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Industrial Wireless Division

2014 MTSC Training Course. MOXA Wireless Session. Industrial Wireless Division. 2013 MTSC IW Presentation (Agenda). What’s New for IW AWK-3131-M12-RCC WLAN 101 WiFi Troubleshooting MUST Know Antenna Deployment Know How OnCell FAQ NAT/Port Forwarding Hands-on

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Industrial Wireless Division

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  1. 2014 MTSC Training Course • MOXA Wireless Session Industrial Wireless Division

  2. 2013 MTSC IW Presentation (Agenda) • What’s New for IW • AWK-3131-M12-RCC • WLAN 101 • WiFi Troubleshooting MUST Know • Antenna Deployment Know How • OnCell FAQ • NAT/Port Forwarding • Hands-on • Wireless Packets Sniffer • Automatic Carriage Connection (ACC) Configuration Setup Confidential

  3. What’s New for IW

  4. ACC (Auto Carriage Connection) • Creates Carriage-to-Carriage Wireless Links AWK-3131-M12-RCC Series • Automatic inter-carriage bridge links • Automatically connect and disconnect • inter-carriage APs • Minimize manual efforts and errors • 802.11n network • Support bandwidth-heavy multimedia services • Stable link • Detect link timeouts to ensure link stability • Precise match • Customize ACC to fit unique vehicle types 802.11n Single/Dual-RF M12 -40 to 75o C EN 50155 Confidential

  5. Train on-board Application AWK-4131-RTG 802.11n Outdoor Single-RF AP Controller-based Turbo Roaming (Handoff < 50 ms) M12 IP Camera ACC AWK-3131-M12-RCC M12 Single-RF AP ACC LED ACC TN-5508-4 PoE PoE Switch NVR Fiber Optic Cable Twisted Pair Cable PoECable LED NVR Confidential

  6. Carriage to Carriage Connection • In the railway environment, wireless connections between two carriages can be achieved by using two Aps. • WDS can be used for carriage to carriage connection. However, carriage re-arrangement will require re-configuration of all MAC addresses in WDS settings. WDS Confidential

  7. Moxa’s Solution:Automatic Carriage Connection (ACC) • ACC provides a “bridge” function, as well as stronger security modes, such as WPA-PSK, WPA2-PSK, WPA-Enterprise, and WPA2-Enterprise. It is a better solution than WDS mode. • ACC allows carriages to be re-arranged dynamically in any combination without any re-configuration required. Confidential

  8. ACC Requirements • The antenna between two APs should be: • low gain • directional in order to maintain correct association between adjacent carriages. ACC Confidential

  9. How Does ACC Work? • All APs’ wireless are configured with the same settings. (OP mode = ACC mode, SSID, RF band, RF channel, wireless security) • Two APs in the adjacent carriages will connect to each other, “automatically”. Confidential

  10. WLAN 101WiFi Troubleshooting MUST Know Confidential

  11. CSMA/CACarrier Sense Multiple Access with Collision Avoidance • Concept: only one device on a single channel should transmit data at a time! • When one is talking, everyone else should remain silent. Otherwise, they will interfere with each other. • CSMA/CA defines a mechanism to avoid transmission collision. • Before starting transmission, detects the current channel to see if it is clear. • If clear: start transmission • If not clear: back off and wait for a random period of time Confidential

  12. AP Client 1 Client 2 CSMA/CA Flow Chart Confidential

  13. Positive Acknowledgment (ACK) • To ensure every data frame is received successfully Atomic operation : Time Data Frame ACK No ACK = No data = transmission failed Transmission successful Confidential

  14. 802.11: Passive/Active Scanning Client Client • Active Scanning: • Probe Request frame broadcast from Client • Probes response frame sent from APs • Association Request frame sent: Client to selected AP • Association Response frame sent: Client to selected AP • Passive Scanning: • beacon frames sent from APs • association Request frame sent: Client to selected AP • association Response frame sent: Client to selected AP Confidential

  15. Passive/Active Channels Country JP Country ETSI Country FCC * = means Passive channel Confidential

  16. Hidden Node Problem • Problems: • (Hidden nodes are very difficult to diagnose) • Throughput value under the • theoretical value • Network not stable, • sometimes connect/disconnect • Solutions: • Enable RTS/CTS. • Increase TX power for Client. • Move Client near to AP • B is a Hidden Node to A ACK RTS CTS Confidential

  17. RTS(B) RTS(A) reservation collision RTS(A) CTS(A) CTS(A) DATA (A) ACK(A) ACK(A) Collision Avoidance: RTS-CTS exchange B A AP defer time

  18. OSI 7 Layer Data Link Layer MAC Layer = Sub-data link Layer 802.3 802.5 802.11 802.3 MAC 802.3 PYH 802.5 MAC 802.5 PYH 802.11 (MAC) 802.11 FHSS PHY 802.11 DSSS PHY 802.11a OFDM PHY 802.11b HR/DSSS PHY 802.11g ERP PHY PHY Layer IEEE 802 family & structure 802.1 802.2 (LLC) Confidential

  19. Lv 1 Lv 2 Lv 3 Service Scanning BSS Authentication Un-authentication Un-association Deauthentication Association Authentication Un-association Disassociation Data transmission Authentication Association Confidential

  20. Frames and Open Authentication 1. The Access points continuously send out Beacon Frames, which are picked up by nearby WLAN clients. 2. The client can also broadcast on its own probe request frame on every channel. 3. Access points within range respond with a probe response frame. 4. The client decides which access point (AP) is the best for access and sends an authentication request. 5. The access point will send an authentication reply. 6. Upon successful authentication, the client will send an association request frame to the access point. 7. The access point will reply with an association response. 8. The client is now able to pass traffic to the access point Authentication in the 802.11 specification is based on authenticating a wireless station or device instead of authenticating a user Confidential

  21. Example Confidential

  22. General 802.11 MAC Frame • 00: Management Frames • 01: Control Frames • 10: Data Frames Confidential

  23. Management Frame Type : 00 Association issue : The STA associates with AP Scanning issue : To obtain or provide STA information Authentication issue : To verify STA is qualified to join AP Confidential

  24. Control Frame :01 Confidential

  25. Data Frame : 10 Confidential

  26. WLAN 101Antenna Deployment Know How Confidential

  27. 4 Important Values for WLAN Deployment WLAN Deployment Case 1 ? Wireless Device Data Rate Distance Antenna Confidential

  28. 4 Important Values for WLAN Deployment WLAN Deployment Case 2 ? Wireless Device Data Rate Distance Antenna Confidential

  29. RF Factors for Long Distance 3 2 Tx Rx 4 1 4 Important Factors: Transmission Power (Tx Power) Transmission side’s Antenna Gain Receiver side’s Antenna Gain Receiver Sensitivity (Rx Sensitivity) Confidential

  30. Factor 1: Transmission Power 1 3 2 • RF mode: Different RF mode transmit different power • Data Rate: Different data rate transmit different power • Power range: 16.5 dBm ~ 19.5 dBm @ 6 Mbps, G mode Confidential

  31. Factor 2 & 3:Antenna Gain Comparison • Higher Gain Means Stronger (both) Sent and Received Signals • Watch for The Regulation in Country Confidential

  32. Factor 4: Rx Sensitivity Spec 1 2 • RF mode: Different RF mode can receive different minimum power • At 6 Mbps, the power received must be greater than -87 dBm forsignal to be recognizable. Confidential

  33. Power Budget Calculation Step 1 Step 2 How to Calculate Wireless Device (Rx) + Antenna How to Calculate Wireless Device (Tx) + Antenna Confidential

  34. Distance Lost Calculation Step 3 How to MeasureDistance Lost Confidential

  35. Step 1: How to Calculate Wireless Device (Tx) + Antenna -3dB -1dB 18dBm -1dB 18dBm =18-3-1-3+12 (dBm) 23 dBm Confidential

  36. Step 2: How to Calculate Wireless Device (Rx) + Antenna -3dB -1dB -87dBm +3dB -12dBi +1dB +3dB -87dBm = -87+3+1+3-12 (dBm) -92dBm Confidential

  37. EIRP • Equivalent Isotropic Radiated Power • EIRP = Pt + Lc + Ga Pt:AP’s output power Lc:Cable and connector loss Ga:Antenna Gain (Ga) Antenna (Lc) (Pt) Antenna’s EIRP output power Connector EIRP includes Equipments Confidential

  38. FCC Regulation for EIRP Confidential

  39. Step 3: How to Measure Distance Lost • Method of Calculation: • Using computer • Pen and paper calculation Tx = 23dBm Rx = -92dBm Distance = Lost ? Free-Space Path Loss d = distance f = frequency Confidential

  40. Distance vs Path Loss Reference 2400 Loss 110 Example for 5km vs 6Mbps: Example for 10km vs 6Mbps: Fail Pass Tx = 23 dBm Rx = -92 dBm Tx = 23 dBm Rx = -92dBm Lost = 120 Lost = 115 23-120 = -97 dBm 23-115 = -92 dBm Confidential

  41. What is Interference? Unwanted signals degrading the quality of the desired signal • Environment interference - Building, metal, weather, motor…etc • 3 Types of interference: • Narrow-Band Interference - will not effect 802.11 • Broad-Band Interference - Bluetooth, ZigBee, Microwave oven, Cordless phone ( same 2.4GHz ) • Co-channel Interference Confidential

  42. Antenna．Connector．Booster Omni-Directional Antenna Dish (Parabolic) Directional Antennas Panel Yagi Connectors Splitter Power Amplifiers (Booster) Male Connectors SMA RP-SMA QMA N-type TNC Female Connectors SMA RP-SMA QMA N-type TNC Confidential

  43. RF 60% Fresnel Zone All Obstructions Must Be Outside of 60% of The 1st Fresnel zone Confidential

  44. Non-free Space vs. Free Space • Non-free space • Line of sight required • Objects protrude in the fresnel zone, but do not block the path • Free Space • Line of sight • No objects in the fresnel zone • Antenna height is significant Confidential

  45. FAQ 1: Booster Splitter • When to use? • Depends on your application • Benefit: • Extend the coverage area • Disadvantage: • Hidden Nodes • How does it work? Tx = 18 dBm Good Bad Can’t Perceive 12 dBi Tx = 18 dBm 16 dBm -3 dB -3 dB -4dB Note: As a result, most long distance setups are done without using boosters. Aux Purpose: Enhance EIRP Disadvantages: • Regulatory Concerns • Compatibility Issues - Although a booster has its own specs, true power enhancement results can only be determined through testing. - Noise magnification Confidential

  46. FAQ 2: If your application requires directional antennas to be used when the clients are located linearly to the left and right of the AP. Which installation is suggested? Example Application 1 Example Application 2 Client Client Client Client Client Client Client Client Client Client Client Client Client Client Client Client Client Client Client Client Client Client AP Client Client Building Client Client Client Client Confidential

  47. Solution: No Splitter VS Splitter With Splitter Without Splitter splitter Data out Data out Data out Data in Data in Directional antenna Directional antenna Directional antenna Directional antenna Aux Main Main Aux AP AP • AP’s Main/Aux will be switching all the • time, depending on the signal strength • receive by the AP (switching behavior is • determined by the wireless chipset) • - Packet loss may occur during constant • antenna switching • No antenna switching issues • Note: • Please make sure UI antenna is set in MAIN only • RTS/CTS enable Suggested Not suggested Confidential

  48. FAQ 3: Omni-directional Antenna Deployment AWK AP1 AWK AP2 Omni-directional Antenna AWK Client

  49. FAQ 4: Directional Antenna Deployment Directional Antenna AWK AP1 AWK AP2 AWK Client

  50. FAQ 5: Leaky Coaxial Cable Deployment AWK AP1 AWK AP2 Leaky Coaxial Cable Jumper Splitter Overlap AWK Client

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