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L1A L23 Interface » History » Version 2

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spaar, 02/19/2016 10:48 PM
the payload is 23 bytes !?!


= Minimalistic L1 interface =

This is the description of the minimal interface between L1 and higher layers (L23)
neccessary to establish a dedicated channel with the cell and perform procedures like
LOCATION UPDATE or AUTHENTICAITON.

Message Types

=== SYNC_NEW_CCCH_REQ ===

Triggers the following actions in L1: * switch to new ARFCN * perform AGC + AFC * synchronize to FCCH * decode SCH and determine frame number

==== parameters ==== * ARFCN + BAND

==== response ==== * SYNC_NEW_CCCH_RESP

=== SYNC_NEW_CCCH_RESP ===
Sent from the L1 to the L23 after it has synchronized to a new cell (FCCH and SCH acquisition)

==== parameters ==== * struct l1_info_dl * ARFCN + BAND * GSM frame number (t1/t2/t3) * Rx Level * SNR * BSIC

=== CCCH_INFO_IND ===

Sent by the L1 to the L23 whenever it has successfully decoded four consecutive bursts on
the CCCH.

It is up to the L23 to decide whether the burst belongs to BCCH, AGCH, PCH or SDCCH/4.

==== parameters ==== * ARFCN + BAND * GSM frame number * Rx Level * SNR * 23 bytes L1 payload

=== RACH_REQ ===

Sent from the L23 to the L1 to instruct the L1 to send a RACH request to the current cell.

==== parameters ==== * struct l1_info_ul * Tx power * TDMA frame number * channel type * channel number (timeslot, subslot) * 8 bit RA Reference

==== response ====
No response by L1.

The response by the serving cell will be an IMMEDIATE ASSIGNMENT in the AGCH on
the CCCH downlink.

=== DEDIC_MODE_EST_REQ ===

Sent from the L23 to the L1 to instruct switching from CCCH mode to a dedicated
channel.

Initially we only implement SDCCH/4 and SDCCH/8 on a non-hopping cell.

==== parameters ==== * struct l1_info_ul * (arfcn|hsn,maio)

=== DEDIC_MODE_DATA_IND ===

Sent by the L1 to the L23 to convey the successful reception of four
consecutive bursts on the dedicated channel.

It is up to the L23 to do the time demultiplex of multiple SDCCHs in the same
on-air timeslot.

==== parameters ==== * struct l1_info_dl * 23 bytes L1 payload

=== DEDIC_MODE_DATA_REQ ===
Sent by the L23 to the L1 to send payload data on a dedicated channel such as
SDCCH.

==== parameters ==== * struct l1_info_ul * 23 byte L1 payload