L1A L23 Interface » History » Version 1
laforge, 02/19/2016 10:48 PM
describe the minimal required interface between L1A and L23
1 | 1 | laforge | = Minimalistic L1 interface = |
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2 | |||
3 | This is the description of the minimal interface between L1 and higher layers (L23) |
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4 | neccessary to establish a dedicated channel with the cell and perform procedures like |
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5 | LOCATION UPDATE or AUTHENTICAITON. |
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6 | |||
7 | == Message Types == |
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8 | |||
9 | === SYNC_NEW_CCCH_REQ === |
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10 | |||
11 | Triggers the following actions in L1: |
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12 | * switch to new ARFCN |
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13 | * perform AGC + AFC |
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14 | * synchronize to FCCH |
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15 | * decode SCH and determine frame number |
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16 | |||
17 | ==== parameters ==== |
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18 | * ARFCN + BAND |
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19 | |||
20 | ==== response ==== |
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21 | * SYNC_NEW_CCCH_RESP |
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22 | |||
23 | |||
24 | === SYNC_NEW_CCCH_RESP === |
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25 | Sent from the L1 to the L23 after it has synchronized to a new cell (FCCH and SCH acquisition) |
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26 | |||
27 | ==== parameters ==== |
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28 | * struct l1_info_dl |
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29 | * ARFCN + BAND |
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30 | * GSM frame number (t1/t2/t3) |
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31 | * Rx Level |
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32 | * SNR |
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33 | * BSIC |
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34 | |||
35 | |||
36 | === CCCH_INFO_IND === |
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37 | |||
38 | Sent by the L1 to the L23 whenever it has successfully decoded four consecutive bursts on |
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39 | the CCCH. |
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40 | |||
41 | It is up to the L23 to decide whether the burst belongs to BCCH, AGCH, PCH or SDCCH/4. |
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42 | |||
43 | ==== parameters ==== |
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44 | * ARFCN + BAND |
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45 | * GSM frame number |
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46 | * Rx Level |
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47 | * SNR |
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48 | * 33 bytes L1 payload |
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49 | |||
50 | |||
51 | === RACH_REQ === |
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52 | |||
53 | Sent from the L23 to the L1 to instruct the L1 to send a RACH request to the current cell. |
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54 | |||
55 | ==== parameters ==== |
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56 | * struct l1_info_ul |
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57 | * Tx power |
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58 | * TDMA frame number |
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59 | * channel type |
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60 | * channel number (timeslot, subslot) |
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61 | * 8 bit RA Reference |
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62 | |||
63 | |||
64 | ==== response ==== |
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65 | No response by L1. |
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66 | |||
67 | The response by the serving cell will be an IMMEDIATE ASSIGNMENT in the AGCH on |
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68 | the CCCH downlink. |
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69 | |||
70 | |||
71 | === DEDIC_MODE_EST_REQ === |
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72 | |||
73 | Sent from the L23 to the L1 to instruct switching from CCCH mode to a dedicated |
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74 | channel. |
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75 | |||
76 | Initially we only implement SDCCH/4 and SDCCH/8 on a non-hopping cell. |
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77 | |||
78 | ==== parameters ==== |
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79 | * struct l1_info_ul |
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80 | * (arfcn|hsn,maio) |
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81 | |||
82 | |||
83 | === DEDIC_MODE_DATA_IND === |
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84 | |||
85 | Sent by the L1 to the L23 to convey the successful reception of four |
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86 | consecutive bursts on the dedicated channel. |
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87 | |||
88 | It is up to the L23 to do the time demultiplex of multiple SDCCHs in the same |
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89 | on-air timeslot. |
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90 | |||
91 | ==== parameters ==== |
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92 | * struct l1_info_dl |
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93 | * 33 bytes L1 payload |
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94 | |||
95 | |||
96 | === DEDIC_MODE_DATA_REQ === |
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97 | Sent by the L23 to the L1 to send payload data on a dedicated channel such as |
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98 | SDCCH. |
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99 | |||
100 | ==== parameters ==== |
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101 | * struct l1_info_ul |
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102 | * 33 byte L1 payload |