TDMA Frame

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4615 ms (1 TDMA Frame) -gtgtgtgt

577 us

MS1

OMCR --gt BCC SDC TCH TCH TCH TCH TCH TCH

TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7

These TSs (0 -gt 7) will take the foll Forms each 4615 ms

23

53

65

ms

12

0 m

s

TDMA Frame 0 FCH SDCCH(0) TCHF TCHH TCH TCH TCH TCH

TDMA Frame 1 SCH SDCCH(0) TCHF TCHH TCH TCH TCH TCH

TDMA Frame 2 BCCH SDCCH(0) TCHF TCHH TCH TCH TCH TCH

TDMA Frame 3 BCCH SDCCH(0) TCHF TCHH TCH TCH TCH TCH

TDMA Frame 4 BCCH SDCCH(1) TCHF TCHHTDMA Frame 5 BCCH SDCCH(1) TCHF TCHH

TDMA Frame 6 PAGCH SDCCH(1) TCHF TCHH




TDMA Frame 10 FCH SDCCH(2) TCHF TCHH

TDMA Frame 11 SCH SDCCH(2) TCHF TCHH

TDMA Frame 12PAGCH SDCCH(3)

SACCH














IDLE






MS2 MS3

SACCH for MS2

SACCH for MS3

23

53

65

ms


TDMA Frame 32 PAGCH SACCH(0) TCHF TCHH






TDMA Frame 38PAGCH SACCH(1)

SACCH


TDMA Frame 40 FCH SACCH(2) TCHF TCHH

TDMA Frame 41 SCH SACCH(2) TCHF TCHH







TDMA Frame 48 PAGCH IDLE TCHF TCHH


TDMA Frame 50 IDLE IDLE TCHF TCHH

TDMA Frame 51FCH SDCCH(0)

IDLE


TDMA Frame 53 BCCH SDCCH(0) TCHF TCHH












SACCH







SACCH for MS2

SACCH for MS3

SACCH for MS2








IDLE

TDMA Frame 78 PAGCH SDCCH(6)



TDMA Frame 81 FCH SDCCH(7)

TDMA Frame 82 SCH SDCCH(7)

TDMA Frame 83 PAGCH SACCH(4)








TDMA Frame 91 FCH SACCH(6)

TDMA Frame 92 SCH SACCH(6)







TDMA Frame 99 PAGCH IDLE


TDMA Frame 101 IDLE IDLE

SACCH for MS3

so each TS (egSDCCH) will repeat after 4615 ms - 577 us

26 Frame Traffic Channel MF TCH

51 Frame Control Channel MF BCC

51 Frame Control Channel MF SDC

Every TCH amp SDCCH has one SACCH

associated with it

Four PAGCH TSs = one CCCH block so

9 CCCH block in DL for paging and access

Through parameters we can set eg

2 blocks for AGCH and 7 blocks for PCH

in each 51 frame MF

eg n=8

One PCH block corresponds to one

paging subgroup if repeated after n

51 frame MFs called a paging cycle

1 paging cycle contains 1 pagingblock of each paging group

first FCH occupies TS0 then SCH in next frame then BCCH

completed in 102 frames

UPLINK

4615 ms (eg each RACH TS will be received in 4615 ms)

577 us

MS1 MS2 MS3



23

53

65

ms

12

0 m

s

TDMA Frame 0 RACH SDCCH(0) TCHF TCHH TCH TCH TCH TCH




TDMA Frame 4 RACH SDCCH(1) TCHF TCHH








TDMA Frame 12RACH SDCCH(3)

SACCH














IDLE







TDMA Frame 32 RACH SACCH(0) TCHF TCHH



SACCH for MS2

SACCH for MS3

23

53

65

ms




TDMA Frame 38RACH SACCH(1)

SACCH










TDMA Frame 48 RACH IDLE TCHF TCHH




IDLE














SACCH












SACCH for MS2

SACCH for MS3

SACCH for MS2



IDLE

TDMA Frame 78 RACH SDCCH(6)





TDMA Frame 83 RACH SACCH(4)
















TDMA Frame 99 RACH IDLE



SACCH for MS3


51 Frame Control Channel M BCC

51 Frame Control Channel M SDC

1 Burst = 1 TS

only RACH received by BTS in uplink


Superframes 1326 TDMA frames (26 x5 612 sec = 51 (26 Frame) or 26 (51 Frame ) MFHyperframes 2048 superframes 3 hr 28 min 53 sec 760 ms

Important

1 SACCH message = 4 SACHH TSs = complete measurement report

It is not by accident that the control channel multiframe is not a direct multiple of thetraffic channel multiframe From the diagram it can be seen that any given framenumber will only occur simultaneously in both multiframes every 1326 TDMA frames (26x 51) This number of TDMA frames is termed a ldquosuperframerdquo and it takes 612 s totransmit This arrangement means that the timing of the traffic channel multiframe isalways moving in relation to that of the control channel multiframe and this enables a MSto receive and decode BCCH information from surrounding cellsIf the two multiframes were exact multiples of each other then control channel timeslotswould be permanently lsquomaskedrsquo by traffic channel timeslot activity This changingrelationship between the two multiframes is particularly important for example to a MSwhich needs to be able to monitor and report the RSSIs of neighbour cells (it needs to beable to lsquoseersquo all the BCCHs of those cells in order to do this)The ldquohyperframerdquo consists of 2048 superframes this is used in connection with cipheringand frequency hopping The hyperframe lasts for over three hours after this time theciphering and frequency hopping algorithms are restarted

SACCH Multiframe - SACCH TSs in four consecutive 26-Frame TCH MFs or two 51 frame SDCCH MFsAs the MS only transmits or receives its own physical channel (normally containing TCHand SACCH) for one-eighth of the time it uses the remaining time to monitor the BCCHsof adjacent lsquotargetrsquo cells

It completes the process every 480 ms or four 26-TCH MFs (104 consecutive assigned TS) in dedicated mode and 47073 ms in idle mode ( 2 51-frame MFs)

The message that it sends to the BSS (on SACCH uplink) contains theRxLev RxQual RxLev_ncell(n)

The measurements are made over each SACCH multiframe which is 104 TDMA frames (480 ms)for a TCH and 102 TDMA frames for an SDCCH (idle amp dedicated modes respectively)

612 sec = 51 (26 Frame) or 26 (51 Frame ) MF Transmission Timing

Timing Advance TA

This advance is then superimposed upon the three timeslot nominal offset

BTS-MS


MS-BTS

- TA TS0 TS1 TS2 TS3 TS4

To simplify the design of the MS the GSM specifications specify an offset of threetimeslots between the BSS and MS timing thus avoiding the necessity for the MS to

The synchronization of a TDMA system is critical because bursts have to be transmitted and received within the ldquoreal timerdquo timeslots allotted to them

The GSM BTS caters for this problem by instructing the MS to advanceits timing ((that is transmit earlier) to compensate for the increased propagation delayThis advance is then superimposed upon the three timeslot nominal offset

The maximum timing advance is approximately 233 1048576s This caters for a maximum cell radius of approximately 35 km

TS5 TS6 TS7

DL

UL

Notes

23

53

65

ms








TDMA Frame 38PAGCH SACCH(1)

SACCH


TDMA Frame 40 FCH SACCH(2) TCHF TCHH

TDMA Frame 41 SCH SACCH(2) TCHF TCHH









TDMA Frame 50 IDLE IDLE TCHF TCHH

TDMA Frame 51FCH SDCCH(0)

IDLE














SACCH







SACCH for MS2

SACCH for MS3

SACCH for MS2








IDLE

























SACCH for MS3






associated with it





in each 51 frame MF

eg n=8







UPLINK


577 us

MS1 MS2 MS3



23

53

65

ms

12

0 m

s














SACCH














IDLE










SACCH for MS2

SACCH for MS3

23

53

65

ms





SACCH














IDLE














SACCH












SACCH for MS2

SACCH for MS3

SACCH for MS2



IDLE

























SACCH for MS3




1 Burst = 1 TS




Important








Timing Advance TA


BTS-MS


MS-BTS






TS5 TS6 TS7

DL

UL

Notes








IDLE

























SACCH for MS3






associated with it





in each 51 frame MF

eg n=8







UPLINK


577 us

MS1 MS2 MS3



23

53

65

ms

12

0 m

s














SACCH














IDLE










SACCH for MS2

SACCH for MS3

23

53

65

ms





SACCH














IDLE














SACCH












SACCH for MS2

SACCH for MS3

SACCH for MS2



IDLE

























SACCH for MS3




1 Burst = 1 TS




Important








Timing Advance TA


BTS-MS


MS-BTS






TS5 TS6 TS7

DL

UL

Notes






associated with it





in each 51 frame MF

eg n=8







UPLINK


577 us

MS1 MS2 MS3



23

53

65

ms

12

0 m

s














SACCH














IDLE










SACCH for MS2

SACCH for MS3

23

53

65

ms





SACCH














IDLE














SACCH












SACCH for MS2

SACCH for MS3

SACCH for MS2



IDLE

























SACCH for MS3




1 Burst = 1 TS




Important








Timing Advance TA


BTS-MS


MS-BTS






TS5 TS6 TS7

DL

UL

Notes



UPLINK


577 us

MS1 MS2 MS3



23

53

65

ms

12

0 m

s














SACCH














IDLE










SACCH for MS2

SACCH for MS3

23

53

65

ms





SACCH














IDLE














SACCH












SACCH for MS2

SACCH for MS3

SACCH for MS2



IDLE

























SACCH for MS3




1 Burst = 1 TS




Important








Timing Advance TA


BTS-MS


MS-BTS






TS5 TS6 TS7

DL

UL

Notes

23

53

65

ms





SACCH














IDLE














SACCH












SACCH for MS2

SACCH for MS3

SACCH for MS2



IDLE

























SACCH for MS3




1 Burst = 1 TS




Important








Timing Advance TA


BTS-MS


MS-BTS






TS5 TS6 TS7

DL

UL

Notes



IDLE

























SACCH for MS3




1 Burst = 1 TS




Important








Timing Advance TA


BTS-MS


MS-BTS






TS5 TS6 TS7

DL

UL

Notes




1 Burst = 1 TS




Important








Timing Advance TA


BTS-MS


MS-BTS






TS5 TS6 TS7

DL

UL

Notes




Important








Timing Advance TA


BTS-MS


MS-BTS






TS5 TS6 TS7

DL

UL

Notes


Timing Advance TA


BTS-MS


MS-BTS






TS5 TS6 TS7

DL

UL

Notes

TS5 TS6 TS7

DL

UL

Notes

TDMA Frame

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