The neighborhood Mesh Network

Wireless IP Ethernet (802.11) technology has been around for a while.  Many know it as “WIFI” but you could also call it “WLAN” or something similar.  Like many other Ethernet technologies, WLAN relies on a spoke and hub connection system.  The hub being the wireless access point or router and the individual hosts (PC’s, tables, phones, etc) being the end point for each connection.  In a wired network, it is usually some type of switch that forms the center of the network data distribution system.

With a wireless mesh network or ad hoc network (802.11s), each wireless device can connect to any other wireless device within range.  In this type of peer to peer network, there is no central access point, although something can act as an internet gateway or there can be several gateways.    This type of topology functions much like the public network (AKA the internet), where there are many different paths to any one (major) destination.  If any one of those paths goes down, another route is quickly found.

This technology was developed by several vendors for military communications systems and for OLPC (One Laptop Per Child) programs in Africa and other places.    Each link acts to extend the boundaries of the network, thus the more users there are, the more useful the network becomes.

Wireless Mesh Network diagram
Wireless Mesh Network diagram

Advantages of mesh networking:

  • Networks are self forming; once the nodes are configured and can see other network nodes, the the network automatically forms
  • Networks are self healing; if one node drops off line, traffic is automatically routed to other nodes.  If the node comes back up, it is included back into the network
  • High fault tolerance; in areas where many nodes exist and can see each other, the failure of any single node does not effect the rest of the network
  • Low cost to deploy; mesh networks use standard off the shelf WLAN (802.11) devices.  Choice of software will dictate which hardware will work the best
  • Crowd sourced infrastructure; as each network node is owned by an individual, the cost and responsibility is shared among the community

Several specific routing protocols have been developed for the network side of the system.  Hazy Sighted Link State Routing Protocol (HSLS), BATMAN, OLSR  HWMP and others. These work well with the existing 802.11 a/b/g wireless network hardware currently available.

On the host side, a good IBSS capable wireless network adapter is needed, which many of the newer ones are.  Several of the software programs have lists of WLAN adapters that work with their software.  Open Garden is a free App for Windows, Mac OSX, Android, and they are working on an iOS version.  This leaves out certain devices like tablets and iPhones for now.

Since existing wireless adapter drivers do not yet support mesh networking, usually an additional piece of software is needed.  There are several interesting ones, including HSMM-MESH, which was developed by Amateur Radio operators.  Open source programs for Linux, Free BSD and other are available as well as commercial versions for Windows.

I was thinking that this might be useful for broadcast applications.  For obvious reasons, this type of system would work best in densely populated urban and suburban areas, which is exactly the type of area that LPFM licenses might be hard to come by.  For those who do not have the time or wherewithal to apply for an LPFM license, or for those that simply don’t get a license due to scarcity of available channels, this could be a great way to cover a neighborhood or section of a city.  The more people that participate in the mesh network, the stronger the network becomes.  Additionally, by using FCC type accepted part 15 FM and AM transmitters as broadcast nodes, carrier current transmitters and leaky coax systems, the presence of the mesh network can be advertized to potential listeners, including directions on how to take part.

Wireless mesh network example
Wireless mesh network example, courtesy of Meraka Institute

Wireless LAN bridges or broadband internet connections can act as a backbone between distant nodes.

For bandwidth efficiency sake, AOIP services should be limited to multicast addresses.

A good site with more wireless mesh network information is

Two sub-reddits on the subject: /r/meshnet and /r/darknetplan

Then there is project meshnet and the project meshnet wiki

Oh, by the way, go ahead and ask me what I have been learning about in school these days…

Cost of Starting a LPFM vs Cost of Internet Streaming

I have been watching the LPFM proceedings with some interest. The FCC has not exactly promised to have a filing window by end of 2012, but indicates that it might try to do that. In comparison to such evolutions in the past, this is moving pretty fast. Those that want an LPFM station need to start planing now.  As in previous LPFM windows, the availability is for non-profit organizations only.  This does not mean all hope is lost; NPR stations are all non-profits and most of them are very successful.

One of the biggest questions is: How much will it cost?  Like all things, it varies greatly.  If I were to put an LPFM or internet radio station on the air, there would be certain minimums, such as the use of professional audio equipment, a new antenna, and some type of redundancy.

Generally speaking, radio stations and internet stations both need some type of office/studio space.  This can range from large and opulent to a closet.  The costs for these would depend on the type and quantity of equipment installed, whether the equipment is new or used, the building, the area, etc.  Those facilities also have monthly reoccurring costs such as rent, electric, telephone service, internet service, etc.

Since internet radio stations and traditional terrestrial over the air radio would use the same type of studio equipment, those costs will be similar.  Here is a breakdown of the studio equipment:

Nomenclature Cost new (USD) Cost used (USD) Comments
12 Channel professional audio console $6,000.00 $2,500.00 Analog, 4 buss, telephone mix minus
Studio Furniture $5,500.00 $1,000.00 Can also be fabricated locally
Microphones, RE-20 or SM-7B $250-350 $100-150 Per unit, several required
Monitor Amp $250.00 $100.00 Can also use consumer version
Monitor speakers $500.00 $200.00 Can also use consumer version
CD Player $500.00 $200.00 Professional unit with balanced outs
Computer w/ professional sound card $1,500.00 $500.00 For automation and sound file storage
Computer, general use $700.00 $300.00 General information web browsing
Computer, Streaming w/sound card $900.00 $400.00 Sound card should be good quality
Studio Telephone system $1,900.00 $300.00 Used for call in/on air
Barix remote box $240.00 (x2) N/A Used for IP remote broadcasts
Comrex Matrix POTS codec $3,200.00 $700.00 Used for telephone line remote broadcasts
Misc wiring, hardware, ect $1,000.00 $800.00 Connectors, mic booms, wire, etc
Total $21,780.00 $7,930.00

Some equipment is not available used such as Barix boxes.  Of course, not all of this is required for a radio station, however, most local radio stations would want the capability to do remote broadcasts, take phone callers on the air, have multiple guests in the studio, etc.

For a traditional LPFM station, the transmitting equipment would entail:

Nomenclature Cost New (USD) Cost Used (USD) Comments
300 watt transmitter and exciter 4,400.00 2,000.00 Smaller transmitters with higher gain antennas can also be used
2 Bay ½ wave spaced antenna $1,900.00 $700.00
125 feet ½ inch coax $350.00 N/A
100 foot guyed tower and installation $4,000.00 $3,500.00 Not needed if station is on tall building or leased site
STL; IP radio w/ barix boxes $850.00 In lieu of standard 950 MHz STL
STL standard 950 MHZ $6,500.00 $3,500.00  Used in lieu of IP STL
STL antennas, transmission line $2,500.00 $1,500.00
FM Processor $10,000.00 $1,200.00 Can also use software such as Breakaway Broadcast
Misc connectors, grounding kits, etc $1,100.00 N/A
EAS unit $1,900.00 N/A Fully operational CAP compliant
Processing software, Breakway broadcast $200.00 N/A In lieu of standard FM processor
Total $12-24K $8-12K

This is a generic station, most will be somewhat different due to antenna supporting structures, transmitter powers and antenna types.  For the best possible signal, a circularly polarized antenna should be used.  A two bay, 1/2 wave spaced antenna will give the maximum signal density, while minimizing downward and upward radiation.  The upward radiation is simply wasted energy, as no one in space is listening to FM radio.  The downward radiation reduction is key if located in congested areas.

For internet radio station, the following would be required:

Nomenclature Cost New IUSD) Cost Used (USD) Comments
Streaming Server 2,100.00 1,100.00 Includes professional sound card
Audio processing software 200.00 N/A Recommend software such as Breakaway Broadcast
Audio Processing, outboard hardware 650.00 400.00 In lieu of software
Audio Streaming aggregator  1,200 to 2,400 N/A Annually

While LPFM’s are much more expensive than internet only stations, LPFM’s have the advantage of built in marketing, which is the on air signal.  If it is broadcasting on the air, word will get out.  On the internet, some other type of marketing will be needed to spread the word.  Also, LPFM’s should also be streaming, which would incur the same costs above.

The long and short of it is, to put a technically viable LPFM on the air is not an inexpensive proposition.  It is worth the effort, however, because the advantages of an LPFM over an internet only station are great.

All those servers do not run cheaply

Rack Mounted servers in data center
Rack Mounted servers in data center

As Google can verify.  According to the NYT piece: Google Details Electricity Usage, Google said its operations draw approximately 260 million watts continuously to run their online services and office buildings.  That figure  includes all of the e-mail applications, Youtube videos, Google searches, Google documents, etc.  That works out to be about 6.24 million KWh per day or 21,292,752,000 BTU per day.  Here are some of the amounts and costs for other fuels:

Fuel Unit Amount Average cost $ Cost per day
Electricity KWh 6,240,000 0.05 312,000
Gasoline Gallon 185,963 3.61 671,326
Diesel Gallon 170,342 4.05 689.885
Coal Ton 819 156.40 128,091
Natural Gas CCF 211,868 2.335 494,712
Propane Gallon 231,443 3.02 698,957

Those figures do not take into account the efficiency of the generation process.  For example, the average coal fired power plant is 32% efficient, thus the actual tonnage of coal needed to produce 6.24 million KWh is 1,376 at a cost of $215,194.  Other fuels have similar electrical conversion efficiency, with the internal combustion engine being about 19% efficiency for any given fuel.

Some other interesting tidbits from the article:

  • Each Google search uses about 0.3 Watt-hours of electric
  • The average user uses 180 Watt-hours per month
  • Approximately 12.5 million Watts or 30,000 KWh per day are used by search engine traffic
  • 25% of Google’s energy is supplied from renewables
  • Google designs and builds it’s own data centers using energy efficient technology

One can assume that other data centers are not as efficient as Google’s.  It would be interesting to do a comparison between the electrical use by AM and FM broadcast transmitter sites and the energy used by data centers that stream radio content.  Right now the data center’s electrical costs are still relatively low because over the air radio listenership far out strips on line listenership.  Eventually, those numbers will flip and I’d think the increased costs associated with greater streaming will be paid by somebody, likely the content generator.

All those webstreams, videos, search engine queries are not free.