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 |
