Wireless & Mobile Technology

When two or more computing devices share data or resources with each other, it is called a Computer Network. These computing devices can be computers, laptops, smartphones, tablet devices, or any other computing device. To create a computer network, specific hardware and software are both required, which help build the network system.

Computing devices use a medium to connect with each other in a network. This medium can be wired or wireless. In a wired network, computing devices share data through cables; in wireless networks, no cable is needed.

Wireless networks use radio waves to connect devices. The main types of wireless networks are:

Mobiles, laptops, tablet computers, internet audio systems, gaming consoles, and internet-enabled home appliances can be connected via WLAN. The connection is made via radio waves through transmitters and receivers built into these devices or via antennas. WLAN keeps users connected to the network while remaining within a limited area. Through a gateway, a WLAN can also provide a connection to the broader internet.

The IEEE 802.11 family of standards defines technologies for wireless LANs. The 802.11 standard uses the Ethernet protocol and CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) for path sharing. It also uses a Wired Equivalent Privacy (WEP) encryption algorithm.

4.1.1 Advantages of WLAN

4.1.2 Limitations of WLAN

Bluetooth usage has increased enormously today. Transferring data from smartphones and laptops to speakers, car music systems, and Bluetooth earphones is common for almost everyone.

Bluetooth is a wireless communication standard that allows electronic devices to connect and interact with each other. It is found in smartphones, loudspeakers, laptops, and many gadgets. Bluetooth does not depend on Wi-Fi, mobile data, or cell networks — as long as devices are Bluetooth-compatible and close to each other, they can communicate wirelessly in two directions. A Bluetooth-enabled device equipped with a Bluetooth receiver can link and communicate with up to seven nearest Bluetooth devices.

4.2.1 Bluetooth Architecture

Bluetooth architecture defines two types of networks:

4.2.2 Advantages of Bluetooth

• Low installation cost — Bluetooth is usually built into electronic gadgets.
• Easy to use — connectivity without internet.
• Bluetooth waves can pass through walls within their limited range.
• Can instantly create ad-hoc connections without any wires.
• Used for both voice and data transfer.

4.2.3 Limitations of Bluetooth

You may have experienced that at railway stations, restaurants, or shopping malls, even if your mobile internet is off, your phone shows internet availability — that's because of free Wi-Fi service at those locations. Wi-Fi internet connectivity comes from a wireless router. When you connect to this router, devices like mobiles and laptops get internet access.

4.3.1 How Wi-Fi Works

Technically, the IEEE 802.11 standard defines the protocols that communicate with Wi-Fi enabled wireless devices, including wireless routers and access points. Different standards operate at different frequencies and provide varying bandwidths.

4.3.2 Wireless Access Point (AP)

A Wireless Access Point allows wireless devices to connect to a wireless network. It takes the bandwidth coming from a router and extends it so that devices at remote locations can also benefit from the network. An access point also provides useful data about devices, active security, and many other practical purposes.

4.3.3 Wireless Router

Wireless routers are commonly found in homes. They are hardware devices used by internet service providers to connect you to their cable or xDSL internet network. A wireless router combines the functions of a wireless access point and a router.

4.3.4 Desktop Wi-Fi Router

The most common way to connect users wirelessly to the internet is through a desktop wireless (Wi-Fi) router — small boxes with multiple antennas that broadcast signals across a home or workplace. Range extenders are often placed throughout work areas to extend coverage.

4.3.5 Mobile Hotspot

A mobile hotspot is a common feature on smartphones. When you turn on your phone's mobile hotspot, you share your wireless network connection with other devices. A WiFi hotspot is an area where a wireless network is available — such as a hotel, railway station, etc. You can also create a hotspot from your mobile, through which other mobiles or laptops can access the internet.

WiMAX is based on the IEEE 802.16 standard for delivering high-speed data over a wide area. WiMAX technology facilitates wireless data transmission through portable or fully mobile internet access via several points without any cable infrastructure requirement. WiMAX technology provides approximately 72 Megabits per second without requiring any cable infrastructure.

When you use the internet, its speed depends on signal strength — shown as 2G, 3G, 4G, etc. on your device screen. Each "G" stands for Generation — the network standard on which the network operates. Both network technology and speed have been increasing together.

Usually printed on the back of the mobile battery. The IMEI number tells the current location of any phone. If a person's phone is lost or stolen, its location can be traced via the IMEI number. To know your IMEI number, dial *#06# on your phone.

IMEI Number Structure: AA.BBBBBB-CCCCCC D/EE

The subscriber ID (and personal number) is linked to the SIM card, not to a fixed mobile phone — making it easy to move from one phone to another. All GSM phones require a SIM card to operate. A SIM allows the phone to connect to GSM or CDMA networks and allows the network to track the phone's usage.

SIM cards can also store SMS messages and user contacts. Current SIM cards can store up to 250 name/number pairs and up to 50 SMS text messages.

SIM Card Sizes

IP Telephony converts analogue audio signals into digital data and sends them through the internet. It allows calls via standard internet connections at far less cost than traditional telephone calls. WhatsApp calling uses this technology — it uses the internet (available worldwide) to enable voice calls without the high STD/ISD rates. WhatsApp mainly uses VoIP (Voice over Internet Protocol), which uses voice traffic on the public internet.

IP Phone systems, also called IP PBX, do not use the public internet but make internet phone calls within a private data network — suitable for business environments. Businesses use this to contact people at remote sites at internet rates.

VoIP is an organized attempt to standardize IP Telephony. IP Telephony is an important part of the convergence of computers, telephone, and television into a single unified information environment. Currently, IP telephony service is relatively unregulated by governments.

Most softphone applications work with a headset and microphone, a special VoIP phone (sometimes called a hardphone), or an Analog Telephone Adapter (such as Magic Jack) to enable VoIP calling from a standard telephone handset.

While softphones are often associated with mobile or home users, office employees also prefer them as convenient replacements for traditional desk phones. This can create a problem for network administrators because softphone traffic can cause network congestion.

4.10.1 Voicemail Features

• Receive voice mail messages from multiple callers simultaneously.
• Forward voice mail messages to other people's mailboxes.
• Add a voice introduction to the message you are forwarding.
• Broadcast voice messages — send one message to multiple people at once.
• Store voice messages for a long time.
• Receive notification of incoming voice mail via mobile phone or pager.
• Give different greetings to different users.
• Transfer and save voice messages to storage media like a hard drive; can be sent as email attachments.
• Play back voicemail online or via email without using a phone.

4.10.2 Visual Voicemail

Visual Voicemail is an interface for voice messages that allows viewing, deleting, calling back, etc. in sequence — without listening to everything. It presents your voicemail like an email list. You can then choose options like re-listening, deleting, transferring, etc. — actions that are impossible or very difficult with regular voicemail.

"Ad hoc" is a Latin phrase meaning "for this purpose." It is often used to describe solutions developed for a specific purpose. In computer networking, an ad hoc network describes a network connection established for a session — without requiring a router or wireless base station.

Ad hoc networks are mostly wireless LANs. Instead of depending on base stations or access points, devices communicate directly with each other. Each device participates in routing activity — determining routes using routing algorithms and forwarding data to other devices through these routes.

An ad hoc network is a temporary network connection (like data transfer from one computer to another) made for a specific purpose. If kept for longer, it becomes a regular Local Area Network (LAN).

A sensor network consists of small, usually battery-powered devices and a group of wireless infrastructure that monitors any number of environments and records data — from factories to data centers, hospital labs, and even forests.

WSN (Wireless Sensor Network) is a wireless network consisting of base stations and a number of nodes (wireless sensors). These networks are used to monitor physical or environmental conditions like sound, pressure, temperature, and transfer data through the network to a main location.

Main Applications of Wireless Sensor Networks

GIS Stands For

4.13.1 How GIS Works

• Visualising Data: Geographical data stored in a database is displayed in GIS software.
• Combining Data: Layers are combined to create desired maps.
• Querying: Search for what's important in layers or perform geographical queries.

4.13.2 Advantages of GIS

• Getting specific and detailed information about locations makes decision-making easier.
• Traffic status and distances help determine travel time; additional tasks can be pre-planned.
• Helps identify communities that are at risk or lack basic infrastructure.
• Helps identify criminology cases.
• Better management of natural resources; geographical changes are easily recorded.
• Better communication during emergencies.
• Better decisions lead to cost savings.
• Helps identify various trends within communities and plan for demographic changes.

4.13.3 Components of GIS

Types of GIS Applications

ISP has both domestic and international networks so that customers connected through the ISP can connect to the global network. It streams data via wired (modem, leased line, broadband), radio, and other network transmission media. With cloud computing, ISPs offer even more services at different models and prices.

4.14.1 Functions of ISP

• Providing internet service as required to individuals, companies, or other business activities.
• ISPs can provide dial-up or broadband service to consumers — the most common way is through telephone lines.
• Dial-up connections require a phone line and typically provide speeds of 56 Kbps or less.
• Broadband connections (ISDN, wireless, cable modem, DSL, satellite, Ethernet) vary in speed from 64 Kbps to 20+ Mbps.
• All ISPs have their own servers, and users are connected to those servers.

Main Components of Mobile Computing

Main Uses of Mobile Computing

• Web or internet access.
• Global Positioning System (GPS).
• Emergency services.
• Entertainment services.
• Educational services.

Old wireless systems used powerful transmitters that served an entire area, requiring very high power. Current wireless networking uses cellular systems. Cellular networks use low power, transmit data with more transmitters over short distances. The coverage area is divided into cells — each cell has its own antenna for transmitting signals and its own frequency.

In simple terms: a cell is a geographical area covered by a cellular telephone transmitter. The transmitter facility itself is called a cell site. A cell can be square or hexagonal in shape. Frequency reuse allows the same radio frequency to be used within a given area with minimum interference between cells.

4.17 MTSO – Mobile Telephone Switching Office

The MTSO is the mobile equivalent of a public switched telephone network (PSTN) central office. It contains switching equipment to route mobile phone calls and control units for the cell sites connected to the Mobile Switching Center (MSC). MTSO handles call interconnection with local and long-distance landline telephone companies, billing, registration, authentication, location updates, and call routing.

4.17.1 Handoff in Mobile Connection

Conditions that Trigger Handoff

• A subscriber moves out of one cell's coverage area and enters another cell's coverage.
• A cell reaches its pre-configured capacity — some calls are transferred to neighbouring cells.
• Cells are subdivided into microcells — handoff occurs when duties transfer between large and small cells.
• Interference in calls using the same frequency.

4.17.3 Types of Handoff

4.17.4 Base Station

A base station is a fixed communication location and part of the network's wireless telephone system. It transmits information from the transmitting unit and receives from the receiving unit (such as mobile phones). Often known as a cell site, a base station allows mobile phones to work in a local area as long as it is connected to a mobile or wireless service provider.

Types of Base Stations

Source: 2DCA1 IT Trends – Unit 4 | Makhanlal Chaturvedi National University of Journalism & Communication, Bhopal
Authors: Dr. Sunita Dwivedi & Prashant Parashar