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Wireless Networks in the Factory Introduction : Fundamentals of Wireless

Wireless Networks in the Factory Introduction : Fundamentals of Wireless. 9-Apr-2012 Fanny Mlinarsky octoScope, Inc. Contents. Radio technologies Radio propagation Frequency bands. Wireless Technologies. Standards based. Proprietary. Cordless phone. Smoke detector. Baby monitor.

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Wireless Networks in the Factory Introduction : Fundamentals of Wireless

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  1. Wireless Networks in the FactoryIntroduction: Fundamentals of Wireless 9-Apr-2012 Fanny Mlinarsky octoScope, Inc.

  2. Contents Radio technologies Radio propagation Frequency bands

  3. Wireless Technologies Standards based Proprietary Cordless phone Smoke detector Baby monitor Motion detector Flood/water detector Alarm panel Smart meter

  4. Personal GSM, WCDMA, LTE 802.15 Bluetooth ZigBee 60 GHz UWB Wide (3GPP* based) TVWS 802.22 802.11af Regional NAN Metro 802.16 WiMAX 802.11ad 802.11 Wi-Fi LAN = local area networking PAN = personal area networking MAN = metropolitan area networking WAN = wide area networking NAN = neighborhood area network RAN = regional area networking TVWS = television white spaces 3GPP = 3rd generation partnership project Local

  5. White Space Technologies GPS Satellite DB 1 DB 2 Mode II Device Geolocation Source: Neal Mellen, TDK Available channels DB 3 Mode I Device

  6. Near Field Communications (NFC) • Key benefit: simplicity of use • No configuration by user; data stored in NFC tag automatically triggers application • Use cases include • Poster • NFC tag in the poster automatically triggers the appropriate application in the reading device (e.g. URL stored in poster opens browser on handset) • Mobile payments • Pay with NFC phones at any POS terminal • Store vouchers and coupons in NFC phones • Authentication, access control • Unlock car doors • Secure building access • Secure PC log-in Poster Point of Sale (POS) terminal for mobile payments

  7. Common Access Protocols • TDMA (time division multiple access) • AMPS, GSM • CDMA (code division multiple access) • CDMA, W-CDMA, CDMA-2000 • SDMA (space division multiple access) • MIMO, beamforming, sectorized antennas • FDMA (frequency division multiple access) • OFDM (orthogonal frequency division multiplexing) • OFDMA (orthogonal frequency division multiple access)

  8. Courtesy of Suresh Goyal & Rich Howard CDMA

  9. FDMA OFDM Power Power Multiple orthogonal carriers Channel Frequency Frequency TDMA … Time User 1 User 2 User 3 User 4 User 5

  10. OFDM (Orthogonal Frequency Division Multiplexing) Multiple orthogonal carriers Wi-Fi WiMAX LTE • OFDM is the most robust signaling scheme for a hostile wireless channel • Works well in the presence of multipath thanks to multi-tone signaling and cyclic prefix (aka guard interval) • OFDM is used in all new wireless standards, including • 802.11a, g and draft 802.11ac, ad • 802.16d,e; 802.22 • DVB-T, DVB-H, DAB • LTE is the first 3GPP standard to adopt OFDM Voltage Frequency DVB = digital video broadcasting DVB-T = DVB terrestrial DVB-H = DVB handheld DAB = digital audio broadcasting LTE = long term evolution

  11. FDMA vs. OFDMA • OFDMA is more frequency efficient than traditional FDMA • Orthogonal subcarriers require no guard bands Guard band Channel FDMA OFDMA

  12. OFDMA OFDM is a modulation scheme OFDMA is a modulation and access scheme LTE Time Time Frequency Multiple Access Frequency allocation per user is continuous vs. time Frequency per user is dynamically allocated vs. time slots User 1 User 2 User 3 User 4 User 5 OFDM = orthogonal frequency division multiplexing OFDMA = orthogonal frequency division multiple access

  13. OFDMA Resource Allocation 180 kHz, 12 subcarriers with normal CP • Resources are allocated per user in time and frequency. RB is the basic unit of allocation. • RB is 180 kHz by 0.5 ms; typically 12 subcarriers by 7 OFDM symbols, but the number of subcarriers and symbols can vary based on CP User 2 User 3 User 2 User 1 0.5 ms 7 symbols with normal CP LTE User 2 User 3 User 2 User 1 User 2 User 3 User 3 User 2 Time User 2 User 1 User 3 User 2 User 1 User 1 User 3 User 1 Resource Block (RB) Frequency CP = cyclic prefix, explained ahead

  14. Resource Block A resource block (RB) is a basic unit of access allocation. RB bandwidth per slot (0.5 ms) is 12 subcarriers times 15 kHz/subcarrier equal to 180 kHz. LTE 1 slot, 0.5 ms … Resource block 12 subcarriers … … Subcarrier (frequency) Resource Element 1 subcarrier QPSK: 2 bits 16 QAM: 4 bits 64 QAM: 6 bits 1 subcarrier v … Time

  15. Scalable Channel Bandwidth Channel bandwidth in MHz Transmission bandwidth in RBs LTE Center subcarrier (DC) Channel bw MHz Transmission bw # RBs per slot RB = resource block

  16. FDD vs. TDD • FDD (frequency division duplex) • Paired channels • TDD (time division duplex) • Single frequency channel for uplink an downlink • Is more flexible than FDD in its proportioning of uplink vs. downlink bandwidth utilization • Can ease spectrum allocation issues TD-LTE DL UL DL UL

  17. Contents Radio technologies Radio propagation Frequency bands

  18. Wireless Channel • Frequency and time variable wireless channel • Multipath creates a sum of multiple versions of the TX signal at the RX … … Channel Quality Frequency-variable channel appears flat over the narrow band of an OFDM subcarrier. Frequency OFDM = orthogonal frequency division multiplexing

  19. Wireless Channel Multipath clusters Composite angular spread Per path angular spread Composite angular spread Line of sight Multipath and Doppler fading in the channel

  20. Path Loss and Multipath Devices supporting antenna diversity or MIMO help mitigate the effects of multipath. • In a wireless channel the signal propagating from TX to RX experiences fading and multipath • Free space loss (flat fading) increases vs. frequency Fading can be ‘flat’ or it can have multipath components • Loss (dB) = 20 * Log10 (frequency in MHz) + 20 * Log10 (distance in miles) + 36.6 Multipath can be caused by mobile or stationary reflectors. Multipath fading component +10 dB 0 dB • In ideal free space propagation, range doubles for every 6 dB of path loss. • Typically 6-9 dB of increase in link budget doubles outdoor range and 9-12 dB increase in link budget doubles indoor range. -15 dB flat fading component Time MIMO = multiple input multiple output

  21. Cyclic Prefix ↔ Guard Interval Guard interval > delay spread in the channel • The OFDM symbol is extended by repeating the end of the symbol in the beginning. This extension is called the Cyclic Prefix (CP) or Guard Interval (GI). • CP is a guard interval that allows multipath reflections from the previous symbol to settle prior to receiving the current symbol. CP has to be greater than the delay spread in the channel. • CP minimizes Intersymbol Interference (ISI) and Inter Carrier Interference (ICI) making the data easier to recover. Useful data TS copy

  22. Multiple Antenna Techniques • SISO (Single Input Single Output) • Traditional radio • MISO (Multiple Input Single Output) • Transmit diversity (STBC, SFBC, CDD) • SIMO (Single Input Multiple Output) • Receive diversity, MRC • MIMO (Multiple Input Multiple Output) • SM to transmit multiple streams simultaneously; can be used in conjunction with CDD; works best in high SNR environments and channels de-correlated by multipath • TX and RX diversity, used independently or together; used to enhance throughput in the presence of adverse channel conditions • Beamforming SM = spatial multiplexing SFBC = space frequency block coding STBC = space time block coding CDD = cyclic delay diversity MRC = maximal ratio combining SM = Spatial Multiplexing SNR = signal to noise ratio

  23. NxM TX TX 2x2 MIMO radio channel MIMO systems are typically described as NxM, where N is the number of transmitters and M is the number of receivers. RX RX TX TX RX RX 2x2 radio 2x2 radio

  24. Fresnel Zone Source: Wikipedia http://en.wikipedia.org/wiki/Fresnel_zone r D r = radius in feet D = distance in miles f = frequency in GHz Example: D = 0.5 mile r = 30 feet for 700 MHz r = 16 feet for 2.4 GHz r = 10 feet for 5.8 GHz Fresnel zone is the shape of electromagnetic signal and is a function of frequency The higher the frequency the smaller the radius of the Fresnel zone Constricting Fresnel zone introduces attenuation and signal distortion Fresnel zone considerations favor higher frequencies, but path loss considerations favor lower frequencies of operation

  25. Contents Radio technologies Radio propagation Frequency bands

  26. Standards-based Key Unlicensed Services proprietary IEEE 802.11 (Wi-Fi) operates in the ISM-2400 and ISM-5800 bands and in the 5800 UNII band; recently standardized for 3650-3700 contention band IEEE 802.16 (WiMAX) operates in the UNII/ISM band and in the 3500-3700 MHz contention band UWB based WiMedia is a short-range network operating in the noise floor of other services ISM-900 traditionally used for consumer devices such as cordless phones, garage openers and baby monitors, now also used on smart meters • FCC spectrum allocation chart • http://www.ntia.doc.gov/osmhome/allochrt.PDF Cordless phones

  27. Unlicensed Bands and Services Medical devices Remote control RFID and other unlicensed services Smart meters, remote control, baby monitors, cordless phones 802.11b/g/n, Bluetooth 802.15.4 (Bluetooth, ZigBee), cordless phones 802.11a/n, cordless phones European analog of the ISM-900 band Americas, Australia, Israel Emerging 802.11ad 802.15.3c, ECMA-387 WirelessHD ISM = industrial, scientific and medical UNII = unlicensed national information infrastructure

  28. ISM and UNII Bands For frequency hopping services regulatory requirements also include dwell times, which impact the power spectrum. To operate in the 5 GHz bands radios must comply with the DFS and TPC protocol of 802.11h. EIRP = equivalent isotropically radiated power PtMP = point to multipoint PtP = point to point DFS = Dynamic Frequency Selection TPC = Transmitter Power Control

  29. UHFSpectrum CH 52-59, 692-746 MHz A BC DE A BC Acquired by AT&T Band17 Band17 Band12 Band12 US (FCC) White Spaces 54-72, 76-88, 174-216, 470-692 MHz Low 700 MHz band European (ECC) White Spaces (470-790 MHz) MHz High 700 MHz band A A B B CH 60-69, 746-806 MHz ECC = Electronic Communications Committee

  30. High 700 MHz Band D-Block MHz 758 763 775 788 793 805 Band 13 Band 13 Band 14 Band 14 Guard band Guard band Public Safety Broadband (763-768, 793-798 MHz) Public Safety Narrowband (769-775, 799-805 MHz), local LMR LMR = land mobile radio

  31. LTE Frequency Bands - FDD Source: 3GPP TS 36.104; V10.1.0 (2010-12)

  32. LTE Frequency Bands - TDD TD-LTE Source: 3GPP TS 36.104; V10.1.0 (2010-12)

  33. WiMAX Frequency Bands - TDD WiMAX Forum Mobile Certification Profile v1.1.0 A universal frequency step size of 250 KHz is recommended for all band classes, while 200 KHz step size is also recommended for band class 3 in Europe.

  34. WiMAX Frequency Bands - FDD Source: WiMAX Forum Mobile Certification Profile R1 5 v1.3.0

  35. Global Unlicensed Bands Summary

  36. Next Session Part II: What You Need to Know about 802.11 • When: April 10th at 2 p.m. Thank you! Please see more info and white papers at www.octoscope.com

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