Page 1 of 2 1 2 LastLast
Results 1 to 15 of 24

Thread: Why Park on Mid-Band?

  1. #1
    Join Date
    Aug 2008
    Posts
    6,871
    Device(s)
    SGS 7
    Carrier(s)
    MSV 10GB plus 10GB free, 4 lines
    Feedback Score
    0

    Why Park on Mid-Band?

    Why do AT&T and other carriers park their phones mostly on B2/4, and then CA in the lower bands until you're at the extreme edge of the cell? Couldn't they just as well do the parking on B17, and then CA in the upper bands, or does this inherently use more bandwidth in the low band, leaving less for phones at the extreme edge of the cell that can't see B2/4? I wonder because their parking has gotten very aggressive. At work, my phone sits on B4 (it used to sit on B2), both of which are pretty weak, and result in having only one bar.
    Happy AT&T customer and addicted Speedtester in CT
    AT&T Galaxy S7
    If you text while driving, you're an idiot. End of story.

  2. #2
    Join Date
    Aug 2017
    Location
    Chattanooga, TN
    Posts
    449
    Device(s)
    SM-G935U
    Carrier(s)
    Verizon Wireless
    Feedback Score
    0
    Quote Originally Posted by GSMinCT View Post
    Why do AT&T and other carriers park their phones mostly on B2/4, and then CA in the lower bands until you're at the extreme edge of the cell? Couldn't they just as well do the parking on B17, and then CA in the upper bands, or does this inherently use more bandwidth in the low band, leaving less for phones at the extreme edge of the cell that can't see B2/4? I wonder because their parking has gotten very aggressive. At work, my phone sits on B4 (it used to sit on B2), both of which are pretty weak, and result in having only one bar.
    I've wondered the same thing. It would seem that for marketing purposes, you'd want more bars showing. It must be that the primary band gets more of the traffic, and carriers can obviously afford more use on the mid-band than low-band.

  3. #3
    Join Date
    Jul 2009
    Posts
    898
    Feedback Score
    0
    PCC should have wider capacity, especially since uplink is non-CA.

    It depends if Ericsson/Nokia can distinguish cell camping priority for CA vs non-CA devices. If they can't make that distinction, then non-CA devices would obviously suffer when everyone is on low band only.
    Want to learn more about how LTE works?
    https://productioncommunity.publicmo...ls/td-p/130581

  4. #4
    Join Date
    Oct 2014
    Posts
    2,534
    Device(s)
    LG G4
    Carrier(s)
    T-Mobile
    Feedback Score
    0
    B17 is 700 Mhz which spectrum goes greater distances and penetrate building better. Great distances better building penetration mean more customer to service which saturate the bandwidth of a single B17 cell tower. B2/B4 with shorter distances is the safety valve to keep B17 from getting saturated by serving the customers with B2/B4. One B17 tower would require at least four or more B2/B4 cell towers to service the same customer area. Since each cell tower has their own internet backhaul the shorter distances of B2/B4 allows for a faster network for all the customers in that area of the B17 tower. Parking the customers on B2/B4 frees up B17 that also has the ability to penetrate building that is much better than B2/B4. When your phone can't see B2/B4 then it uses B17.
    Last edited by shilohcane; 11-08-2017 at 01:51 PM.

  5. #5
    Join Date
    Jul 2016
    Location
    Chantilly, VA
    Posts
    356
    Device(s)
    Moto G4 Play
    Carrier(s)
    H2O (AT&T), Red Pocket (AT&T)
    Feedback Score
    0
    What's weird is band 4 dies out much sooner than band 2 when moving from the tower. (Even though band 4 is a lower frequency) I'm assuming lower transmit power?

    Verizon is just the exact opposite. Band 2 goes first ,then 4, then 13, then 3g (ugh), then 1x (double ugh).

  6. #6
    Join Date
    Jul 2017
    Location
    U.S.A
    Posts
    405
    Device(s)
    AT&T S8+
    Carrier(s)
    AT&T
    Feedback Score
    0
    Quote Originally Posted by Digital Rules View Post
    What's weird is band 4 dies out much sooner than band 2 when moving from the tower. (Even though band 4 is a lower frequency) I'm assuming lower transmit power?

    Verizon is just the exact opposite. Band 2 goes first ,then 4, then 13, then 3g (ugh), then 1x (double ugh).
    Nope it's actually the gap between the 2 frequencies that B4 uses that makes its propagation weaker. Band 2 has relatively close frequencies as does band 13. Band 4 is also 20x20 usually so that does make it worse for some reason, can't remember why, someone else can chime in with more information.

    Sent from my SM-G955U using Tapatalk

  7. #7
    Join Date
    Aug 2017
    Location
    Chattanooga, TN
    Posts
    449
    Device(s)
    SM-G935U
    Carrier(s)
    Verizon Wireless
    Feedback Score
    0
    Quote Originally Posted by ZeroSignal View Post
    Nope it's actually the gap between the 2 frequencies that B4 uses that makes its propagation weaker. Band 2 has relatively close frequencies as does band 13. Band 4 is also 20x20 usually so that does make it worse for some reason, can't remember why, someone else can chime in with more information.

    Sent from my SM-G955U using Tapatalk
    You guys almost got it right.

    Band 4 DL frequency (which is what your bars display depends on), is actually 2100. That's higher than PCS. So in theory, for the same power, it should die sooner than band 2.

    You are correct that channel width has something to do with it, as well. But it won't affect your bars display (unless it's based on RSRQ or SNR). Wider channels require better field strength to be able to actually use. So if you had to get 0 bars of something, you'd want it to be the narrowest channel possible, in order to be usable.

  8. #8
    Join Date
    May 2014
    Location
    Minnesota
    Posts
    2,781
    Device(s)
    iPhone X 256 GB Space Gray
    Carrier(s)
    AT&T Mobility
    Feedback Score
    0
    Quote Originally Posted by Digital Rules View Post
    What's weird is band 4 dies out much sooner than band 2 when moving from the tower. (Even though band 4 is a lower frequency) I'm assuming lower transmit power?

    Verizon is just the exact opposite. Band 2 goes first ,then 4, then 13, then 3g (ugh), then 1x (double ugh).
    Band 4 has a much lower Tx power than Band 2.

  9. #9
    Join Date
    Aug 2008
    Posts
    6,871
    Device(s)
    SGS 7
    Carrier(s)
    MSV 10GB plus 10GB free, 4 lines
    Feedback Score
    0
    Quote Originally Posted by weskeene View Post
    I've wondered the same thing. It would seem that for marketing purposes, you'd want more bars showing.
    Yeah, that's what I was thinking. The coverage is as good or better than ever, but due to the parking rules, so the speak, I often have fewer bars, as my phone will rarely park on B17, and usually holds on to B4 at work, which is in a weak area between sites (even though I can see one of them out the window maybe a mile away).

    Quote Originally Posted by sheytoon View Post
    It depends if Ericsson/Nokia can distinguish cell camping priority for CA vs non-CA devices. If they can't make that distinction, then non-CA devices would obviously suffer when everyone is on low band only.
    That's an interesting thought. I didn't think of towers not being able to differentiate, or older devices without CA being on the network.

    Quote Originally Posted by shilohcane View Post
    B2/B4 with shorter distances is the safety valve to keep B17 from getting saturated by serving the customers with B2/B4.
    Yeah, I get that. My post was specifically wondering why they have to park on the mid-band in the days of CA where most of the bandwidth can be coming from a band that you're not parked on. My phone tends to park on mid-band and CA from B17 (at least on the few occasions I've checked to see what I'm CA'ed on).

    Quote Originally Posted by weskeene View Post
    Band 4 DL frequency (which is what your bars display depends on), is actually 2100. That's higher than PCS. So in theory, for the same power, it should die sooner than band 2.
    I thought that we were limited by the UL, not the DL for the range a phone can operate from the tower? Hence the whole big deal with HPUE?

    Quote Originally Posted by jakeuten View Post
    Band 4 has a much lower Tx power than Band 2.
    Ah, that's interesting. That explains why B2 is almost as good as B17, and B4 is definitely not. I've seen a LOT of B2, even in rural or weak signal areas.

  10. #10
    Join Date
    Aug 2017
    Location
    Chattanooga, TN
    Posts
    449
    Device(s)
    SM-G935U
    Carrier(s)
    Verizon Wireless
    Feedback Score
    0
    Quote Originally Posted by GSMinCT View Post
    I thought that we were limited by the UL, not the DL for the range a phone can operate from the tower? Hence the whole big deal with HPUE?
    Yes, that's a major limiting factor. However, all the papers on this subject that I can get my hands on, indicate that the tower equipment simply asks the UE what RSRP/RSRQ it could receive on the other band before deciding to hand off. Perhaps the tower also takes into account RSRP/RSRQ on the received signal from the UE (it would make sense), but I haven't yet unearthed anything to that effect.

  11. #11
    Join Date
    Dec 2014
    Posts
    475
    Device(s)
    iPhone, iPad
    Carrier(s)
    Verizon Wireless, AT&T
    Feedback Score
    0
    I wonder how this will work once uplink aggregation is enabled on the network side, since (almost?) every 2017 flagship phone supports UL CA now.

  12. #12
    Join Date
    Sep 2011
    Location
    Chicago/Northwest Indiana
    Posts
    3,753
    Device(s)
    iPhone 6
    Carrier(s)
    Verizon
    Feedback Score
    0

    Why Park on Mid-Band?

    It's ideal to use mid/high band for PCC since that will keep the most load off of low band. If you're doing 2+12 it's easy for the network to pull traffic off of B12 as it loads up, not sure how easy that is with B12 PCC. It also keeps the low band UL clearer which is crucial in keeping it usable as those distant devices are gonna have a hard time communicating back to the site on the airlink as it is, to introduce unnecessary noise will just make it less usable overall.

    In my area AT&T has no problem using B12 PCC and aggregating other bands with it, but it will always prefer mid/high band. Verizon won't do CA with 13 PCC in their Ericsson markets for some reason, except the 13+2 combo.

    As for UL CA I'm very curious to see how that plays out, I think ideally it should be preferred to keep it on mid/high band and only use low band when mid/high band signal is weak. That will open up a lot of opportunity to use fringe mid band using B12 as SCC on UL where B4/2 UL is completely unusable rendering mid band useless otherwise. They'll have to be careful doing this as it could easily overload the low band UL.

  13. #13
    Join Date
    Jul 2009
    Posts
    898
    Feedback Score
    0
    Quote Originally Posted by ZeroSignal View Post
    Band 4 is also 20x20 usually so that does make it worse for some reason, can't remember why, someone else can chime in with more information.

    Sent from my SM-G955U using Tapatalk
    If two radios are transmitting at the same total power (like 30 W), the narrower channel will always have higher RSRP. That's because the power will be distributed along the entire channel bandwidth.

  14. #14
    Join Date
    Jul 2009
    Posts
    898
    Feedback Score
    0
    Quote Originally Posted by weskeene View Post
    Yes, that's a major limiting factor. However, all the papers on this subject that I can get my hands on, indicate that the tower equipment simply asks the UE what RSRP/RSRQ it could receive on the other band before deciding to hand off. Perhaps the tower also takes into account RSRP/RSRQ on the received signal from the UE (it would make sense), but I haven't yet unearthed anything to that effect.
    In rural areas, coverage will always be uplink limited. In urban areas, it will be more of a DL interference issue rather than limited UL power.

    Handovers are generally measurement based, which require measurement reports from the UE to indicate events for intra-frequency (A3), inter-frequency (A2/A4/A5), or inter-RAT (A2/B1) scenarios. RSRP or RSRP+RSRQ can be used to trigger events.

  15. #15
    Join Date
    Aug 2017
    Location
    Chattanooga, TN
    Posts
    449
    Device(s)
    SM-G935U
    Carrier(s)
    Verizon Wireless
    Feedback Score
    0
    Quote Originally Posted by sheytoon View Post
    In rural areas, coverage will always be uplink limited. In urban areas, it will be more of a DL interference issue rather than limited UL power.

    Handovers are generally measurement based, which require measurement reports from the UE to indicate events for intra-frequency (A3), inter-frequency (A2/A4/A5), or inter-RAT (A2/B1) scenarios. RSRP or RSRP+RSRQ can be used to trigger events.
    So in your experience, the handover is based on the UE RSRP or RSRP + RSRQ, not the tower's? That's what I've seen so far. You're right though. The UE uplink connection would be the most limiting factor. Perhaps the designers assume that DL is a reasonable proxy for UL. I.E. If we're still the best sector/band for DL, then UL wouldn't be better on another sector/band, either. Just a guess.

Page 1 of 2 1 2 LastLast

Similar Threads

  1. Replies: 21
    Last Post: 09-14-2007, 12:51 PM
  2. Replies: 13
    Last Post: 09-10-2007, 03:00 PM
  3. Why no 900 MHz band on phones?
    By blueandwhiteg3 in forum AT&T
    Replies: 23
    Last Post: 12-24-2004, 12:07 AM
  4. Replies: 37
    Last Post: 06-09-2004, 01:07 PM
  5. why snaked 2...why not on damn 8290
    By autoslidematrix in forum Nokia
    Replies: 6
    Last Post: 09-09-2001, 03:38 PM

Tags for this Thread

Bookmarks