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WiWavelength

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Posts posted by WiWavelength

    Floating Cell Towers

    in General Topics

    Posted

    What is the FCC thinking? Will signal even reach the ground?

     

    Yes, easily.

     

    Free space path loss for an antenna 50 km away but with a clear LOS (line of sight) above the horizon is ~132 dB (i.e. the signal spreads out and loses intensity by 132 dB). Path loss for a cell site only 1 km away but in an urban area with no clear LOS can be roughly similar to that 132 dB figure.

     

    In other words, a floating cell site 50 km distant could provide signal strength similar to that of a ground based cell site only 1 km distant.

     

    AJ

    • Like 1

    FCC Announces Two Spectrum-Sharing Agreements With Mexico

    in General Topics

    Posted

    Let me rephrase: can Sprint use a G-block 5x5 carrier nationwide, even near border areas (sounds like that's a question mark at this point)?

     

    For Sprint, the 3 MHz x 3 MHz LTE carrier possibility is relevant only to SMR 800 MHz (bands 18/26), not to PCS 1900 MHz (G block; band 25). Ask Robert to confirm, but I know of no Network Vision sites anywhere that are precluded from LTE 1900 in the G block.

     

    AJ

    FCC Announces Two Spectrum-Sharing Agreements With Mexico

    in General Topics

    Posted

    WiWavelength, is that in the G Block or in ESMR that they would otherwise be limited to 3x3?

     

    Only ESMR. Sprint will be able to deploy a single CDMA1X 800 carrier everywhere, including the international border coordination zones. However, under current guidelines, Sprint may be able to deploy only a 3 MHz x 3 MHz LTE carrier in the Mexican border zone and no LTE at all in certain areas (e.g. Seattle) of the Canadian border zone. The reason for this is that 800 MHz public safety rebanding is a US endeavor, not necessarily conducted in parallel by Canada and Mexico. In short, within a specified distance of the international boundary, Sprint cannot operate broadband LTE across the same frequencies that Canadian or Mexican carriers/agencies operate iDEN or other narrowband airlinks. Otherwise, Sprint LTE could interfere with those narrowband operations.

     

    I have no idea what Mexico is doing (if anything at all) with its equivalent to the PCS G block. In the US, the PCS G used to be part of BAS (Broadcast Auxiliary Service), which provides microwave link style spectrum for TV broadcasters' remote pick ups. Sprint had to foot the bill for relocating BAS from ~2000 MHz up to ~2100 MHz as one of its conditions of being granted the PCS G block nationwide.

     

    AJ

    Expansion. Is there any?

    in Network, Network Vision/LTE Deployment

    Posted

    It would only be a very general guideline. AJ recently posted that Nextel iDEN 800 produced a pretty poor signal and could not be useful as far of a distance as CDMA on 800 will.

     

    iDEN does not transceive a "pretty poor signal" as much as it does a more complex signal. Since iDEN uses only 25 kHz channels, it requires 16-QAM to achieve sufficient throughput within such narrowband channelization. The downside is that 16-QAM makes iDEN signals more susceptible to fading, noise, and interference.

     

    For a layman's analogy, imagine that someone a block or two away repeatedly holds up a sign with a single letter on it. In one scenario, the letter is one of only four: Q, R, S, or T. In a second scenario, the letter is one of 16: A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, or P.

     

    In the first scenario, you can likely make out the letter each time the sign goes up because Q, R, S, and T are all quite orthogonal. In other words, even at a distance, their "signals" remain quite distinct.

     

    In the second scenario, however, you can likely make the letter sometimes but not other times, as B and E, C and O, F and P, I and L, for example, are not as easily distinguishable at a distance.

     

    Now, the first scenario represents QPSK, a four symbol RF modulation scheme that CDMA1X uses, while the second scenario represents 16-QAM, the 16 symbol RF modulation scheme that iDEN uses. Below, you can see how the layman's visual analogy applies, as these are the symbol constellations for QPSK and 16-QAM, respectively:

     

    200px-QPSK_Gray_Coded.svg.png

     

    200px-16QAM_Gray_Coded.svg.png

     

    In short, it is more difficult for a receiver to tell apart each of the 16 symbols in the 16-QAM constellation than it is the four symbols in the QPSK constellation. This is especially true as the signal is increasingly degraded by fading, noise, and interference. And that is basically why, despite a much lower frequency, iDEN 800/900 is generally similar to CDMA1X 1900 in site spacing and successful propagation distance.

     

    AJ

    • Like 7

    Requests for Information from S4GRU

    in General Topics

    Posted

    LMAO AJ. When is a S4GRU fan going to make a video to this effect?

     

    If I recall correctly, the guy who made the infamous Britney Spears YouTube clip is from Tennessee. I wonder, might there be a special S4GRU fan from Tennessee who could make a similarly impassioned fan video...

     

    ;)

     

    AJ

    • Like 1

    Galaxy SIII FCC RF Specs vs. EVO LTE

    in Samsung

    Posted

    Neither souce link mentioned receiver sensitivity, the other half of the transmit/receive story, so I think what's there is necessary but not sufficient information to decide which radios are going perform better.

     

    And absent tens of thousands of dollars worth of RF test equipment, we will probably never be privy to receiver sensitivity, unfortunately. The FCC requires transmitters be tested (conducted power, radiated power, spurious emissions, etc.) because the FCC has to ensure that authorized devices do not cause undue interference. The FCC does not require receivers be tested, as receivers do not cause interference yet must accept any interference from other transmitters.

     

    AJ

    • Like 1

    FCC approves LTE deployment in 800MHz SMR band!

    in Network, Network Vision/LTE Deployment

    Posted

    Is the Montana 800 FIT in Kalispell? Nextel has a tower(1) set up there. It serviced a Nextel call center there.

    It could be. All the docs I have seen say "Montana." They never reference a community name or region of the state.

     

    I had considered the same possibility, as the only Nextel iDEN site(s) in the state of Montana is in the Flathead Valley. However, Kalispell is close enough to the border that it is in the SMR 800 MHz channel coordination zone with Canada. As such, Sprint is limited in its ability to employ broadband operations in its SMR 800 MHz spectrum. In a nutshell, Sprint likely cannot deploy 5 MHz x 5 MHz LTE in Kalispell. So, unless Sprint plans to use the Montana FIT to practice cross border spectrum coordination, the FIT area will likely be located well away from the Canadian border.

     

    AJ

    • Like 4

    HTC Evo 4g LTE text message problem?

    in HTC

    Posted

    Not sure, but... Do you have the same problem when you use the stock messenger/text app? Maybe Go Messenger Pro is the problem? I'd delete it and use the stock text app for a bit and see how that goes.

     

    Geez, Ben, how can you come to such a reasoned conclusion that the problem might lie with the installed app and not the device?

     

    ;)

     

    AJ

    • Like 3

    bad data signal

    in HTC

    Posted

    I picked up my HTC Evo 4G Lte saturday and am very disappointed in the data speed. My original Evo 4G was much better. The people at sprint can't explain why. Anybody else have probs with there Evo lte? BTW I live in sarasota, FL.

     

    Were you using 4G WiMAX with your previous EVO?

     

    AJ

    HTC EVO 4G LTE

    in HTC

    Posted

    Then again, its not like I have enough in my wallet long enough to pay for anything lmao.

     

    And if you get overextended on a Google Wallet credit card account and your transaction is declined, the clerk might be instructed to cut up your phone.

     

    :P

     

    AJ

    • Like 1

    HTC EVO 4G LTE

    in HTC

    Posted

    I made my first NFC transaction using Google Wallet this morning. It was the coolest thing ever! After completing the transaction I looked around triumphantly. The other denizens of the 7-11 were unimpressed.

     

    Maybe it was the bag of Funyuns and pack of Skoal you bought that left them underwhelmed.

     

    AJ

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