Wireless communications is a type of data communication that is performed and delivered wirelessly. This is a broad term that incorporates all procedures and forms of connecting and communicating between two or more devices using a wireless signal through wireless communication technologies and devices. ↓↓↓↓ Read More: Watch my videos on snack here: --> --> http://sck.io/x-B1f0Iy @ Kindly Follow my Instagram Page to discuss about your mental health problems- -----> https://instagram.com/mentality_streak?utm_medium=copy_link @ Appreciate my work: -----> behance.net/burhanahmed1 Thank-you !

1. Wireless Mobile
Communication

2. Wireless Mobile Communication
• Introduction
• Cellular Systems and Topology
• From Analog to Digital Systems
• Wireless Data Networking

3. Introduction
There are a variety of wireless communication systems for
transmitting voice, video, and data in local or wide areas.
There are point-to-point wireless bridges, wireless local area
networks, multidirectional wireless cellular systems, and
satellite communication systems.
This topic discusses "mobile" wireless technologies that provide
voice and data communication services to mobile users who use
cell phones, PDAs, Internet terminals, and related computing
devices.
The number of wireless mobile devices is increasing globally. At
the same time, wireless systems are achieving higher data rates
to support Internet and other data-related applications. The
newest mobile communication systems are targeting data rates as
high as 2-159 Mbits/sec.

4. Cellular Systems and Topology
A cell in a cellular system is a roughly circular area with a central transmitter/receiver base station. The
station is raised up on a tower or placed on top of a building. Some are located on ware houses and trade
centers. The station has a 360-degree omnidirectional antenna (except when directional transmissions are
required) that is tuned to create a cellular area of a specific size. Cells are usually pictured as hexagonal in
shape and arranged in a honeycomb pattern. Cell size varies depending on the area. In a city, there are
many small cells, while rural area may have very large cells.
Cellular topology provides a way to maintain an adequate number of call channels even though the actual
number of channels available to the entire service area is small. This is possible through frequency reuse.
Each cell is assigned a set of channel frequencies, and no adjoining cells may use those frequencies.
However, cells further away may use those frequencies because the distance between cells provides a
buffer zone that prevents frequency interference.

5. From Analog to Digital Systems
Mobile wireless analog communication systems have been around since
the 1950s. The early systems were single channel "over-and-out"
systems. Analog cellular services were introduced by AT&T in the
1970s and became widespread in the 1980s. The primary analog
service in the United States is called AMPS (Advanced Mobile Phone
Service). There are similar systems around the world that go by
different names. The equivalent system in England is called TACS
(Total Access Communications System). The AMPS system is a circuit-
oriented communication system that operates in the 824-MHz to 894-
MHz frequency range. This range is divided into a pool of 832 full-
duplex channel pairs (1 send, 1 receive). Any one of these channels
may be assigned to a user. A channel is like physical circuit,
except that it occupies a specific radiofrequency range and has a
bandwidth of 30 kHz. The circuit remains dedicated to a subscriber
call until it is disconnected, even if voice or data is not being
transmitted.

6. Cellular systems are described in multiple generations, with third- and fourth-
generation (3G and 4G) systems just emerging:
1G systems
These are the analog systems such as AMPS that grew rapidly in the 1980s and are
still available today. Many metropolitan areas have a mix of 1G and 2G systems. The
systems use frequency division multiplexing to divide the bandwidth into specific
frequencies that are assigned to individual calls.
2G systems
It uses either TDMA (Time Division Multiple Access) or CDMA (Code Division Multiple
Access) access methods. The European GSM (Global System for Mobile communications)
is a 2G digital system with its own TDMA access methods. The 2G digital services
began appearing in the late 1980s, providing expanded capacity and unique services
such as caller ID, call forwarding, and short messaging.
Cellular Generations

7. 3G systems
3G has become an umbrella term to describe cellular data communications with a
target data rate of 2 Mbits/sec. The ITU originally attempted to define 3G in its
IMT-2000 (International Mobile Communications-2000) specification, which specified
global wireless frequency ranges, data rates, and availability dates. According to
Nokia, a 3G device is a personal mobile, multimedia communications device that
supports speech, colour pictures, and video, and various kinds of information
content. However, 3G systems will certainly support more phone calls per cell.
4G Systems
There are 4G systems that become available even before 3G matures. While 3G is
important in boosting the number of wireless calls, 4G is offering true high-speed
data services. 4G data rates are in the 2 to 156-Mbit/sec range, and possibly
higher. 4G also fully supports IP. High data rates are due to advances in signal
processors, new modulation techniques, and smart antennas that can focus signals
directly at users.
Cellular Generations

8. Advantages of Wireless
Communication
• Any data or information can be transmitted faster and with a
high speed.
• Maintenance and installation is less cost for these networks.
• The internet can be accessed from anywhere wirelessly.
• It is very helpful for workers, doctors working in remote
areas as they can be in touch with medical centers.

9. Disadvantages of Wireless
Communication
• An unauthorized person can easily capture the wireless
signals which spread through the air.
• It is very important to secure the wireless network so that
the information cannot be misused by unauthorized users.

10. In a circuit-switched wireless network, a dedicated radio channel is allocated to a
single transmission. As long as data transmissions are long and continuous (file
transfers), a circuit is used efficiently. However, most data transmissions are
bursty, and dedicating an entire circuit to them is usually a waste of valuable
wireless bandwidth. During idle periods when no data is being sent, bandwidth is
still dedicated to the user and not available for others to use.
Packet-switching schemes are best for bursty data traffic. Several packet-switching
schemes may be used. In one technique, packets are inserted into the idle space on
any available channel. The busier the network, the less bandwidth that will be
available for data. An entire network may be designed just for packet data. Most
wireless data systems offer minimal data rates, usually in the 10-Kbit/sec range.
That's really only useful for short messaging and occasional Web page lookups.
However, new wireless protocols bond multiple channels to increase data rates.
For example; When you connect over a circuit-switched line, the phone company bills
you for the entire duration of the call. With packet-switching systems, you are
typically billed by the packet.
Wireless Data Networking

11. Several packet data schemes are outlined here:
CDPD (Cellular Digital Packet Data)
CDPD provides packet switching on AMPS systems. Data packets are sent when there is
idle time on a channel. The system has a limited data rate, usually about 9,600
bits/sec.
Data over GSM networks
A channel bonding technique called HSCSD (high speed circuit switched data) extends
GSM channel capacity to 14.4 Kbits/sec and allows up to four channels to be
combined to provide up to 57.6 Kbits/sec throughput.
GPRS (General Packet Radio Service)
Provides packet switching for TDMA circuit-switched networks and data rates of 115
Kbits/sec or higher. GPRS is a tunnelling protocol that delivers IP packets across
the mobile network to a router that puts them on the Internet.
EDGE (Enhanced Data Rates for Global Evolution)
Improves GSM system data rates with the modified 8PSK (phase shift keying)
modulation technique. The combination of GPRS and EDGE boosts the data rate of GSM
to 384 Kbits/sec.

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