Page 40 - DCAP311_DCAP607_WIRELESS_NETWORKS

Wireless Networks

Notes Self-Assessment

Fill in the blanks:
1. PMP is usually used for establishing private enterprise connectivity to offices in
.............................. locations
2. Point-to-point is sometimes abbreviated as ..............................
3. Examples of .............................. communications systems are radio and television
broadcasting.
4. ................................. stations are sometimes called control or fixed stations in US Federal
Communications Commission licensing
5. .............................could be defined as receiving any signal other than from a radio in your
own system.
6. An ................................. controller is a device that sits between the local and remote network
and adds a layer of security to the network, determining whether connections are secure
and should be allowed.
7. .......................... provide the basic ability of transferring data from one computer to another.

8. A ..................................... is a Physical layer and Data Link layer device.

2.2 Network Architecture

Network architecture is the design of a communications network. It is a framework for the
specification of a network’s physical components and their functional organization and
configuration, its operational principles and procedures, as well as data formats used in its
operation.

In telecommunication, the specification of a network architecture may also include a detailed
description of products and services delivered via a communications network, as well as detailed
rate and billing structures under which services are compensated.

The network architecture of the Internet is predominantly expressed by its use of the Internet
Protocol Suite, rather than a specific model for interconnecting networks or nodes in the network,
or the usage of specific types of hardware links.

2.2.1 Network Architecture (OSI)

The Open Systems Interconnection model (OSI model) is a product of the Open Systems
Interconnection effort at the International Organization for Standardization. It is a way of sub-
dividing a communications system into smaller parts called layers. A layer is a collection of
similar functions that provide services to the layer above it and receives services from the layer
below it. On each layer, an instance provides services to the instances at the layer above and
requests service from the layer below.

z z Physical Layer: The Physical Layer defines the electrical and physical specifications for
devices. In particular, it defines the relationship between a device and a transmission
medium, such as a copper or optical cable. This includes the layout of pins, voltages,
cable specifications, hubs, repeaters, network adapters, host bus adapters (HBA used in
storage area networks) and more. Its main task is the transmission of a stream of bits over
a communication channel.
z z Data Linking Layer: The Data Link Layer provides the functional and procedural means
to transfer data between network entities and to detect and possibly correct errors that

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