RRLP » History » Version 1
admin, 02/19/2016 10:52 PM
add page on RRLP
1 | 1 | admin | = RRLP = |
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3 | RRLP is the ''Radio Resource LCS (Location Service) Protocol'' as specified first in GSM TS 03.41 |
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5 | It allows the GSM network operator to obtain very precise location information about a mobile phone, |
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6 | much more precise than is required for normal operation of the cellular network. |
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8 | The use of RRLP has been specified for emergency calls. However, nothing in its specification |
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9 | restricts its use to this application. |
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11 | In all known phones, RRLP operation is completely invisible to the user of the phone. |
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13 | As GSM networks do not need to authenticate themselves, anyone can run a ''false BTS'' attack and |
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14 | successively obtain precise position information on a given mobile phone. |
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16 | == RRLP Modes == |
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18 | RRLP operates in different ''modes''. |
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20 | == MS-based GPS == |
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22 | In this method, the phone operates a stand-alone GPS receiver like it can be found in personal navigation devices. |
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24 | The GPS receiver will do the regular GPS receive process, i.e. |
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25 | * iterate over the list of 64 possible scrambling codes and acquire the C/A signal |
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26 | * decode the actual data signal modulated onto the C/A carrier |
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27 | * measure the timing difference of arrival (TDOA) of the various satellite signals |
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28 | * compute a location estimate (GPS coordinates) based on the measurements |
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30 | This complete GPS position fix is then communicated to the SMLC inside the GSM core network. |
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32 | === Assistance Data === |
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34 | Most RRLP capable phones will request GPS assistance data from the network. |
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36 | The operation of the GPS receiver is similar to the regular MS-based GPS aporach described above, |
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37 | however the GPS receiver is now an A-GPS receiver that already knows the almanac/ephemeris data and |
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38 | can thus much more quickly acquire the signal. |
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40 | == MS-assisted GPS == |
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42 | In MS-assisted GPS, the MS does not compute the actual location. Instead, the location/position |
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43 | of the phone is computed in the SMLC (part of the GSM core network). |
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45 | FIXME |
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47 | == E-OTD == |
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49 | FIXME |