Big Data Generation and Acquisition - Big Data: Related Technologies, Challenges and Future Prospects - page 20

data, and financial data, etc., also constitute enterprise internal data, which aims to
capture informationized and data-driven activities in enterprises, so as to record all
activities of enterprises in the form of internal data.
Over the past decades, IT and digital data have contributed a lot to improve
the profitability of business departments. It is estimated that the business data
volume of all companies in the world may double every 1.2 years [ 1 ], in which,
the business turnover through the Internet, enterprises to enterprises, and enterprises
to consumers per day will reach USD 450 billion [ 2 ]. The continuously increasing
business data volume requires more effective real-time analysis so as to fully harvest
its potential. For example, Amazon processes millions of terminal operations and
more than 500,000 queries from third-party sellers per day [ 3 ]. Walmart processes
one million customer trades per hour and such trading data are imported into a
database with a capacity of over 2.5PB [ 4 ]. Akamai analyzes 75 million events per
day for its target advertisements [ 5 ].

3.1.2 IoT Data

As discussed, IoT is an important source of big data. Among smart cities constructed
based on IoT, big data may come from industry, agriculture, traffic and transporta-
tion, medical care, public departments, and households, etc., as shown in Fig. 3.1 .

Fig. 3.1 Illustration of the prime source of sensory data

According to the processes of data acquisition and transmission in IoT, its
network architecture may be divided into three layers: the sensing layer, the network
layer, and the application layer. The sensing layer is responsible for data acquisition