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Nowadays, most smartphones (or other smart mobiles) have some kind of wireless communication for short range and medium range. For short range, the most widespread technology in use is, probably, WiFi:

  • standard: IEEE 802.11
  • indoor range: 15m
  • outdoor range: 40m
  • frequency: 2.4GHz
  • power consumption: 100mW
  • throughput: 5Mbps

For medium range, the most widespread technology in use is, probably, GSM:

  • standard: ETSI GSM
  • urban range: 500m
  • frequency: 1500MHz
  • power consumption: 1W
  • throughput: 300kbps

The differences between such technologies are mainly due to the communication protocols and the operating frequencies. Each one optimized for its own specifications.

1st Issue
Sometimes, when a technology has several updates and add-ons (as is in this case), it is not that easy to develop a simple comparison table. Therefore, does the simplified comparison above make sense or is it too unrealistic?

2nd Issue
It is well know that software developers can use WiFi features to transfer packets directly between mobiles. However, if you want to increase the range, is there any hardware constraint that would undermine using the GSM radio module (or other widespread mobile wireless technology for medium range) to transfer packets directly between smart mobiles?

  • Actually with the cellular networks like GSM (and not only it) you can communicate with any point in the world where there is network coverage, because networks are interconnected. That is why I don't think it is middle range communication, but quite long range communication. As far as I know there is no way to use the mobile to directly connect to another one without using the network infrastructure. and if there is it may be illegal, because the spectrum is not free for use.. – vladiz Jan 25 '16 at 19:43
  • @vladiz I don't think it is middle range communication, but quite long range The range I've mentioned is within the data-link level. Of course, if we consider a multi-hop scenario the range would be infinite, but this is not the case. – Mark Messa Jan 25 '16 at 19:56
  • @vladiz there is no way to use the mobile to directly connect to another one Ok, bad news. However, just as food for though: there are some apps claiming to be walk-talkies and ram radios for smartphones (I don't know the specifics). – Mark Messa Jan 25 '16 at 20:01
  • If you are talking about Push-to-talk over cellular, it uses the network. The connection is not directly between the two UEs. And it have to be supported by the mobile operator. The apps you are talking about may use Wifi. Can you tell which exactly apps are these? I am interested, too. – vladiz Jan 26 '16 at 8:06
  • If you are talking about Push-to-talk over cellular, it uses the network. I'm not talking about PTT carriers (pe: Nextel). – Mark Messa Jan 26 '16 at 14:05
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I'm not sure if you can use GSM in a peer to peer manner; but even if you would devise a way to do it in software (that is, rewrite the firmware in a GSM radio or such), I'd guess the range would not be as if you're communicating via a BTS, as both sides would be using poor, built-in antenna.

  • I'd guess the range would not be as if you're communicating via a BTS Ok, good point. I agree with you. I'm wondering how much the range would decrease due to that ... – Mark Messa Jan 25 '16 at 20:05
  • even if you would devise a way to do it in software This is another important issue, whether the operating system would allow you to use the GSM radio. However, I guess this is off-topic here at 'Network Engineering'. Later I will ask this software issue on another 'StackExchange' forum. – Mark Messa Jan 25 '16 at 20:10
  • First of all, there is a project called OsmocomBB, which implements a lot of the GSM stack, and can be loaded in some phones, and used with some basestations. I've never used, as I've never found out how to do so, since the documentation is kind of chaotic. But it's there. – Krakonos Jan 25 '16 at 21:05
  • As for the range, it's hard to guess. I just tried some numbers with this calculator, and 2dBi antenna has approximately 1/3 the range of 9dBi antenna. Although I have no idea which antennae are used in GSM networks, I would guess the phone antenna would be approximately 2dBi, and the BTS would have much better one (as I have 9dBi at home). But that's not the only parameter, as it heavily depends on the receiver sensitivity as well. In the end, I think you'd end up somewhere in the WiFi ballpark, but with a lot of trouble on your hands. – Krakonos Jan 25 '16 at 21:14
  • 2dBi antenna has approximately 1/3 the range of 9dBi antenna This is interesting. It means that, at most, the connection between two phones would have 1/3 of the range of the connection between a phone and a BTS. So, if we consider the range of a phone/BTS to be 500m, then the range of a phone/phone would be at most 150m. Which is still 10 times better than the WiFi range. Very interesting ... – Mark Messa Jan 25 '16 at 21:37

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