Transmission Media

Physical Transmission Media

Wireless Transmission Media

• Cellular radio is a form of broadcast radio that is used widely for mobile communications

• Microwaves are radio waves that provide a high speed signal transmission.

• A communications satellite is a space station that receives microwaves signals from an earth-based station, amplifies it and broadcasts the signal over a wide area.

Home Network and Communications Channel

• Many home users connect multiple computers and devices together in a home network

• Communications channel refers to transmission media on which data, instructions, or information travel in a communications system.
• Transmission media carries one or more signals.
• Bandwidth refers to the amount of data that can travel over a communications channel Latency is the time it takes a signal to travel from one location to another on a network.
• Broadband media transmit multiple signals simultaneously.

Communications Devices

• A communication device is any type of hardware capable of transmitting data, instructions and information between a sending device and a receiving device.

• A dial-up modem converts signals between analog and digital.
• A digital modem sends and receives data and information to and from a digital line.
• A wireless modem uses the cell phone network to connect to the Internet wirelessly from a notebook computer, a smart phone, or other mobile device.

• A network card enables a computer or device to access a network.
• A wireless access point is a central communications device that allows computers and devices to transfer data wirelessly among themselves or to a wired network.

• A router connects multiple computers or other routers together and transmits data to its correct destination on a network. 

• A hub or switch connects several devices in a network together.

Communication Software

• Communications Software consists of programs that:

Communications Over the Telephone Network

• The public switched telephone network (PSTN) is the worldwide telephone system.

Network Communications Standards

• Wi-Fi identifies any network based on the 802.11 standard that facilitates wireless communication,
• Sometimes referred to as wireless Ethernet 

• Bluetooth defines how two Bluetooth devices use short-range radio waves to transmit data.

• UWB (ultra-wideband) specifies how to UWB devices use short-range radio waves to communicate at high speeds.
• IrDA transmits data wirelessly via infrared (IR) light waves
• RFID uses radio signals to communicate with a tag placed in or attached to an object, animal, or person.

Networks

• A network is a collection of computers and devices connected together via communications devices and transmission media.

• Advantages of network include:

          

Type of Networks

Network Topologies

• A network topology refers to the layout of the computers and devices in a communications network.

Network Architechtures

• The design of computers, devices, and media on a network.

Communications

• Computer communications describes a process in which two or more computers or devices transfer data, instructions, and information.

• Components for successful communications:

Uses of Computer Communications