Glen Popiel KW5GP. High Speed Microwave Networking For Amateur Radio

Transcription

1 Glen Popiel KW5GP High Speed Microwave Networking For Amateur Radio KW5GP 7/12/2016

2 What is High Speed Microwave Networking? Hams have frequency allocations in the 900MHz, 1.2 GHz, 2.4GHz, 3.4 GHz, and 5GHz bands that are being used to set up high speed amateur radio wireless networks Interestingly enough, some of these allocations include portions of the commercial WiFi bands And the really cool part is that we can run the full legal amateur power limits in these bands

3 2.4 and 5GHz Band Allocations

4 Why High Speed Microwave Networks? At frequencies below 900MHz, hams are severely limited in terms of data rates At 900MHz and above, there is no data speed limit, allowing hams to create high speed data networks Using the TCP/IP protocol, these networks can do just about anything you can do with the regular Internet You can even link your amateur radio network to the public Internet as long as you remain compliant with FCC Part 97 rules

5 Part 15 versus Part 97 FCC Rules Standard off-the-shelf commercial WiFi devices operate under Part 15 of the FCC rules that govern unlicensed radio devices Typically, Part 15 devices have very short range and are limited to 1W of output power Part 97 of the FCC rules govern amateur radio. In the microwave bands (in most cases) Part 97 rules allow up to 1500W PEP of output power Since b is classified by the FCC as a Spread- Spectrum Transmission, power output is limited to 10W PEP

6 Operating Under Part 97 Rules To use a device designed for Part 15 under Part 97, all you have to do is follow the usual FCC rules for amateur radio Identify every 10 minutes No business use No encrypted data No music, pornography, etc. You can use a commercial WiFi device out of the box under Part 97 rules without making any modifications As long as you operate in the amateur radio portion of the WiFi band and follow Part 97 rules You can use WEP/WPA encryption, however you must make the encryption keys publicly available

7 A Word on Wireless Encryption FCC Part 97 rules state that you cannot encrypt data for the purpose of obscuring the meaning of any communication Encoding a signal, such as DSTAR or using a Voice-over-IP codec is not considered encryption. Codecs are simply standard methods of encoding data and are not intended to obscure the meaning of the data Theoretically, you can use the standard wireless WPA and WEP encryption methods as long as you make the keys public. But if the keys are public, what s the point? This is a concern because amateur radio wireless networks often overlap in frequency with standard Part 15 WiFi devices and Part 97 rules require that we prevent unauthorized use

8 There Is A Better Way While we can use an unmodified Part 15 WiFi device to build an amateur radio microwave network, several development groups have developed firmware for these devices exclusively for the purpose of creating amateur radio microwave networks. Broadband-Hamnet (BBHN) and the Amateur Radio Emergency Data Network (AREDN) have developed firmware for the Linksys WRT54G and Ubiquiti wireless routers to create a Mesh network topology This is why the microwave networking technology is often (and not always correctly) referred to as Mesh Networking HamWAN uses MikroTik wireless routers to create a Star or Hub and Spoke network topology. This topology is similar in many ways to the public Internet

9 Network Topologies Currently, there are two types of network topologies used in amateur radio microwave networks The Mesh topology, also referred to as an Ad-hoc network, links all the user, or client nodes together and can relay data through any node, similar to Packet Radio Used by the BBHN and AREDN technology In the Star, or Hub and Spoke topology, all client nodes communicate only with a central node, also known as a cell site. The cell sites relay data between other cell sites and the client nodes Used by the HamWAN technology

10 Mesh Topology

11 Star Topology

12 Which Is Better? Both and neither - Each has their own pros and cons BBHN/AREDN is easier to set up and use, however, data rates are typically limited to 54 Megabits per second (Mbps) Uses inexpensive and readily available Linksys and Ubiquiti gear Subject to hidden node issues Often uses the portions of the bands that are shared with Part 15 WiFi devices and are subject to interference from these devices Can relay data through any node it can hear HamWAN is a more traditional network design Allows for higher data rates, currently up to 300 Mbps Not subject to the hidden node issue Typically operates in the non-part 15 portion of the bands and is not subject to interference from Part 15 devices Cell sites can be a Single Point of Failure. If a cell site is down, all users in that cell site s coverage area are offline

13 What Equipment Do I Need? Because many of the amateur microwave bands overlap the commercial WiFi bands, hams are using repurposed WiFi gear such as the Linksys WRT54G, Ubiquiti, and MikroTik wireless routers Several ham development groups have written firmware for these devices that replace the original operating system and convert the device for Part 97 ham use The Linksys and Ubiquiti devices are used to create the Mesh version of ham microwave networks The MikroTik wireless router does not require any firmware modification and is used in HamWAN implementations

14 The Linksys WRT54G

15 The Linksys WRT54G

16 The Ubiquiti M5

17 MikroTik Metal 5SHPN Wireless Router

18 Antennas Antennas for amateur radio microwave networks are small, often no larger than a typical satellite television dish antenna While omnidirectional antennas can be used, most nodes use wire mesh barbeque grill antennas with a typical gain of 24 to 31db The exception is a HamWAN cell site, which typically uses three 120 degree sector antennas to provide omnidirectional coverage At microwave frequencies, feedline loss is a major concern. Most of the devices we use are mounted next to, or part of, the antenna to keep feedline length to a minimum These devices are powered using Power-over-Ethernet (PoE) on the standard CAT5/6 data cable used to connect to the device

19 HamWAN Client Node

20 HamWAN Cell Site

21 Feedline Loss Feedline loss at microwave frequencies is a major issue Remember, power is cut in half for every 3db of loss At 2.4 GHz RG-58 has a loss of 32db per 100 feet, LMR400 has a loss of 6.8db per 100 feet and 3/8 heliax has a loss of 5.9db per 100 feet At 5GHz, RG-58 has a loss of 51db/100 feet, LMR400 has a loss of 10.8db/100 feet, and ½ heliax has a loss of 6.6db per 100 feet. The moral of the story is to keep your feedline as short as possible This makes things a little tricky if you re planning on using the Linksys WRT54G

22 Installing the WRT54G Outdoors The Linksys WRT54G used in the BBHN mesh network is designed to be used indoors This poses an issue when we need to connect it to an outside antenna The best solution is to install the WRT54G in an outdoor box and power it using PoE This allows you to use a very short length of coax to connect the antenna

23 WRT54G Outdoor Installation

24 WRT54G Outdoor Installation

25 Why Build A Network? We already have the public Internet, why do we need another network? In a disaster, often the primary means of communications fail as happened with Hurricane Katrina An amateur radio microwave network is ideally suited for portable operation with minimal setup required Nodes can be powered by solar or other alternative means for extended periods of time Can provide data communications, including links to the Internet, allowing the transmission of data and video outside the disaster area

26 Fuel For The Road Amateur radio wireless networks, just like the public Internet, use the Transmission Control Protocol/Internet Protocol (TCP/IP) to send data Every device on the network has an IP address, such as The IP address is actually 32 bit number, that in combination with the subnet mask is used to uniquely identify each device on the network Although I am sure we ll see IP version 6 at some point in the future, today s amateur microwave networks use IP version 4 IPv4 has 4.2 billion possible addresses IPv6 has 340 undecillion (340 trillion trillion trillion) addresses Discussing and understanding TCP/IP is a whole other critter that we don t have time to cover in a single session. For now, all you need to know is that every device on your amateur radio network uses TCP/IP

27 AMPRNet The available public IP address space for IPv4 was exhausted in February of 2011, meaning there are no new IPv4 address blocks available In order to access your network from the public Internet, you need public IP addresses Fortunately for hams, an entire Class A (16.7 million) block of IPv4 addresses was reserved for amateur use by Dr. Hank Magnuski, KA6M The entire /8 block is managed by the Amateur Radio Packet Network (AMPRNet) Hams can get their own sub-block of public IP addresses for ham use through AMPRNet at

28 So What Can I Do? Amateur radio microwave networks are very similar to the public Internet. In fact, you can even link your network to the public Internet, as long as you maintain compliance with Part 97 rules It is up to you and others on your network to build and set up the applications for your network You can set up applications such as web servers, voice-over- IP (VoIP) phone systems, and messaging (chat) servers You can even create your own miniature version of YouTube for sharing videos and photos

29 Voice Over IP (VoIP) Many hams already use VoIP without even knowing it AllStar and EchoLink are examples of VoIP applications hams already use You could set up your own VoIP system on your network You can use both IP phones and softphone apps on PCs and handheld devices to provide reliable backup communication services between agencies in a disaster VoIP software is free and used IP phones are readily available

30 A Typical VoIP Phone

31 VoIP Softphone App

32 Instant Messaging Instant Messaging allows for text chat, video, image and file transfers HamChat runs directly on the BBHN/AREDN Linksys/Ubiquiti implementation Text only with a single chat area for all users OpenFire is an open source messaging application that allows for chat and file transfer, including screen shots. TeamSpeak allows multiple chat and conference areas, allowing you to create independent chat rooms for each agency in a disaster

33 TeamSpeak Messaging App

34 Web and File Servers Since everything on the network is TCP/IP-based, you can set up Web, File Transfer (FTP), and Application servers ClearOS is a free open source Linux distribution that allows you to quickly and easily set up Web, File, and application servers ClipBucket is a free open source YouTube-style server that allows you to share videos and images on your network

35 ClipBucket

36 The Raspberry Pi The Raspberry Pi is a small single board computer that runs the Linux Operating System With its low power requirements, the Raspberry Pi is ideally suited to serve as a portable application server for an amateur radio microwave network Since the Raspberry Pi runs Linux, there are thousands of applications available to choose from

37 The Raspberry Pi

38 Maintaining Part 97 Compliance While the transmitting station is ultimately the one responsible for ensuring they remain compliant with FCC Part 97 rules, it is incumbent for everyone to do what they can to help maintain Part 97 compliance The no encryption part of the rules means that we can t run any encrypted traffic such as Secure Shell (SSH) or HTTPS The ClearOS Linux distribution includes a Firewall and Content Filter to allow us to control and manage the traffic we allow between our amateur radio networks and the public Internet

39 Deploying The Network Once you decide which network technology you will use, you should map out the terrain and paths between your planned nodes to ensure that they will be usable RF Path Profile tools such as SPLAT!, Ubiquiti Link Calculator, and Radio Mobile Online can be used to graph the path and terrain to ensure the link is viable You will want the path to be clear to at least 60% of the first Fresnel Zone to ensure a good path

40 Fresnel Zones Pronounced Fray-nel As the microwave signal travels along the intended path, the signal broadens until it begins to be reflected by obstacles in the path and the terrain itself If the reflected path is one-half of the wavelength, the out-of-phase reflected signal will work to cancel out the direct signal. If the reflected path is less than a half-wavelength, it actually adds to the direct signal, improving the overall signal strength These points of reflected signals create what is known as a Fresnel zone, and can be used to calculate the overall signal strength of the projected RF path

41 The Ubiquiti Link Calculator

42 Radio Mobile Online

43 My Latest Book My latest ARRL book, High Speed Multimedia for Amateur Radio is now available through the ARRL store ( This book covers all aspects of setting up and using amateur radio microwave networks It has a complete chapter on the dreaded TCP/IP monster, including addressing, subnetting, routing, and other TCP/IP features Covers Broadband-Hamnet, AREDN, and HamWAN networks

44 High Speed Multimedia for Amateur Radio

45 Thank You Questions? Just remember I reserve the right to make up an answer