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Cellular Data Card Comparison

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  • Cellular Data Card Comparison

    Trying to figure out why i should chose one aircard over another. Can't find a aircard feature comparison to compare sprint vs verizon, seierra wireless vs novatel etc - anyone know where i can get this.

  • #2
    Cellular Data modem feature comparison

    Interesting that you bring this up since our wireless support reps are working on this right now (we'll post the comparison instructions when thats complete)....

    The main aspects of comparing a cellular data card fall into 3 main categories

    1) The cellular carrier
    2) The 3G coverage available
    3) The form factor required
    4) If you will be using it with other hardware e.g mobile router, antennas etc
    5) Other technical specs for the tech junkies

    Let's break this down ...
    1) At the end of the day most people go with what cellular carrier they like for whatever reason ... unfortunately not all cellular carriers have fast/reliable cellular data coverage. E.g my favorite carrier of all time is T-Mobile but the fastest cellular data protocol they support is EDGE which is not the fastest out there

    2) So depending on where you leave you may not have access to all 3G protocols (unless you are lucky to live in a major city). GSM carriers have EDGE/UMTS/HSDPA and CDMA carriers have 1xRTT/EVDO/EVDO RevA. I guess it also depends on where you will travel to as EVDO has a larger nationwide footprint than HSdPA.

    3) Form factor has to do with what you will use your cellular data modem with. Most common is a laptop so you need to figure out if your laptop supports Express cards or PC Cards. If you need it to work on a desktop (or both laptop and desktop) consider the USB modems. There are not equal in performance so check with us if you have any questions since using an adapter might in some cases be a better choice.

    4) If planning to use a mobile router (which converts from the cellular 3g protocol to regular 802.11 WiFi allowing multiple users to be online concurrently) or high gain cellular antennas check first if the cellular data modem is compatible with the hardware you intend to get. We offer nice bundles here that we already know are compatible.

    5) For the tech junkies that want to disect these devices ... the main technical specs that i care about in my opinion are the transmit power, receiver sensitivity & power dissipation. The first 2 determine how reliable the device will be. Remember that transmit power for cellular radio modems are tower controlled so technically speaking a more accurate spec to focus on would be how accurate the transmit power control is. The better the power control (and stronger the transmit power when i need it) the farther away from the cellular tower my cellular modem can go and still "talk" reliably with the cellular tower. Receiver sensitity (for cellular usually in -dBm quantities) represents the weakest signal that can be received reliably (again being technical we have to define what "reliably" means and this is defined in terms of a pre-defined BER=Bit Error Rate). So the better the Rx sensitivity (more negative) the weaker the signal my modem can detect. Lastly power dissipation affects battery life which is important especially if you are using your laptop without a power cord - well even if ur using a powercord we need to look out for mother earth

    I specifically don't mention speed & cost since those are no-brainers. Almost everyone would want the card that supports the fastest 3G network available in their area (EVDO RevA or HSDPA) and the cheapest cellular data modem that achieves this.

    Again look out for our new cellular modem feature comparison links coming soon .....
    Last edited by thuor; 08-01-2007, 01:14 PM.
    KF7RCQ

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    • #3
      Comparison feature for aircards

      Update- The comparison feature for the aircards is up now.

      To compare the different aircards that we carry, click on this link http://www.rfwel.com/shop/choosing.php?fclassid=4 ...

      Key points to note...
      1) Do you want a PC aircard? If so check out the differences between the S720 vs AC595 vs PC5750 vs PX500 ...

      2) Do you want a USB Modem? If so compare the U720 vs 595U vs U727 (coming soon)...

      3) Do want to compare the different Express Card modems that we offer.. eg EX720 vs AC597E vs PC 680...

      4) You can also check and compare the features between different Sprint aircards like the S720 vs U720 vs PX500 vs 595U vs EX720 vs AC595 vs AC597E

      5) If you prefer Alltel aircards, then you can click to compare different alltel cards like PC5750 vs KPC680 vs PC650

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      • #4
        HSDPA/HSUPA card specs

        Hello,
        do you guys have an updated comparison table WITH the maximum transmit power and receive sensitivity?
        I see this but it doesn't have the values:

        http://www.rfwel.com/shop/comparison...ort_direction=

        The maximum transmit power capability seems important, and it may well define the range you get with your card. A HSDPA/HSUPA card is supposed to transmit +24dBm maximum (controlled by the tower to be normally less, but at the edge of the cell when you are about to drop the call, it maxes out). Many cards actually have a much lower power capability (can be as low as +21dBm max and still "meet the specs."). Thanks!

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        • #5
          HSDPA/HSUPA Tx power, power control & Rx sensitivity

          We are in the process of updating these specs and will post a notice once we get this done. Main problem is that this data is usually not immediately available and is usually not available from the carriers - we have to either get this from modem/chipset datasheets, FCC filings or directly from modem manufacturer. On the other hand, as you correctly point out, relying on the maximum transmit power spec to compare two modems can be deceptive especially if difference is minimal; even considering that HSDPA does not use fast power control techniques as other W-CDMA networks do which would suggest that static tx power would be more significant (in EVDO modems and indeed cellular amplifier/repeaters fast and accurate packet power control seems arguably more important than absolute tx power).

          In fact, rather than transmit power, we have found that HSDPA or EVDO modems are more often range-constrained by receiver sensitivity as well as other parameters which are not easily quantized and mainly residing in the radio baseband as opposed to RF front end. Specifically how well the modem manufacturer or chipset vendor implements algorithms for H-ARQ as well as firmware to interface TCP/IP protocol stack in computer. The receiver side is perhaps also more important probably since the user device for HSDPA has to report on forward link channel quality to BTS for packet scheduling and the channel quality reported will be as perceived at the receiver.

          H-ARQ = Hybrid ARQ. Channel specific modulation & coding utilized for retransmission to minimize bit errors which maximizing SNR at receiver.
          KF7RCQ

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