ECEN 621 600 Mobile Wireless Networking Course Materials
ECEN 621 -600 “Mobile Wireless Networking” Course Materials: Papers, Reference Texts: Bertsekas/Gallager, Stuber, Stallings, etc Grading (Tentative): HW: 20%, Projects: 40%, Exam-1: 20%, Exam-II: 20% Lecture notes and Paper Reading Lists: available on-line Class Website: http: //ece. tamu. edu/~xizhang/ECEN 621/start. php Research Interests and Projects: URL: http: //ece. tamu. edu/~xizhang Instructor: Professor Xi Zhang E-mail: xizhang@ece. tamu. edu Office: WERC 331 ECEN 621, Prof. Xi Zhang
Lecture notes 5. ECEN 621, Prof. Xi Zhang
Asynchronous Transfer Mode (ATM) Also known as cell relay Ø Operates at high data rates Ø Resembles packet switching Ø Ø Ø Involves transfer of data in discrete chunks, like packet switching Allows multiple logical connections to be multiplexed over a single physical interface Minimal error and flow control capabilities reduces overhead processing and size Ø Fixed-size cells (53 bytes) simplify processing at ATM nodes Ø ECEN 621, Mobile Wireless Networks Prof. Xi Zhang
ATM Network Architectures ECEN 621, Mobile Wireless Networks Prof. Xi Zhang
ATM Terminology Ø Ø Virtual channel connection (VCC) Ø Logical connection in ATM Ø Basic unit of switching in ATM network Ø Analogous to a virtual circuit in packet switching networks Ø Exchanges variable-rate, full-duplex flow of fixed-size cells Virtual path connection (VPC) Ø Bundle of VCCs that have the same end points ECEN 621, Mobile Wireless Networks Prof. Xi Zhang
ATM Connections Relationships ECEN 621, Mobile Wireless Networks Prof. Xi Zhang
Advantages of Virtual Paths Ø Simplified network architecture Ø Increased network performance and reliability Ø Reduced processing and short connection setup time Ø Enhanced network services ECEN 621, Mobile Wireless Networks Prof. Xi Zhang
Call Establishment ECEN 621, Mobile Wireless Networks Prof. Xi Zhang
Virtual Channel Connection Uses Ø Between end users Ø Ø Between an end user and a network entity Ø Ø Can carry end-to-end user data or control signaling between two users Used for user-to-network control signaling Between two network entities Ø Used for network traffic management and routing functions ECEN 621, Mobile Wireless Networks Prof. Xi Zhang
Virtual Path/Virtual Channel Characteristics Ø Quality of service Ø Specified by parameters such as cell loss ratio and cell delay variation Switched and semipermanent virtual channel connections Ø Cell sequence integrity Ø Traffic parameter negotiation and usage monitoring Ø Virtual channel identifier restriction within a VPC Ø ECEN 621, Mobile Wireless Networks Prof. Xi Zhang
ATM Cell Header Format Ø Generic flow control (GFC) – 4 bits, used only in usernetwork interface Ø Ø Virtual path identifier (VPI) – 8 bits at the user-network interface, 12 bits at network-network interface Ø Ø Used to alleviate short-term overload conditions in network Routing field Virtual channel identifier (VCI) – 8 bits Ø Used for routing to and from end user ECEN 621, Mobile Wireless Networks Prof. Xi Zhang
ATM Cell (Packet) Format ECEN 621, Mobile Wireless Networks Prof. Xi Zhang
ATM Cell Header Format Ø Payload type (PT) – 3 bits Ø Ø Cell loss priority (CLP) – 1 bit Ø Ø Indicates type of information in information field Provides guidance to network in the event of congestion Header error control (HEC) – 8 bit Ø Error code ECEN 621, Mobile Wireless Networks Prof. Xi Zhang
ATM Service Categories Ø Ø Real-time service Ø Constant bit rate (CBR) Ø Real-time variable bit rate (rt-VBR) Non-real-time service Ø Non-real-time variable bit rate (nrt-VBR) Ø Available bit rate (ABR) Ø Unspecified bit rate (UBR) ECEN 621, Mobile Wireless Networks Prof. Xi Zhang
Examples of CBR Applications Ø Videoconferencing Ø Interactive audio (e. g. , telephony) Ø Audio/video distribution (e. g. , television, distance learning, pay-per-view) Ø Audio/video retrieval (e. g. , video-on-demand, audio library) ECEN 621, Mobile Wireless Networks Prof. Xi Zhang
Examples of UBR applications Ø Text/data/image transfer, messaging, distribution, retrieval Ø Remote terminal (e. g. , telecommuting) ECEN 621, Mobile Wireless Networks Prof. Xi Zhang
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