Computer Engineering Articles - Page 26 of 37

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 More

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 More

Fourth Generation (4G) mobile phones provides broadband cellular network services and is successor to 3G mobile networks. It provides an all IP based cellular communications. The capabilities provided adhere to IMT-Advanced specifications as laid down by International Telecommunication Union (ITU).FeaturesIt provides an all IP packet switched network for transmission of voice, data, signals and multimedia.It aims to provide high quality uninterrupted services to any location at any time.As laid down in IMT-Advanced specifications, 4G networks should have peak data rates of 100Mbps for highly mobile stations like train, car etc., and 1Gbps for low mobility stations like residence etc.It also ... Read More

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 More

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 More

Third generation mobile phones, or “3G Internet” mobile phones, is a set of standards for wireless mobile communication systems, that promises to deliver quality multimedia services along with high quality voice transmission.Features3G systems comply with the International Mobile Telecommunications-2000 (IMT-2000)specifications by the International Telecommunication Union (ITU).The first 3G services were available in 1998.It provides high speed transmission having data transfer rate more than 0.2Mbps.Global roaming services are available for both voice and data.It offers advanced multimedia access like playing music, viewing videos, television services etc.It provides access to all advanced Internet services, for example surfing webpages with audio and video.It ... Read More

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 More

Priority inversion is a operating system scenario in which a higher priority process is preempted by a lower priority process. This implies the inversion of the priorities of the two processes.Problems due to Priority InversionSome of the problems that occur due to priority inversion are given as follows −A system malfunction may occur if a high priority process is not provided the required resources.Priority inversion may also lead to implementation of corrective measures. These may include the resetting of the entire system.The performance of the system can be reduces due to priority inversion. This may happen because it is imperative ... Read More

Multithreading allows the execution of multiple parts of a program at the same time. These parts are known as threads and are lightweight processes available within the process. Therefore, multithreading leads to maximum utilization of the CPU by multitasking.The main models for multithreading are one to one model, many to one model and many to many model. Details about these are given as follows −One to One ModelThe one to one model maps each of the user threads to a kernel thread. This means that many threads can run in parallel on multiprocessors and other threads can run when one ... Read More

Process communication is the mechanism provided by the operating system that allows processes to communicate with each other. This communication could involve a process letting another process know that some event has occurred or transferring of data from one process to another. One of the models of process communication is the message passing model.Message passing model allows multiple processes to read and write data to the message queue without being connected to each other. Messages are stored on the queue until their recipient retrieves them. Message queues are quite useful for interprocess communication and are used by most operating systems.A ... Read More