Introduction Cell phones have immensely changed the way people communicate today. A cell phone can be all a person need for interaction. From a cell phone, a person can make calls, send text messages, emails, and send and also receive directions, buy things online, do online banking, listen to music and much more Mobile Generation Essay Words | 7 Pages Talking on a digital cell phone, a caller hears less of the sound of someone's voice. Disadvantages In less crowded areas, the weaker digital signal conveyed by a cellular phone may not be enough to reach a cell Base Station Aug 08, · + Words Essay on Mobile Phone. Essay on Mobile Phone: Mobile Phone is often also called “cellular phone”. It is a device mainly used for a voice call. Presently technological advancements have made our life easy. Today, with the help of a mobile phone we can easily talk or video chat with anyone across the globe by just moving our blogger.comted Reading Time: 5 mins
Have Mobile Phones Improved Communication? - Words | Help Me
Any radiotelephone capable of operating while moving at any speed, battery operated and small enough to be carried by a person comes under the mobile communication systems. These communication systems may have different facilities. The different types of mobile communication systems are a mobile two-way radio, public land radio, mobile telephone and amateur HAM radio. Mobile two-way radios are one-to-many communication systems that operate in half-duplex mode, i.
The most common among this type is citizen band CB radio, which uses amplitude modulation AM. It operates in the frequency range of It is a non-commercial service that uses a press-to-talk switch.
It can be amplitude modulated having double-sideband suppressed carrier or single-sideband suppressed carrier. Public land mobile radio is a two way FM radio system, used in police, fire and municipal agencies. It is limited to small geographical areas. Mobile telephones offer full-duplex transmission.
These are one-to-one systems that permit two simultaneous transmissions. For privacy, each mobile unit carries a unique telephone number. Amateur HAM radios cover a broad frequency band from 1. These include continuous wave CWAM, FM, radio teleprinter, HF slow-scan still picture TV, VHF or UHF slow-scan or fast-scan TV, facsimile, frequency-shift keying and amplitude-shift keying. Before I narrate the journey from 1G to 4G, let me explain the important technologies behind the phenomenal growth of mobile communication systems.
Since the commercial introduction of the essay on mobile communication mobile phone system AMPS service inmobile communication systems have witnessed explosive growth. The most important breakthrough was the cellular concept. The advent of cellular operation brought frequency reuse capabilities, essay on mobile communication. Advances in wireless access, essay on mobile communication, digital signal processingintegrated circuits, increased battery life, etc led to exponential growth of personal communication services.
The cellular system works as follows: An available frequency spectrum is divided into discrete channels, which are assigned in groups to geographic cells covering a service area. The discrete channels are capable of being reused in different cells with diameters ranging from 2 to 50 km. The service area is allotted a radio frequency RF transmitter, whereas adjacent cells operate on different frequencies to avoid interference, essay on mobile communication. Cellular telephones began as a simple two-way analogue communication system using frequency modulation for voice and frequency-shift keying for transporting control and signalling information.
Other cellular systems are a digital cellular system, cordless telephony, satellite mobile and paging. Analogue cellular systems fall in the first-generation 1G category and digital cellular low-power wireless fall in the second-generation 2G category, essay on mobile communication.
InBell Labs in New Jersey proposed a cellular telephone concept as advanced mobile telephony system AMPS. AMPS is a standard cellular telephone service placed into operation on October 13,by Illinois Bell. It uses narrow-band FM with a usable audio frequency band of kHz and maximum frequency deviation of ±12 kHz for per cent modulation.
AMPS uses frequency-division multiple access FDMAwhere transmissions are separated in the frequency domain. Subscribers are assigned a pair of voice channels forward and reverse for the duration of their call. Analogue cellular channels carry both voices using FM and digital essay on mobile communication information using binary FSK. It provides improvements in both capacity and performance.
FDMA uses a frequency canalisation approach to spectrum management, while time-division multiple access TDMA utilises a time-division essay on mobile communication. The entire available cellular RF spectrum is sub-divided into narrow-band radio channels to be used as a one-way communication link between cellular mobile units and base stations.
Generally, a fixed amount of frequency spectrum is allocated to a cellular system. Multiple access techniques are deployed so that the users can share the available spectrum in an efficient manner. For wireless communication, multiplexing can be carried out in three dimensions: Time TDMA essay on mobile communication, frequency FDMA and its variation OFDMA and code CDMA. In TDMA the available spectrum is partitioned into narrow frequency bands or frequency channels, which, essay on mobile communication, in turn, are divided into a number of time slots.
In case of North American digital cellular standard IS, each frequency channel 30 kHz is divided into three-time slots, whereas in European digital cellular system GSM each frequency channel kHz is divided into eight time slots.
Guard bands are needed both between frequency channels and time slots. In FDMA, users share the available spectrum in a frequency band called traffic channel. Different users are assigned different channels on demand basis. All the analogue cellular systems used FDMA system. OFDM is a multi-cellular transmission technique where a data stream is carried with many lower-rate subcarrier tones.
It has been adopted in mobile communications to combat hostile frequency-selective fading and has been incorporated into wireless network standards. OFDM is a multi-cellular transmission technique where a data stream is carried with many lower-rate sub-carrier tones. OFDM combines the advantages of coherent detection and OFDM modulation and has many merits that are critical for future high-speed transmission systems. Communication systems often involve the modulation of a carrier, which results in a bandpass waveform.
A digital signal can be used to modulate the amplitude, frequency or phase of a sinusoidal carrier producing three different forms of digital modulation: amplitude-shift keying ASKfrequency-shift keying FSK and phase-shift keying PSK. In addition to these basic techniques, there are some modulation schemes that employ a combination of amplitude and phase modulation.
It may be noted that unlike ASK signal, PSK transmission is polar. At the same time, ASK is a linear modulation scheme, whereas PSK is a non-linear modulation scheme. PSK has a superior performance over ASK. Digital modulation techniques mentioned above are spectrally inefficient in the sense that the available channel bandwidth is not fully used, essay on mobile communication. Spectral efficiency can be improved by using QPSK.
It is a system for two message sources. In this system modulation carriers in phase quadrature are combined to form the output waveform. In QPSK the amplitude of the modulator waveform and modulator gains are made as nearly equal as possible.
DPSK is a modification of PS that avoids the need to provide synchronous carrier required for detection of PSK signals, essay on mobile communication. It is an ingenious technique whereby the carrier reference is derived from the received waveform in the preceding bit interval by use of a 1-bit delay.
In essence, the received waveform delayed by 1-bit duration serves as its own reference. This is done by supplying various addressed packets, which are interconnected to have the conversation. New dedicated paths are created for sending the data, essay on mobile communication. From the multiple paths to the destination, any path can be used to send data.
Cellular digital packet data was designed for optimal operation with an analogue cellular system, especially AMPS.
Short message service is the most common packet service that is supported on digital cellular networks like GSM, IS, EDGE and PDC packet data service. For message transfer between relevant network entities, control and signalling channels instead of normal traffic channels are generally used for data transmission. GPRS essentially represents add-on capabilities to the basic voice-optimised cellular network that nevertheless maintain the essential characteristics of radio-access technology.
You can use these using GPRS or GSM modules. In order to enhance the data handling capabilities of 2G service, the radio-access portion had to be modified. This modification was evolved in Europe in the form of EDGE. EDGE also supports a link adaptation mechanism that selects the best combination of modulation and encoding schemes based on the time varying link quality. EDGE concept applies to both circuit-mode and packet-mode data and is sufficiently generic for application to other digital cellular essay on mobile communication. It works in the kHz essay on mobile communication with one or more high-level modulation schemes and a range of efficient coding methods.
Modulation schemes are offset QPSK and offset 16 QAM. It is a special essay on mobile communication technique that purposefully uses much more RF bandwidth than necessary to transmit a signal, essay on mobile communication. The main advantages of this technique are secure communication and resistance to intentional jamming. There are 75 channels in the This technique spreads the narrow-band signal as a function of time.
The transmitted frequency is changed to a different pre-assigned channel several times per second hopped. The specificorder in which frequencies are occupied is a function of code sequence and the rate essay on mobile communication hopping from one frequency to another is a function of information rate.
This technique spreads a signal by expanding the signal over a broadband portion of the radio band. It uses a locally generated pseudo noise PN code to encode digital data to be transmitted.
The most practical all-digit version is direct sequence. Binary phase-shift keying is the simplest and most often used modulation technique. One of the most important features of spread-spectrum essay on mobile communication is that these contain a large number of very different signaling formats, used for communicating data symbols.
It means that the receiver which detects one of these formats cannot detect any other format within a single message. The number of formats used in a spread-spectrum system is called multiplicity factor of the communication link and amounts to thousands. CDMA assigns each user a unique spreading code to spread the baseband data before transmission, in order to help differentiate signals from various users in the same spectrum.
It is the platform on which 2G and advanced 3G services are built. After speech, the codec converts voice into digital signal. CDMA spreads the voice stream over the full 1. The receiver uses a correlator to despread the wanted signal, which is passed through a bandpass filter. Unwanted signals are not despread and not passed through the filter. CDMA provides more than ten times the capacity of the analogue AMPS and fivetimes the calling capacity of GSM and TDMA systems.
It requires fewer cell sites than GSM and TDMA. Personal communication system PCS is a new class of cellular telephone system such as AMPS. PCS systems are a combination of cellular telephone network and intelligent network, which is the entity of super-simple transfer SST inter-office protocol tha distinguishes physical components of the switching network such as signal service point, essay on mobile communication, signal control point and signal transfer point from the services provided by SST network.
English Essay on Mobile Phone A Curse or Blessing - English Essay By Alexandra Daddario
, time: 4:49Mobile Communication: From 1G to 4G | Electronics For You
The Positive Impacts Of Mobile Computing. The James Kendrick from ZDnet states, “Communication is wonderfully impacting our ability to stay close to friends and family. We can talk to them anytime to find out how they are doing. We can have video chats to not only stay in touch but to reach out and touch with a nearly physical presence Aug 08, · + Words Essay on Mobile Phone. Essay on Mobile Phone: Mobile Phone is often also called “cellular phone”. It is a device mainly used for a voice call. Presently technological advancements have made our life easy. Today, with the help of a mobile phone we can easily talk or video chat with anyone across the globe by just moving our blogger.comted Reading Time: 5 mins Introduction Cell phones have immensely changed the way people communicate today. A cell phone can be all a person need for interaction. From a cell phone, a person can make calls, send text messages, emails, and send and also receive directions, buy things online, do online banking, listen to music and much more
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