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Wimax frequency

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  1. JCampbell

    JCampbell Well-Known Member

    Okay, so I've done a little looking to find a thread about wimax frequency and I can't find one, so if I missed it I'm sorry :) What I was wondering though is why on earth sprint/clearwire would choose the 2.5 GHz frequency for it. It doesn't penetrate well, and from what I understand it doesn't even cover the same area as the lower frequency verizon/att networks when there aren't buildings interfering! Was it just them being cheap and buying a crappier frequency to save a few bucks? Please clarify this for me!

  2. There is a few dozen reasons that higher frequency is better.

    1.) It was dirt cheap and they could buy a whole section at one time. A larger section is needed because of the low wattage. In the case of lte, there is very high wattage broadcast on both side of their used frequency. As the frequency shifts, it causes interference into the their frequency. You can think about it as your neighbor having a very loud tv that drowns out your own tv. Unlike like you, lte can not tell the neighbor to turn it down or pad the walls. TV antennas, power lines, house lines, electrics, and even large body of water can shift this loud volume into lte frequency. The only way to prevent interference is to move alway from the outer frequencies and into the inner frequency. LTE only have 10 mhz play with, wimax has 50+mhz to play with. Even though building penetration is an issue with the higher frequency, 3-18%. LTE suffers about the same interference rate 3-18% with power lines, tv/radio antennas, house power lines, transformers and large bodies of water. Interference wise it is a really a wash.

    2.) Duplicity and faster rate. The higher the frequency the higher rate of data, which means faster data, with less errors. This does consume more battery but because the number of errors are less and there is no reason to resent the information, it keeps the battery usage about the same as lte. But it will allow faster speeds at higher throughput. Duplicity is inherent at higher frequency. Duplicity simply means one hz can double as both the upload and download at the same time. Do to the longer wave lengths, 700 and 800 mhz can not do both the upload and download at the same time on the same hz. Since you don't have to divide the the upload and download into separate mhz, you double not only your speed but double your efficiency.

    3.) What does not have anything to do with frequency but has everything to do with question is cost to build. For the hardware and software to build a wimax base station, you are looking at about 10,000-15,000 dollars a piece. LTE cost about 100,000-150,000 dollars for each base station. Now as above you are going to suffer the same problems with interferences, what is going to be best. Wimax can support about 2000-9000 people per base station, lte can support about 200 people at 5mhz. Wimax stations can be built right on top of each other, you could add 5 station per pole. LTE need about 3 miles between stations. If you want to fully build out a tower, with lte, you could only support about 800 people per tower per 3 miles per 5mhz. If you wanted to fully build out a wimax station would could cover 2000 people in about 100 feet, what is going cover more people? At 1 mile, wimax could load in about 10 stations covering about 60,000 people costing about 100,000 dollars OR you could cover about 800 people over 3 miles for 100,000 dollars.

    Because you can shove so many base stations in such a small area and they cost soo little, you can create a network with zero interference areas, covering tens of thousand of people for the same price you paid for 1 lte tower covering 800 people (edit:in theory, 1600 people at the full 10mhz) with 3-18% interference. Building penetration goes away because you can offer your costumers repeaters for their homes that allows anyone in the area to use the service. This repeaters cost as little as 100 dollars installed and can cover about 1.5 mile area.

    To review. There are many reason the higher frequency is better then lower.

    1.) Interference is a dead wash between 2.5ghz and 700mhz.

    2.) Speeds will always be higher, efficiency doubles, and battery life improves. Will errors decrease as you move higher in frequency. At higher frequency you can double the mhz to allow both uploads and downloads on the same mhz, lte can never do that. Really requires above 2ghz.

    3.) The cost of wimax stations allow them to be build right on top of each other, canceling any interference problems and fully covering high density population areas like Metro areas. In Manhattan, there is 66,000 people per sq mile. LTE can over about 250 of those people (standard build out) for the same mile. Wimax, at the higher frequency, can cover all those people easy, for about 1/10th the cost (standard build out). You can add more lte towers in that area, but at 100,000 dollars a piece and offering the same speeds and less efficiency, it is hardly worth it.

    Now move into rural areas and everything gets completely turned around. LTE because the better choice and wimax falls behind.

    If you want more I can do it. I am trying to cut myself off at 1000 words or less, as requested.
  3. TheEngineer

    TheEngineer Well-Known Member

    Why is the cost so much higher for the LTE installation? I always read that there was great similarity between the hardware for LTE and Wimax. Or is the difference in price between the lower and higher frequency installations and not really due to LTE or Wimax?
  4. Wimax is open source, and patent pooled. The software is free to use and install. It uses common parts that can put together easily.

    Just for the wimax vs lte chip, just the chip, lte is 3 times more costly.

    LTE is proprietary. You just use lte's development tools, use lte software, and uses very specific hardware. You can make wimax run on lte equipment, but it would be pretty hard to make lte run on wimax equipment.

    LTE has some limitations do to it's spectrum. IE you need to make sure the interference from tower to tower is limited which mean you may have to randomly place a tower where you don't actually own one, very rarely.

    In the real world the cost of lte can range from as little as 10,000 dollars and as much as 3,000,000 dollars, depending on location. We quote 150,000 dollars as a base.

    But the number one factor is the patent costs.

    Almost anyone can buy a wimax base station.


    Now do the same for lte, you will not find one for sell. Open source vs closed source.
    OutofDate1980 and TheEngineer like this.
  5. TheEngineer

    TheEngineer Well-Known Member

    Excellent info. Thank you!
  6. OutofDate1980

    OutofDate1980 Well-Known Member

    RoI..."If you want more I can do it. I am trying to cut myself off at 1000 words or less, as requested." Please, but don't want you to suffer carpal tunnel syndrome.
  7. I guess I need to state this again. I dont hate lte. I have no problem with lte. LTE is going to be the future of cellphone data. Regardless of how much it cost and what it does, it is a great technology.

    But lte is not wireless broadband, verizon seems to tells that to the fcc daily. It is not created to connect homes, business, and cities to the internet. It is created to connect cellphones to the internet.

    Wimax was created to connect homes, business, and cities to the internet, it really was not made for cellphone use.

    A last warning, some times I do get it out and out wrong, I don't really have much time to focus on every little detail and make sure everything is 100% accurate to the cutting edge of the world we live in. If I tried I would do nothing but read paper after paper on the "next big thing".

    I do try to make sure the basic points are good, but please feel free to fact check me. I would rather be wrong and give good information, then be right and gave bad information.

    As for the rest. LTE is the future of cellphone data (mobile broadband in the marketing term). Wimax is the future of wireless broadband data. One connects your cellphone to a cellphone network. The other connects your computers, homes, business, and cities to each other and the internet. They are made to cover two completely different usages. Both are needed and both are going to be used in the future.

    Today you have 3g and wifi on the same device. Tomorrow you will have lte and wimax on the same device.
  8. OutofDate1980

    OutofDate1980 Well-Known Member

    RoI; "...I don't really have much time to focus on every little detail and make sure everything is 100% accurate to the cutting edge of the world we live in. If I tried I would do nothing but read paper after paper on the "next big thing".

    A short excerpt from a 1 page summary of the "next big thing". :eek:

    "The researchers looked at what happens when, instead of having many antennas of their own, a user shares the antennas of a nearby device, to create a 'virtual' MIMO terminal. This technique is likely to enter service in 4G wireless technologies like LTE and WiMAX, but the researchers showed that very careful design is needed in such systems."

    What's mine is virtually yours: Collaboration between mobile phone users can speed up communications
  9. It physically hurt to read and would be a security nightmare.

    The problem is simple, only a limited amount of data can go through a limited amount of antennas. Someone will have to be hurt for someone to gain.


    If you add the technology to outside sources, lets say plugins, tvs, toaster, light poles, buses, and even cloths, would get their own mini antenna, then it would be quite interesting.

    On the other hand, you could get instant hack-ability of a lot of devices, with just a few lines of code. You would have to find a way to both allow others to use the system while filtering out the bad people.

    It would have to be used very carefully.
    OutofDate1980 likes this.
  10. JCampbell

    JCampbell Well-Known Member

    thanks RoI, great info! I had never realized the technology was so different between the two, but now I feel safer with wanting a 4g phone on sprint :)

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