Broadband Wireless Access Technologies Qian Li Ph.D. student of UiO Research interests: Computer networks and protocols Current project: Less than Best Effort TCP Passt project: A geographic routing protocol for mobile adhoc Cognitive Radio Networks March 23rd, UiO 1 / 40
Presented papers IEEE 802.11 Tutorial J. Zyren and A. Petrick IEEE 802.11 Wireless Local Area Networks B.P. Crow, I. Widjaja, L.G. Kim, and P.T. Sakai IEEE Communications Magazine 1997 A Survey on Emerging Broadband Wireless Access Technologies M. Kuran and T. Tugcu Computer Networks 2007 2 / 40
Agenda 802.11, HiperLAN WM AN WiMax, WiBro, HAP, 802.22 WL AN 802.20, NGSN N A W W 3 / 40
Wireless Local Area Networks (WLAN) 4 / 40
IEEE 802.11 Standards Standards Release Frequency (GHz) Stream Date Rate (Mbps) Modulation 802.11 1997 1997 2.4 1, 2 DSSS, FHSS 802.11 2007 2007 2.4 / 5 <= 54 DSSS, OFDM 802.11 2012 2012 2.4 / 5 <= 150 DSSS, OFDM 802.11 2016 2016 2.4, 5, 60 <= 866.7 / <= 6757 DSSS, OFDM Source: https://en.wikipedia.org/wiki/ieee_802.11 5 / 40
802.11 PHY Amendments Amendments Release Frequency (GHz) Bandwidth (MHz) Stream Date Rate (Mbps) Modulation a 1999 5 / 3.7 20 6, 9, 12, 18, 24, 36, 48, 54 OFDM b 1999 2.4 22 1, 2, 5.5, 11 DSSS g 2003 2.4 20 6, 9, 12, 18, 24, 36, 48, 54 OFDM n 2009 2.4 / 5 20 <= 288.8 MIMO-OFDM 40 <= 600 20 <= 346.8 40 <= 800 80 <= 1733.2 160 <= 3466.8 0.054 0.79 6-8 <= 568.9 60 2 <= 6757 OFDM, SC, LPSC <= 347 MIMO-OFDM ac ad 2013 2012 5 160 ah 2016 0.9 Source: https://en.wikipedia.org/wiki/ieee_802.11 1-16 MIMO-OFDM 6 / 40
802.11 Miscellaneous Amendments IEEE 802.11c: Bridge operation procedures; included in the IEEE 802.1D standard (2001) IEEE 802.11d: International (country-to-country) roaming extensions (2001) IEEE 802.11e: Enhancements: QoS, including packet bursting (2005) IEEE 802.11F: Inter-Access Point Protocol (2003) Withdrawn February 2006 IEEE 802.11h: Spectrum Managed 802.11a (5 GHz) for European compatibility (2004) IEEE 802.11i: Enhanced security (2004) IEEE 802.11j: Extensions for Japan (2004) IEEE 802.11k: Radio resource measurement enhancements (2008) IEEE 802.11p: WAVE Wireless Access for the Vehicular Environment (such as ambulances and passenger cars) (July 2010) IEEE 802.11r: Fast BSS transition (FT) (2008) IEEE 802.11s: Mesh Networking, Extended Service Set (ESS) (July 2011) Source: https://en.wikipedia.org/wiki/ieee_802.11 7 / 40
802.11 Miscellaneous Amendments Cont. IEEE 802.11T: Wireless Performance Prediction (WPP) test methods and metrics Recommendation cancelled IEEE 802.11u: Improvements related to HotSpots and 3rd-party authorization of clients, e.g., cellular network offload (February 2011) IEEE 802.11v: Wireless network management (February 2011) IEEE 802.11w: Protected Management Frames (September 2009) IEEE 802.11y: 36503700 MHz Operation in the U.S. (2008) IEEE 802.11z: Extensions to Direct Link Setup (DLS) (September 2010) IEEE 802.11aa: Robust streaming of Audio Video Transport Streams (June 2012) IEEE 802.11ae: Prioritization of Management Frames (March 2012) IEEE 802.11af: TV Whitespace (February 2014) IEEE 802.11ai: Fast Initial Link Setup (December 2016) Source: https://en.wikipedia.org/wiki/ieee_802.11 8 / 40
802.11 2.4GHz Band Source: https://en.wikipedia.org/wiki/list_of_wlan_channels 9 / 40
802.11 5GHz Band Non-overlapping channels Source: http://slideplayer.com/slide/4353682/, Fanny Mlinarsky, 2013 10 / 40
802.11 Modulation Techniques Spread Spectrum Frequency Hopping Spread Spectrum (FHSS) Direct Sequence Spread Spectrum (DSSS) Advantages Resistance to narrow band interference Resistance to jamming Resistance to eavesdropping Resistance to fading Multiple access capabilities Orthogonal Frequency Division Multiplexing (OFDM) High spectrum efficiency Resistance to narrow band interference Resistance to frequency selective fading Elimination of inter symbol interference by introducing guard intervals between symbols Improved signal to noise ratio by utilizing echo and time spreading 11 / 40
Frequency Hopping Spread Spectrum (FHSS) Frequency f8 Energy f7 5 8 3 7 1 4 6 2 f6 f5 f4 f3 f2 f1 f1 f2 f3 f4 f5 f6 f7 f8 (a) Channel assignment Frequency Time (b) Channel use Source: https://witestlab.poly.edu/blog/frequency-hopping-spread-spectrum/, Fraida Fund, 2017 12 / 40
FHSS PN Sequence Generators A linear feedback shift register as a psudeo noise sequence generator Source: https://witestlab.poly.edu/blog/frequency-hopping-spread-spectrum/, Fraida Fund, 2017 13 / 40
Direct Sequence Spread Spectrum (DSSS) Resultant high rate data (*) Bandwidth thereom: (Width in frequency domain) * (Width in time domain) 2π (#) Sources: (*) http://einstein.informatik.uni-oldenburg.de/lehre/semester/seminar/02ss/wlan/wlannode7.html (#) https://www.scribd.com/document/345992891/bandwidth-theorem 14 / 40
DSSS Transmitter & Receiver Source: https://www.slideshare.net/ajal4u/dsss-final, Ajal A.J., 2014 15 / 40
DSSS Correlator 0 0 1 16 / 40
Orthogonal Frequency Division Multiplexing (OFDM) Source:https://www.nutaq.com/blog/introduction-orthogonal-frequency-division-multiplex-ofdm 17 / 40
OFDM Transmitter & Receiver OFDM Transmitter Block Diagram OFDM Receiver Block Diagram Source: https://en.wikipedia.org/wiki/orthogonal_frequency-division_multiplexing 18 / 40
IEEE 802.11 MAC Frame Format Bytes 2 2 6 6 6 0/2 6 0/2 0/4 var 4 (#) Bits (*) 19 / 40 Source: (*) https://community.arubanetworks.com/t5/technology-blog/802-11-mac-header-breakdown/ba-p/219264 (#) https://mrncciew.com/2014/10/20/cwap-ht-control-field/
802.11 MAC Distributed Coordination Function (DCF) Carrier Sensing Multiple Access with Collision Avoidance (CSMA/CA) Part of the Wi-Fi Alliance's interoperability standard, widely supported Contention Window (CW) = 2 ^ (2+i), i = 1, 2,, in number of time slots Backoff time = floor(cw * ranf()), 0 <ranf() < 1 20 / 40
802.11 MAC Hidden Node 21 / 40
802.11 MAC Point Coordination Function (PCF) Not part of the Wi-Fi Alliance's interoperability standard, not widely implemented CFP Repetition Interval: an integral number of beacon frames Time used to successfully transmit 2 max-size MPDUs + overhead + B + CF_END <= CFP <= CFP Repetition Interval time used to successfully transmit 1 max-size MPDU (+ ACK + handshake) in CP period Polling mechanism: Round robin, polling position is memorized to the next CFP. Paper 2 proposal: a station is dropped from the polling list after K consecutive times of no data to transmit. Optimal setting K = 1 End of CFP: Paper 2 proposal: When the polling list becomes empty CFEnd CFEnd 22 / 40
802.11 MAC PCF Cont. PC to station transmission Station to station transmission 23 / 40
802.11 MAC Simulation Results DCF Suggested RTS_Threshold: 250 400 octets Optimal Fragmentation_threshold: 500 800 octets Suggested MSDU for a low BER (10 ^ -5) channel: the larger the better PCF Optimal voice payload length: CFP = 4 becons: 100 400 octets CFP = 5 becons: 100 200 octets Suggested polling parameter K: 1 Maximum number of voice stations can be supported: 16 (CFP = 4 becons) 24 / 40
802.11 Miscellaneous Security Authentication: Open system, shared key, 802.1X authentication Encryption: WEP, WPA, WPA2 QoS 802.11e Hybrid Coordination Function: priority based round robin scheduler Enhanced Distributed Coordination Function: packets are queued in different Access Categories Block acknowledgments Direct Link Protocol: frames are sent from one WSTA to another directly in an infrastructure QBSS, without using the DS. High throughput: 802.11n Mobility: 802.11r, 802.11p (WAVE) Mesh: 802.11s 25 / 40
ETSI HiperLAN High Performance Radio Local Area Network Discontinued because could not achieve market success Standards Release Frequency (GHz) Bandwidth (MHz) Data Rate (Mbps) Modulation HiperLAN1 1996 5 20 <= 20 OFDM HiperLAN2 2000 5 20 <= 54 OFDM 26 / 40
HiperLAN DLC Controlled by Central Controller (CC) or AP (a) Centralized Mode (b) Direct mode Source:http://www.invocom.et.put.poznan.pl/~invocom/C/P1-4/p1-4_en/p1-4_9_1.htm 27 / 40
Wireless Metropolitan Area Networks (WMAN) Point to Multipoint Mesh 28 / 40
WiMax Source: http://slideplayer.hu/slide/2129723/, T. Gyorgy, 2013 29 / 40
WiMax Deployment 2004: First launch 2010: 11 million subscribers worldwide, 2% of all fix broadband subscribers 2011: Usage declined 2015: Sprint Cooperation began closing its WiMax networks 30 / 40 Source: https://www.telegeography.com/products/commsupdate/articles/2010/12/21/predicted-score-lte-7-wimax-1/
IEEE 802.16 Standards Release Frequency (GHz) Topology/Feature 802.16 2002 10 66 (LOS) PMP 802.16a 2003 2 11 (NLOS) Mesh 802.16-2005 2005 10-66, LOS PMP, Mesh, Mobility 2-11, NLOS 2-6, Mobility 31 / 40
802.16 PHY 32 / 40
802.16 MAC Converting network layer packets into MAC Segment Data Units, Payload Header Suppression, etc. Packing/fragmenting MSDUs into MPDUs, system access, bandwidth allocation Authentication and encryption 33 / 40
802.16 Mesh Centralized scheduling for Internet traffic Distributed scheduling for intranet traffic Make decision based on two-hop neighborhood information Coordinated: collision free Uncoordinated: collisions are possible MBS: Parent of MSS-B MSS-b: Parent of MSS-a <= 64 connections / link MSS-a Scheduling Tree Centralized scheduling Source: http://slideplayer.com/slide/9021617/ 34 / 40
802.16 QoS Connections: established over physical wireless links Service Flows: associated with a connection, comprising QoS parameters Scheduling services allocating resources for each connection based on QoS requirements 35 / 40
Other WMAN Standards Standards Release Connection Frequency (GHz) Bandwidth (MHz) Modulation Aggregate Data rate (Mbps) Topology/F eatures ETSI HiperAccess 2002 LOS 11 43.5 28 OFDM 25-100 PMP ETSI HiperMan 2003 NLOS < 11 varies OFDM 25 per Sec PMP, Mesh TTA WiBro 2004, P1 2005, P2 NLOS 2.3 2.4 9 OFDMA 18/50 per Sec, down 6 per Sec, up Static, mobile 802.22 2011 NLOS 0.054-0.862 (TV white space) 6 OFDMA <= 18 36 / 40
High Altitude Platform (HAP) 17-22KM HAPs data network, LOS: 47 48GHz (ITU) HALO system architecture, Using multiple transmitters to form cells, coverage area: 7200 KM^2, 10Gbps data rate 37 / 40
Wireless Wide Area Networks (WWAN) IEEE 802.20 2002 Supports high velocity: speed up to 250kmph NLOS (f < 3.5GHz) Connectionless Channel bandwidth: 1.25 or 5 MHz 38 / 40
Next Generation Satellite Networks (NGSN) Better mobility support Better coverage 4 GEOs or 11 MEOs give global coverage Longer delay Example NGEO satellite systems 39 / 40 Picture source:http://www.agust.net/wordpress/2018/01/15/observing-satellite-orbits-over-iceland-a-half-century-ago/
Thank you 40 / 40