Introduction to Wireless Networks

Abstract

Wireless Network refers to computer networks without wired connections wherein nodes communicate with each other using radio frequency connections. One of the key benefits of wireless networks is that they can be easily deployed anytime and anywhere for applications such as homes, industry automation, military, agriculture, business, etc. This chapter discusses the basics of wireless networks, followed by wireless network evolution, wireless network challenges, the type of wireless network, and how wireless networks are integrated with the Internet of Things (IoT).

Introduction

A computer network is a collection of two or more connected computers. Through these networks, people can share data as well as hardware resources and communicate with each other. Computer networks are broadly categorized under two headings: Wired and Wireless networks.

The basic component required for building networks is at least two computers. When we say computer, it need not be just a computer; instead, it can be even a small computing device. We can also have wireless Ad hoc networks, where each computing device is a small microcontroller, sensor, or other device. The other requirement is that there should be a Network Interface Card (NIC) in each computer, a connection medium, which can be a wireless medium, and a network operating system software that controls all of these.

In a wired scenario, a hub or switch is used to connect computers in the network. Here, the responsibility of the hub is to forward data packets from one computer to another. In wireless networks, Mobile Switching Centers act like central hubs. Hubs forward any data packet from one workstation to another [1].

We can use hubs to connect to access, wherein we can connect to LANs. Another important networking component is the router. The responsibility of the router is to route the packet from the source node to the destination node, which also maintains a routing table to determine the next hop. The entire data is divided into

packets, which travel in the most efficient paths. It is the responsibility of the router to transmit the packet. Routers are also used to connect any network in a wide area network.

The next device in a wireless network is the access point, which performs the operations like the hub. The access point avoids a wired connection. Some access points have roaming functionality. Access points can connect a wired network to a wireless network so that access points help get service from a wired network to a wireless network. Access points help extend or add more devices to the network. They act like a bridge between wired Ethernet or fast Ethernet Networks. They are very useful in adding more computers to the lab. A sample example wireless network is shown in Fig. (1).

Wireless LAN (WLAN) is an alternative to wired LAN. Using RF technology, users of WLAN can access information over the air without the need to establish a physical connection. By using WLAN, anybody can access shared information without plugging in and looking for a place to plug in. It is a huge advantage of WLAN.

Wireless networks are growing day by day in almost all parts of human life. People cannot survive without them, even for their household work, for example, booking tickets, getting appointments with doctors, paying bills, purchasing items, etc., from anywhere at any point in time.

One of the reasons for using wireless networks in our day-to-day real-life applications is due to their cost-effectiveness. As and when their usage increases, there exist several challenges to be faced while using wireless technology.

Evolution of Wireless Networks

In the first-generation wireless technology, analog ARMs were used. These are cordless telephones (CT) with different standards across the globe. CT1, CT2, and CT3 were the various cordless telephone standards. The specialty of the 1G network is that they were analog and used frequency division multiplexing with limited roaming. There was no real standard across the globe. The MSC was very big. The progress of wireless networks was happening in three geographical regions, which were Europe, the US, and Japan.

In the second-generation GSM technology, GSM 800 and GSM 900 were developed. The specialty of 2G is it uses digital and Time Division Multiplexing Access based primarily on more roaming with better performance and smart billing. Other features are mobile-to-mobile calls, power-controlled Dynamic channel allocation, mobile-assisted handoff, etc. This is more robust compared to 1G systems. GSM is one of the most successful wireless technologies that is used even now across the world. Japan came up with PDC in the second generation. The US went towards digital arms, then IS 54, PCS900, and CDMA-based IS95. Europe moved towards GSM 900. GPRS and Edge are moving towards the 3G system.

In 3G, the basic philosophy is one world standard. Cordless and wireless technology converged. Wireless phones are connected to IP, i.e., we can make VOIP calls through cellular phones. The same device acts like a cordless phone inside a home or a cellular phone outside the home, and if we are near an access point, we can make VOIP. This is how the 3G network has emerged. 3G has a combination of various features with better voice quality and video quality. 3G is not only about higher speed but also about a greater number of services with better Quality of Service (QoS) and mobility.

Wireless Network Challenges

Power Consumption

The first and most important challenge is to consume less power. The reason for less power consumption is important for 2 things: The first reason to consume less power is to have a battery that lasts for a long time. For example, sending a Multimedia Messaging Service (MMS) may consume more power, but a lot of research is being conducted on how to utilize the battery more efficiently. To avoid this, the hardware is designed in such a way that it is less power-hungry. The second reason is to have certain signal processing tools to ensure that it only extends power when required.

Efficient Spectrum Usage

As we know, the spectrum is scarce in wireless communication. If we have finite bandwidth requirements, there are pre-decided capacity relations that tell us how much we can go, provided the signal-to-power ratio is so much. How can we use it better? Why do we have only one transmitter/receiver antenna? Why do not we have multiple input and multiple output systems? The solution is making use of multiple input, multiple output (MIMO) technology.

Integrated Customer Services

Assume that we have data, voice, and multimedia with low power and low bandwidth requirements. Suppose there is a smaller share of bandwidth with a greater number of users sharing bandwidth. We need to see the technique to do so. For example, when we are talking on the phone, the delay should not be greater than a certain amount. While sending VOIP, it goes through a large wireless network where the overall delay should not be so much. We need to take care of packet loss, data rate, and bit error rate. The data rate is very important when streaming videos. A bursty traffic needs to be talked about differently.

Network Support for user Mobility

We must provide the user with enough mobility. Suppose the person is traveling and using a mobile phone; then there will be mobility. Then, a handover may happen, i.e., one base station must hand over the call to another base station.

QoS (Quality of Service)

The performance of the wireless network is measured in terms of QoS parameters such as delay, throughput, jitter, packet loss, etc. QoS in the wireless network is based on various factors such as routing, mobility, transmission medium, noise, and so forth. QoS requirements are different for different applications. To accept the working of any application, it is desirable to meet the required QoS parameters; otherwise, the application will not be sustained.

Connectivity and Coverage

Today, if a new internet service provider or new mobile user comes in, we need to give enough coverage, i.e., 99%. So, coverage is a big issue.

Fading

Fading in wireless communication is largely due to multipath propagation, where signals travel from the transmitter to the receiver through multiple paths. At the receiver end, the shifted rays get superimposed. How does the antenna pick up the signal when more than one radiation comes at the same time from a different transmitter? It superimposes.There is a risk that the signal received may be completely different from what was...