Frame Structure: Aster RNPD Prepared by Sumit Kumar
Frame Structure: Aster RNPD Prepared by Sumit Kumar
Frame Structure: Aster RNPD Prepared by Sumit Kumar
NORMAL BURST
Frame 1 (4.615 ms.)
Frame 2
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
0.577 ms.
0.546 ms.
3
Guard
Period
57 bits
Tail
Bits
Data
1
Flag
Bit
26 bits
Training
Sequence
1
FlagBit
57 bits
Data
Tail
Bit
3
Guard
Period
Normal Burst carries traffic channel and control channels BCCH, PCH,
AGCH, ADCH, SACCH and FACCH.
DESCRIPTION
EQUALISER
The equaliser will mainly address the problems of intersymbol interference
the problem is that the air interface affects the signal in some way that
causes bit error on the receiving side. If it was known in which way the
signals were affected, the system could take measures to correct the errors.
In a normal burst, used for traffic there is a 26 bit training sequence in the
middle of the burst. The bit pattern in this training sequence is known to
the system. By analysing it the system will know what the air interface
looks like and how it is affecting the signal sent.
By analysing the training sequence a channel model can be built. This
channel model is like a filter affecting the transmitted bits in the same
manner that the air interface is affecting them. By running different bit
patterns through the channel model and comparing the resulting signal
with what was actually received, the system can reach a conclusion as
to what was actually sent.
SYNCHRONIZATION BURST
Frame 1 (4.615 ms.)
Frame 2
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
0.577 ms.
0.546 ms.
3
Guard
Period
39 bits
Tail
Bits
Encrypted
Bits
39 bits 3
64 bits
Synchronization
Sequence
Encrypted
Bits
Tail
Bit
Guard
Period
Frame 2
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
0.577 ms.
0.546 ms.
3
Guard
Period
142 bits
Tail
Bits
Fixed Data
3
Tail
Bit
Guard
Period
ACCESS BURST
Frame 1 (4.615 ms.)
Frame 2
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
0.577 ms.
8
Tail
Bits
41 bits
36 bits
Synchronization
Sequence
Encrypted
Bits
Tail
Bits
68.25 bits
Guard
Period
Carries RACH
Has a bigger guard period since it is used during initial access and the MS.
does not know how far it is actually from the BTS.
DUMMY BURST
Frame 1 (4.615 ms.)
Frame 2
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
0.577 ms.
0.546 ms.
3
Guard
Period
57 bits
Tail
Bits
Data
1
Flag
Bit
26 bits
Training
Sequence
1
FlagBit
57 bits
Data
Tail
Bit
3
Guard
Period
6.12s
2045
2046
47 48 49 50
24
120 ms
0 1 2
2047
0 1 2
0
25
235.38 ms
23 24 25
0 1 2
48 49 50
TDMA Frame
MS Uplink
If Uplink and Downlink are aligned exactly, then MS will have to transmit
And receive at the same time. To overcome this problem a offset of 3
Timeslot is provided between downlink and uplink.
BSS Downlink
MS Uplink
3 Timeslot
offset
As seen the MS does not have to transmit and receive at the same time
This simplifies the MS design which can now use only one synthesizer.
T T T T T T T T T T T T S T T T T T T T T T T T T T
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
120 ms.
MS on dedicated mode on a TCH uses a 26 - frame multiframe structure.
Frame 0 - 11 and 13 - 24 used to carry traffic.
Frame 12 used as SACCH to carry control information from and to MS
To BTS.
Frame 25 is idle and is used by mobile to decode the BSIC of neighbour
cells.