Communication Systems

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Communication Systems Lecturer: M.E. P.T.A. Quang .Contents           Chapter 1: Introductory Concepts Chapter 2: QoS Chapter 3: Transmission and switching Chapter 4: Digital networks Chapter 5: Signaling Chapter 6: PSTN Chapter 7: VoIP Chapter 8: Mobile communication Chapter 9: Satellite communication Chapter 10: Fiber-optic communication .Introductory Topics in Telecommunication            End-users, nodes, and connectivities Telephone numbering and routing Tandem switches Hierarchical structure Busy hour and grade of services Simplex, half-duplex, and full duplex One-way and two-way circuit Double seizure Supervision signals Network topologies Variations in traffic flow .End users, nodes, and connectivities    End-users: inputs to the network / recipients of network outputs...

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Nội dung Text: Communication Systems

Communication Systems Lecturer: M.E. P.T.A. Quang
Contents  Chapter 1: Introductory Concepts  Chapter 2: QoS  Chapter 3: Transmission and switching  Chapter 4: Digital networks  Chapter 5: Signaling  Chapter 6: PSTN  Chapter 7: VoIP  Chapter 8: Mobile communication  Chapter 9: Satellite communication  Chapter 10: Fiber-optic communication
Introductory Topics in Telecommunication  End-users, nodes, and connectivities  Telephone numbering and routing  Tandem switches  Hierarchical structure  Busy hour and grade of services  Simplex, half-duplex, and full duplex  One-way and two-way circuit  Double seizure  Supervision signals  Network topologies  Variations in traffic flow
End users, nodes, and connectivities  End-users: inputs to the network / recipients of network outputs  Node: a point or junction in a transmission system where lines and trunks meet. (switching function)  Connectivity: links an end-user to a node, and from there possibly through other nodes to some final end-user destination
Telephone numbering and routing:  Every subscriber has an unique number related to physical location. trunk Subscriber loop Call 447-8765 Route: look up trunk to 447
Tandem switches in Local Area Connectivity  Traffic concentrator  reduce the connection  economic expedient
Hierarchical structure
Busy hour and grade of service  Busy hour: period of maximum usage demand  Grade of service = blocking probability  B=1% : during busy hour, 1 in 100 calls can be expected to meet blockage
Simplex, half-duplex, and full duplex  Simplex: one way operation; no reply channel  Half-duplex: two-way service. Only one direction at a time  Full duplex: two-way independent transmission (PSTN)
One-way or two-way circuit  Two-way circuit: any trunk can be selected for operation in either direction a) two-way b) One-way c) Hybrid scheme
Double seizure  In bothway groups, it can happen that the exchanges at both ends of a trunk group seize the same trunk at the same time (double seizure).  Solutions: it can be arranged that one exchange continues the setup, and the other exchange backs off (tries to. seize another trunk for its call). The signaling on bothway trunks includes provisions to alert the exchanges when a double seizure occurs.
Supervision signals
Double seizure  After A seizes a trunk, it expects to receive a backward change to off-hook (wink signal). However, this change may also mean that exchange B is sending a seizure signal.  Wink: return on-hook within 100-1000ms. If the off-hook duration >1s  double seizure
Network topologies Mesh Star Multiple-star Full-mesh
Variations in traffic flow:  Busy hour is different from countries to countries  Noncoincident busy hour
Quality of service  How happy the telephone company is keeping the customer  Customer satisfaction  GoS  Can connectivity be achieved?  Delay before receiving dial tone  Post dialing delay  … (refers to material)
Standardization in telecommunications  ITU (international telecommunication union)  ISO (international standardization organization)  IEEE (Institute of Electrical Electronic Engineers)  ETSI (European Telecommunications Standards Institute)  EIA (Electronic Industries Alliance)
Telecommunication companies
Mobile Telecommunication Co. in VN
Mobile Telecommunication Co. in VN