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

Process Creation and Process termination are used to create and terminate processes respectively. Details about these are given as follows −Process CreationA process may be created in the system for different operations. Some of the events that lead to process creation are as follows −User request for process creationSystem InitializationBatch job initializationExecution of a process creation system call by a running processA process may be created by another process using fork(). The creating process is called the parent process and the created process is the child process. A child process can have only one parent but a parent process may ... 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

A process is an active program. It can also be said as a program that is under execution. It is more than the program code as it includes the program counter, process stack, registers, program code etc.A process passes through different states as it executes. A diagram that illustrates all these states is as follows −Details about the running, waiting and terminated process are given as follows −Running ProcessThe process is said to be in running state when the process instructions are being executed by the processor. This is done once the process is assigned to the processor using the ... Read More

Process Scheduling handles the selection of a process for the processor on the basis of a scheduling algorithm and also the removal of a process from the processor. It is an important part of multiprogramming in operating system.Process scheduling involves short-term scheduling, medium-term scheduling and long-term scheduling. Details about these are given as follows −Long-Term SchedulingLong-term scheduling involves selecting the processes from the storage pool in the secondary memory and loading them into the ready queue in the main memory for execution. This is handled by the long-term scheduler or job scheduler.The long-term scheduler controls the degree of multiprogramming. It ... Read More