Presentation on theme: "MTSC Training Course Industrial Wireless"— Presentation transcript:
1MTSC Training Course Industrial Wireless Prepared by: Joe dela CruzDate:
2Training TopicsLet’s take a look at the training topics.
3Training Topics The Basics Antennas and Long Distance Knowledge Wi-fi concepts, Cellular ConceptsAntennas and Long Distance KnowledgeAWK Series Killer FunctionsTurbo RoamingDual RF Redundancy and BridgingVLAN & QoSOnCell Series Killer FunctionsOnCell Central ManagerRouting functionWe are going to start off with the basic concepts on Wi-fi and Cellular technologies. We then move on to talk about antennas and how to use them in long distance applications. Next we are going to introduce some new killer functions for the AWK Series. They include Turbo roaming, dual RF redundancy and bridging, and VLAN & QoS. Lastly we will cover the key functions for the OnCell series, namely, the OnCell Central Manager and routing functions.
4In This Section You Will Learn… What’s new with AWK and OnCell productsWhat’s important about antennas and long distance communications.This training not only has slides but also the practice section.Through the training and the hands-on exercises, you will learn what's new of MiiNePort E1 and how to operate it.
5Wi-Fi BasicsLet’s get started with the wi-fi basics. You may be familiar with some of this material because some of them were covered in last year’s MTSC. If you do, please take this time to review them.
6What is a Wireless Network? A network of devices communicating over radio waves.A wireless network eliminates data cables.What is a wireless network?A wireless network is a network of devices sending/receiving data over radio waves with each other.A wireless network, by definition, eliminates the use to data cables (wires) for data communication.
7What is Wi-Fi?Three short-range, unlicensed radio technologies: IEEE a, b, and gStandardFrequencyMax/Real ThroughputCompatible with bTypical Range802.11b2.4 GHz11 Mbps/5 MbpsYesIndoor: 100mOutdoor: 200m802.11g54 Mbps/20 Mbps802.11a5 GHzNoIndoor: 50mOutdoor: 100mWhat is Wi-Fi?When we refer to Wi-Fi, we are mostly referring to the three short-range, unlicensed radio technologies, namely, IEEE a, b, and g standards. Take a look at the difference in Frequency band, maximum throughput of the different standards.
8802.11b/g802.11b speeds: 11, 5.5, 2, 1 Mbps802.11g speeds: 54, 48, 36, 24, 28, 12, 9, 6 MbpsActual throughput: ~50% of supported speeds (due to network overhead)Channels: 1~11 (US), 1~13 (EU), 1~14 (JP)Recommended channels of use: 1, 6, 11 (avoid frequency overlap)Regulations: FCC (US), ETSI (EU), ARIB (JP)Here is a more detailed overview of the b/g standard. The .11g standards can be viewed as a higher speed version of the .11b standard. They shard the same frequency band and thus are backward compatible. Note that the actual throughput is about half the data rate. This is due to wireless packets having a larger overhead in their headers than Ethernet packets. Also, there is a greater gap between the wireless packets then Ethernet packets. Also note that the recommended channels of use are 1, 6, and 11. These 3 channels’ bandwidth are non-overlapping and thus have minimal interference between each other.
9802.11b/g Advantages/Disadvantages Widely usedBackwards compatibilityLonger communication distanceDisadvantages:More susceptible to interference (more devices communicating in 2.4 GHz band)Overlapping channelsSome advantages of using .11b/g modes are:It is widely usedB and G modes are backward compatible.Compared with .11a mode, .11b/g modes can support longer communication distance.Some disadvantages are:Because is it widely used, there are much more devices using b/g modes than .11a mode. Therefore it means the 2.4 GHz band is likely to be more crowded than the 5GHz band.Although there are a total of 11 channels available (13 for EU standards), only 3 of them are non-overlapping channels, the rest of the channels will overlap with other channels to some extent.
10802.11a802.11a speeds: 54, 48, 36, 24, 28, 12, 9, 6 MbpsActual throughput: ~50% of supported speeds (network overhead)5GHz Frequency bands (4 channels each): UNII-1 , UNII-2, UNII-3Ex: UNII-1 contains ch. 36, 40, 44, 48 (all non-overlap channels)Regulations: FCC (US), ETSI (EU), ARIB (JP)Now let’s take a look at the .11a standard. Again, you can expect a throughput of ~50% of the data rate due to network overhead.
11802.11a Advantages/Disadvantages Less susceptible to interference (fewer devices communicating in 5 GHz band)All non-overlapping channelsRegulators allow higher transmit power at higher frequenciesDisadvantages:Shorter communication distanceNot compatible with b/gSome advantages of .11a mode are:Less users means less interference in this frequency band.All channels in .11a mode are non-overlapping channels, so co-channel interference is less likely to occur.Higher power levels are allowed in the 5GHz range.Some disadvantages are:It has shorter communication distance compared to .11b/g standards.It is not compatible with widely used .11b/g mode.
12Radio Signal Specs Specs Definition Measure Unit Why Important? Frequency RangeThe range of radio frequency which the signal is transmittingMHz/GHzRadio Signal frequency range has to match antenna’s frequency spec.Difference frequency range may have different interferencesLossLoss of power in the radio signaldB/dBmLoss weakens the signal strengthUse low loss cablesTransmit (Tx) PowerThe power level of the signal being transmittedmW/dBmHigher the power, further the distancePower regulations in different countriesReceive (Rx) SensitivityThe recognizable power level of the signal at the receiving enddBmHigher sensitivity, further the distanceHigh gain antennas helps sensitivityWhen we are talking about RF signals, a few key specs are important to know.Take a look at what they are and why they are important.
13AP/Client Concept Access Point (AP) Client LAN 1 Backbone LAN 2 The most simple way to make a WLAN connection is to setup an AP/Client connection. The AP acts as a wireless hub, which can serve multiple clients. Each AP has a coverage range and if an area requires wireless coverage which is greater than the coverage area of a single AP, multiple APs can be deployed to extend the coverage area of the overall wireless network. Client devices acts as a gateway for sub-networks or Ethernet devices to be connected to the backbone network. Clients can also roam between the APs to stay connected to the central network.Access Point (AP)A wireless hubService wireless clientsProvide filtering and securityClientMobile wireless deviceWireless bridge for sub-networksCapable of roaming between APs
14AP/Client Specs and Settings Operation mode: Device plays role of AP or ClientRF type: Select RF modeChannel: AP and Client will use the same channelSSID: AP and Client much have SAME SSID for associationSSID broadcast: AP broadcast SSID for passive scanning clientWDS: AP/Client connection if not enabled.To setup a AP/Client pair connection, you can configure the basic wireless settings in each device.Select the operation mode. This determines whether you would like this device to be an AP or a Client.Select the RF type: this is where you set the wi-fi standard (2.4GHz or 5GHz). AP and Client must be of the same RF typeSelect the channel to use. Select a channel for the AP only. Clients will follow the AP’s channel settings once connected.Set the SSID. SSID is the network identifier for AP and Client to recognize that they belong to the same network. Therefore, for a Client to connect to the AP, they must have the same SSIDEnable or disable SSID broadcast means to hide or display SSID in AP’s beacon packets.Enable or disable WDS to turn on or off the bridge function of the AP.
15WDS/Bridge Concept WDS (Wireless Distribution System) Backbone LAN 1 APAPWDS or bridge mode allows the APs to be connected to each other. They can act as repeaters to extend AP coverage. Each AP in WDS mode can also serve clients.WDS (Wireless Distribution System)Bridging APsWirelessly connect multiple BSS and LANFixed location communication
16Different WDS Configurations WDS links can be configured to different topologies. You can connect them like a star (branch connections from the center device), in a chain, or in a ring (RSTP must be enabled to prevent looping).
17WDS Specs and Settings WDS: Device plays the role as bridge AP functionality: Device also plays the role as AP (allows client connection)WDS Settings: Enter MAC address of each bridge device in WDS link.To setup a WDS link, for example between AP1 and AP2, in AP1’s WDS MAC address field, you enter AP2’s MAC address. And in AP2’s WDS MAC field you enter AP1’s MAC address. In other words, enter opposing devices’ MAC address in the WDS MAC address field.
18What is throughput?Throughput is the actual data rate the device can transfer data.In WLAN devices, throughput is roughly half of theoretical data rate (when bandwidth is not shared)One should measure throughput to determine if actual data rate meets requirement.It is very important to understand throughput in a wireless network because unlike a wired line with a stable throughput, the throughput of a wireless connection may vary due to may different factors such as distance, interference, antenna positioning, line of sight, and RF type. Therefore, throughput should always be measured to ensure your setup allows enough throughput to meet the applications requirements.
19Throughput Measuring Tool Jperf: WLAN throughput measurement tool.In measuring the throughput of a wireless link, there are many licensed tools on the market for such task. Iperf is a tool that is free of charge and can be downloaded at listed website. Iperf has a text based interface where the execution file can be edited and allow the throughput be displayed on a command prompt window. Jperf is a java based Iperf tool. It’s graphical interface makes it much easier for the user to use and to see the throughput graph. Jperf will need to be executed on the two endpoints with one running as the server, and the other the client. After performing the throughput measurement for the specified time, an average throughput will be displayed.Confidential
20Cellular BasicsNow let’s take a look at some cellular basic concepts.
21What is Cellular?A radio communication system that can send data over a wide areaA wireless network that gives access to network subscribers through base stationsWhat is cellular? A cellular network is an area network using a radio communication system that is divided into cells. Base stations are located in each cell to provide subscribers the access to the public phone and/or internet lines.
22Cellular Network Service Standards 1GNMTAMPS/TACS/ETACS2GGSMCSDPHSGPRS / EDGECDMA20003GW-CDMAUMTS (3GSM)TD-CDMA/UMTS-TDDTD-SCDMAHSPAHSDPAHSUPAHSPA+HSOPAFor Voice OnlyFor Voice and DataThis diagram shows the evolution of the cellular technologies. From 1st generation voice only standards to currently 3rd generation voice and data applications. With each upgrade, the bandwidth increases to allow for higher speed communication over the cellular network.
232G/3G Telecom Technology 2G: CSD/SMS/GPRS/EDGE3G: UMTS/HSDPAServiceDownloadUploadCharge RateCSD9.6 kbpsBy connection timeSMS1120 bits/msgBy number of messageGPRS80 kbps20 kbpsBy amount of data trafficEDGE237 kbps59 kbpsUMTS384 kbps64 kbpsHSDPAUp to 7.3 mbpsHere is a comparison of different services which different download and upload speeds and how are fees charged.
24What is CSD?CSDLike reserving a seat for dining: Exclusive Service, Needs SetupPeer-to-Peer ConnectionLow cost, charges are just like Voice CallsStands for GSM Phase 2 “Circuit Switched Data”Let’s first take a look at the circuit switch data (CSD) service. It is a peer to peer connection similar to a phone call. This service are gradually phasing out due to the continual advancements in packet switch data services such as GPRS and HSDPA
25Modem and CSD via PSTN CSD Features Simulates a long serial cable Transmit and receive dataTransmit and receive dataCSD FeaturesSimulates a long serial cableDynamic destinationEstablish connectionEstablish connectionModemModemModemModemThis is an example of how a CSD connection is established.SerialSerialSerialCOM1Legacy DOSsoftwareCNC machineCNC machineCNC machine25
26OnCell G2150 CSD Application 2. Transmit and receive data1. Establish connectionElectricMeterCellularStationPBX / AdministratorCellularStationElectricMeterAnd here is an example of a CSD application to read electric meters from a SCADA software.26
27Dialing (Command Mode) AT Command DialingCommand ModeData ModeDialing (Command Mode)Modem AModem BATDRINGRINGRING…ATACONNECTCONNECTabcd1234abcd1234+++The AT commands for dialing a CSD connection is shown here. For OnCell G2100 series, you may also set it to auto answer the dial-in so you do not have to pick up the call with the “ata” command.OKATHNO CARRIEROK27
28What is GPRS? GPRS When Will You Need GPRS? Typically charged per megabyte of transferred dataStands for “General Packet Radio Service”When Will You Need GPRS?If you need ADSL-like modem behaviorIf you want to use the Internet…As mentioned before, the CSD service due to its costly time based fees, slow speed and dial-in dial-out hassles, the industry have long switched to the popular GPRS service as the primary service for connecting their devices. With GPRS, not only can you make IP based peer to peer connections, you can also access the internet through the GPRS network.
292.5G – GPRS (General Packet Radio service) Mobile Data Service available to GSM usersGSM combined with GPRS is called 2.5 GBilled per kbyte/Mbyte/package (128 bytes)Packet SwitchedPPP, IP supportedMMS (Multimedia Message Service)Push MailHigh-speed Internet access for mobile phonesHigh-speed Internet access for PCsGPRS is different from the older CSD connection included in GSM standards. In CSD, a data connection establishes a circuit, and reserves the full bandwidth of that circuit during the lifetime of the connection. GPRS is packet-switched which means that multiple users share the same transmission channel, only transmitting when they have data to send. This means that the total available bandwidth can be immediately dedicated to those users who are actually sending at any given moment, providing higher utilization where users only send or receive data intermittently. Web browsing, receiving s as they arrive and instant messaging are examples of uses that require intermittent data transfers, which benefit from sharing the available bandwidth.
30What is APN?APN (Access Point Name) is the domain name for gateway to GPRS/internet networkAPN is different for different countries and cellular operatorsAPN must be set correctly in order to properly register onto the 2G/3G networksOperator may assign private APN for specific users.To access the GPRS network (meaning connecting to the internet), you must be provided with a proper APN. The IP modem must know the APN of your service provider so that your device can pass through the proper gateway in order to access the internet. It is important to know that APNs are different for different countries and may be different for different cellular service providers. Some providers can provide private APN for specific users to access the units within a private network. Note that a private APN network may not have access from and to the internet.
31What is SMS? SMS When will you need SMS? Short Message Service, for human-readable messagesLow data volume: 140 bytes maximum140 hexa characters or160 ACSII characters or70 uni-codesWhen will you need SMS?If you want to receive text messages…If your application transfers messages infrequentlyOr you have a low volume of messagesLastly, SMS may be a useful option for users with very little data to send or send alarm messages to notify events.
32SMS to Whom? Set 7-bits Ascii Send my message to… Press Ctrl+Z here Here is the sequence of how to send SMS messages via AT commands.Press Ctrl+Z here
33You’ve Got Mail!! You’ve Got Mail!! Show Me!! Detailed Message & Info At the receiving end, this is how to read the received messages.Show Me!!Detailed Message & Info
34SMS Tunnel without AT Commands Serial-to-SMSSMS-to-SerialSMS Data FormatTextBinary (8 bits)Unicode (UCS2)A useful proprietary function call SMS tunnel mode was developed by MOXA and is included in both OnCell G2100 and G3100 series. SMS tunnel mode allow for transparent serial tunneling via SMS without using AT commands.
35Antenna and Long Distance Knowledge In this next section, we are going to discuss antenna characteristics and long distance knowledge.
36Basic Antenna Concept Transmit Power flow thru induces RF wave Receive RF wave induces powerReceiver tuned to a specific frequency to pick up specific RFFirst, it is important to understand antennas are used for transmit and receive purposes. An antenna transmits the signal by converting current to RF wave and radiate them into the air. The antenna receives the RF waves and reverse the process and convert the radio signals back to current flowing through the conductor.
37Antenna Selection (Omni Antenna) Longer Distance But narrow range due to the same powerHere are some examples of different types of omni directional antennas.
38Antenna Selection (Semi-Directional Antenna) Yagi AntennaPatch AntennaHere are some examples of semi-directional antennas.
39Characteristics of the Antennas Omni-directional Dipole-360 degree coverage-Short distance applications-Service mobile clientsDirectional Panel / Patch Less than 90 degrees of coverage-Long distance applications-Service fixed location clients/bridges.It is important to know the difference and application of different types of antennas. In general, omni-directional antennas are for shorter range but 360 degree angle coverage areas. Directional are more for long range and point to point applications due to narrow antenna angle.
40Basic Antenna Spec Example Technical informationFrequency： MHzGain：12 dBiPolarization：VerticalBeamwidth deg vertical & horizontal：Horz.360°Vert.7°VSWR：≦1.5：1Impedance：50 OhmDimensionsLength：H1500㎜Weight：850 gConnector：N-type / femaleWhen selecting an antenna to use, it is important to be able to understand the antenna specs. First and foremost is to make sure the frequency and gain meets the requirements of the application. Then make show the antennas have the same polarization, the beamwidth provides enough coverage angle and the impedance is matched to 50 ohms. The VSWR value usually is not a critical issue (anything lower than 2:1 is acceptable). Lastly, make sure the antenna connectors and your RF cable match.
41Antenna Gain Comparison Higher gain means stronger (both) sent and received signals; watch for the regulation in your countryAntenna TypeGain RangeOmni Antenna2~12dBiSemi-Directive Antenna5~18dBiHigh Gain Antenna20~40dBiHere is a general comparison of the gain range of different antenna types.
42Beamwidth and plane field pattern HPBW – Half Power Beamwidth ( 3dB )The beam width is about 65° and the gain is about 9 dBi. (Patch panel example)When reading the antenna pattern, note the beamwidth is the angle drawn between the 3dB drop off points from the point of maximum gain. Thus the beamwidth is also referred to as the 3dB beamwidth.
43Deployment Consideration Matching polarity on both sidesPower Budget – Enough Gain? Low loss?Free space loss – is the distance achievable?Site Survey – Use Network StumblerAntenna heightAntenna alignment (pointing direction)Jperf or Chariot is useful!Use GPS and compass for tuning angleCheck RSSI, bit rate, noise level, throughput…Here is some tips when deploying the antenna:Make sure the polarity of the antennas are the sameEstimate the overall power budget of the link to have an idea of how much you will need in the antenna to transmit at the desired distance.Estimate the free space loss to see if the distance is actually achievable.Any time you are setting up a wireless system, you always want to site survey first to see what kind of co-channel interferences are present. Network Stumbler is a very useful tool for site surveyHow high does the antennas have to be to provide enough line of sight.Specially critical for long distance communications. Antenna alignment can be tuned by a throughput measuring tool such as Jperf. If the distance is very far (5, 10 km or more), you may need to use GPS devices to position each site. During antenna tuning, parameters indicating good or bad alignment are RSSI, bit rate, noice level, throughput…etc.
44Polarity must match (vertical or horizontal) Antenna PolarityPolarity must match (vertical or horizontal)Here is an example of polarity matched and mismatched antennas.Confidential
45RSL (receive signal level) > sensitivity + Fade Margin Power BudgetWP IIAPpigtail cableLightning ProtectorRF CableAntennaClient+ Transmit Power- LOSS Cable/connectors+ Antenna GainRSL (receive signal level) > sensitivity + Fade Margin- Path Loss over link distanceIn this power budget diagram, you see each component introduces either gain or loss to the radio signal. Therefore you want to estimate how much loss/gain the signal experiences in the overall system by adding the gain and subtracting the losses so that the received signal level (measured in dbm) at the client input is larger than the sensitivity of the client device plus some fade margin.
46Free space Loss Loss of power in free air Free Space Loss (dB) = Log10(Frequency) + 20Log10(Distance in miles)Lower the frequency for less loss of free space Use 2.4 GHz for long distance!In wireless communications the medium that introduces the most loss in the signal path is air. Therefore it is important to be able to calculate the free space loss to see how much attenuation does the signal power level experience after traveling through the air. Note that one of the parameters in the free space loss equation is frequency, which means lower frequency results in less free space loss. Thus for long distance applications, 2.4 GHz is preferred over 5GHz.
47Antenna Height Antenna height helps to avoid obstacles Higher Antenna helps LOS (line of sight) and Fresnel ZoneOne other important factor when setting up a long distance WLAN system is the antenna height. Due to earth bulge, if the 2 points are on the horizontal plane, the antennas will still need to be elevated if the distance between them are far.
48MOXA Wireless Distance Calculator The above mentioned distance, free space loss and antenna height can be easily estimated by using MOXA’s online wireless distance calculator. By selecting the device, transmission frequency, the antenna type and RF cable, you can estimate the distance with a click of a button.
49Calculated DistanceThis calculator provides a straightforward way to calculate the theoretical transmission distance. These calculations are based on an unobstructed line-of-sight signal with no electronic interference. In fact, the real world presents many variables that result in less-than-perfect wireless performance, such as mismatched impedance, electronic noise, building obstructions, reflected signals, etc. However, there can be a big difference between the theoretical transmission distance and the actual results in the field. But thanks to this calculator, you can now easily estimate whether you will be able to achieve your desired transmission distance with a given set of hardware. Using this calculator, you can make an informed decision when selecting antennas and devices for different wireless applications.
50Antenna Height Estimation By inputting the distance between 2 points, the Fresnel zone height and earth bulge height will be added up to give you a minimum antenna height to keep a stable connection.
51Free Space Loss Estimation Free space loss can be estimated by entering the distance between the antennas.
52Antenna Tilting Angle Estimation When the antennas are at unequal heights, it is necessary to adjust the tilting angle of the antennas so that their main lobes can be aimed more precisely to each other.
53Flexible and Powerful Solutions for Long-distance Transmission Extend your IEEE applications farther (10-20km)Protocol-level solution (~10km)Communication Parameter adjustmentHigh-gain antennaPHY-level solution (~20km)Booster/ Power AmplifierHigh-power RF module(200/800mW)We have performed outdoor testing of the AWK series to collect data for the devices long distance performance. Our solution for distances up to 10 km are to adjust communication parameters and use high gain antennas so that the throughput is still at an acceptable range. For distances up to 20 km, we are prepared to test with additional power boosters and use high-power RF modules as our solution.
54Fix Antenna to have higher Performance APClientDistanceTXRXLaptop1Endpoint 1Laptop2Endpoint 2Set DistanceThe AWK series are ready for long distance applications. As you can see, we have setting specifically aimed for long distance applications. You can set your transmission distance to trigger communication parameter changes to compensate for noise and propagation delays. Also, you may enabled Transmission enhancement function to maximize the transmission power output so to improve throughput performance. Please note that both Transmission distance and Transmission enhancement settings must be set the same on both the AP and client for the optimization to work. Lastly, you want to have the antenna fixed to the same port for better performance.Enable 200mW Tx Power(Default Disable)Fix Antenna to have higher Performance
55Long Distance Communication Tests 5km testing siteHere is to show you our actual location of our test sites and how GPS or online mapping and help to locate and measure the actual distance between the 2 sites.10km testing site
56Test Results Distance: 5.3 Km Distance: 10.11 Km 2.4G Antenna Gain Throughput (Mbps)9 dBi12 dBi18 dBiTx3.75813.96617.498Rx5.06412.92217.5742.4G Antenna GainThroughput (Mbps)9 dBi12 dBi18 dBiTxUnder Test9.715Rx8.5595G Antenna GainThroughput (Mbps)9 dBi12 dBi18 dBiTxN/A9.662Rx9.508Lastly, here is our test results for 5 km and 10 km. Note that with the 18 dBi antenna at 10 km, we were still able to obtain a throughput of near 10 Mbps. Also note that because at 5 GHz, the free space loss is greater, so the devices can only communicate up to 5 km in distance.
57AWK Series Killer Functions Turbo Roaming Next, we are going to look at one of the killer functions of the AWK series: Turbo Roaming
58Non-proprietary vs. Proprietary Roaming Roaming/ Reconnection Steps: RSSI/DR ↓ Disconnection Scanning Authentication Association DoneNowadays, every client device can roam between APs. Therefore the roaming function itself is nothing really special. But what does make a different is the how fast can the client device roam. The longer it takes the clients to roam from AP to the next AP, the longer the break in your communication. Therefore, with MOXA’s proprietary roaming technology, we can reduce the standard roaming time (5~10 seconds) down to less than 100 ms. In the near future, we are looking at reducing it even further to less than 50 ms.How do we do it? Basically, we want to reduce the most time consuming process in a AP/Client connection sequence, namely, scanning and authentication. These 2 processes takes the majority of the time during reconnection. During scanning, the client will have to sniff out all the APs on all channels and decide which AP is the best for it to connect to. After it finds the target AP, it then has to sync security settings to make sure the client passes all security checks. These will take a lot off time, but we managed to reduce them significantly.
59Techniques to improve roaming efficiency 1. Separate the APs properlyAP1AP2Not only do we want to roam fast, but we also need to optimize the deployment of APs to ensure more efficient roaming (as little roaming at possible). For example, you do not want to have the APs located to close to each other. If you do so, not only are you not getting the maximum total coverage ranger for these APs, but since roaming occurs in the overlapping coverage areas, larger the overlaps, more roaming is likely to occur. Therefore, you want to separate the APs properly, so that clients can roam smoothly in the overlapping areas while enjoying the maximum coverage area from the AP.AP1AP2Lower the frequencyof roaming switch andmake roaming efficient
602. Unify the channel utilization AP1AP2AP3AP42Ch=1Ch=4Ch=7Ch=10AP1AP2AP3AP42Ch=1Ch=6Ch=1Ch=6Lower the time consumptionof dedicated AP searchingto make roaming efficientAnother way to optimize roaming time is to keep the number of roaming channels small so to reduce the required channels scanned by the client during roaming. For example, if your application requires many different clients to roaming between many APs, you have no choice but to separate the channels (so that clients do not all share the same channel) to ensure you have the best throughput for the overall wireless network. However, if the number of clients is not many, then the number of channels may to reduced so that both throughput and roaming time is kept to an optimal value. In applications such as rolling stock, only 1 or 2 clients are connected to an AP at a given time (thus throughput should be enough), setting all the APs to the same channel can further improve the roaming time.AP1AP2AP3AP42Ch=1Ch=1Ch=1Ch=1
61High Speed Mobile Client For high speed mobile applications where the client device is traveling at a high speed (up to 100 km/hr) and roaming between APs. This kind of high speed roaming was tested and verified by the MOXA test team to be ready. Please also note that a fiber mode for the AWK-3121 series is on the way to be launched.
62Turbo Roaming™ Technology for Rapid Handovers within WLAN AWK client supports fast handover, even with a speed up to 100km/hrEasy-to-use solutionNo proprietary protocol or AP neededOne click to enable Turbo RoamingNo performance drop during background scanningThe Turbo Roaming technology is so easy to use, you just need to enable it on the client device and selected the scanning channels (channels of the APs which you know the client will be roaming between), and you are ready to go.
63Deploy APs properly and avoid bug light effect and ping-pong effect site survey and planning 1152343Once again, we want to remind you that proper AP deployment is critical to improve roaming efficiency. In the example on the left, if a moving vehicle with a client device is to turn the corner and only needs to roam from AP1 to AP5. However, due to overlapping coverage area of AP2, AP3 and AP4, the client device will probably roaming between all these APs first as it turns the corner before it roams to AP5, resulting in extra roaming sequences taking place. You can improve the situation by better AP deployment. In the example to the right, if you increase the coverage area of AP2 (by moving it closer to the corner or by setting it to higher tx power) and separate the coverage area of other APs (move them further away or reduce power settings), the client device then probably will only need to roam to AP2 before it reaches AP3, saving 2 extra roaming hops.2Avoid unnecessary roaming andmake roaming efficient
64AWK Series Killer Functions Dual RF Redundancy & Bridging Now let’s take a look at the newest product from Industrial Wireless, the AWK The AWK-5222 is a high end product in the AWK series. It has 2 RF modules giving the user a greater flexibility in implementing their wireless network. In this section, we will be talking about the 2 key operation modes on the AWK-5222 using the dual RF architecture: Dual RF Redundancy and Bridging.
65Redundant Wireless Link 2.4GHzor 5GHz(Stand-by)Typically a wireless connection may give some user an image of a non-stable link. Because of interference and signal attenuation issues, it is difficult to rely on a wireless link to as robust as a wired link. To improve this issue, the obvious answer would be to form a redundant link to backup a primary wireless link. As you can see from the illustration, a possible way to implement a backup path is to have a backup RF link standing by so that when the primary link is interrupted, the backup link can recover the communication between the devices.Dual-RF(as Master)Dual-RF(as Slave)
66Redundant Wireless Link The wireless link is recovered,but some packets may be lost…2.4GHzor 5GHz(Active)This mechanism is a typical redundant path solution. However, during the hand over of the RF links, there will be some packet loss. This may be unacceptable for some critical applications.Dual-RF(as Master)Dual-RF(as Slave)
67Highly Stable and Reliable Wireless Network – Redundant Dual RF Solution (1)(3)(2)(4)Therefore what we have done is we made both RF links connect at the same time and also transmit the data at the same time. The receiving end will then determine which data arrived first and which data is just a duplicate of the previously received data packet. The receiving device will then go ahead and drop the latter.
68Advanced Redundant Wireless (1) The wireless link can performquite well in a normal state.2.4GHzor 5GHz(Concurrently used)This implementation then will not cause any packet loss during backup path recovery. In normal state (no interference), both RF links are concurrently used so you have a backup to your transmitted data constantly.AWK-5222(as Master)AWK-5222(as Slave)Chance for better Throughput
69Advanced Redundant Wireless (2) The wireless link remains,and no packet will be lost…2.4GHzor 5GHz(in use)The dual backup path allow for no packet loss during any one of the link failures.AWK-5222(as Master)AWK-5222(as Slave)Max throughput for the utilized channel
70Dual RF AWK-5222/6222 – Wireless Redundancy Mode To setup the redundant link, you simply select the operation mode (Wireless Redundancy) and then select the role of your device (Redundant AP or Redundant Client)
71Also supports single RF clients Note that a redundant AP can also serve non-redundant clients, so that client devices such as AWK-3121/4121 can also connect to a redundant AP.
72Dual RF – Wireless Bridge Mode Another useful operation mode is the Wireless Bridge Mode. What the wireless bridge mode is capable of is connect a chain of APs together wirelessly without losing throughput after each stage. If a WDS topology was to be used to chain APs, throughput degradation will be a major concern due to all APs has to share the same channel. If you have 2 RFs at your disposal, you can set them to different frequencies and channels so that they do not interfere with each other and thus will be not result in lowered performance.
73High-performance Wireless Bridging for NLOS Communication WLAN2 as MasterWLAN1 as slaveWLAN2 as MasterWLAN1 as slaveWLAN1 as slaveWLAN2 as MasterWith Wireless bridge mode, you can now chain as many bridges as you like with good throughput performance. By using APs as repeaters, in a non-LOS simulation, you can setup APs around the obstacle to resolve the issue. An important note in deploying the bridges are to make sure the RF frequency for WLAN1 and WLAN2 are in different bands (2.4GHz and 5GHz) or they are in the same band but different channel with external antennas far apart from each other to avoid co-channel interference.WLAN2 as MasterWLAN1 as slave
74The local clients can be served as well… WLAN1 as slaveWLAN2 as MasterWLAN1 as slaveWLAN2 as MasterWireless bridge mode can also be used as a wireless backbone in which each Master WLAN can serve locate clients.AWK-3121(Client mode)
75Bridge Mode – Provide Extra AP Function As you can see here, you can “grow” another AP from the Master node to serve other clients.
76AWK Series Killer Functions VLAN & QoS The third function we are going to introduce here is the VLAN and QoS function on the AWK-3121/4121
77What is multiple SSID?An SSID is similar to a wireless LAN port, wherein an SSID serves clients with the same SSID.An AP with multiple SSIDs can allow clients with different SSIDs to connect to the AP (similar to devices connected to different ports on a switch)Before we discuss VLAN in a wireless network, we need to understand what is multiple SSID. A typical AP usually offers only 1 SSID to serve clients. If an AP can support multiple SSIDs then each SSID can be divided into different VLAN between the client devices. For example, you may only want your home client devices to connect to the SSID (HOME) while when guests visit your home, they can access the SSID GUEST.Client SSID = HOMEAPSSID1 = HOMESSID2 = GUESTClient SSID = GUEST
78Multiple SSID + VLANWireless VLAN (802.1Q) can be realized based on SSID grouping.Wireless VLAN1Client SSID = HOMEClient SSID = HOMETRUNKVLAN SWAPSSID1 = HOMESSID2 = GUESTFor AWK-3121, the VLAN standard used is 802.1Q and is only based on different SSIDs, namely, clients connected to the same SSID are grouped in the same VLAN. If you are familiar with 802.1Q, you can view each SSID as a VLAN port. The trunk port can be either the LAN port on the AWK-3121 or a WDS connection (not shown).Wireless VLAN2Client SSID = GUESTClient SSID = GUEST
79Multiple SSID Settings This is the setup page for multiple SSIDs. You may add up to a total of 9 SSIDs in the list.
80VLAN Settings TRUNK VLAN1 VLAN2 Once multiple SSIDs are set, you can now group them into different VLANs in VLAN settings.
81Why is QoS (quality of service) important? Give priority to strict latency data traffic such as multimedia data (voice > video > best effort > background)Improve user experience for voice and video streaming applications.Traffic contention managementLet’s now look at QoS. QoS allows you to prioritize your traffic data so that more latency critical data can have priority to bandwidth before non-latency critical data. For example, you would not mind waiting a few seconds more to send an out, but if you are chatting over a wi-fi phone, you cannot tolerate any break in voice. Therefore, voice data should have higher priority than data (best effort) when it comes to occupying the bandwidth. You can download a useful whitepaper on WMM (QoS for Wi-Fi) from the WiFi Alliance to understand more about QoS.The Wi-Fi Alliance started interoperability certification for WMM (Wi-Fi Multimedia) as a profile of the IEEE e QoS extensions for networks.Download WMM for WiFi whitepaper from WiFi Alliance:
82Example: Wi-Fi Multimedia Network Here’s is an example of why QoS is important: when you have numerous client device connect to the same AP, traffic should be prioritized to allow appliances such as phones and video players to have priority to the bandwidth.
83WMM Access CategoriesIf a device does not support WMM, the data is tagged in default as best effort priority. If WMM is enabled, then WMM supporting devices’ traffic will be tagged according to they data type and assigned different priority.
84Example of effect on WMM on a video stream If you were to monitor the traffic with and without WMM enabled, you will notice that without WMM, all kinds of traffic contend for the bandwidth and results in low and unstable data rate for all types of traffic as seem in the bottom graph. With WMM enabled, you can see that even when background traffic is introduced after 10 seconds, the video data is still kept at a steady 10 Mbps while the other background data stream is “pulled down” by the new data stream.
85Enable WMM on AWK WMM Enabled To enabled WMM on the AWK-3121, you simple have to enable it in Advanced Wireless Settings. Make sure that both AP and Client devices have WMM enabled to have QoS working in the whole system.WMM Enabled
86AWK WMM test results WMM Enabled WMM Disabled Confidential From our in-lab tests, the AWK is indeed capable of WMM functions.Confidential
87OnCell Series Killer Functions OnCell Central Manager Let’s now move on to the OnCell series. First, the monumental function of this year’s OnCell product line: the OnCell Central Manager.
88What is the problem with having private IPs? Private IPs are hidden from the public domainIf both Host and Modem have private IPs, they will not be able to “see” each other and thus cannot communicateWhy is OnCell Central Manager such a break through function? First we have to understand what is the problem with having private IPs. The problem with private IPs are that they are private, hidden from the outside world and thus cannot be access from the public domain. A private IP device can initiate a connection to a public IP, but not vice versa.
89Issues with Private IP Public IP Domain Private IP Domain OnCell CentralManagerPrivate IP DomainOnCell CentralServerPrivate IP DomainEthernet DeviceLet’s explain the issue with an example. Suppose you have a PLC and SCADA system setup. The PLC may be a Ethernet or Serial device, and the Host needs to poll raw data from the PLC either through a COM port or through TCP connection. In this case, the Host must be a TCP client mode needing to poll data periodically from the PLC through GPRS. Now if the OnCell that is service as a gateway to GPRS for this application gets a private IP, then the Host computer will not be able to access it from the public internet domain and thus cannot access the devices behind it. For this reason, the OnCell Central Server act as a bridge and when both the OnCell and Host connects to it, it can relay the connection so that the Host can still act as TCP client but now it can connect to the OnCell and the devices behind it. This then is the solution to private IP limitations.Serial DeviceOnCell DeviceDeviceHostEthernetSerial
90MOXA’s Solution: OnCell Central OnCell Central Server allows private IP hosts and OnCells to communicate with each other.Again, by placing the OnCell Central Manager on the internet (public IP or behind a firewall) anywhere in the world, the Host computer can initiate a connection to an OnCell device with a private IP.
91OnCell Central Basic Idea Host and OnCell both make connection with OnCell Central ServerOnCell Central Server assigns designated ports for Host to connect to Serial and/or Ethernet devices attached to OnCellOnCell Central Manager allows Host to monitor the connection status of OnCell and devicesHow the OnCell Central works is the host and the OnCell both makes a connection to the OnCell Central Server and the server bridges the connections together. The OnCell central Server will assign designated ports for the host to connect to access the OnCell. As an added value, the OnCell Central Manager is also a useful manage utility to allow the user to monitor the status of the OnCells on the field at the same time.
92Install OnCell Central Manager Select Network Connection Interface OnCell Central ServerInstall OnCell Central ManagerSelect Network Connection InterfaceSet Control PortsThe OnCell Central Manager is easy to install. Just simply run the .exe file and follow the on screen instructions. To start, select a Network connection interface and set the port range you want to connect from the host and click startup.Set User PortsSTARTUP
93OnCell Device Configuration Enable OnCell Central ServerSet Ethernet DeviceOn the OnCell device itself, all you need to do is enabled the OnCell Central Server function, enter the server IP and if you are connecting to an Ethernet device, you need to setup service forwarding to forward the connection to each Ethernet devices behind it.Set Device Settings
94Solution: Public IP Private IP Private IP OnCell Central Server Device ManagerPrivate IPPublic IP address + Port #TCP ServerOnCell CentralServerPrivate IPEthernet DeviceFrom the stand point of the Host PC, all the remote devices on the field whether Ethernet or Serial devices can be accessed by a single public IP address (OnCell Central Server) and the corresponding port #.Serial DeviceOnCell DeviceTCP ClientDeviceEthernetHostSerial
95Connection and management of remote devices Standard TCP/IP socket connectionCompatibility with application softwareThe OnCell Central uses standard TCP/IP socket connection which is compatible with an any software application that support such basic connection method.
96OnCell Series Killer Functions Routing Function The OnCell G3100 series is now upgraded to be an IP gateway instead of just an IP modem. This is because we added the routing functions.
97LAN routed to InternetEthernet data can be transferred transparently via cellular network to establish remote control of Ethernet devicesA cellular IP gateway allows Ethernet device to access the internet. The Ethernet device simply needs to set the gateway to the LAN IP of the OnCell statically or through DHCP, then the Ethernet device can access the internet through the OnCell.Connection to the internet
98NAT Routing FunctionNAT function allows LAN data to be routed onto the public WAN portOnCell G3100 has NAT automatically enabledOnCell 5004 has NAT manually enabledThe LAN to cellular connection is enabled by the implementation of the NAT function. NAT (network address translation) allows the data to be routed from a LAN network to a public WAN network. It is automatically enabled in the OnCell G3100 series, and can be manually enabled in the OnCell 5004 series.Confidential
99Virtual Server ModeA virtual server device acts as a server device on the public domainThe virtual server device port forwards data to the actual physical serverNot only does the OnCell allow Ethernet device to access other devices on the internet, devices on the internet can also access the Ethernet device behind the OnCell. This is accomplished by OnCell being a virtual server for client devices on the internet to connect to it while forwarding the connection to the Ethernet device behind it. You can understand it as port forwarding.Connection from the internet
100OnCell’s Virtual Server Mode 234561Here is an example of how to setup a virtual server in a OnCell unit. As a general note, Virtual Server is useful when the OnCell gets a public WAN IP address from the cellular provider. If the OnCell have a private address, you’ll have to use the service forwarding function of the OnCell Central Server to establish your connection.7Click System Management Misc. Network Settings Virtual Server SettingsSelect TCPEnter TCP Client’s (Host) Dest. Port.Enter TCP Server’s (Ethernet Device) LAN IPEnter TCP Server’s (Ethernet Device) Local Port6. Check Enable7. Click Submit
101OnCell 5004 supports static routing Lastly, the OnCell 5004 which is a cellular router supports static routing as you can configure the static routing table as you see here.
102Thank you for joining MTSC 2009! Thank you for your time. See you at MTSC 2009.