A handoff is the transfer of a call or data session from one cell to another as the user moves. The connection continues instead of being dropped at the cell boundary.

Which part of the network decides that a handoff should take place?

The base station controller decides when to hand a connection over and to which cell. The controller receives the measurement reports from every base station under its control.

Describe the steps involved in handing a call to a new cell.

The network selects a target cell during a handoff and reserves a channel on it. The handset is then instructed to retune, and the old channel is released once the new link works.

What is a hard handoff?

A hard handoff breaks the link with the old cell before the handset connects to the new one. The connection is therefore interrupted very briefly during the change.

CCEA A-Level Digital Technology 2650

Systems Analysis and Development Approaches

Topic overview The software crisis and the need for systems development User needs, time and cost Roles in a systems development team The purpose of analysis Fact-finding techniques Functional and non-functional requirements Data flow diagrams The waterfall model Rapid application development and Agile Resources, constraints and risks in a software project Project management, Gantt charts and critical path analysis Version management

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Programming

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Data, Information and Data Representation

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Computer Architecture and Processing Systems

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System Software, Application Software and the User Interface

Topic overview User interfaces: WIMP, command line and forms dialogue Choosing and evaluating a user interface Inputting text, sound and video The purpose of an operating system How an operating system manages memory and processes Types of operating system Utility programs The need for data compression, lossless and lossy Zipping and archive files Common data file formats Application software: generic and special purpose Obtaining and delivering software

Web Technology and Multimedia

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Networks

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Databases

Topic overview The relational database and its main features Logical and physical data models Entities, attributes and keys Entity-relationship modelling Normalisation to third normal form The data dictionary Structured Query Language: creating and changing data Structured Query Language: retrieving data Query By Example and alternatives to SQL Database security, integrity and recovery

Artificial Intelligence, Expert Systems and Robotics

Topic overview What artificial intelligence means The Turing test and machine intelligence Neural network modelling The structure of an expert system The knowledge base and the inference engine Shells, heuristics, fuzzy logic and the knowledge engineer Expert systems in medicine, fault diagnosis and insurance Natural language processing Voice recognition technology Evaluating natural language and voice recognition systems The technology of robotics Robotics in commercial situations

Mobile Technology, Data Mining and Cloud Computing

Topic overview Cells, masts and frequency reuse Handoff between cells The base station controller, the mobile switching centre and the PSTN What data mining is Gathering and storing data for mining Processing and analysing large volumes of data Big data in health, finance and retail Data mining and the privacy of the individual What cloud computing is Virtualisation, hosted instances, hosted solutions and clustering Cloud services: storage, email, software and backup Evaluating cloud computing for business

Individual, Social and Legal Considerations

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The Development Project: Analysis and Design

Topic overview Scheduling the project with a Gantt chart Internal and external constraints on the solution Detailing user requirements as inputs, processes and outputs Prioritising requirements as essential and non-essential Data flow diagrams at level 0 and level 1 Specifying hardware and software requirements The overall system design Process descriptions and algorithms User interface design and validation Data modelling and normalisation for the solution Designing the queries and reports Developing a comprehensive test plan

The Development Project: Build, Testing and Evaluation

Topic overview Choosing software to develop the solution Building the solution Test data and the types of testing Carrying out and recording the testing Documenting a strategy for system implementation Evaluating the solution against the user requirements Identifying extensions to the system The electronic user guide Bringing the system into use and supporting it Documentation for the completed system

Mobile Technology, Data Mining and Cloud Computing

Handoff between cells

3 things to know
A2 Unit 1

Overview

Steps involved in handing a call to a new cell, hard handoff and soft handoff.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What is a handoff?

Key term

What other term is used for a handoff?

Key term

How does the network know that a handoff is needed?

Questions from this subtopic

Each one with the model answer underneath.

1
What is a handoff?
Model answer
A handoff is the transfer of a call or data session from one cell to another as the user moves. The connection continues instead of being dropped at the cell boundary.
2
What other term is used for a handoff?
Model answer
A handoff is also called a handover, and both terms describe the transfer of an active connection from one base station to another.
3
How does the network know that a handoff is needed?
Model answer
The handset continually measures the signal strength of its own cell and of the neighbouring cells. The measurements are reported to the network, which decides when another cell would serve the handset better.
4
Which part of the network decides that a handoff should take place?
Model answer
The base station controller decides when to hand a connection over and to which cell. The controller receives the measurement reports from every base station under its control.
5
Describe the steps involved in handing a call to a new cell.
Model answer
The network selects a target cell during a handoff and reserves a channel on it. The handset is then instructed to retune, and the old channel is released once the new link works.
6
What is a hard handoff?
Model answer
A hard handoff breaks the link with the old cell before the handset connects to the new one. The connection is therefore interrupted very briefly during the change.

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Systems Analysis and Development Approaches

Design, Development and Testing

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