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Bug #4102

osmo-bts-trx: incorrect PTCCH handling

Added by fixeria 5 days ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
osmo-bts-trx
Target version:
-
Start date:
07/12/2019
Due date:
% Done:

0%

Spec Reference:
3GPP TS 45.002, 3GPP TS 45.010

Description

According to 3GPP TS 45.002, section 6.3.2.2.2, and 3GPP TS 45.010, section 3.3.4.2:

  • PTCCH/D (Packet Timing advance control channel, Downlink) is used to transmit Timing Advance updates for several MS. One PTCCH/D is paired with several PTCCH/U's. PTCCH/D frames are encoded using CS-1.
  • PTCCH/U (Packet Timing advance control channel, Uplink) is used to transmit random access bursts to allow estimation of the Timing Advance for one MS in packet transfer mode. PTCCH/U has 16 sub-channels (0..15) assigned to different MS using TAI.

Therefore, neither we properly handle Downlink PTCCH nor Uplink PTCCH in osmo-bts-trx:

https://git.osmocom.org/osmo-bts/tree/src/common/scheduler.c#n536

[TRXC_PTCCH] = {
    .name = "PTCCH", /* 3GPP TS 05.02, section 3.3.4.2 */
    .desc = "Packet Timing advance control channel",
    .chan_nr = RSL_CHAN_OSMO_PDCH,

    /* Same as for TRXC_BCCH (xCCH), see above. */
    .flags = TRX_CHAN_FLAG_PDCH,
    .rts_fn = rts_data_fn,
    .dl_fn = tx_data_fn, /* FIXME: we need tx_pdtch_fn() here! */
    .ul_fn = rx_data_fn, /* FIXME: we need rx_rach_fn() here! */
},

Related issues

Related to OsmoPCU - Feature #1545: continuous timing advance loop using PTCCHStalled02/23/2016

History

#1 Updated by fixeria 5 days ago

  • Related to Feature #1545: continuous timing advance loop using PTCCH added

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