Communication systems

1
Communication systems
Dr. Bahawodin Baha School of Engineering Universi
ty of Brighton, UK July 2007
2
Block diagram of a Communication System
3
COMMUNICATION SYSTEMS

• Provide electronic exchange of multimedia data,
  Voice, data, video, music, email, web pages, etc.
• Communication Systems of today Radio and TV
  broadcasting, Public Switched Telephone Network
  (voice, fax, modem)
• Cellular Phones
• Computer networks (LANs, WANs, and the Internet)
• Satellite systems (pagers, voice/data, movie
  broadcasts)
• Bluetooth

4

• Provide electronic exchange of multimedia
  information
• The information to be transmitted is
  electromagnetic wave or electrical signal may
  represent multimedia data, Voice, data, video,
  music, email, web pages, etc.
• The frequency bandwidth occupied by the
  information signal is called the baseband, and
  the signal is often referred to as the baseband
  signal.
• Channel is the medium by which the transmitted
  signal is propagated
• Various layers of atmosphere, cable for telephone
  or date link, cable TV or
• Electrical signals are converted to a
  corresponding light signal that is propagated
  through a fiber optic channel

5
Electromagnetic Spectrum
6
Based on these conditions, the radio spectrum is
divided into the following sub bands

• Extra Low Frequency (ELF) 300 3000 Hz (l
  1000 100km)
• Very Low Frequency (VLF) 3 30 kHz (l 100
  10 km)
• Applications mining, underwater communication
  (submarine), Sonar
• Low Frequency (LF) 30 300 kHz (l 10 1
  km)
• Applications broadcasting, radio navigation
• Medium Frequency (MF) 300 3000 kHz (l 1000
  100 m)
• Applications AM radio broadcasting (550 1600
  kHz)
• High Frequency (HF) 3 30 MHz (l 100 10
  m)
• Applications Broadcasting over large areas,
  amateur radio (ham), citizens band (CB) radio.
• Very High Frequency (VHF) 30 300 MHz (l 10
  1 m)
• Applications TV, FM radio (88 1108 MHz ), radio
  beacons for air traffic control
• Ultra High Frequency (UHF) 300 3000 MHz (l
  1 m 10 cm)
• Applications broadcasting, satellite (TV)
  broadcasting, all (1G to 3G) land mobile
  telephones, cordless telephones, some air traffic
  control.
• Super High Frequency (SHF) 3 30 GHz (l 10
  1 cm)
• Applications Satellite service for telephony and
  TV, mobile services in the future
• Extremely High Frequency (EHF) 30 300 GHz (l
  10 1 mm)
• Applications communications at short distances
  (within Line-Of-Sight), broadcast satellite for
  HDTV (for satellite communication between
  satellites in space, not space to earth).

7
Communication theories

• Communication systems send and receive
  information electronically over communication
  channels
• Modulation
• Demodulation
• Amplification
• Filtering
• Signal detection
• Digital Signal Processing, DSP

8
Wireless Communication

• Objectives
• Multimedia wireless Communications at any Time
  and Anywhere
• Brief history
• Ancient Systems Smoke Signals, Carrier Pigeons
• Radio invented in the 1880s by Marconi
• Many sophisticated military radio systems were
  developed during and after WW2
• Cellular has enjoyed exponential growth since
  1988, with more than 1 billion users worldwide
  today
• Ignited the recent wireless revolution, 1980-2003
• Growth rate tapering off
• Is there a future for wireless?

9
Design Challenges

• Hardware Design
• Precise components
• Small, lightweight, low power
• Cheap
• High frequency operations
• System Design
• Converting and transferring information
• High data rates
• Robust to noise and interference
• Supports many users
• Network Design
• Connectivity and high speed
• Energy and delay constrains

10
Main Points

• Introduction to Communication Systems
• Block diagram of a Communication System
• Electromagnetic spectrum
• Main theories
• Wireless and mobile Communications
• Design challenges include hardware, system and
  network issues

11
The END
http//www.uobkupartnership.talktalk.net