IEEE Technology and Society Magazine - Summer 2013 - 34

and sustainable systems that consider
evolving trust relationships between
entities. For more details on how to
measure trust or components of trust,
readers are referred to [4], [6].
We consider how trusting and
trusted behaviors are motivated by
the goal of fostering trust relationships that are "sustainable" in the long
term. The assumption enabling this
study is that, between entities A and
B, how much A trusts B also depends
on how much B trusts A. That is, trust
of a trustee (trusted entity) towards
a trustor (trusting entity) is significantly influenced by that of the trustor towards the trustee. Trivers [16]
believes that this reciprocal relationship among entities boosts trust relationships. For example, in military
coalition networks, members with
no prior interactions or information
about each other are often required to
collaborate to perform a common but
complex task. In this highly uncertain environment, responses to each
other can be critical to establishing
trust and will impact the dynamics of
their next interactions.

Multi-Dimension
of Sustainability
Networks for military operations
currently may have multiple system
goals such as scalability, resiliency,
reconfigurability (for agility), or survivability in very harsh environments
due to highly constrained resources

(e.g., mobile devices, wireless channels), network dynamics (e.g., mobility, terrain, and membership), selfish
or malicious entities, and system
heterogeneity. In order to accommodate the extreme demands of
military environments, we borrow
the concept of "sustainability" from
healthy ecological and biological
nature-inspired systems that thrive in
environmental, economic, and social
dimensions [1]. We propose a sustainable network to be a system that
is capable of maintaining well-being
by considering the following factors:
■

■

resource-restricted environments;
Self-interested entities (i.e.,
rational behavior to maximize
their individuality); and
Misbehaving nodes in terms of
environmental, economic, and
social perspectives.

The sustainable network concerns
current and future mission performance with the goal of maintaining
the system's performance over time.
Trends in military operations show
that long-term cooperation or collaboration is required among diverse
groups or entities with different
nationals, purposes (e.g., humanitarian or military), and cultures (local
civilian, non-government organizations). recently, these missions
include counterinsurgency (COIN)

Social
Security

Bearable
Resilience

Environmental
Resource Constraints,
Risk, Uncertainty

Equitable
Fairness

S u s t a i n a bl e
Viable
Survivability

Economic
Performance

Fig. 1. Characteristics and goals of sustainable networks.
34

operations such as humanitarian
relief and refugee care. We discuss
how socio-cognitive responses/reactions in relationships increase trust
among entities in the network and
ultimately lead to positive impact on
sustainability in networks. We also
note that promoting trust based on
the analysis of interactions between
entities should be based on methods
that accurately and appropriately
assign trust to other entities [7].
We define the characteristics and
goals of sustainable networks, as
shown in Fig. 1 [1]. Our proposed system considers resource constraints,
risk, or uncertainty (e.g., less or no
evidence) as the environmental factors. Performance (e.g., scalability,
efficiency, quality-of-service) represents the economic factor to best
utilize available resources. Security
represents the social factor by being
robust against attackers. Each of
these factors in a network is designed
with the common goal of building
sustainable networks. The proposed
system has the three objectives of 1)
being bearable (tolerable or recoverable) against attacks or failures (i.e.,
resilience); 2) being viable despite
penalties (e.g., some untrustworthy
nodes are evicted from the system) or
lack of resources (i.e., survivability);
and 3) being equitable in resource
sharing or allocation (i.e., fairness).
To maximize sustainability (i.e.,
resilience, survivability, and fairness) through trust relationships
among entities in the network, we
need to examine how trust can be
created, fostered, and enhanced
through intelligent decision making or interactions between the
sub-components of the system.
Many tactical networks aiming
for sustainable operations as a longterm goal also struggle with maintaining a sufficient level of performance at current times under lack
of resource-restricted network environments. That is, the proposed system may have two conflicting goals:
preserve its future well-being from a
global system perspective and also
maintain its current performance.

IEEE TECHNOLOGY AND SOCIETY MAGAZINE

SuMMEr 2013

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