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L1A L23 Interface » History » Version 1

laforge, 02/19/2016 10:48 PM
describe the minimal required interface between L1A and L23

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= Minimalistic L1 interface =
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This is the description of the minimal interface between L1 and higher layers (L23)
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neccessary to establish a dedicated channel with the cell and perform procedures like
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LOCATION UPDATE or AUTHENTICAITON.
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== Message Types ==
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=== SYNC_NEW_CCCH_REQ ===
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Triggers the following actions in L1:
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 * switch to new ARFCN
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 * perform AGC + AFC
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 * synchronize to FCCH
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 * decode SCH and determine frame number
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==== parameters ====
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 * ARFCN + BAND
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==== response ====
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 * SYNC_NEW_CCCH_RESP
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=== SYNC_NEW_CCCH_RESP ===
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Sent from the L1 to the L23 after it has synchronized to a new cell (FCCH and SCH acquisition)
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==== parameters ====
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 * struct l1_info_dl
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  * ARFCN + BAND
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  * GSM frame number (t1/t2/t3)
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  * Rx Level
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  * SNR
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 * BSIC
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=== CCCH_INFO_IND ===
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Sent by the L1 to the L23 whenever it has successfully decoded four consecutive bursts on
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the CCCH.
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It is up to the L23 to decide whether the burst belongs to BCCH, AGCH, PCH or SDCCH/4.
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==== parameters ====
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 * ARFCN + BAND
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 * GSM frame number
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 * Rx Level
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 * SNR
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 * 33 bytes L1 payload
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=== RACH_REQ ===
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Sent from the L23 to the L1 to instruct the L1 to send a RACH request to the current cell.
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==== parameters ====
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 * struct l1_info_ul
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  * Tx power
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  * TDMA frame number
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  * channel type
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  * channel number (timeslot, subslot)
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 * 8 bit RA Reference
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==== response ====
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No response by L1.
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The response by the serving cell will be an IMMEDIATE ASSIGNMENT in the AGCH on
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the CCCH downlink.
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=== DEDIC_MODE_EST_REQ ===
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Sent from the L23 to the L1 to instruct switching from CCCH mode to a dedicated
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channel.
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Initially we only implement SDCCH/4 and SDCCH/8 on a non-hopping cell.
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==== parameters ====
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 * struct l1_info_ul
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 * (arfcn|hsn,maio)
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=== DEDIC_MODE_DATA_IND ===
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Sent by the L1 to the L23 to convey the successful reception of four
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consecutive bursts on the dedicated channel.
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It is up to the L23 to do the time demultiplex of multiple SDCCHs in the same
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on-air timeslot.
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==== parameters ====
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 * struct l1_info_dl
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 * 33 bytes L1 payload
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=== DEDIC_MODE_DATA_REQ ===
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Sent by the L23 to the L1 to send payload data on a dedicated channel such as
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SDCCH.
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==== parameters ====
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 * struct l1_info_ul
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 * 33 byte L1 payload
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