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  1. jtlapp's Avatar
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       #1  
    This is a question about how the Palm Pre works. The answer may help me troubleshoot a problem I'm having using it with the Airrave mini-tower.

    How does the Pre decide when to switch to a new wireless cell? (I assume a "cell" is the region covered by a particular cell phone tower.)

    Does it switch when the bar strength drops below a certain point? My experience says that this is not the criterion. My Airrave gives my full bars, but I can be standing next to it with full bars, when suddenly I get the beep on my phone indicating that the phone is switching off the Airrave, and then I have 2 or 3 bars. Still next to the Airrave, I am suddenly on the public cell, which drops to zero every few minutes, thus ending my call.

    I'd be surprised if the Airrave controlled the phone this way, but do enlighten me if it does. Until then, I think this post belong in the Palm Pre forum, where people might have some idea about the answer.

    Can anybody explain what's going on? I'm looking for a solution. I'm ready to dump, Sprint, the Airrave, and the Palm Pre in order to start from scratch with a solution whose components are all different.

    Thanks for your help!
  2. jtlapp's Avatar
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       #2  
    I figured it out. I did an experiment comparing the behavior of an old Sanyo phone with the Palm Pre. Because of how the Palm Pre selects a signal, the Pre does not work great with an Airave when the public Sprint signal varies a lot.

    The Pre appears to be switching cells whenever it detects a new cell increasing in signal strength. That is, when it detects a different signal going from 1 bar to 2 bars (for example), the Pre thinks that it's approaching a new cell tower and so switches over to it. The problem is that it will do this even if I'm standing next to the Airave getting 5 bars. And since an in-progress call can't switch back onto the Airave, I'm stuck with the poor public signal until it becomes unusable or dies.

    To determine all this, I moved my phone number back to my old Sanyo phone, disabling the Pre. In the few hours I've spent trying out the Sanyo with the Airave, it has not once left the Airave network, and signal quality has remained great. The Pre would typically degrade in quality after 10 minutes and die 10 minutes later.

    Sanyo may be doing the more intelligent thing of sticking with the strongest signal instead of switching to a signal that is growing in strength. That's my theory, anyway.
  3. jtlapp's Avatar
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       #3  
    Just spoke with a Sprint rep about this. Sprint has been very good about keeping in touch. She's guessing that the Pre is prioritizing the data signal over the voice signal, even though I'm using WiFi at home. So the Pre will switch towers to improve data even if it means degrading voice. She didn't think Android would have this problem, but had no technical reason for the gut feeling.
  4. jtlapp's Avatar
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       #4  
    Bye everyone. I had to dump my Pre for the above reason -- it's unable to support voice calls from my home, due to my specific situation.

    To summarize, the Pre is unable to support voice calls in the following situation:

    (1) The public Sprint network at the location is too erratic to support calls -- the signal varies dramatically, often dropping to zero.

    (2) The public Sprint network data signal at the location is better than the data signal available from the Airave. (That's a Sprint rep's theory. Another possibility is that the Pre switches to a rising public signal, regardless of the Airave signal strength.)

    In this circumstance, the Pre will start with the Airave but quickly switch over to the public network. Since it won't switch back to the Airave, your call then rides the public network down to no signal and the call drops.

    I wish Palm and its fans luck. I still think webOS is the future.
  5. Analog's Avatar
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    #5  
    How can this be brought to Palm's attention?
  6. #6  
    I had similar issues when I had an airave. But worse, was the backend connection. One day, it just stopped communicating. So I returned it. Hoping the newer version is nicer.

    One workaround is when at home to turn off data on the phone, and use wifi. Still not perfect though. I still noticed the airave 'fighting' with the local towers. *sigh*.

    When on the road, it seems the algorithm prefers sprint towers, even if the signal strength is horrible compared to roaming too. I wish they would change that.
    : (){:|:&};:
  7. #7  
    Can your old Sanyo do data at all? Can it make an EVDO connection or is it 1x only?

    I don't know anything about the Airwave but I'm guessing it doesn't support data at all. Is that correct?

    On your your dialer screen, there is a Preferences menu you can access. If you scroll down, there is a Network box with a Data Usage option. Turn Data Usage off and see if that allows the phone to stay on your Airwave.
  8. Minsc's Avatar
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    #8  
    Interesting. I wouldn't have thought that the Pre would behave differently with regard to this kind of thing. Isn't this logic just built in to the radio's firmware? Why would the Pre be any different than any other 3G Sprint phone? (BTW, this is has to be a carrier issue not a Palm issue - I would think the carrier is responsible for the radio's firmware)
  9. #9  
    Turning data off would be a good way to test your theory like mentioned previously. Plus I agree with the view that it is more a carrier issue than a palm issue.
  10. #10  
    Yes, the logic for switching between base stations is built into the phone but the base stations play a role too. It's called System Selection. Qualcomm provides the basic algorithms but the phone manufacturers can tweak it. The carriers provide a lot of input too.

    I only know a little about System Selection and how the algorithms grade out the channels. The PRL plays a big role in this. A phone will prefer it's home carrier system over any roaming station. I'm not sure what role data plays in the grading but the 1x voice and the EVDO data channel are physically separate channels that are logically paired. A phone looking for data will first acquire a 1x channel and the data on that channel will tell the phone where to find the associated EVDO data channel. I'm guessing that looking for data is what is causing the phone to switch away from the Airwave.

    It might be interesting to see how an Airwave identifies itself. Switching between cells is usually done with a process called soft-handoff. The base-stations communicate with each other to smoothly pass a phone from one cell to another. But I'm guessing a base station has no knowledge of an Airwave so can't pass it off a phone to the Airwave even though the Airwave is receiving a phone with a stronger signal. The phone will have to initiate the switch through a re-scan timer but that is typically minutes.
  11. jtlapp's Avatar
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       #11  
    Well, my correction to my phone situation was pretty drastic, but I yearned for webOS. All carrier signals are poor at my house. I switched from Sprint to Verizon, got their Network Extender (an Airave equivalent), and a dumb no-data phone.

    That worked beautifully, as had my dumb phone on Sprint. But I got lost once looking for a specialty store, and the Verizon Navigator feature didn't show it, so I never made it. Then someone was texting me for help and couldn't talk, but I couldn't type fast enough, and each new text of their interrupted and threw out my unfinished text. I really really missed my Palm.

    So I took the risk and bought a Palm Pixi on Verizon. I'm back! Just on a different network. The experiment continues.

    So far I am not having any trouble with this phone -- it is clearly performing better than my Palm Pre on Sprint. The public Verizon signal appears to be poorer at my house than the Sprint signal, so the Palm logic may still be wrong and I'm just impacted less on Verizon. Or it could be a carrier problem after all and not a Palm one. In any case, it's clearly specific to data phones. I have not tried any non-webOS data phone, though.

    God I love the webOS operating system. The move from the Pre to the Pixi was a pleasant one, too. Though the screen is smaller, I was never able to type with two thumbs at once on the Pre like I can on the Pixi. I'm typing twice as fast now. And those chiclet keys are just plain fun! The USB port on the Pixi is beautiful too, unlike the Pre's. HP please keep webOS alive and well.

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