Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
Computer Engineering Articles
Page 34 of 35
Second-Generation (2G) Mobile Phones
Second generation (2G) mobile phones switched from analog system of 1G to digital system. It was commercially launched in 1991 as GSM standard in Finland. As with 1G phones, 2G phones didn’t have any worldwide standardizations. 2G systems were also known as personal communications services (PCM). Advantages of 2G over 1G It allows voice signals to be digitized and compressed. So, they are more efficient on frequency spectrum than 1G. They introduced data services for mobile in form of SMS text messaging. Data and voice signals are digitally encrypted. So, security against eavesdropping and fraud increased manifold. Digital signals ...
Read MoreDigital Advanced Mobile Phone System
Digital Advanced Mobile Phone System (D-AMPS)is a digital version of Advanced Mobile Phone Systems (AMPS), the original analog standard for cellular phones. D-AMPS uses a combination of time division multiple access (TDMA) and frequency division multiple access (FDMA). It adds TDMA to get three channels per AMPS channel, thus tripling the number of calls on a channel. Features They are standardised by IS-54 and IS-136. As in AMPS, D-AMPS also uses frequencies from 800 to 900MHz for transmission. Half of the spectrum is used for sending signals and the other half is used for receiving signals. The frequency ...
Read MoreGlobal System for Mobile Communications
Global System for Mobile communication (GSM) is the most widely used digital mobile telephony system. GSM technology was first launched in Finland in 1991. It was developed by European Telecommunications Standards Institute (ETSI) to describe the protocols for 2G mobile communications.Presently, GSM comprises of approximately 90% of mobile connections worldwide. Features Original 2G standard was a digital, circuit-switched, full duplex network. GSM is part of the evolution of wireless mobile telecommunications including High-Speed Circuit-Switched Data (HSCSD), General Packet Radio Services (GPRS), Enhanced Data GSM Environment (EDGE), and Universal Mobile Telecommunications Service (UMTS). GSM operates at either 900 MHz ...
Read MoreHandoff in Mobile Connections
Definition In cellular communications, the handoff is the process of transferring an active call or data session from one cell in a cellular network or from one channel to another. In satellite communications, it is the process of transferring control from one earth station to another. Handoff is necessary for preventing loss of interruption of service to a caller or a data session user. Handoff is also called handover. Situations for triggering Handoff Handoffs are triggered in any of the following situations − If a subscriber who is in a call or a data session moves out of ...
Read MoreEnhanced Data rates for GSM Evolution (EDGE)
Enhanced Data-rates for GSM Evolution (EDGE) is an improved version of GSM providing higher data transmission rate than GSM, while being compatible with the older systems. Features It was standardized by 3GPP as a part of GSM family and was deployed in GSM networks in 2003. The other names for EDGE are Enhanced GPRS (EGPRS) and IMT-Single Carrier (IMT-SC). It is compatible with any packet – switched application. It is also backward – compatible, i.e. compatible with existing or older versions. It enables data to be sent over a GSM TDMA systems at speeds of 384Kbps. GSM uses the ...
Read MoreCDMA2000
CDMA2000 is a code division multiple access (CDMA) version of IMT-2000 specifications developed by International Telecommunication Union (ITU). It includes a group of standards for voice and data services − Voice − CDMA2000 1xRTT, 1X Advanced Data − CDMA2000 1xEV-DO (Evolution-Data Optimized) Features CDMA2000 is a family of technology for 3G mobile cellular communications for transmission of voice, data and signals. It supports mobile communications at speeds between 144Kbps and 2Mbps. It has packet core network (PCN) for high speed secured delivery of data packets. It applies multicarrier modulation techniques to 3G networks. This gives higher ...
Read MoreLong-term Evolution (LTE)
Long – term evolution or LTE is a standard for wireless technology based upon GSM/EDGE and UMTS/HSPA technologies. It offers increased network capacity and speed to mobile device users. It is an extension of the 3G technology for high-speed mobile communications. LTE-Advanced is an improvement over LTE that meets the criteria of 4G wireless communications as laid down by IMT-Advanced standards. It provides greater speeds and better quality of communications. Both LTE and LTE-A are used for mobile broadband communications and in VoIP. Features of LTE LTE was specified by The 3rd Generation Partnership Project (3GPP) release 8 was ...
Read MoreVoice over LTE (VoLTE)
Voice over long-term evolution or Voice-over LTE (VoLTE) are the standards in all-IP networks for voice communication as well as data communication over 4G LTE networks. VoLTE offers services like creating, provisioning and managing high-speed voice, data, multimedia and messaging services on a 4G wireless network for mobile and portable devices. It uses the IP multimedia subsystem (IMS) to deliver the services. It transmits everything through only packets and thus supports only packet switching. So, all data from any circuit-switched networks like GSM need to be converted to packets before they are transmitted by VoLTE. The communication is depicted ...
Read MoreCable Television
Cable television is a popular television system that delivers television programming services through cables. This is different from terrestrial television (where radio waves are transmitted over air and received by antennas) and satellite television (where signals are sent by communication satellites and received by satellite dish). Types of cables used in cable TV coaxial cables through which radio-frequency signals are transmitted fiber optic cables through which light pulses are sent Services offered by Cable TV Originally used for broadcasting television services, the functionalities of cable TV has now been extended for providing different services of computer ...
Read MoreCommunity Antenna Television
Cable television in their early days were called Community Antenna Television (CATV) or sometimes as Community Access Television. It was originally conceived as a method to provide cable TV services to rural areas and hilly terrains. The subscribers who want to avail the cable TV services need to pay a specified monthly subscription charge as well as an initial establishment charge. System Layout The system comprises of a big sized community antenna, installed on a hilltop that can receive broadcast signals from communication satellites. The signals received are amplified, corrected and strengthened by a device attached to the antenna, popularly ...
Read More