ITTC © James P.G. Sterbenz Communication Networks The University of Kansas EECS 780 MAC; Mobile and Wireless Networks James P.G. Sterbenz Department of Electrical Engineering & Computer Science Information Technology & Telecommunications Research Center The University of Kansas [email protected] http://www.ittc.ku.edu/~jpgs/courses/nets 19 November 2018 rev. 18.1 © 2004–2018 James P.G. Sterbenz ITTC © James P.G. Sterbenz MAC; Mobile and Wireless Networks Outline MW.1 Wireless and mobile networking concepts MW.2 MAC functions and services MW.3 MAC algorithms MW.4 Wireless networks MW.5 Mobile networks MW.6 Internet of Things 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-2 ITTC © James P.G. Sterbenz Wireless Networks Classification of Types • Geographic scope – distance over which links operate – area of layer 2 subnetwork (not IP subnet) • Mobility – mobility of wireless nodes • Coördination – centralised vs. distributed control 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-3 ITTC © James P.G. Sterbenz Wireless Networks Classification of Types: Scope • Geographic scope – WBAN: wireless body area network – WPAN: wireless personal area network – WLAN: wireless local area network – WMAN: wireless metropolitan network – WWAN: wireless wide area network • Mobility • Coördination 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-4 ITTC © James P.G. Sterbenz Wireless Networks Classification of Types: Mobility • Geographic scope – WBAN, WPAN, WLAN, WMAN, WWAN • Mobility – fixed: nodes are stationary • WMN: wireless mesh network – mobile: nodes are mobile • some nodes may be fixed (e.g. base stations) • nodes mobile and self-organizing: MANET (mobile ad hoc net) – nomadic: nodes are highly and routinely mobile may be frequently out of range of one-another • DTN: disruption-tolerant network • Coördination 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-5 ITTC © James P.G. Sterbenz Wireless Networks Classification of Types: Coördination • Geographic scope – WBAN, WPAN, WLAN, WMAN, WWAN • Mobility – fixed, mobile, nomadic – WMN, MANET, DTN • Coördination – infrastructure: base station controls and transit traffic – ad hoc or peer-to-peer: mobile nodes directly communicate • WMN (wireless mesh network) • MANET (mobile ad hoc network) 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-6 ITTC © James P.G. Sterbenz Wireless Networks Characteristics • Wireless LANs very different from wired why? 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-7 ITTC © James P.G. Sterbenz Wireless Networks Characteristics • Wireless LANs very different from wired – always use shared medium; MAC is required • Wireless characteristics – significant attenuation 1/r 2 • multipath reflections increases attenuation to ≈ 1/r 4 – noise and interference • from one-another • from other devices • from environment • jamming (physical DoS) – open channel • subject to eavesdropping 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-8 ITTC © James P.G. Sterbenz Wireless Networks Network Elements: Base Station • Base station (BS) or cell Access point (AP) – fixed wireless node BS • one or more antennæ • may be small (e.g. home gateway) • may have huge tower Internet – range may be called a cell • particularly in context of mobile telephony – typically connected to Internet via wired link • in which case it is an intermediate system 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-9 ITTC © James P.G. Sterbenz Wireless Networks Network Elements: Base Station • Base station (BS) or cell Access point (AP) – fixed wireless node BS BS • one or more antennæ • may be small (e.g. home gateway) • may have huge tower Internet – range is frequently called a cell – typically connected to Internet via wired link – or wireless multihop to Internet access • wireless backhaul through other BSs • peer-to-peer multihop between wireless nodes 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-10 ITTC © James P.G. Sterbenz Wireless Networks Network Elements: Wireless Node • Base station or access point cell • Wireless node (WN) – also called untethered node BS BS – no wired network connection – fixed or stationary node doesn’t move Internet • wireless does not imply mobility WN • typical example: laptop personal computer – mobile node later WN 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-11 ITTC © James P.G. Sterbenz Wireless Networks Network Elements: Wireless Link • Base station or access point cell • Wireless node • Wireless link BS BS – formed when 2 nodes in range associate Internet – MAC needed to arbitrate medium access WN WN 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-12 ITTC © James P.G. Sterbenz Wireless Networks Network Elements: Wireless Link • Base station or access point cell • Wireless node • Wireless link BS BS – nodes associate; MAC arbitrates – interconnects BSs Internet • for backhaul to Internet WN • as mesh network infrastructure WN 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-13 ITTC © James P.G. Sterbenz Wireless Networks Network Elements: Wireless Link • Base station or access point cell • Wireless node • Wireless link BS BS – nodes associate; MAC arbitrates – interconnects BSs Internet – interconnects WNs to BSs for access WN WN 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-14 ITTC © James P.G. Sterbenz Wireless Networks Network Elements: Wireless Link • Base station or access point cell • Wireless node • Wireless link BS BS – nodes associate; MAC arbitrates – interconnects BSs for backhaul Internet – interconnects WNs to BSs WN – interconnects WNs WN • for multihop access to BS • peer-to-peer in ad hoc net • multihop WNs are both ES and IS 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-15 ITTC © James P.G. Sterbenz Wireless Networks Network Elements: Wireless / Mobile • Base station or access point cell • Wireless node • Wireless link BS BS – nodes associate; MAC arbitrates – interconnects BSs for backhaul Internet – interconnects WNs to BSs WN – interconnects WNs WN • for multihop access to BS • peer-to-peer in ad hoc net • multihop WNs are both ES and IS • Wireless does not imply mobile 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-16 ITTC © James P.G. Sterbenz MAC; Mobile and Wireless Networks MW.2 MAC Functions and Services MW.1 Wireless and mobile networking concepts MW.2 MAC functions and services MW.3 MAC algorithms MW.4 Wireless networks MW.5 Mobile networks MW.6 Internet of Things 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-17 ITTC © James P.G. Sterbenz Medium Access Layer Hybrid Layer/Plane Cube management plane MAC layer: data plane control plane arbitration to shared L8 social medium in L7 application control plane L5 session L4 transport L3 network L2.5 virtual link L2 link L1.5 MAC L1 physical 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-18 ITTC © James P.G. Sterbenz Medium Access Layer MAC Definition network CPU CPU M app M app station station • Medium access control (MAC) arbitrates a channel in shared medium (free space, guided wire, or fiber) among stations (end systems, hosts) 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-19 ITTC © James P.G. Sterbenz Link and MAC Layer MAC Protocol application application session session transport transport network network network network link/MAC link/MAC link/MAC link/MAC end system intermediate intermediate end system network (station) system system (station) link/MAC network intermediate system • MAC protocol (or algorithm) – responsible for determining when node can transmit frame – may fully distributed or coördinated 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-20 ITTC © James P.G. Sterbenz MAC Layer Service and Interfaces • MAC is in between physical layer 1 and link layer 2 – lower link sublayer in IEEE 802 model • MAC layer in control plane – control over when to transmit a L2 frame – but may have its own encapsulation (e.g. IEEE 802 legacy) • layer 2 addresses needed for shared medium • MAC layer service to link layer (L2) – MAC layer encapsulate/decapsulate if appropriate – initiate transfer of frame into the medium 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-21 ITTC © James P.G. Sterbenz MAC Layer Service and Interfaces • MAC layer frame may encapsulate link layer frame – done for link layer / MAC protocol independence • IEEE 802: 802.2 LLC (logical link control) over 802.N MAC link layer link layer H NPDU T frame H NPDU T MAC layer MAC layer H H NPDU T frame H H NPDU T …10111001010… physical layer physical layer 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-22 ITTC © James P.G. Sterbenz MAC; Mobile and Wireless Networks MW.3 MAC Algorithms MW.1 Wireless and mobile networking concepts MW.2 MAC functions and services MW.3 MAC algorithms MW.3.1 Channel partitioning MW.3.2 Coördinated access MW.3.3 Random access MW.3.4 Spread spectrum MW.4 Wireless networks MW.5 Mobile networks MW.6 Internet of Things 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-23 ITTC © James P.G. Sterbenz Link Sharing Multiplexing vs. Multiple Access • Multiplexing vs. multiple access • Link multiplexing Lecture LL – single transmitter – dedicated point-to-point link • Multiple access: – multiple transmitters – shared medium – essentially physical layer multiplexing – MAC algorithm needed to arbitrate free space RF 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-24 ITTC © James P.G. Sterbenz MAC Algorithms MW.3.1 Channel Partitioning MW.1 Wireless and mobile networking concepts MW.2 MAC functions and services MW.3 MAC algorithms MW.3.1 Channel partitioning MW.3.2 Coördinated access MW.3.3 Random access MW.3.4 Spread spectrum MW.4 Wireless networks MW.5 Mobile networks MW.6 Internet of Things 19 November 2018 KU EECS 780 – Comm Nets – MAC Mobile Wireless NET-MW-25 ITTC © James P.G.