2.4GHz Wi-Mi -Systems

Transcription

1 2.4GHz Wi-Mi -Systems Management workflow and setup suggestions Ron Bakker Introduction MHz: TV-Band (classic UHF range) MHz: WiFi-Band Ultra High Frequency Band

2 WiMi system design challenges Absorption 12,5 cm wavelength Absorbed by materials Attenuation/blocking Reflection Complex transfer function RX to TX Cancellations, multipath interference 2.4GHz applications WiFi, Bluetooth, remote applications Shared spectrum, same transmission power Same transmission priority System scope 2.4GHz ISM band: MHz (100 MHz bandwidth) - Shared spectrum - License free worldwide, general allocation WiFi: - 14 channels (center freq.) - 22 MHz width, 5 MHz distance - CH 1, 6, 11: no overlap/interference WiMi: - Utilize same frequency range as WiFi - We have to co-exist

3 WiMi system design strategies / Setup workflow 1) WiFi management 2) Channel configurations 3) Frequency diversity 4) Antenna diversity 5) Error detection 6) Antenna strategy Scan RF environment Avoid occupied bandwidth Signal quality comparison Reception quality comparison Constant data checking Type, placement, alignment, WiFi & RF management

4 Channel configurations WiFi Channels Line 6 System Channel 4 9 A B 5 10 Channel Center Freq (GHz) x x x x x x x x x x x x x x x x x x x x x x x x x x x x Frequency diversity / Antenna diversity A RX TX B

5 Error detection & correction fading Antenna system design

6 Test sessions: Confirming strategies 1) Varying conditions 2) Adding WAP 3) The Facebook Sessions Test sessions: confirm strategies Quantifier: Q = Total drop-outs for all scenarios INCLUDING INAPPROPRIATE SCENARIOS, PROVOKING DROP-OUTS BY SABOTAGE! Q = Σ (Q DIRECTIVITY, Q DIVERSITY, Q ROTATION, Q BLOCKING, Q ENVIRONMENT, Q DISTANCE ) Q DIRECTIVITY variable: using omni vs directional antenna Q DIVERSITY variable: disabling one antenna Q ROTATION variable: static position vs rotation Q BLOCKING variable: block path with guitarist + guitar (SG300) Q ENVIRONMENT variable: outside & inside Q DISTANCE variable: distance between transmitter and antennas

7 Session 1: distance, path, line of sight Antenna set-up Rotating platform Receiver rack Session 1: Distance, environment, line-of-sight Outside session 5m 15m 25m 35m 45m 55m 65m 100m Inside session

8 Total error counts for all scenarios Variable Directivity Diversity Rotation Blocking Environment Distance Conditions directional 40 omnidirectional 124 dual static 54 rotation 114 free 41 blocked 127 outside 148 inside m m 318 Session 2: The effect of WiFi IP-Video connections over WAP RF and WiFi monitoring Set-up

9 Session 2: Test results Distance to antennas Line6 Channel 6 Line6 Channel 1 dual dual no WAP X WAP behind antennas WAP between antennas & transmitter WAP behind transmitters Session 3: The Facebook sessions Venue Band Audience Patronaat, Haarlem: Chef Special Rock band: drums, guitar, bass, keyboard, vocals 1000 Mellkweg, Amsterdam: B-Brave Boy band, 5 boys 1000 P60, Amstelveen: InFloyd Tribute band: drums, guitar, bass, keyboard, vocals 500 Paard van Troye, The Hague: Daddy Long Legs Bluegrass band: drums, guitar, harmonica 150 Alster Open Air, Hamburg: Die PanikExperten rock band: drums, 2 guitars, bass, keyboard, 3 vocals

10 Session 3: Facebook posts RF energy (average/peak) on 2.4 GHz spectrum Occupation of WiFi channels 1-14 Patronaat, Haarlem (NL) Visitors - Public WiFi on Ch. 6 Conclusions WiMi systems support a limited amount of channels even in congested WiFi environment WiMi systems provide drop-out free connections at full audio quality under strict quality management: Always use antenna and frequency diversity systems Always use directional antennas Instruct performers to keep line of sight Instruct performers not to cover transmitter s antennas Control & manage WAP environment (RF scanner/wifi scanner) Standard WAP traffic is not a problem even with many concert goers connected to WiFi

11 Thanks for your attention. Measurements (inside) Distance (m) Total static transmitter (free line of sight) static transmitter (guitarist blocking) rotating transmitter (free line of sight) rotating transmitter (guitarist blocking) dual dual dual (X) (X) dual

12 Measurements (outside) Distance (m) Total static transmitter (free line of sight) static transmitter (guitarist blocking) rotating transmitter (free line of sight) rotating transmitter (guitarist blocking) dual dual dual (x) 17 (x) (x) 49 (x) 0 dual Measurements (WAP effect) Distance to antennas Line6 Channel 6 Line6 Channel 1 dual dual no WAP X WAP behind antennas WAP between antennas & transmitter WAP behind transmitters