Lecture 5: Telephony

Transcription

1 Lecture 5: Telephony Dr. Mohammed Hawa Electrical Engineering Department University of Jordan EE7: Telephony. Public Switched Telephony Network (PSTN) or Plain Old Telephony System (POTS) Local Loop, orlast Mile Core Public Switched Telephone Network Up to 0,000 local loops (Analog, Twisted Pair) Main Exchange, or Toll Office or Central Office Local Exchange, or End Office (Codec, Digital) Medium-bandwidth Trunks (Digital, Optical Fiber) (E, E, T, T) High-bandwidth Trunks (Digital, Optical Fiber) (E, STM-) Trunks between PSTNs/Countries (STM-6, STM-6) Public Switched Telephone Network

2 Plesiochronous Digital Hierarchy (PDH) European Standard: Carrier Multiplex Data Rate MUX Level E0 channel (voice or signaling) 6 kbps E 0 speech + framing + signaling channels.08 Mbps st Level E Four E carriers + framing 8.8 Mbps nd Level E Four E carriers + framing.68 Mbps rd Level E Four E carriers + framing 9.6 Mbps th Level E5 Four E carriers + framing Mbps 5 th Level U.S. Standard: Carrier Multiplex Data Rate MUX Level T0 channel (voice and signaling combined) 6 kbps T PCM channels + framing.5 Mbps st Level T Four T carriers + framing 6. Mbps nd Level T Seven T carriers + framing.76 Mbps rd Level T Six T carriers + framing 7.76 Mbps th Level PDH: T Hierarchy

3 PDH: E Hierarchy... One phone call (6 kbit/s) E- Multiplexer (MUX) E- signal (0 calls + signaling + synchronization) (.08 Mbit/s) (0 calls) E- MUX E- signal (four E-s) (8.8 Mbit/s) (0 calls) European PDH Hierarchy E- MUX E- signal (four E-s) (.68 Mbit/s) (80 calls) E- MUX E- signal (four E-s) (9.6 Mbit/s) (90 calls) 5 SDH (Synchronous Digital Hierarchy) / SONET (Synchronous Optical NETwork) European Standard: Optical Carrier Multiplex Data Rate STM- Basic 55.5 Mbps STM- Four STM- carriers 6.08 Mbps STM-6 Four STM- carriers.88 Gbps STM-6 Four STM-6 carriers Gbps STM-56 Four STM-6 carriers 9.8 Gbps STM-0 Four STM-56 carriers 59.5 Gbps U.S. Standard: Optical Carrier Electrical Carrier Multiplex Data Rate OC- STS- Basic 5.8 Mbps OC- STS- Three OC- carriers 55.5 Mbps OC- STS- Four OC- carriers 6.08 Mbps OC-8 STS-8 Four OC- carriers.88 Gbps OC-9 STS-9 Four OC-8 carriers Gbps OC-768 STS-768 Four OC-9 carriers 9.8 Gbps OC-07 STS-07 Four OC-768 carriers 59.5 Gbps 6

4 Remember SDH is an ITU-T standard (G.707, G.708, G.709) STM-n stands for: Synchronous Transport Module Level n STS-n stands for: Synchronous Transport Signal Level n OC-n stands for: Optical Carrier Level n Benefits of SDH/SONET over PDH: simpler and a more flexible multiplexing at high data rates. Huge capacity of extra bits dedicated for network management and maintenance functions to allow protection rings. 7 Busy Hour Businesses 8

5 Business and Residential Traffic 9 Busy Hour with dial-up modems 0 5

6 Cellular Telephony: Wireless resources are limited GSM uses Circuit Switching 6

7 Erlang B Traffic Table: Maximum offered load versus B and S End of Erlang B Traffic Table Dr. Mohammed Hawa 7

8 Erlang C Traffic Table: Maximum offered load versus B and S End of Erlang C Traffic Table Dr. Mohammed Hawa 6 8

9 Poisson Traffic Table: Maximum offered load versus B and S End of Poisson Traffic Table Dr. Mohammed Hawa 8 9