1
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Series of minimal messages exchanged bitween BSC1, BSC2 and MSC.
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2
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================================================================
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3
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4
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HANDOVER REQUIRED (BSC1->MSC, 3.2.1.9)
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5
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(Source BSC asks to handover a subscriber)
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6
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Cause Tell the reason why we want to handover
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7
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Cell Identifier List (Preferred) Tell to which cell(s) do we want to handover.
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8
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Current Channyl Type 1 Tell which channel type we are currently using (e.g. 0001 = Voice)
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9
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Old BSS to New BSS information This is an optional field, but the spec says it should always be include, what do we put in here?
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10
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Speech version (used) Tell which speech version we are currently using (see also ASSIGNMENT COMPLETE msg)
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11
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AoIP: Speech Codec (used) Tell which codec we are currently using (see also ASSIGNMENT COMPLETE msg)
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12
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13
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HANDOVER REQUEST (MSC->BSC2, 3.2.1.8)
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14
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(MSC asks the target BSC for to take handover, much like ASSIGNMENT REQUEST)
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15
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Channel Type (see also ASSIGNMENT COMPLETE msg)
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16
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Encryption Information Tell the session key and the algorithm (but why is there a field "supported algorithms"? it can only one algo/one key!?)
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17
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Classmark Information 1 Tell clasmark information?
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18
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Classmark Information 2 Tell clasmark information?
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19
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Cell Identifier (Serving) Tell which cell is currently serving the subscriber (How are we supposed to know that?)
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20
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Cell Identifier (Target) Tell the cell that the MSC has decided for
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21
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AoIP Transport Layer Address (MGW) Tell where the target BSC should send its RTP stream
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22
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Codec List (MSC Preferred) Tell which codecs we prefer
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23
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Current Channel type 1 Tell channel type (same as in HANDOVER REQUIRED)
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24
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25
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HANDOVER REQUEST ACKNOWLEDGE (BSC2->MSC, 3.2.1.10)
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26
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(Other BSC acknowledges the handover, much like ASSIGNMENT COMPLETE
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27
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Layer 3 Information DTAP (RR) message to assign a new channel on the new BSC/Cell?
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28
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AoIP Transport Layer Address (BSS) Tell where the MSC side should send its RTP stream (MGW on the BSC2 side)
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29
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Codec List (BSS Supported) Tell which codecs the BSS supports (mandatory for AoIP, but probably not that important for us at the moment?)
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30
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Speech Version (Chosen) (See ASSIGNMENT COMPLETE)
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31
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Speech Codec (Chosen) (See ASSIGNMENT COMPLETE)
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32
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33
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HANDOVER COMMAND (MSC->BSC1, 3.2.1.11)
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34
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(Make the MS transitioning to the new cell)
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35
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Layer 3 Information DTAP (RR) message to assign a new channel on the new BSC/Cell?
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36
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37
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HANDOVER DETECT (3.2.1.40)
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38
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(MS got detected by the new cell and is in transition)
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39
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(no elements)
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40
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41
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HANDOVER COMPLETE (BSC1->MSC, 3.2.1.12)
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42
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(MS transition is complete, maybe this is also a good location to perform the
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43
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MDCX. Maybe its also a bit late until here. HANDOVER REQUEST ACKNOWLEDGE would
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44
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also be a candidate)
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45
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(no elements)
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46
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47
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CLEAR (MSC->BSC1)
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48
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49
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CLEAR COMPLETE (BSC1->MSC)
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50
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