Chapter 4.pdf

CCCN 422 Wireless Communication Networks Dr. Mohammed Balfaqih Assistant Professor [email protected] @modditto Lecture Outline ▪ Wireless Metropolitan Area Networks • • • • Concepts and Architecture Broadband Access Technology IEEE 802 Architecture WiMax: IEEE 802.16 Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Concepts and Architecture • Wireless Metropolitan Area Networks (WiMANs): provide wireless connectivity across a geographical area the size of a city Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Broadband Access Technology • Broadband data rates for last mile connectivity to businesses, homes and network bridging • Wireless alternative to (DSL/cable modem/Fiber to the Home) services for last mile broadband access. • Potential Advantages: support for QoS, lower cost than cabling, user mobility in later releases • Currently variety of technologies, speeds, cost, coverage range, spectrum, etc. • Market is fragmented among technologies • Proprietary Solutions - Free Space Optical LMDS (Local Multipoint Distribution Systems) MMDS (Multipoint Microwave Distribution Systems) Wireless multi-hop mesh networks (based on 802.11) • Standards Based Solutions Dr. Mohammed Balfaqih IEEE 802.16 also called WiMAX, WirelessMAN IEEE 802.11 with multi-hop extension standard 802.11s CCCN 422: Wireless Communication Networks Broadband Access Technology ▪ Proprietary Solutions - Free Space Optical: • point to point high data rates (100 Mbps -2.5Gbps) over short distances • Unlicensed, uses infrared lasers • LOS required – severely effected by weather - LMDS (Local Multipoint Distribution Systems) • Bulk of deployment focused on backhaul extension of fiber infrastructure and cellular networks • Operates in 28, 29 GHz spectrum • Range 3-5 miles, weather effects - MMDS (Multipoint Microwave Distribution Systems) • • • • • Operates in 2.5-2.7GHz licensed spectrum Originally intended for wireless cable TV distribution 200MHz Spectrum → 99 10Mbps channels Range ~25Km (LOS and NLOS possible) Data rates ~ .5-1 Mbps on 10Mbps channel - WLAN equipment with mesh routing, scheduling, flow control • Use 802.11a/g equipment to build mesh – need many APs Dr. Mohammed Balfaqih IEEE 802 Architecture • Functions of physical layer: - IEEE 802 Protocol Layers Compared to OSI Model Encoding/decoding of signals Preamble generation/removal (for synchronization) Bit transmission/reception Includes specification of the transmission medium • Functions of medium access control (MAC) layer: - - On transmission, assemble data into a frame with address and error detection fields On reception, disassemble frame and perform address recognition and error detection Govern access to the LAN transmission medium • Functions of logical link control (LLC) Layer: - Provide an interface to higher layers and perform flow and error control Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks IEEE 802 Architecture IEEE 802 Protocols in Context Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks IEEE 802 Architecture ▪ Separation of LLC and MAC • The logic required to manage access to a shared-access medium not found in traditional layer 2 data link control • For the same LLC, several MAC options may be provided ▪ MAC Frame Format • MAC control - Contains Mac protocol information • Destination MAC address - Destination physical attachment point • Source MAC address - Source physical attachment point • CRC - Cyclic redundancy check Dr. Mohammed Balfaqih LLC PDU in a Generic MAC Frame Format IEEE 802 Architecture ▪ Logical Link Control • Characteristics of LLC not shared by other control protocols: - Must support multi-access, shared-medium nature of the link - Relieved of some details of link access by MAC layer ▪ LLC Services • Unacknowledged connectionless service - No flow- and error-control mechanisms - Data delivery not guaranteed • Connection-mode service - Logical connection set up between two users - Flow- and error-control provided • Acknowledged connectionless service - Cross between previous two - Datagrams acknowledged - No prior logical setup Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks WiMax: IEEE 802.16 • • • • • • Started in 1999 Use wireless links with microwave or millimeter wave radios Use licensed spectrum Create wireless metropolitan area networks (WMANs) Provide public network service to fee-paying customers Use point-to-multipoint architecture with stationary rooftop or tower-mounted antennas • Provide efficient transport of heterogeneous traffic supporting quality of service (QoS) • Use wireless links with microwave or millimeter wave radios • The WiMAX (Worldwide Interoperability for Microwave Access) Forum - Industry consortium - Formed to promote the 802.16 standards and to develop interoperability specifications Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks WiMax: IEEE 802.16 ▪ WiMAX network reference model • Access Service Network (ASN) - Functions to provide radio access to WiMAX subscribers • Network Access Provider (NAP) - Provides path between a WiMAX radio access infrastructure to one or more WiMAX Network Service Providers. • Connectivity Service Network (CSN) - Provides IP connectivity services to WiMAX subscribers • Network Service Provider (NSP) - A business entity that provides IP connectivity and WiMAX services to WiMAX subscribers • ASN Gateway - Connectivity from an ASN to an NSP Dr. Mohammed Balfaqih WiMax: IEEE 802.16 ▪ IEEE 802.16 Protocol Architecture • Physical and transmission layer functions: - • Medium access control layer functions: - • Encoding/decoding of signals Preamble generation/removal Bit transmission/reception On transmission, assemble data into a frame with address and error detection fields On reception, disassemble frame, and perform address recognition and error detection Govern access to the wireless transmission medium Convergence layer functions: - Encapsulate PDU framing of upper layers into native 802.16 MAC/PHY frames Map upper layer’s addresses into 802.16 addresses Translate upper layer QoS parameters into native 802.16 MAC format Adapt time dependencies of upper layer traffic into equivalent MAC service Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks WiMax: IEEE 802.16 ▪ IEEE 802.16 MAC PDU Format • • • Header - protocol control information - Downlink header – used by the base station Uplink header – used by the subscriber to convey bandwidth management needs to base station Bandwidth request header – used by subscriber to request additional bandwidth Payload – either higher-level data or a MAC control message CRC – error-detecting code Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks WiMax: IEEE 802.16 ▪ Scheduling Services and QOS Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks WiMax: IEEE 802.16 ▪ IEEE 802.16 Services Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks WiMax: IEEE 802.16 ▪ 802.16 Physical Layer • Wireless MAN-SC - 10-66 GHz bands Line of sight required TDMA and demand-assignment multiple access • Wireless MAN-OFDM - Below 11 GHz LOS is not necessary • Wireless MAN-OFDMA - Enhanced version of Wireless MANOFDM for OFDMA IEEE 802.16 OFDMA Frame Structure in TDD Mode Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks WiMax: IEEE 802.16 ▪ 802.16 Physical Layer Dr. Mohammed Balfaqih IEEE 802.16 OFDMA Frame Structure in FDD Mode Thank you Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 1) Which of the following IEEE 802 protocol layers assembles data on transmission into a frame with address and error detection fields? a) medium access control b) logical link control c) physical d) transportation 2) Which of the following IEEE 802 protocol layers provides an interface to higher layers and perform flow and error control? a) medium access control b) logical link control c) physical d) transportation Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 3) Which of the following IEEE 802 protocol layers encodes/decodes of signals? a) medium access control b) logical link control c) physical d) transportation 4) The type of Logical Link Control (LLC) services that provides Flow- and error-control is__________. a) Unacknowledged connectionless service b) Connection-mode service c) Acknowledged connectionless service d) None of them Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 5) Which of the following IEEE 802.16 Protocol layers encapsulates PDU framing of upper layers into native 802.16 MAC/PHY frames? a) Physical and transmission layer b) Medium access control layer c) Convergence layer d) Security layer 6) Which of the following IEEE 802.16 Protocol layers disassembles frame, and perform address recognition and error detection? a) Physical and transmission layer b) Medium access control layer c) Convergence layer d) Security layer Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 7) What are Broadband access technologies? Their advantages? Give examples of broadband access technologies 8) The figure below shows IEEE 802 Protocol Layers Compared to OSI Model. What are the functions of Medium Access Control (MAC) and Logical Link Control (LLC) layers? 9) What are the types of Logical Link Control (LLC) services? Give TWO examples of differences between these services? Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks Review Questions 10) The figure below shows WiMAX network reference model, what are the functions of the following elements: a) Access Service Network (ASN) b) Network Access Provider (NAP) c) Connectivity Service Network (CSN) d) Network Service Provider (NSP) e) ASN Gateway 11) Identify IEEE 802.16 service class in the following: Dr. Mohammed Balfaqih CCCN 422: Wireless Communication Networks

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