RR conection establishment GSM/RRC connection procedure
BSSMAP call setup to MSC /MS service request/accept
Authebtication
Ciphering
CC setup
CC call proceeding
BSSMAP assignment requets from MSC to SS for voice /RANAP RAB setup
RR channel modify from BSC to BTS
IAM
ACM
CC alerting
ANM
http://www.eventhelix.com/RealtimeMantra/Telecom/GSM_Originating_Call_Flow.pdf
Tuesday, March 4, 2008
Location Update Procedure
Broad steps
Location Update request to VLR
Autentication
Autentication
Update lcoation to HLR
Cancel location to old VLR
Insert Subsriber data
TMSI reallocation
Cipheing
Location Update Accept
Routing ae Update
Saturday, February 16, 2008
Transport Formats
uConversational Speech (12 Kbps)
–12.2 Kbps max.
–TTI: 20 msec
–Transport Formats (TF) available:
TF RAB1 RAB2 RAB3
TF0v 0 x 81 0 x 103 0 x 60 (e.g., silence)
TF1v 1 x 81 1 x 103 1 x 60 (e.g, active voice)
two other formats too (see Stds. Doc.)
–TFC: (TF0, TF0, TF0) e.g., during silence
(TF1, TF1, TF1) e.g., during active voice periods
uInteractive/Background Data (64 Kbps)
– 64 Kbps max.
–TTI: 20 msec
–Transport Block (TB) size = 336 bits
–Transport Formats (TF) available:
»TF0 - 0 x 336
»TF1 - 1 x 336
»TF2 - 2 x 336
»TF3 - 3 x 336
»TF4 - 4 x 336
uConversational speech (12 Kbps) + Interactive/Background Data (64 Kbps)
Voice TrCH Data TrCH
TFC1: (TF0v, TF0v, TF0v) TF0d
TFC2: (TF0v, TF0v, TF0v) TF1d
TFC3: (TF0v, TF0v, TF0v) TF2d
TFC4: (TF0v, TF0v, TF0v) TF3d
TFC5: (TF0v, TF0v, TF0v) TF4d
TFC6: (TF1v, TF1v, TF1v) TF0d
TFC7: (TF1v, TF1v, TF1v) TF1d
TFC8: (TF1v, TF1v, TF1v) TF2d
TFC9: (TF1v, TF1v, TF1v) TF3d
TFC10: (TF1v, TF1v, TF1v) TF4d
TTI depends on the transport channel; {2,10, 20, 40, 80 ms})
–12.2 Kbps max.
–TTI: 20 msec
–Transport Formats (TF) available:
TF RAB1 RAB2 RAB3
TF0v 0 x 81 0 x 103 0 x 60 (e.g., silence)
TF1v 1 x 81 1 x 103 1 x 60 (e.g, active voice)
two other formats too (see Stds. Doc.)
–TFC: (TF0, TF0, TF0) e.g., during silence
(TF1, TF1, TF1) e.g., during active voice periods
uInteractive/Background Data (64 Kbps)
– 64 Kbps max.
–TTI: 20 msec
–Transport Block (TB) size = 336 bits
–Transport Formats (TF) available:
»TF0 - 0 x 336
»TF1 - 1 x 336
»TF2 - 2 x 336
»TF3 - 3 x 336
»TF4 - 4 x 336
uConversational speech (12 Kbps) + Interactive/Background Data (64 Kbps)
Voice TrCH Data TrCH
TFC1: (TF0v, TF0v, TF0v) TF0d
TFC2: (TF0v, TF0v, TF0v) TF1d
TFC3: (TF0v, TF0v, TF0v) TF2d
TFC4: (TF0v, TF0v, TF0v) TF3d
TFC5: (TF0v, TF0v, TF0v) TF4d
TFC6: (TF1v, TF1v, TF1v) TF0d
TFC7: (TF1v, TF1v, TF1v) TF1d
TFC8: (TF1v, TF1v, TF1v) TF2d
TFC9: (TF1v, TF1v, TF1v) TF3d
TFC10: (TF1v, TF1v, TF1v) TF4d
TTI depends on the transport channel; {2,10, 20, 40, 80 ms})
Friday, February 15, 2008
Stop & Wait ,Selective Repeat
HARQ can be used in stop-and-wait mode or in selective repeat mode. Stop-and-wait is simpler, but waiting for the receiver's acknowledgment reduces efficiency. Thus multiple stop-and-wait HARQ processes are often done in parallel in practice: when one HARQ process is waiting for an acknowledgment, another process can use the channel to send some more data.
Friday, February 8, 2008
Hyperframes
Hyperframes are 2048 superframe lasting 3.30 hrs approx.This hyperframe structure was uilt for ciphering so that the frame no does not repeat till 3hrs.
Radio connection set up fo dummies
The first procedure any mobile does after cell and plmn selection when it has to "do"(Locatio update,take call,make call) is to estalish a Radio connection first that is reserve physical path and logical resources at all nodes in between MS->BTS->BSS and MS->NodeB->RNC.
1.Initial access
2.Initial Message
So when Ms has to update its location or make a call or answer to a paging it first sends a RIL-3 RR channel request message with 3 its indicating cause and 5 bits as a random id to BTS.Th random id helps distingusish its request from other mobiles.In the case of UMTS the message is RRC connection request.This message is sent on a RACH transport channel which is mapped on to a physical Common Control Channel CCCH.
MS------RIL-3 channel request(3 bits,5bits)---------->BTS
UE-------RRC Connection Request----------------->BTS
IL-3 btw is Radio Interface Layer 3 .
The BTS on receivng this message knows that an MS is wanting a radio esource.So it asks BTS through RSM Channel Required message and sends it an approx timing delay for this MS which it knows y oserving the RACH.s
BTS(estimates delay)-------RSM Ch. Reqd---------------------->BSC
The BSC on receiving this reserves a Traffic channel for the mobile TCH/8/F in GSM or DCH in UMTS and when the BTS acknowleges this activation ,it sends a RR Immediate assignment with timing advance,power,time slot no,and reference.In case of UMTS it will the scrambing code and channelisation code
Idiots ways.BTS resolves contention among the various moiles trying for a radio connection and and informs BSC about their transmission delay.BSC actually reserves traffic channel and infoms BTS in turn MS about max tx power,timing advance delay etc.
1.Initial access
2.Initial Message
So when Ms has to update its location or make a call or answer to a paging it first sends a RIL-3 RR channel request message with 3 its indicating cause and 5 bits as a random id to BTS.Th random id helps distingusish its request from other mobiles.In the case of UMTS the message is RRC connection request.This message is sent on a RACH transport channel which is mapped on to a physical Common Control Channel CCCH.
MS------RIL-3 channel request(3 bits,5bits)---------->BTS
UE-------RRC Connection Request----------------->BTS
IL-3 btw is Radio Interface Layer 3 .
The BTS on receivng this message knows that an MS is wanting a radio esource.So it asks BTS through RSM Channel Required message and sends it an approx timing delay for this MS which it knows y oserving the RACH.s
BTS(estimates delay)-------RSM Ch. Reqd---------------------->BSC
BTS<------------activate chaanel inform------------------------------
BTS
BTS-----------activated-----------------------------------------?
The BSC on receiving this reserves a Traffic channel for the mobile TCH/8/F in GSM or DCH in UMTS and when the BTS acknowleges this activation ,it sends a RR Immediate assignment with timing advance,power,time slot no,and reference.In case of UMTS it will the scrambing code and channelisation code
Idiots ways.BTS resolves contention among the various moiles trying for a radio connection and and informs BSC about their transmission delay.BSC actually reserves traffic channel and infoms BTS in turn MS about max tx power,timing advance delay etc.
What is transmission delay?
The transmission delay is the delay that a timeslot in a fame takes to reach BTS.
The MS Tx is synchronized with BTS Rx ( both know that the beginning of the RACH TS number N is moment "t0" ).
lets say ms decides to tansmit access burst at slot N at time t0.Bts on receiving that n frame knows that it was to be received in time t0 but has en received at t1.So it will ask MS to advance its time for the the slot by t1-t0 so that when traffic resumes on traffic channel SDCCH/DCH/TCH it will arrive in time.
http://www.erlang.com/forum/erlang/thread.htx?thread=3614
MS meanwhile should monitor the whole PAGCH for its ref no (40 bursts in a 51 *8 burts tp) of the corresponding RACH since the immediate assignment can come in any of the 9 blocks of 51*8 BP.
PAging contol and broadcast channel use 40 slots per 51 *8 cycle .PAGCH uses 9 blocks pe cycle.
These 40 slots are divided into 10 blocks of 4 .The BCCH uses first block after which PAGCH uses 9 blocks .
A parameter tells which of these blocks belongs to which paging subchannel and immediate assignment.There will e atleast one for imm asignment so the rest are reserved for paging suchannels which will vary from 2 to 9.
Paging subchannel is cyclic from 2 to 9 times th 51*8 P.So a paging subchannel can be numbered from 2 to 81.
MS----------------SABM L0 id,class,reason-------------->BTS
BTS------------RSM Establish Indiaction-------------------BSS------->SCCp Conn Req+ initial message RIL-3 MMpaging resp/lu Req/imsi detach/cmservice request)---->MSC
Now MSC is aware of the MS.
RR access ends here after a connection between MS and MSC.RR session is fully established.
MS<---------------UA id------------------------------>BTS
After the MS knows of the traffic channel and SDCCH it sends a SABM link layer message with its unique id and classmark,reason .In case another mobile had the same ref and reason this SABM will distinguish who the immediate assignment was for.BTS
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