hi,
i just encountered the following problem:
the network assigns me from TS 1 to TS 3 it worked, but not when it did
another assigment from TS 3 to TS4. i just got noise instead of valid
SACCH frames.
TS Chg forth: 1 -> 3 | 1856
...
TS Chg forth: 3 -> 4 | 1875
this is the wireshark trace of both assignments. they only differ in the
assigned slot:
Frame 3225: 81 bytes on wire (648 bits), 81 bytes captured (648 bits)
Ethernet II, Src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst:
00:00:00_00:00:00 (00:00:00:00:00:00)
Internet Protocol Version 4, Src: 127.0.0.1 (127.0.0.1), Dst: 127.0.0.1
(127.0.0.1)
User Datagram Protocol, Src Port: 52261 (52261), Dst Port: gsmtap (4729)
GSM TAP Header, ARFCN: 34 (Downlink), TS: 1, Channel: SDCCH/8 (0)
Link Access Procedure, Channel Dm (LAPDm)
GSM A-I/F DTAP - Assignment Command
Protocol Discriminator: Radio Resources Management messages
DTAP Radio Resources Management Message Type: Assignment Command (0x2e)
Channel Description 2 - Description of the First Channel, after time
0000 1... = TCH/F + FACCH/F and SACCH/F
.... .011 = Timeslot: 3
000. .... = Training Sequence: 0
...1 .... = Hopping channel: Yes
Hopping channel: MAIO 0
Hopping channel: HSN 0
Power Command
0... .... = Spare: 0
.0.. .... = EPC_mode: Channel(s) not in EPC mode
..0. .... = FPC_EPC: FPC not in use/C not in use for uplink
power control
...0 0101 = POWER LEVEL: 5
Frequency List - Frequency List, after time
Element ID: 5
Length: 16
00.. 000. = Format Identifier: bit map 0 (0x00)
List of ARFCNs = 99 34
Channel Mode - Mode of the First Channel(Channel Set 1)
Element ID: 99
Channel Mode: speech full rate or half rate version 2(GSM EFR) (33)
No. Time Source Destination Protocol
Info
3243 464.672890 127.0.0.1 127.0.0.1 LAPDm
I, N(R)=1, N(S)=2(DTAP) (RR) Assignment Command
Frame 3243: 81 bytes on wire (648 bits), 81 bytes captured (648 bits)
Ethernet II, Src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst:
00:00:00_00:00:00 (00:00:00:00:00:00)
Internet Protocol Version 4, Src: 127.0.0.1 (127.0.0.1), Dst: 127.0.0.1
(127.0.0.1)
User Datagram Protocol, Src Port: 52261 (52261), Dst Port: gsmtap (4729)
GSM TAP Header, ARFCN: 99 (Downlink), TS: 3, Channel: FACCH/F (0)
Link Access Procedure, Channel Dm (LAPDm)
GSM A-I/F DTAP - Assignment Command
Protocol Discriminator: Radio Resources Management messages
DTAP Radio Resources Management Message Type: Assignment Command (0x2e)
Channel Description 2 - Description of the First Channel, after time
0000 1... = TCH/F + FACCH/F and SACCH/F
.... .100 = Timeslot: 4
000. .... = Training Sequence: 0
...1 .... = Hopping channel: Yes
Hopping channel: MAIO 0
Hopping channel: HSN 0
Power Command
0... .... = Spare: 0
.0.. .... = EPC_mode: Channel(s) not in EPC mode
..0. .... = FPC_EPC: FPC not in use/C not in use for uplink
power control
...0 0101 = POWER LEVEL: 5
Frequency List - Frequency List, after time
Element ID: 5
Length: 16
00.. 000. = Format Identifier: bit map 0 (0x00)
List of ARFCNs = 99 34
Channel Mode - Mode of the First Channel(Channel Set 1)
Element ID: 99
Channel Mode: speech full rate or half rate version 2(GSM EFR) (33)
any idea why this does not work? i used the "[WIP] Ugly hack to
compensate lost time on TS change (high TS -> low TS)" path.
regards,
andreas
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Hi,
i just encountered the following problem:
the network assigns me from TS 1 to TS 3 it worked, but not when it did
another assigment from TS 3 to TS4. i just got noise instead of valid
SACCH frames.
TS Chg forth: 1 -> 3 | 1856
...
TS Chg forth: 3 -> 4 | 1875
My guess is that somehow the fact they're contiguous makes something fail ...
This whole timeslot alignement thing is highly unstable ...
I think I need to code a special version of OpenBTS that broadcast on
each burst the TS it belongs to and the frame number and then do some
stress test of timeslot changing.
Cheers,
Sylvain
TS Chg forth: 1 -> 3 | 1856
...
TS Chg forth: 3 -> 4 | 1875
i wonder why the network pushs me from one slot to another... i have no
idea what this might be good for.