2.1. Planning Stage.
Identifcation of the objectives of the
study and development of the review protocols comprised
the planning stage of the review. After a preliminary search
of the available research material, the necessity for further
study of the smart home system was identifed. Following the
establishment of the feld of study, specifc protocols were
developed for the study, which included the search criteria,
database selection, inclusion and exclusion criteria, and the
process of searching.
2.1.1. Formulation of the Research Questions.
At an early
point of the planning stage, a list of questions that specify the
key objectives of the research is created. Te Goal-Question-
Metrics approach proposed by Van Solingen [21] was used
to construct the most relevant research questions for this
study. Following this approach, four main coordinates were
obtained as follows:
(i) Purpose: investigate, evaluate, and assess
(ii) Issue: complete analysis of the smart home system
(iii) Object: smart home system
(iv) Viewpoint: a researcher’s point of view
Based on these points, four major research questions
were formulated as follows:
(i) What are the tactics or methods for constructing
a smart home system?
(ii) What types of sensors were utilized in the devel-
opment of the smart home system?
(iii) What kinds of communication protocols and net-
working tools were implemented?
(iv) What types of security measures were considered
for smart home systems?
Te main objective of this research work is to review the
existing research work on smart home systems and discover
the approaches adapted, the hardware and networking
technologies utilized, and the security systems considered.
Te four previously mentioned questions are linked to these
objectives. Apart from that, the formulated research ques-
tions were also used to detect keywords such as “smart,”
“home,” “system,” “solution,” “sensors,” “communication,”
“networking,” and “security.” Based on these keywords,
initial search strings were established to detect the
literary works.
2.2. Search and Review Stage.
Te second stage consists of
a systematic search in preselected databases, which are
shown in Table 1, based on search terms found in the
planning stage and fltering through the search results for the
most relevant research papers.
Te most important term here is “smart home,” and all
the keywords are selected based on it. As the goal is to cover
the entire zone of the smart home system, the technologies
utilized inside the house and beyond, and the overall features
and comfort provided by the system, the application of the
term “smart home” is validated.
Te keywords formulated in the planning stage were
used as the primary search string, and several types of lit-
erature reviews were obtained from the search. To keep the
review most up-to-date, only the papers published in the last
ten years were analyzed, where priority was given to the
papers from the last six years.
Following the primary search, papers were inspected and
sorted manually by reviewing the title, abstract, and con-
clusion. In this manual sorting, if a paper is found to include
keywords and could provide necessary details to satisfy the
inclusion criteria for this review, it was selected. For this
purpose, a set of inclusion and exclusion criteria were
created. Te inclusion criteria for review materials are
provided as follows:
(i) Te article’s keywords must match at least some of
the search terms defned.
(ii) Simple and understandable English is used to write
the paper.
(iii) Articles/papers that concentrated on the activity
recognition of inhabitants, monitoring, and gath-
ering information about the user experience and
comfort.
(iv) Te article must be published within the last
six years.
Te exclusion criteria were as follows:
(i) Potentially duplicate reports on the same research
(ii) Papers that are not published in the English
language
4
Journal of Electrical and Computer Engineering
(iii) Te research focused on smart grid-connected
smart homes, smart cities, and outdoor in-
telligence services
(iv) Specifcally, tailored studies on certain smart home
appliances such as smart refrigerators, smart mir-
rors, and robots
(v) Not related to the research question
After fltering the papers through these criteria, for more
accurate and defnite results, the primary search string was
modifed with additional keywords such as “smart sensors,”
“risk,” “threat,” “elderly,” “AI,” “IoT,” and “wireless.” Using
this modifed search string, the electronic databases were
searched again, and the resultant papers were again man-
ually inspected. Finally, all the selected research materials
were meticulously revised for the result stage. Figure 3
represents the article selection process from diferent da-
tabases through multiple searches.
2.3. Result Stage.
In the last phase of the review process, an
analytical report is presented, which includes the year of
studies, the research process, the region of technology
considered, and publishing organizations. Te fndings were
utilized to establish the fundamental segments of this review
and reveal the technological developments in the smart
home system throughout the years.
A total of 111 research papers were selected (excluding
review papers) after the methodological process of sorting
them. Based on the selected articles and the information
provided, fve important graphical portrayals can be
achieved. Figure 4 depicts the year-wise amount of the
literature published from 2012–2021, based on the selected
papers. Tis representation shows that the highest number of
papers was published during the 2018–2020 period.
Figure 5 depicts the publisher-wise number of the lit-
erature collected. Five diferent electronic databases have
been used for collecting papers. Te highest number of
papers was collected from IEEE Xplore totaling 47 papers, 9
from ScienceDirect, 19 from MDPI, 16 from SpringerLink,
10 from ACM Digital Library, and 10 from Hindawi.
Figure 6 represents the types of research material
published by the authors. It can be seen that the majority of
the authors (66) tended to create experimental design-based
articles. Te other types include 45 theoretical or conceptual
works, 16 reviews, and 3 case studies. It should be noted that
the review articles and case studies were not used as review
materials for this article; instead, they were used for aca-
demic references.
Planning Stage
Set Objective
Question
Related
Keyword
selection
Select
Scientific
Database
Primary
Search string
Formulation
Search & Review Stage
Content
Revision
Scientific
Database
Queries
Primary
Search
Result
Time Based
Sorting
Manual
Sorting
Result of
first sorting
process
Second
sorted result
Manual
Sorting
Scientific
Database
queries
Fine-tuned
search
string
Result Stage
Classification of Core Parts
Figure
2: Research method in detail.
Table
1: List of electronic databases used for searching articles.
No.
Electronic databases
1
IEEE Xplore
2
SpringerLink
3
ScienceDirect
4
ACM Digital Library
5
MDPI
6
Hindawi
Journal of Electrical and Computer Engineering
5
IEEE Xplore (124)
SpringerLink (89)
ScienceDirect (57)
ACM (95)
MDPI (87)
Hindawi (23)
Modified Search
String (475)
Final Selection
(111)
Figure
3: Paper selection process from diferent databases.
1
1
1
1
11
11
20
20
23
23
0
5
10
15
20
25
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
Number of Papers
Year
Figure
4: Year-wise frequency of literature publication.
42%
8%
15%
9%
17%
9%
IEEE Xplore
ScienceDirect
SpringerLink
ACM digital Library
MDPI
Hindawi
Figure
5: Publisher-wise percentage of the papers reviewed in this work.
6
Journal of Electrical and Computer Engineering
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