Data Communication

The purpose of data communication is to transmit data from one location to

another so information can be shared with people at a distance. Forouzan (2007) explained five components of data communication include sender, receiver, message, medium and protocol. A transmission medium is a physical path by which a message propagates from sender to receiver. A protocol is a set of rules specifying the formats

of data communication between devices. Only when using the same protocol, a receiving device can recognize the same “language” and interpret the message provided

by a sending device. Messages transmitted across media of different protocols require a gateway to act as a protocol translator to bridge the communications.

IEEE 1451 standards define the protocol for smart sensors to communicate with each other, so smart sensors can coordinate mutually and collectively constitute wireless sensor networks. If smart sensors are embedded into objects, the objects can communicate with each other via the established wireless sensor networks. In other words, the objects form Internet of Things (IoT).

The “Internet of Things” concept was firstly proposed by Kevin Ashton in 1999 to link the idea of RFID in Procter & Gamble’s supply chain management (Ashton,

2009). By empowering sensor technology, computers and the Internet don’t need to depend on human beings to manually capture and enter data. Human resources can be freed up and employed more productively. The definition of IoT varied with the improvements of technologies over the past two decades. Today, Internet of Things represents a world-wide communication network composed by interconnected objects with unique identities. The objects can be still or moving, such as buildings, home appliances, meters, physical devices, vehicles, trains, electrical devices, etc.

Figure 17: Data Communication between Internet of Things, Internet and Cellular Mobile Network

Figure 17 depicts data communications between Internet of Things, the Internet and cellular mobile network. Internet of Things connects objects. The Internet connects websites. Cellular mobile network connects people. Once parameters about the world are captured by smart sensors in a wireless sensor network, the acquired data can be forwarded within the network from the source sensor to the gateway. Then, the data are further transferred to the Internet via wired or wireless media. The wired transport network includes optical network, cable television (CATV) network, Ethernet network, etc. Wireless transmission can be implemented via various protocols. Medina et al.

(2017) compared various wireless technologies according to range of available areas.

Among all the wireless technologies, the most popular ones are Wi-Fi network and cellular mobile network. Wi-Fi networks specified in the IEEE 802.11 standards are existing wireless networks commonly installed in buildings and public areas for short to medium rage connectivity. Based on current deployment of Wi-Fi networks, the acquired data can be transferred from the gateway to the Internet without any significant extra infrastructure cost. As the acquired data are available on the Internet, people can access the data through servers or personal computers. In other words, people can remotely understand and monitor the parameters of a far field by establishing the link between Internet of Things and the Internet. If smart sensors are equipped with functions of accepting commands and activating objects to execute tasks, people can control operations of objects via the established link and expand scopes of their influences.

Instead of using servers or personal computers, mobile devices provide alternative terminals for human interactions. The prevalence of smartphones and tablets enables people to surf on the Internet with mobility and flexibility. Actually, smartphones play an increasingly important role in connecting people to the world. Thus, as long as the data acquired by smart sensors are accessible on the Internet, people can perceive the data via connected mobile devices wherever they go. Another route to obtain the acquired data from mobile devices is to bypass the Internet and interconnect Internet of

Things and cellular mobile network directly. To achieve this, the gateway of a wireless sensor network needs to possess capabilities of interacting with a base station (BS) of cellular mobile networks. Besides, a base station will have to support enormous number

of gateways if smart sensors are deployed extensively on billions of objects. However, this can’t be fulfilled by the existing 4^th Generation (4G) cellular mobile networks.

Mobile communications systems have been evolving tremendously from the 1^st Generation to the 4^th Generation since 1981. Each generation incorporates cutting-edge technological advancement for better user experiences. The 4G mobile networks can support downlink data rates up to 100 Mbps (megabit per second) for high mobility access and up to 1 Gbps (gigabit per second) for low mobility access. End-to-end latency is reduced to less than 100 millisecond (ms) (Abdullah et al., 2011). The 4G networks realize faster broadband internet access from mobile devices, which causes exponential growth of data traffic in mobile networks. The growth momentum is expected to continue stably. By 2020, mobile users on average will download 1 terabyte of data each year (Rappaport et al., 2014).

Faced with the steady demand for data traffic and preparing for the era of smart city, academia and the technology industry are aiming at the 5^th Generation (5G) cellular mobile networks. Standards for the 5G communications are still under development and will not be completed before 2020. Wang et al. (2014) and Sasipriya

& Vigneshram (2016) have identified that the 5G networks’ performances should support 10,000 times data traffic, 10-100 times more devices, 10 Gbps peak data rate for low mobility access and 1 Gbps for high mobility access, less than 1 ms of latency and 10 years of machine-to-machine battery life.

To achieve the fabulous performances, architecture of cellular mobile network will be fundamentally redesigned. Agiwal et al. (2016) clarified the high frequency millimeter wave (mm-wave) bands, typically locate from 30 GHz to 300 GHz on the spectrum with wavelengths from 1 millimeter to 10 millimeters, will be exploited to accommodate vast data traffic. As wireless communications run at higher frequency bands, signals decay much more quickly during transmission. To adapt this physical characteristic and fulfill the less than 1 ms of latency requirement, mm-wave Base Stations will be densely deployed. Coverage areas, called as cells, will be much smaller for wave Base Stations compared with 4G Base Stations. Large number of mm-wave Base Stations together with legacy 4G Base Stations will transform mobile networks from Base Station-centric architecture into User-centric architecture.

Communications running at the mm-wave bands also shrink antennas’ sizes. Smaller antennas will be extensively used to form large antenna arrays and cooperate with the massive Multiple Input Multiple Output (massive MIMO) technology to enhance spectral and energy efficiency.

If the excellent performances of the 5G networks are achieved as expected, mobile network system will furnish people with seamless and ubiquitous wireless connectivity to anyone and anything at anytime and anywhere. At that moment, Internet of Things will be fully merged with the 5G cellular mobile network. The integration of Internet of Things, the Internet and the 5G cellular mobile network will greatly stimulate realization of smart city.