BSSPAR115 Chapter 01 Radio Resource Administration MO v3.2

 

Radio Resource Administration CHAPTER 1

©  NOKIA

BSSPAR / 11.2006-V3

 

Module Objectives • Give an overview about the TDMA frame structure • Describe the logical channels, their mapping to TDMA frames frames and their parameters • Demonstrate, how the signalling capacity effect the mapping of the logical channels • Give an overview about the use of extended cells • Describe the purpose of the Base Station Identity Code and the Training Sequence

Code • Explain the use of FDMA and frequency reuse • Discuss the parameter settings required for base band and RF frequency hopping

©  NOKIA

BSSPAR / 11.2006-V3

 

Radio Resource Administration

Basic TDMA Structure 5 3 4

2

physical channel

1

e.g. allocated to one subscriber with FR voice and no frequency hopping

0 7 6 4

5

frame  TDMA frame  = 8 timeslots = 4.615 ms

3

2 1 0 7

6 5

2 2 2

4 3

2

frame  TDMA frame 

1 0

200 kHz ©  NOKIA

BSSPAR / 11.2006-V3

frequency

 

Radio Resource Administration

Multi, Super and Hyper Frame

2048 super frames = hyper frame

2047

0

0 1 2 0 1

0

1

2

Super frame = 26 x 51 multi frames or 51 x 26 multi fram frames es

24 25

0 7 TDMA frame = 4.615 ms BSSPAR / 11.2006-V3

0 1 22

48 49 50 24 25

49 50 50 49

51 multi frame = 235 ms

26 multi frame = 120 ms

©  NOKIA

TDMA frame numbering

 

Radio Resource Administration

GSM Channel Organisation

Logical Channels for transport of specific content mapping

Physical Channels

MS

transport medium Physical channel parameters ARFCN Time slot number Frequency hopping algorithm ©  NOKIA

BSSPAR / 11.2006-V3

Base Station Subsystem

 

Radio Resource Administration

Logical Channels

BCH

DL

Common Channels

DL UL CCCH

DL DL

DCCH Dedicated Channels TCH ©  NOKIA

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UL/DL UL/DL

FCCH   FCCH

Frequency Correction Channel

SCH   SCH

Synchronisation Channel

BCCH   BCCH

Broadcast Control Channel

CBCH

Cell Broadcast Channel

PCH   PCH

Paging Channel

RACH   RACH

Random Access Channel

AGCH   AGCH

Access Grant Channel

NCH   NCH

Notification Channel

SDCCH   SDCCH

Stand alone Dedicated Control Channel

SACCH   SACCH

Slow Associated Control Channel

FACCH   FACCH

Fast Associated Control Channel

...  ... 

 

Radio Resource Administration

TCH

Traffic Channels TCH/FR

TCH for Full Rate speech

TCH/EFR

TCH for Enhanced Full Rate speech

TCH/HR

TCH for Half rate Speech

TCH/F9.6

TCH for full rate data transmission with 9.6 kbit/s

TCH/F4.8

TCH for full rate data transmission with 4.8 kbit/s

TCH/H4.8

TCH for half rate data transmission with 4.8 kbit/s

TCH/F2.4

TCH for full rate data transmission with  2.4 kbit/s

TCH/H.2.4

TCH for half rate data transmission with  2.4 kbit/s

 

. . .

©  NOKIA

BSSPAR / 11.2006-V3

 

Radio Resource Administration

Traffic Channel Mapping

Full Rate Traffic Channel Configuration (UL & DL) 26 TDMA frames = 120 ms

t t t t t t t t t t t t sf t t t t t t t t t tf t t i 1

26

t = full rate TCH, s = SACCH/T SA CCH/T,, i = idle TDMA T DMA frame

Half Rate Traffic Channel Configuration (UL & DL) 26 TDMA frames = 120 ms t

t

t T

T

t T . .

©  NOKIA

BSSPAR / 11.2006-V3

T

t T

T

s f

t T

t T

t T

t T

T

t f

t T

S

  26 t = half rate TCH, s = SACCH/T (first user) T = half rate TCH, S = SACCH/T (second user) TDMA T DMA frame .

1

t

 

Radio Resource Administration

Signalling Channel Mapping (BCCH + SDCCH/4 + SACCH/C4)

Downlink

51 TDMA frames = 235 ms

1 f s

f sf BCCH CCCH

f s

CCCH CCCH

51

f s

f s

SDCCH 0 SDCCH 2 SDCCH 1 SDCCH 3

SACCH 0/2 SACCH 1/3

Uplink 51 TDMA frames = 235 ms

1 f

rr

SDCCH 3

BSSPAR / 11.2006-V3

51

r r r r r r r r rf r r r r r r r r r rf r r r r

SACCH 2/0 SACCH 3/1

©  NOKIA

-

f

r r

SDCCH 0 SDCCH 3 SDCCH 1 f = FCCH, s = SCH, r = RACH TDMA frame - = dummy burst

 

Radio Resource Administration

Signalling Channel Mapping (BCCH +CCCH/9)

Downlink

51 TDMA frames = 235 ms

1 f s

f sf BCCH CCCH

Uplink

f s

CCCH CCCH

f s CCCH CCCH

51 f s

CCCH CCCH

CCCH CCCH

51 TDMA frames = 235 ms

1

r r r r r r r r r r r r rf r r r r r r r r r rf r r r r r r r r r rf r r r r r r r r r rf r r r r r r r r

f = FCCH, s = SCH, r = RACH TDMA frame - = dummy burst

©  NOKIA

BSSPAR / 11.2006-V3

51

 

Radio Resource Administration

Signalling Channel Mapping (SDCCH/8 +SACCH/C4)

Downlink

51 TDMA frames = 235 ms

1

51 i i i

f

SDCCH 0 SDCCH 6 SDCCH 2 SACCH SDCCH 4 SACCH 0/4 SDCCH 1 SDCCH 7 SDCCH 3 SACCH 2/6 SACCH SDCCH 5 1/5 3/7

Uplink 1

51 TDMA frames = 235 ms

f

fi i i

SACCH SACCH 6/2 SACCH 7/3 5/1

SACCH SDCCH 6 SDCCH 2 SDCCH 4 SDCCH 0 SDCCH 1 SDCCH 7 4/0 SDCCH 3 SDCCH 5 i = idle TDMA frame

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BSSPAR / 11.2006-V3

51

 

Radio Resource Administration

Channel Mapping (Parameter Setting)

Channel configuration defined by parameter channelType TCHF TCHH TCHD ERACH NOTUSED SDCCH MBCCH MBCCHC MBCCB SDCCB MPBCCH

©  NOKIA

= full rate traffic channel = half rate traffic channel = dual rate traffic channel = random access channel of extended area = timeslot has no radio definition or Abis allocation = SDCCH/8 +SACCH/C4 = broadcast control channel = BCCH + SDCCH/4 + SACCH/C4 = BCCH + SDCCH/4 with CBCH = SDCCH with CBCH = PBCCH + PCCCH + PTCCH packet control channels

BSSPAR / 11.2006-V3

 

Radio Resource Administration

Dynamic SDCCH Allocation

Static SDCCHs overbooked -> Free TCHs used for SDCCH traffic

Rules for dynamic SDCCH allocation:   • SDCCH is configured to TRX with least leas t number of SDCCHs or no SDCCHs yet at all • SDCCH is configured to TRX with least number of occupied channels • If between different types of TCHs TCHs must be selected, the preference order is: HR, FR, DR TCH • Intelligent underlay overlay network: dynamic SDCCHs supported by regular TRXs only Dynamic SDCCH allocation + FACCH call set up enabled simultaneously -> dynamic SDCCH allocation has higher priority Exceptions: • Configuration of any dynamic SDCCH resource in the BTS not possible • Only one TCH of the BTS is available

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Maximum SDCCH Capacity •

The upper limit for the number of SDCCHs in the BSC depends on the number of TRXs that are connected to the BSC Signalling Units (BCSU) and the number of BCSUs that are working in the BSC.

•

The maximum SDCCH capacity of the BCSU is calculated with the following formula:

•

Max_ SDCCH SDCCH _count_per_BCSU = 12 * Max_TRX_count_per_BCSU

•

Max_ SDCCH SDCCH _count_per_BCSU includes both the static SDCCHs, which you configure, and an d

•

the dynamic dynamic   SDCCH resources The absolute limit is that the maximum SDCCH number in a TRX must not exceed 16 channels .

•

• •

The maximum number of dynamic and static SDCCH channels together is limited to 12 subchannels (that is, SDCCH/4 and SDCCH/8) in the TRXs that use the 16 kbit/s link for the Telecom signalling. TRXs of higher capacity signalling link (32 kbit/s or 64 kbit/s) can be configured up to 16 SDCCHs. The above constraint is due to the fact that with 16kbps TRX signaling, only 18 RTSLs per TRX can be supported. This is a theoretical limitation, and higher configurations are possible but not advisable.

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BSSPAR / 11.2006-V3

 

Radio Resource Administration

FACCH Call Set Up

Alternative to dynamic SDCCH allocation • Assignment of TCH to MS from CCCH instead of SDCCH • Call set up on FACCH instead on SDCCH

Parameters newEstabCausesSupport(NECI) ordinaryCallOnFacch (EOF) emerCallOnFacch (EEF) reestablishOnFacch (ERF)

Y/N Y/N Y/N Y/N

Enables feature is general Enables ordinary call set up on FACCH Enables emergency call set up on FAC FACCH CH Enables call reestablishment on FA FACCH CCH

•Main difference between FACCH Call Set-Up and Dynamic SDCCH is that in the former, same TSL as used for SDCCH is used for TCH, done through “MODE MODIFY” command from MSC. 

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BSSPAR / 11.2006-V3

 

Radio Resource Administration

PCH Parameters

Mobile terminating call -> MSC performs paging MS identifies paging message with the IMSI/TMSI MS listens to own paging group only

BSC parameters noOfMultiframesBetweenPaging (MFR) listens to

2..9 multi frames

Defines how often MS paging

MSC parameters  parameters  Repaging Interval

50..100 ms

Repaging Attempts

0..5

Time between consecutive paging attempts Number of paging repetitions

Buffering BTS stores up to 8 paging messages of the MSC in page group buffer BTS sends paging messages to MS according noOfMultiframesBetweenPaging ©  NOKIA

BSSPAR / 11.2006-V3

 

Radio Resource Administration

RACH Parameters

Mobile sends channel requests to BTS seperated by random time intervals in case of no answer! Parameters maxNumberRetransmission (RET) numberOfSlotsSpreadTrans (SLO)

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BSSPAR / 11.2006-V3

1,2,4,7

Defines maximum allowed

3..12,14,16,20,25,32,50

number of retransmissions Defines time interval between consecutive retransmissions

 

Radio Resource Administration

AGCH Parameters

Network gives the MS dedicated resources Downlink CCCH blocks PCH can be used for AGCH messages AGCH cannot be used for PCH messages Reservation of CCCH blocks bloc ks for AGCH noOfBlocksForAccessGrant

0..7 possible number, if CCCH and SDCCH are not combined 1..7 possible number, if CBCH is used in non combined configuration 0..2 possible number, if CCCH and SDCCH are combined

Preference of AGCH messages on PCH  0 noOfBlocksForAccessGrant =0

PCH can be used only, only, if no paging messages have to be send AGCH messages have higher priority than PCH ones

Number of paging groups N = (number of CCCH blocks – noOfBlocksForAccessGrant) * noOfMultiframesBetweenPaging ©  NOKIA

BSSPAR / 11.2006-V3

 

Radio Resource Administration

Chs

©  NOKIA

Erlang B Table 1%

2%

3%

5%

1

0 .0 1

0 .0 2

0 .0 3

0 .0 5

2

0 .1 5

0 .2 2

0 .2 8

3

0 .4 6

0 .6 0

4

0 .8 7

5

1%

2%

3%

5%

21

1 2 .8 0

1 4 .0 0

1 4 .9 0

1 6 .2 0

0 .3 8

22

1 3 .7 0

1 4 .9 0

1 5 .8 0

1 7 .1 0

0 .7 2

0 .9 0

23

1 4 .5 0

1 5 .8 0

1 6 .7 0

1 8 .1 0

1 .0 9

1 .2 6

1 .5 2

24

1 5 .3 0

1 6 .6 0

1 7 .6 0

1 9 .0 0

1 .3 6

1 .6 6

1 .8 8

2 .2 2

25

1 6 .1 0

1 7 .5 0

1 8 .5 0

2 0 .0 0

6

1 .9 1

2 .2 8

2 .5 4

2 .9 6

26

1 7 .0 0

1 8 .4 0

1 9 .4 0

2 0 .9 0

7

2 .5 0

2 .9 4

3 .2 5

3 .7 5

27

1 7 .8 0

1 9 .3 0

2 0 .3 0

2 1 .9 0

8

3 .1 3

3 .6 3

3 .9 9

4 .5 4

28

1 8 .6 0

2 0 .2 0

2 1 .2 0

2 2 .9 0

9

3 .7 8

4 .3 4

4 .7 5

5 .3 7

29

1 9 .5 0

2 1 .0 0

2 2 .1 0

2 3 .8 0

10

4 .4 6

5 .0 8

5 .5 3

6 .2 2

30

2 0 .3 0

2 1 .9 0

2 3 .1 0

2 4 .8 0

11

5 .1 6

5 .8 4

6 .3 3

7 .0 8

31

2 1 .2 0

2 2 .8 0

2 4 .0 0

2 5 .8 0

12

5 .8 8

6 .6 1

7 .1 4

7 .9 5

32

2 2 .0 0

2 3 .7 0

2 4 .9 0

2 6 .7 0

13

6 .6 1

7 .4 0

7 .9 7

8 .8 3

33

2 2 .9 0

2 4 .6 0

2 5 .8 0

2 7 .7 0

14

7 .3 5

8 .2 0

8 .8 0

9 .7 3

34

2 3 .8 0

2 5 .5 0

2 6 .8 0

2 8 .7 0

15

8 .1 1

9 .0 1

9 .6 5

1 0 .6 0

35

2 4 .6 0

2 6 .4 0

2 7 .7 0

2 9 .7 0

16

8 .8 8

9 .8 3

1 0 .5 0

1 1 .5 0

36

2 5 .5 0

2 7 .3 0

2 8 .6 0

3 0 .7 0

17

9 .6 5

1 0 .7 0

1 1 .4 0

1 2 .5 0

37

2 6 .4 0

2 8 .3 0

2 9 .6 0

3 1 .6 0

18

1 0 .4 0

1 1 .5 0

1 2 .2 0

1 3 .4 0

38

2 7 .3 0

2 9 .2 0

3 0 .5 0

3 2 .6 0

19

1 1 .2 0

1 2 .3 0

1 3 .1 0

1 4 .3 0

39

2 8 .1 0

3 0 .1 0

3 1 .5 0

3 3 .6 0

20

1 2 .0 0

1 3 .2 0

1 4 .0 0

1 5 .2 0

40

2 9 .0 0

3 1 .0 0

3 2 .4 0

3 4 .6 0

BSSPAR / 11.2006-V3

Chs

 

Radio Resource Administration

Paging Example

Combined CCCH / SDCCH configuration noOfBlocksForAccessGrant 

=1

-> 2 CCCH blocks for PCH PCH  

3 MSs paged per paging message 2 blocks per multi frame

-> 3 pages per block -> 3 * 2 = 6 pages per multi frame

Number of pages per hour

-> 3600 s / 0.235 s * 6 = 91915

2 pages required per MS

-> 91915 / 2 = 45957 MSs per hour

©  NOKIA

BSSPAR / 11.2006-V3

BTS

3 MS

Paging_Request

BTS

3 MS

Paging_Request

 

Radio Resource Administration

Call Establishment & Location Update Example

Cell with 325 subscribers 1 call per subscriber once in a hour 1 location update (LU) per subscriber once in 2 hours

Duration of call assignment = 7 s 325 subscribers

-> 7 s / 3600 s = 1.94 mErl on SDCCH per subscriber -> 325 * 1.94 mErl = 0.6305 Erl on SDCCH

Reservation time for LU = 7s 325 subscribers

-> 7 s / 7200 s = 0.97 mErl on SDCCH per subscriber -> 0.3153 Erl on SDCCH

Total SDCCH traffic

-> 0.6305 Erl + 0.3153 Erl = 0.9458 Erl

Blocking probability = 1%

-> 5 SDCCHs required -> not combined with CCCH

©  NOKIA

BSSPAR / 11.2006-V3

 

Radio Resource Administration

Example Including SMS

Same cell with 325 subscribers Additional SMS traffic of 1 mErl per subscriber 325 subscribers

-> 325 * 1 mErl = 0.325 Erl on SDCCH

Total SDCCH traffic

-> 0.6305 Erl + 0.3153 Erl + 0.325 Erl = 1.2708

Blocking probability = 1%

-> 5 SDCCHs required -> not combined with CCCH

©  NOKIA

BSSPAR / 11.2006-V3

 

Radio Resource Administration

Base Station Identity Code

Base Station Identity Code BSIC = Network Colour Code NCC + Base Station Colour Code BCC bsIdentityCode

Setting of BSIC

NCC BCC

0..7, distinguishes between PLMNs 0..7, distinguishes between clusters

BSIC + frequency channel -> unique identity of adjacent cell

bcc = 1 f2 f1 f3

f1

bcc = 2

f1 bcc = 3

©  NOKIA

BSSPAR / 11.2006-V3

 

Radio Resource Administration

Training Sequence Code

Training Sequence Code TSC tsc

0..7

Setting of TSC

Used to determine signal distortion and bit error rate 57 bits 3

26 bits

encrypted bits

tail bits

1

57 bits

training sequence

stealing flag

1

encrypted bits

stealing flag

3

Burst on TCH

tail bits

received burst data* training sequence* data*

correlation expected burst ? ©  NOKIA

training sequence

BSSPAR / 11.2006-V3

difference

?

data*

± difference =

data

 

Radio Resource Administration

Frequency Division Multiple Access Example: GSM 900

Absolute radio frequency carrier number ARFCN 890

915

1

2

3

4

123 124

935

960 1

2

3

4

123 124

duplex distance 200 kHz

uplink direction ©  NOKIA

BSSPAR / 11.2006-V3

downlink direction

 

Radio Resource Administration

Frequency Reuse

Frequency to be used by TRX Setting of ARFCNs 

initialFrequency

f2 f2 f4

f1 f6

f3 f5

f3 f5

f4

f1

f7

f2

f7 f6 f4

f1 f3 f5

f7 f6

©  NOKIA

BSSPAR / 11.2006-V3

 

Radio Resource Administration

Frequency Information for MS

Idle mode -> MS listens on BCCH idleStateBCCHAllocation

0..255

0 = MS gets frequency information from initialFrequency lists of adjacent cells 1..255 = MS gets frequency information from double BCCH allocation list Indicates ARFCN values given by double BCCH allocation list

bCCHAllocationList

Dedicated mode -> MS listens on SACCH measurementBCCHAllocation

ADJ,IDLE

ADJ = MS gets frequency information from initialFrequency lists of adjacent cells IDLE = MS uses same double BCCH allocation  allocation  list as in idle mode

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BSSPAR / 11.2006-V3

 

Radio Resource Administration

Principle of Frequency Hopping

Frequency hopping techniques btsIsHopping (HOP)

BB,RF,N BB = base band hopping RF = RF hopping N = no frequency hopping at all  all 

Frequency  Call is transmitted through several frequencies to  to   • average the interference (interference diversity) • minimise the impact of fading (frequency diversity)

F 1  F 2  F 3 

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BSSPAR / 11.2006-V3

Time   Time

 

Radio Resource Administration

Base Band Hopping

TRXs do not hop Physical channels moved from one TRX to another Hopping sequence hoppingSequenceNumber

0..63 0 = cyclic hopping 1..63 = pseudorandom hopping  hopping 

Baseband Hopping 0 TRX 1 TRX 2

1

2

BC CH

7 Timeslot f1 f2

TRX 3

f3

TRX 4

f4

©  NOKIA

BSSPAR / 11.2006-V3

HSN1 Timeslot 0 hops over TRXs 2-4 only BCCH does not hop HSN2 Timeslots 1-7 hop over all TRXs

 

Radio Resource Administration

RF Hopping (Standard Technique)

TRXs do hop except TRX1 (provides BCCH) Up to 63 frequencies available defined by mobile allocation list -> better hopping gain mobileAllocationLi st mobileAllocationList 0..255

0 TRX 1

1

2

BC CH

Setting of ARFCN values usedMobileAlloca usedMobileAllocation tion 0 = BTS detached from any list 1..255 = indicates list which shall be used

7

Timeslot f1  – no hopping

TRX 2 TRX 3

f2,f3..fn – hopping according mobile allocation list One hopping sequence

TRX 4

number only

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BSSPAR / 11.2006-V3

 

Radio Resource Administration

RF Hopping (Flexible MAIO Management) MAIO

Freeform hopping Not adequate for MA list with consecutive ARFCN values Avoids co-channel interference But not adjacent channel interference

Sector 1

Flexible MAIO management MAIO increases with constant step size from one TRX to the next one  one  maioStep

Sector 2

0..62

maioOffset = 0, 6, 12 for sector 1, 2, 3 maioStep = 2 18 frequencies required (2 * number of hopping TRXs) Sector 3

©  NOKIA

BSSPAR / 11.2006-V3

TRX-1

BCCH

0

TRX-2

TCH

2

TRX-3

TCH

4

TRX-4

TCH

TRX-5

BCCH

6

TRX-6

TCH

8

TRX-7

TCH

10

TRX-8

TCH

TRX-9

BCCH

12

TRX-10

TCH

14

TRX-11

TCH

16

TRX-12

TCH

 

Radio Resource Administration

RF Hopping (Tight Frequency Reuse) Flexible MAIO management MAIO Offset + MAIO Step

Freeform hopping MAIO Offset

Band allocation:

Band allocation:

BCCH

BCCH

MA list Discrete ARFCN

MA list and BCCH frequency planning required

©  NOKIA

BSSPAR / 11.2006-V3

MA list Consecutive ARFCN

Only BCCH frequency planning required

 

Radio Resource Administration

Frequency Plan Changing

BSIC / TSC Frequencies Frequency hopping setting Intelligent underlay overlay TRX settings

©  NOKIA

BSSPAR / 11.2006-V3