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  • Clear 4G Service outside the coverage area

    I have Clear 4G Service and my house is technically outside the coverage area. The USB modem on my laptop detects the signal (outside my house about 50ft), giving me the opportunity to "connect", which subsequently fails while "acquiring the network". I imagine this suggests the signal is too weak to complete whatever health checks it is doing. Would using an external antenna + amp + Clear Series M CPE Modem work better? If I need to mount this stuff 50ft from my house, do I locate the modem + wireless router in an outdoor enclosure, or can I cable the antenna/amp to a modem in the house?


    What should I order (part #'s, etc) from your site to make this work?

  • #2
    First thing we have to do is verify that your signal is strong enough to be boostable (i.e above the noise floor). If you get a chance measure the received signal strength as reported by the modem outside the house. Based on this we can determine if adding a high gain directional antenna can solve your problem.

    The most powerful practical USB modem antenna kit is here: http://www.rfwel.com/shop/4G-USB-Mod...tenna-Kit.html

    Do you know how far you are from a Clear tower? If you are too far you would have other connection issues even when your signal is acceptable mainly related to network timeouts since it takes a finite amount of time to for your modem to acknowledge data transmission from the tower. These antennas are typically not intended for extending coverage outside official coverage zones.
    Last edited by thuor; 05-07-2012, 10:27 PM.
    KF7RCQ

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    • #3
      The Clear connection manager software claims anywhere from half to full signal using my laptop + USB modem connected, but then fails to connect. Basically, I press the “Connect” button but then after several seconds messages “Acquiring Networks” (or whatever) and eventually fails back to asking if I want to connect. The modem itself never does any green blinking like it does when I’m firmly in a coverage area.

      re: tower distance
      Not sure – I would guess as much as 4-5 miles away. I can actually connect with my USB modem while driving in my car about 1.5 miles from my house (my house is 400ft higher in elevation on a mountain-side, more or less facing the tower).

      I’m happy to try some stuff at home. What’s the best solution for a fixed modem like the Clear Series M CPE Modem? Should I locate my modem near the antenna (e.g., in an outdoor enclosure), or can it be as much as 100ft of cable away?

      Comment


      • #4
        If you are getting half-to-full signal (i.e better than about -90dBm of received signal strength) and you are unable to connect then there’s something else going on which might have to do with either interference or just range from tower. Please check with what Clear support has to say about this. Now 5-6miles is somewhat within the range of Clear wimax network. What is your CINR reading?

        The CPE modems without external antenna ports are not too amenable to attaching external antennas. For some like the Series-G Modem (Gemtek WIXB-175) we do have a U.FL pigtail that can be attached after detaching the integrated antenna connected to the PCB - NOTE however that this pigtail is NOT designed for frequent removal and re-attachment.

        You can try to locate it outdoors. Although this beats the purpose of a CPE modem we do have customers who have successfully done this. CAT5 cable will go as much as 100m (330ft) without a repeater. What others have done is use a Point-to-Point radio to link the CPE modem to their indoor network (something like this: http://www.rfwel.com/support/tech-dr...x_Backhaul.pdf where the wimax router or the wimax CPE modem is in an outdoor enclosure such as: http://www.rfwel.com/shop/home.php?cat=187)

        If you do go with the USB antenna kit option we recommend keeping the coaxial cable length as short as possible. 100ft is too far. This is so as to minimize losses through the cable which would defeat the purpose of the high gain antenna. For LMR-400 cable with a 2.6GHz signal the loss is 6.9dB/100ft.
        KF7RCQ

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        • #5
          Clear 4G base station problems

          Dear Thuor,

          I have been a Sprint 4G customer for a year and a half now. Their WEB site predicted good indoor reception at my address, however it took a long time to find a location inside my house that provided any signal lights on the Motorola desktop (CPE) modem Sprint provided. The one spot produced two, sometimes three lights and signal strength was in the range of -83 to -88 dBm with CNRs in the range of 9 to 1 dB. Data rates were poor - no better then HS DSL, but I had a falling out with my local phone company and won't be dealing with them - so there was no turning back.

          That was in January of 2011. By March, i was seeing significant amounts of time (up to hours) when the modem would be scanning. As the months slid by, the outages became longer and more frequent. I'm sure some of this was that trees leafed out, but then warm days seemed to be worse. This continued until about November, and then the situation went back to whatnot saw in the beginning - generally three lights and sometimes four and with only very infrequent outages. It is now May 2012 and I am back to seeing the same problems as last year.

          Now their are two clear sites nearby, the closest (not providing my signal) is .6 miles and the one I connect to is ~ .8 miles. I have taken my modem and sometimes the notebook too and stuck them in my car for a drive. I have taken them to within 700 feet of the tower that provides my signal. If the signal was gone at home, I might see three lights near the tower and signals about what I see at home with three lights. If I have three lights at home, I have five lights by the tower with signals of - 65 dBm, CNRs of 25 dB or better and download rates of > 12 Kbps and uploads > 2 Kbps. I am not line of site to either tower. Terrain is flat and there are no more then two story houses in the path - but it is mostly trees that prevent a direct view of the towers.

          I know that vegetation is a factor, as are atmospheric conditions. I have seen the modem go from three signal lights to one in a heavy rain storm. But it seems totally ridiculous, that under clear conditions, I should see two to three lights here that degrade to the modem scanning, and then find the signal also degraded 700 feet from the tower.

          The other closer site is even worse. I have to be within 500 feet of the site to even see any lights. They peak to five lights as I pass within a hundred feet of the tower, and then fade just as rapidly as I continue down the road.

          Now Sprint says their diagnostics shows everything is fine (at the same time I am without signal). But when I ask them what they are monitoring, they can not tell me. I have been an analog / RF designer all my working life and I designed analog cellular base station Power Amplifiers. If I had to guess what is wrong, I would list seveveral possibles, including:

          Inadequate power amp air flow (all our PAs had thermal protection that would cut back power by as much as ten dB if cooling were impaired).

          Intermittent problems with feed lines, or antennas. Our base stations actually included remote antennas to monitor transmit field strength and provide alerts if degraded.

          There may be a combination of issues involved, but it is hard to get anyone to do anything, when their diagnostics say everything is OK.

          There was a time when I questioned if there were modem issues. Sprint was going to replace the modem, but it turns out the CPE was discontinued and what they offered involved paying more. I did take my modem out to their store and switched it for the demo that had hooked up. Mine seemed to be working fine, at least at that moment. And with the other observations, I have made - I don't think the modem is at fault.

          The one thing I don't know is if Clear uses any sort of adaptive beam steering on their antennas. Their signals do seem stronger and equivalent distance in the other direction. But then I don't know if I am then working on another tower. I live near one of the great lakes, and there are no towers closer to the lake, other then that one other I mentioned. I am not in the direction of maximum population as there is a lot of park land
          North of me. Could it be they have optimized their patterns away from me?

          If you have any thoughts, I would appreciate hearing from you.

          Pete
          Last edited by thuor; 05-07-2012, 10:25 PM.

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          • #6
            You are absolutely right about the foliage and time of year having a possible effect on your RSSI. While line-of-sight (LOS) does help it is not absolutely necessary for 4G WiMax which was designed to take advantage of multipath propagation.


            I know that vegetation is a factor, as are atmospheric conditions. I have seen the modem go from three signal lights to one in a heavy rain storm. But it seems totally ridiculous, that under clear conditions, I should see two to three lights here that degrade to the modem scanning, and then find the signal also degraded 700 feet from the tower.
            Too close may not necessarily give you the results you expect because of how the base-station antenna is oriented, down-tilted, it's beamwidth etc. i.e. it may be oriented to hit a cell that doesn't coincide with where you were standing. Also if your problem is poor CINR rather than poor RSSI then proximity to the tower may not necessarily change the interference power causing the poor "Carrier-to-Interference-Plus-Noise ratio" even if your carrier RX power could be stronger. Remember also on the upload the modem's radio does a power output control (power backoff) to account for radios that are closer to the tower (otherwise they would drown out distant modems) so this is again why the uploads may not appear to vary.

            The other closer site is even worse. I have to be within 500 feet of the site to even see any lights. They peak to five lights as I pass within a hundred feet of the tower, and then fade just as rapidly as I continue down the road.
            Curious what would be your result if you lingered around the site for several minutes to give the modem sufficient time to soft-handoff to that site. You can tell if you have switched from the base-station ID value reported by your modems diagnostics.

            Inadequate power amp air flow (all our PAs had thermal protection that would cut back power by as much as ten dB if cooling were impaired).
            Intermittent problems with feed lines, or antennas. Our base stations actually included remote antennas to monitor transmit field strength and provide alerts if degraded.
            There may be a combination of issues involved, but it is hard to get anyone to do anything, when their diagnostics say everything is OK.
            Good points. But you left out one that might be hard for any carrier to admit - capacity limitations.

            The one thing I don't know is if Clear uses any sort of adaptive beam steering on their antennas. Their signals do seem stronger and equivalent distance in the other direction. But then I don't know if I am then working on another tower.
            To the best of my knowledge (and anyone please clarify if this is incorrect) Clearwire, and indeed most WiMax deployments to date, only utilize open-loop MIMO (WiMax standard refers to these as Matrix-A or Matrix-B). Beam forming, i.e. closed-loop MIMO or TX-AA (Transmitter Adaptive Antenna) techniques are not used. But i could be wrong here because I have seen some information about Clearwire using Samsung WiMax base-stations in some markets which support 4x4 MIMO with beamforming but not sure how accurate this is. The WIXB-175 uses Beceem's BCS5200 chipset which i believe only supports open loop MIMO (beam forming optional to 802.16e std). You can see how with a large number of remote transmitters it would be quite resource intensive to collect channel information from the modems for the basestation to steer the radiation pattern to optimize SNR.

            I am not in the direction of maximum population as there is a lot of park land
            North of me. Could it be they have optimized their patterns away from me?
            Quite likely - but you would think that that would be made up for by lower interference power because of a lower user density at your location.

            Not sure if there's really anything you can control to fix this issue. Hopefully you are in line to get TD-LTE in your area pretty soon which Sprint has already signed up with Clearwire as a wholesale customer.

            Also having multiple external antennas might help with MIMO performance boost (because you can physically keep them farther apart to ensure that the signals to each are as uncorrelated as possible which is hard to achieve with the integrated printed antennas in the CPE). Although from what you describe i don't think high gain outdoor antennas alone could work any miracles for you. If you do end up going that route would love to hear about your results.
            KF7RCQ

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