering capability-based planning as a central element in identifying and analyzing opportunities, as well as in generating, enriching, and screening ideas. Organizational capabilities are integral to the military FEI “engine,” contradicting the notion that they change slowly and are uncontrollable.	Organizational capabilities are classified as an influencing factor and not as part of the FEI’s “engine”, considering that they usually change very slowly and are therefore uncontrollable.
“Implementation” of innovation	In defense, the concept of “implementation” extends beyond market introduction. It is realized when a new product is effectively incorporated into the capability’s portfolio of an Armed Force, necessitating adjustments in various non-technological aspects. The symbiosis between technological and doctrinal advancements defines military innovation, emphasizing the harmonization of both aspects for successful implementation.	It aligns with the definition from the Oslo Manual [71] which asserts that the “implementation” of a product innovation is realized when a new or significantly improved product is introduced to the market, i.e., is commercialized.
Continuity in project leadership	Project leadership continuity is a crucial influencing factor, given the extended duration of defense product development and high turnover among military leaders. Mitigating leadership turnover is addressed through strategies like the continuity of civilian leadership, ensuring stability throughout the NPD phase.	They emphasize the significance of organizational leadership in the context of the FEI, but do not explicitly address managing leadership continuity in NPD project planning.

Table 10.

Peculiarities of FEI in the defense sector.

5.3 Contributions to the FEI literature

The exploration of Scopus and WoS databases revealed a noteworthy observation: the existing academic literature has not systematically delved into the realm of Front End of Innovation (FEI) within the defense sector. In dissecting the distinct aspects of the initial phase of the military innovation process, several novel points of analysis emerged, each offering unique insights not extensively addressed in seminal FEI models. These include:

• Use of systems engineering approach: The defense sector prominently employs systems engineering activities during the early phase of military innovation. This approach encompasses requirements engineering and systems lifecycle management, aspects not explicitly emphasized in traditional FEI models.

• Relevance of technological duality, criticality, and maturity: Concepts such as technological duality, criticality, and maturity play a crucial role in military FEI. These factors, while not extensively covered in established FEI models, are instrumental in decision-making processes, risk mitigation, and the strategic development of defense capabilities.

• Organizational capabilities as the “engine” of FEI: In contrast to seminal NPD models that classify organizational capabilities as influencing factors, the defense sector integrates organizational capabilities as a fundamental component of the FEI “engine.” Capability-based planning is a central element in identifying and analyzing opportunities, as well as in generating, enriching, and screening ideas.

• “Implementation” of military innovation: The implementation of military innovation necessitates a broader interpretation compared to traditional FEI models. In defense, implementation occurs when a new or improved product is seamlessly integrated into the capability’s portfolio of an Armed Force. This integration involves adjustments in various non-technological aspects, emphasizing the symbiosis between technological and doctrinal advancement.

• Continuity in project leadership: Recognizing the high turnover of military leaders and the extended durations of defense projects, the continuity of leadership emerges as a critical consideration. Seminal FEI models do not explicitly address managing leadership continuity in NPD project planning.

Moreover, it is noteworthy that recent contributions in the FEI literature have started to delve deeper into the alignment between organizational strategy and FEI activities. Unlike seminal models that treat this issue generically, recent works, such as the integrative ontologies developed by Pereira et al. [20] and Castro and Ferreira [72, 73], provide management artifacts designed to align organizational strategic vision with FEI activities. Employing the design science paradigm, these artifacts integrate constructs, models, methods, and instantiations, thereby enriching the strategic dimension of FEI literature.

5.4 Contributions to the defense literature

The defense sector, encompassing products ranging from CoPS to mass-produced items, presents a unique challenge due to its diverse complexity and production volume [74]. While the CoPS research area has an established connection with systems engineering literature, the realm of mass-produced products aligns more closely with the theoretical foundations of the FEI literature. Notably, defense documents predominantly draw from the CoPS approach, sparingly incorporating principles from mass production. However, recognizing that the military context spans both worlds, the integration of these approaches becomes crucial, and mapping established FEI models within the dynamics of the initial phase of the military innovation process serves as a valuable step in achieving this harmonization.

Moreover, the FEI literature, characterized by well-defined seminal models and recent integrative ontologies (as discussed in the previous section), contrasts with the more heterogeneous nature of the systems engineering literature. The latter encompasses diverse authors, countries, organizations, and standardization bodies, each adhering to distinct management models with unique nomenclatures and structures [43, 44, 45, 47, 48, 54, 55, 57, 58, 59]. In this context, the FEI literature emerges as a unifying force, facilitating the creation of a common representation of knowledge related to the early stage of the military innovation process. This not only streamlines communication among specialists, decision-makers, managers, researchers, entrepreneurs, and other stakeholders in the defense field but also promotes greater efficiency in navigating the diverse landscape of defense innovation.

5.5 Limitations

Several limitations were identified during this research:

• Selection of seminal FEI models: The identification of seminal FEI models relied on findings from Pereira et al. [12, 20] and co-citation analysis of FEI-related works available in the Scopus and WoS databases. Alternative criteria for model selection might yield a different set of seminal documents, potentially influencing the analysis.

• Data collection in gray literature: The exploration of gray literature related to FEI in the military sector was constrained by the availability of documents on government websites of defense management agencies. This limitation could result in an incomplete representation of the landscape.

• Scope of mapping: The review presented an initial mapping of FEI in the defense sector within seminal models. A more comprehensive and structured mapping could be achieved through the adoption of more robust methodological approaches, such as the design science paradigm [75, 76]. This suggests that there is potential for a more in-depth and detailed examination of FEI activities in the defense sector.

Acknowledging these limitations is essential for a nuanced understanding of the scope and implications of the study, guiding future research endeavors in this domain.

6. Conclusion

This study aimed to comprehensively explore the dynamics of FEI in the defense sector through a systematic review encompassing 24 documents from both academic and gray literature. By analyzing seminal FEI models, the research mapped key activities within the defense context, including the identification and analysis of opportunities, generation, enrichment, and screening of ideas, product concept definition, and consideration of influencing factors.

The study’s contributions extend to both FEI and defense literature, introducing original perspectives. Notably, it emphasized the systems engineering approach, national strategic focus, technological duality, technological criticality, technological maturity, organizational capabilities as the “engine”, the unique concept of “implementation” in military innovation, and the importance of continuity in project leadership.

Acknowledging limitations, such as the criteria for selecting seminal FEI models, constraints in accessing gray literature, and the preliminary nature of the mapping, the study calls for future research to employ more robust methodologies, like the design science paradigm [75, 76], for an in-depth understanding of the initial phase of the military innovation process.

In conclusion, this research lays a foundation for further exploration and synthesis of knowledge, contributing to the advancement of both FEI theory and its application in the defense sector.

Acknowledgments

This work was supported by the Brazilian Army (Atv PCENA V23-011).

We thank Dr. João José Pinto Ferreira (INESC TEC and Faculty of Engineering, University of Porto) for his expertise and help in writing the manuscript.