A Systematic Review of Federated Scheduling in the Cloud-Edge-IoT Continuum

The orchestration of applications across the IoT–Edge–Cloud (CEI) continuum is a fundamental enabler of today’s internet services and
global digitization, supporting adaptive resource management and performance optimization in heterogeneous environments. Within
this orchestration process, scheduling and placement constitute critical decision mechanisms that determine how computational tasks
and services are allocated across federated infrastructures.
This paper presents a survey of scheduling approaches designed to support application orchestration across the continuum. Through
a systematic analysis of 63 peer-reviewed studies published between 2019 and 2025, the survey consolidates a fragmented body
of knowledge encompassing diverse objectives, architectural paradigms, and evaluation practices. A comprehensive taxonomy is
proposed to structure existing work along key analytical dimensions, including scheduling objectives, problem scale, architectural
models, and evaluation methodologies.
The analysis highlights the research gaps and emerging challenges, contributes to an integrated perspective on the status of
federated orchestration and scheduling strategies. This study reveals that scheduling research in CEI continuum remains focused
on single-cluster and small-scale evaluations, as more than 70% of the reviewed articles focused on single-cluster environments and
about 79% of the studies evaluated their methods in small-scale environments. The exploration of fully decentralized multi-cluster
architectures, and using large scale evaluation are still limited.