4.5 mile wifi link

Discussion in 'General Discussion' started by jayhawksigns, Jul 14, 2007.

  1. jayhawksigns

    jayhawksigns LI Guru Member

    I am typing on our "proof of concept" for running a 4.5 mile wifi link from my office to my new house in the country. I am currently using 2 Linksys WRT54GL routers running Tomato, running through 24db gain grid antennas.

    When we actually install the antennas permanently, we will of course spend more time getting the pointed as accurately as possible, but through the link I only am able to get half of our shops bandwidth through the connection. We can pull 1.8Mb at our office, but I only get .8Mb at the house. Power is set at 75% maximum for the routers. I didn't know if someone had a suggestion for another router to use, or if I should switch over the a N spec router when we actually set the connection up. The WRT54GL are our local office wifi units.

    I didn't know if the Bountiful router would be something to look into, I know we will need two antennas at each end, but I want all the speed I can get because I am also going to be running a PVR at my office that will transfer files to a server at my house after they are recorded.

    Thanks for your input.
  2. ifican

    ifican Network Guru Member

    Wow impressive, this is the longest i have of yet. I would'nt know what to expect throughput wise but i would expect some induced delay and therefore suppressed bandwidth. I believe you are most likely running the routers in WDS mode which is going to also slow the link speed slightly.

    Part of me wonders if you took the time to get as direct line of sight as possible if the signal strength wouldnt increase a little also bringing up the throughput a tad.
  3. jayhawksigns

    jayhawksigns LI Guru Member

    Yeah, it was using a WDS link. Surprisingly, the latency was not that much longer then what I get in the office testing through dslreports.com.

    I am open to other suggestions, is there a better setup (i.e. WDS) to use for this?

  4. ifican

    ifican Network Guru Member

    Well a couple things to try is setting up the router at your home as a client of the first, depending on what you are trying to setup you could use the router at home as a router instead of a gateway. Suppose you could also set it up as an extended wireless network. I would play with these other options to see if you get better throughput.
  5. Toxic

    Toxic Administrator Staff Member

    I know there used to be some CLI command for long WDS links used in Sveasoft firmware. I dont know if they would be compatible with tomato firmware. unfortunately I cannot remember the CLI command for it. I take it you have set the router to G only or B only when in WDS and not mixed mode?
  6. jayhawksigns

    jayhawksigns LI Guru Member

    That is correct, had it on G. The one thing I didn't try was different channels.
  7. HennieM

    HennieM Network Guru Member

    To link up with Toxic - some WISPs in our valley reckon that at link speeds of less than 11Mb, B gives better range/speed than G becaus of the different coding. I dunno if that is true, but perhaps worth a try.

    Also, as ifican suggested, a client/AP setup should provide better throughput than WDS.

    Another thing, although this perhaps has a very minor effect, is to use the lowest channel possible, i.e. channel 1. If you have obstacles that could possibly be in the way of your signal, the lower the frequency, the lower the signal loss.
  8. jayhawksigns

    jayhawksigns LI Guru Member

    I read something comparing the different types of setups (i.e. client/AP, WDS, etc) and it told what kind of bandwidth penalties that each incurred. I need to find that article/post again.

    The current .8Mb/s connection I was able to get is slow compared to the 6Mb/s I have presently at home, but its better then dial-up by a long shot. I will be doing some more testing before we actually get the tower up and such and test some of these suggestions first.

    I thought that there was a Buffalo AP/router that ran the tomato firmware that had a higher power output, and as of right now those will probably be the radios I get initially to make the connection.
  9. jayhawksigns

    jayhawksigns LI Guru Member

    This was the post I saw before. The bold part is why I tested only with WDS on Sunday.

    Courtesy of GeeTek

    I just tested every mode and combination. Conclusion - Tomato REALLY ROCKS !! This post may be a bit long. I have some good data that may be useful in deciding which mode is best for what you want to do. My primary interests were bandwidth and client connectivity in the various modes. My test setup was with 2 computers and 2 radios with Tomato 1.01.

    Test 1 ; PC1 connected to Radio1 by LAN port. Radio1 Mode = AP. PC2 connected to R2. R2 mode = Wireless Client, same SSID as R1. Results = Radio of R2 becomes WAN. WAN needs to be in same subnet of R1. R2 LAN is natted into a different subnet, providing 254 addresses to be used by multiple LAN devices. R2 provides no wireless connectivity. PC2 to PC1 bandwidth loops at 24 Mb using Ixia Q-Check.

    Test 2 ; Change R2 mode to Wireless Ethernet Bridge. WAN becomes disabled. LAN ports transparently bridged to R1 LAN ports. R2 Supports multiple computers. PC to PC BW loops at 28.5 Mb. R2 LAN IP can be on any subnet.

    Test 3 ; Changed mode of R1 and R2 to WDS using each other's MAC in the WDS table. No SSID is transmitted by either radio. No wireless client connectivity. PC to PC BW loops 29.5 Mb. This mode would best be suited for a dedicated point to point bridge. If using Lazy WDS mode, only 1 radio can be set for Lazy. (Both Lazy = no connection after 45 seconds. May need more verification).

    Test 4 ; R1 = AP+WDS with R2 MAC in table. R2 = WDS with R1 MAC. R1 supports wireless client. Wireless client (PC2) BW loop to PC1 28 Mb. R2 no SSID xmit, no wireless client connectivity. PC2 connected to LAN of R2 BW loop to PC1 = 28.5 Mb.

    Test 5 ; R1 and R2 set for AP+WDS. Both WDS tables have MAC of other radio. R2 is different SSID. Both radios transmit their own SSID and support wireless clients. PC2 connected to R2 LAN BW loop to PC1 = 28 Mb. Wireless client connected to R1 BW loop to PC1 = 28 Mb. Wireless client connected to R2 BW loop to PC1 = 14 Mb. There is the WDS "Half Bandwidth". In this configuration I changed R1 LAN connection to the internet switch. My online download speeds while using a wireless connection to R2 via WDS to R1 were EXACTLY the same as I get from R1 and from a hard line connection to the internet switch. WDS wireless repeating reduces BANDWIDTH by 50%. It does NOT cut the browser or download speed in half as some may think. As long as my internet download / browser speed does not exceed the available 14 Mb, there is no slowing of internet service.
  10. HennieM

    HennieM Network Guru Member

    I think that might be spot on, as with WDS only and no AP, there's no incoming wireless client traffic that needs to be retransmitted through the same radio. You could perhaps still play with encryption schemes, or maybe drop encryption totally. With WDS only, other people could sniff your traffic, but with internet traffic which goes into the maze that might not matter. Actually using your link would be slightly difficult for the average war driver.
  11. GeeTek

    GeeTek Guest

    The bandwidth problem is likely due to ACK timing. As of Tomato 1.07, there is an ACK adjustment field. I coincidentally have a 4.5 mile link with 24 grids and buffalo HP radios. In G mode WDS PtP and ACK set for 6600 meters, I am getting 24 Mbps throughput with the radio carrier locked at 48 Mbps air rate. Frame bursting gives a 15% boost in throughput. Your model of radio does not have as much power or RX sensativity as the Buffalo HP. The RSSI will determine how much bandwidth you are limited to. -70 dB should get you 6 or 8 Mbps.

    Edit -Spelling, and my link is only 4.2 or 4.3 miles. You may need to go with 6700 or 6750 on your ACK.
  12. jayhawksigns

    jayhawksigns LI Guru Member

    GeeTek - Thanks for doing the previous testing I linked to, and for this reply. I will add those settings to my list of things to test.

    What model of Buffalo radio are you using exactly? They may be the ones I was planning on using anyway.

    And if you could, get a screen capture of the advanced wireless settings.
  13. GeeTek

    GeeTek Guest

    The Buffalo model is WHR-HP-G54 and has extra amplifier stages for TX and for RX that make it ideal for long range. I compressed the screen shot quite a bit so it would upload here. ACK is set to 6600. Both radios in the link are programmed the same.

    Attached Files:

    • ack.jpg
      File size:
      74.3 KB
  14. jayhawksigns

    jayhawksigns LI Guru Member


    So do the G54s put out only 10mW, or is that before the extra amp stage?
  15. GeeTek

    GeeTek Guest

    That is before the extra amp stage. It puts out approx. 200 mW at the 10 mW setting. 25 mW setting is about 500 mW output from my best guestimation as compared to the signal of external half watt amps.

    There is another model of Buffalo router which is the whr-g54s that does not have the extra amplification. The whr-hp-g54 is the amped one. Just wanted you to be sure you knew the difference if you are going to order some.
  16. jayhawksigns

    jayhawksigns LI Guru Member

    Thanks, the Buffalo website doesn't really say.

    Just need to check on the antenna connector on the Buffalo units and see about getting two on order. I doubt that I would be lucky enough for them to use RP-TNCs like the Linksys units.
  17. GeeTek

    GeeTek Guest

  18. leenar

    leenar LI Guru Member

    Have you tried connecting to the WRT54G through ethernet to see if this speeds up your connection or are you wireless on one end of your line?

    WRT54G series are designed to be used with matched antennas connected to both ports. Diversity operation does not like different gain antennas connected to the same unit. You'll run into the same problem even with exact same antennas if they are separated.

    I'm running a similar setup between my home and my office. I get only 300-400 kbps. After I put this together I'm getting 2.5 mbps.
  19. jayhawksigns

    jayhawksigns LI Guru Member

    Yeah, I was connecting to the WRT54GL through an ethernet line during the test.

    The plan is to bridge two Linksys SRW switches so I can get gigabit and VLAN capabilities for each end of the connection. So everything at the remote end of the connection will connect to a SRW switch, either through a wired link, or another AP that I get just for local traffic.

    Network Setup

    Oh, and look at Newegg, IMHO the screwed up their site. At least when I tried to browse looking for the Buffalo router, then old table display format is gone.
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