Telemedicine: Core Technologies (Telecommunication and Networking) Jayanta Mukherjee

Signal Transmission Transmitter Receiver Channel x(t)=A.sin .t) y(t .A.sin( .t 

Channel Bandwidth ● How fast the system responds? ● Range of fequencies transmitted by the channel. ● Modulation is the process of translating signal's bandwidth into a channel's bandwidth.

Modulation ● Amplitude Modulation y(t)=A.x(t).sin( .t  ● Frequency modulation y(t)=A.sin((  k.x(t))t  ● Phase modulation y(t)=A.sin( .t  +k.x(t))

Telephone Line ● Bandwidth for local loop: 4 Khz ● Bandwidth of voice signal: ~ 4 Khz ● Analog Telephony does not require modulation

Modulation for Digital Communication ● Digital Data: Bi-level (0,1) ● Frequency Shift Keying (FSK) ● Phase Shift Keying (PSK) ● QPSK ● QAM ● V.32 Modem:  =2400 Hz., Number of levels=32 Data rate: 2400x6 bps=14.4 Kbps ● V.90 Modem: Data rate: 57.6 Kbps (128 levels)

Quadrature Amplitude Modulation (QAM) ● Two carrier waves with quadrature phase shift A.x1(t).cos(  t)+A.x2(t).sin(  t) ● V.32 Modem:  =2400 Hz., Number of levels=32 Data rate: 2400x6 bps=14.4 Kbps ● V.90 Modem: Data rate: 57.6 Kbps (128 levels)

Communication Channels Communication Links Terrestrial Wireless POTS Leased lines ISDN LAN Satellite Wireless LAN GSM/CDMA GPRS

Different Communication Links LinksBandwidth POTS ISDN(BRI) T-1 and fractional T-1 DSL Primary rate ISDN T-2 Leased lines T-3 leased lines T-4 leased lines Broadband ISDN SONET 2.4 Kbps ~ 57.6 Kbps 128 Kbps 384 Kbps ~ 1.54 Mbps 128 Kbps ~ 9 Mbps 1.54 Mbps Mbps 46 Mbps 273 Mbps 150 ~ 1200 Mbps ~ 4976 Mbps

16 kbps – 2 MbpsKu bandSkybridge 16 kbps – 64 MbpsKa bandTeledesic 155 MbpsKa band and GHzCelestri 400 kbps – 30 MbpsKu, Ka bandCyberstar Satellite 2.4 kbpsL, Ka bandIridium 7.2 kbpsL, S, C bandGlobalstar 2.4 kbpsC, S bandICO Mbps2.4 GHzBluetooth 54 Mbps5 GHzHiperlan2 20 Mbps5 GHzHiperlan1 Wireless LAN 11 Mbps2.4 GHzIEEE b 20 Mbps5 GHzIEEE a GPRS kbps900/1800/1900 MHzGPRS 9.6 – 43.3 kbps1900 MHzGSM – 43.3 kbps1800 MHzGSM-1800 GSM 9.6 – 43.3 kbps900 MHzGSM-900 Data Transfer RatesFrequency BandSub-typeType The main wireless communication networks/standards.

Different Wireless Communication Services LinksBandwidth GSM GPRS Satellite 9.6 Kbps ~ 43.3 Kbps Kbps 2.4 Kbps ~ 155 Mbps

Computer Networking ● Connecting a group of computer for exchange of Information. ● Different roles of a computer Terminal Host Computer Acting like a telephone exchange ● Different Topology A grid of point to point connections Connected to a common channel (Bus) Ring Tree

Open system interconnection layers Physical Data link Network Transport Session Presentation Application ……DNSSNMPHTTPSMTPTelnetFTP UDPTCP IP Token RingATMEthernet Basic signaling through media

Area of Coverage of Networking ● Local Area Networking (LAN) Organisation, Campus ● Wide Area Networking Distant locations

Data Rates Supported by Different LAN technologies LAN Technology Datarate Ethernet Token ring Token bus ATM Gigabit Ethernet 10 Mbps 4 ~ 16 Mbps 16 Mbps 155 Mbps 1000 Mbps

A predefined circuit width dedicated bandwidth for end to end communication is set before the transfer of data. Circuit Switch Predefined Full Bandwidth Used

Pay LoadDST 1Src 1Pay LoadDST 2Src 2 Router To DST 1 ACK To Src1 ACK To Src 2 To DST 2 Packet Switching

Virtual Circuit Dynamic Allocation of connected links with shared B.W. A A A B B B B B A A A B B B A A A

B B A A A B B Permanent Virtual Circuit Predefined Virtual Circuit with shared B.W. B A A B B B B B A A

Packets of fixed size are transmitted at constant rate (irrespective of availability of data for transmission). Cell Switching HeaderPay Load ATMCell

Connectionless Services No defined path for packet transmission. Packet travels and ones it reaches destination, it is accepted by the process.

Users Network Resources Communication Channel User ID & PasswordAuthentification Firewall Encryption Log in restriction Network Security

Encryption Alg Decryption Alg Plain text Cipher text Private Key SenderReceiver Public Key SenderReceiver Private Key Cryptography Public Private Key cryptography