Base station frequency

Hi

I would like to know which frequencies and technologies do base stations use to send information to today's cellphones and computers? and which technology helps them differentiate one cellphone from another ? Do they have some sort of database application? How does it work?

Thank you

Hi,

Did you try wikipedia?
Or Google?

I even recommend to look for informations at the providers.

Klaus

KlausST said:

Hi,

Did you try wikipedia?
Or Google?

I even recommend to look for informations at the providers.

Klaus

Click to expand...

Wikipedia and Google are too complicated because they give clear information to my questions. I don't know which one is the answer to what I am looking for.
What is the main communication technology and frequency to send information to cellphones and computers? And how do they differentiate different cellphones? Is there a difference between the frequencies in which cellphones send information from those at which they receive?

Different frequencies are used in different countries. There is no 'correct' answer to your question.

In most places (but not all):
Cell phones around 650 - 700 MHZ, 880MHz to 980MHZ, 1800 - 1860MHz.
Wireless telephones 1.6 - 1.7MHZ, 36 - 37MHZ, 1900MHz
WLAN 2.4GHz - 2.5GHz, 5.1 - 5.2GHz

The primary distinction is by frequency band but there are different modulation methods and data rates used in most of them. Cell phones are polled by a control station to discover which are in range then allocated time slots so many can share the same frequency.

Brian.

betwixt said:

Different frequencies are used in different countries. There is no 'correct' answer to your question.

In most places (but not all):
Cell phones around 650 - 700 MHZ, 880MHz to 980MHZ, 1800 - 1860MHz.
Wireless telephones 1.6 - 1.7MHZ, 36 - 37MHZ, 1900MHz
WLAN 2.4GHz - 2.5GHz, 5.1 - 5.2GHz

The primary distinction is by frequency band but there are different modulation methods and data rates used in most of them. Cell phones are polled by a control station to discover which are in range then allocated time slots so many can share the same frequency.

Brian.

Click to expand...

Thanks.
How do cellphones communicate with wireless telephones or with WLAN computers when they use different frequencies ? Do base stations convert informations present one cellphone frequency and write it on the wireless telephone frequency or WLAn frequency ? How does it work?

The simple answer is they have more than one system built into them. For example, my cellphone has NFC at 13.56MHz, Bluetooth at 2.4GHz, WLAN at 2.4GHz and 5.1GHz, 4G(LTE) at around 700MHz and also has dual band voice/data over the normal base station frequencies. These all have their own transmitters and receivers in the phone and can work independently, where one 'talks' to another it is done by software reading one and writing to the other.

Note that cell phones do not talk directly to each other, they talk to a base station where the audio is recovered and either re-transmitted to another cell phone in the same 'cell' or via wire/fiber to a more distant base station and then transmitted from there. Mobile cellphones generaly only have a range of a few Km so they need the base station to work as a relay to the other user.

Aside from the different frequencies, each type of transmission has its own format and protocols. These are the construction of the blocks of data and how they are passed from one point to another. They carry information on the type of data, where it originated and the destination it is to reach. The hardware and software in each system has to recognize and process the data to decide what to do with it.

For example: you call up a web page on a smart phone using WLAN -
the phone knows your IP address so it send a request for the page to be sent back to it
the WLAN picks it up and converts it to ADSL format, then passes it down the phone line.
At the far end, the ADSL is converted to ethernet and passed to the web server
The server replies by ethernet and sends the page for conversion to ADSL format
The ADSL arrives at your property where it connects to your WLAN router
The WLAN transmits it to your smartphone
The phone software extract the web content from the data stream and displays it.

There are almost certainly other steps involved, for example DHCP to allocate your IP address and DNS to finds the web page address but these are invisible to you as a user.

Brian.

Cellphone and base station communication

Hi

I would like to know. How do cellphones have enough power to send information to base stations ? Also, could you please describe me how can we calculate the maximum distance a cellphone signal can reach for exemple in desert (in a place where there is no base stations ) ?

Thank you

Cellphone transmitter power is controlled from the base station. It sends a signal back to the phone to tell it what power it needs to use, that way, if the signal is already strong it can extend your battery life by reducing transmitter power. Base stations have to be located in sensible positions to ensure they are visible to as many phones in the area as possible but obviously they do have a limited range.

Where there are no base stations in range, conventional cell phones simply do not work. The ones used in remote locations use a different technology, usually a direct link to a satellite but they are completely different to the ones commonly used and they are far more expensive to buy and use.

The distance a signal will reach is highy dependant on the local surroundings, as you may have noticed on a normal cell phone, the signal can drop significantly if you enter a building because of the shielding effect it has. Nearby objects, terrain and even other users in the vicinity will influence the range you can get.

Brian.