Bsspar1 s14 chapter 02_radio_resource_administration_v1.1

1 © Nokia Siemens Networks

BSSPAR1: Chapter 2Radio Resource Administration


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Module Objectives

• Give an overview about the TDMA frame structure

• Describe the logical channels, their mapping to TDMA frames and their parameters

• Demonstrate, how the signalling capacity effect the mapping of the logical channels

• Describe the purpose of the Base Station Identity Code and the Training Sequence Code

• Explain the use of frequency reuse and the fundamentals of frequency hopping

• Discuss the parameter settings required for base band and RF frequency hopping


TDMA frame= 8 timeslots( 0.577ms * 8 = 4.615 ms)

01

34

5

76

01

23

45

76

01

23

45

200 kHz

Physical channel e.g. allocated to onesubscriber with FR voiceand no frequency hopping

frequency

time

TDMA frame2

2 2 2

Basic TDMA Structure


0 1 2 49 500 1 2 24 25

0 2047

0 1 2 48 49 500 1 24 25

0 7

2048 super frames = hyper frame

Super frame = 26 x (51 multi frame) or 51 x (26 multi frame)

26 multi frame = 120 ms 51 multi frame = 235 ms

TDMA frame = 4.615 ms

TDMA frame numbering

0 1 2 49 50

Multi, Super & Hyper Frames

(Traffic and associated signalling) (Signalling and Control channels)


Base StationSubsystem

Logical Channelsfor transport of specific content

Physical Channelstransport medium

MS

mapping

Physical channel parametersARFCNTime slot numberFrequency hopping algorithm

GSM Channel Organization


SCH

FCCH

PCH

BCCH

AGCH

RACH

SDCCH

SACCH

FACCH

Stand alone Dedicated Control Channel

Frequency Correction Channel

Synchronisation Channel

Broadcast Control Channel

Paging Channel

Slow Associated Control Channel

Fast Associated Control Channel

Paging Channel

Random Access Channel

Access Grant Channel

BCH

CCCH

DCCH

TCH

DL

DL

DL

UL

CommonChannels

DedicatedChannels

UL/DL

UL/DL

CBCH Cell Broadcast Channel

Logical Channels

FR/HR Full rate / Halft rate TCH

EFR Enhanced Full rate TCH

AMR FR/HR Adaptive multirate TCH (FR/HR)


...

26 TDMA frames = 120 ms

1 26

t t tt t t t ft tt t t tt t t tt ft t t ttts i

Full Rate Traffic Channel Configuration (UL & DL)

Half Rate Traffic Channel Configuration (UL & DL)


1 26

t

T T

t t

T

tf

t t

T T T T

t t

T

t

Tf

T

t

T

tt

T

s

S

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

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

Traffic Channel Mapping


f s ff s f s

Downlink51 TDMA frames = 235 ms

-

Uplink

BCCH CCCH

f s f s

CCCH CCCHSDCCH 0

SDCCH 1SDCCH 2

SDCCH 3

SACCH0/2 SACCH

1/3

r r f r r rr r r r fr r r r r rr r r r fr r r r rr f r r

1 51

SACCH2/0 SACCH

3/1

SDCCH 0SDCCH 1SDCCH 3

SDCCH 2

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


1 51

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


f s ff s f s

Downlink51 TDMA frames = 235 ms

-

Uplink

BCCH CCCH

f s f s

CCCH CCCH

r r f r r rr r r r fr r r r r rr r r r fr r r r rr f r r

1 51

CCCH CCCH CCCH CCCH CCCH CCCH

r rr r rr r r r r r r rr r r r r rr rr r r

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


1 51

Signalling Channel Mapping(BCCH +CCCH/9)


f

f

i = idle TDMA frame

f


iii

iii

SDCCH 0SDCCH 1

SDCCH 2SDCCH 3

SDCCH 4SDCCH 5

SDCCH 6SDCCH 7

SDCCH 1SDCCH 2

SDCCH 3SDCCH 4

SDCCH 5

SDCCH 6SDCCH 7

SDCCH 0

Downlink

Uplink

SACCH0/4 SACCH

1/5

SACCH2/6 SACCH

3/7

SACCH6/2 SACCH

7/3

SACCH4/0SACCH

5/1


1 51

1 51

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


Channel configuration defined by parameter channelType

TCHF (0) = full rate traffic channelTCHH (1) = half rate traffic channelTCHD (2) = dual rate traffic channelSDCCH (3) = standalone (SDCCH/8)MBCCH (4) = broadcast control channelMBCCHC (5) = BCCH + SDCCH/4MBCCB (7) = BCCH + SDCCH/3 with CBCHSDCCB (8) = SDCCH/7 with CBCHNOTUSED (9) = timeslot has no radio definition or Abis allocationERACH (10) = random access channel of extended areaEGTCH (14) = EGPRS packed data traffic channel for extended areaLRTCH (15) = long reach traffic channel

Channel MappingParameter Setting

Note: • Some values not allowed in certain tsl (e.g. TSL0 can’t have value 8)• PBCCH is not supported in S13 and onwards

MO Class TR/RTSLParameter channelxType (CHx) where x = 0…7


When static SDCCHs overbooked Free TCHs used for SDCCH traffic

Rules for dynamic SDCCH allocation:

• SDCCH is configured to TRX with least 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 must be selected, the preference order is: HR, FR, DR TCH• DFCA: SDCCH and Dynamic SDCCH not supported on DFCA TRXs (only on regular TRX)

Exceptions:

• Configuration of any dynamic SDCCH resource in the BTS not possible• Only one TCH of the BTS is available

Dynamic SDCCH allocation + FACCH call set up enabled simultaneously dynamic SDCCH allocation has higher priority

Dynamic SDCCH Allocation


S13 Feature (Licence Based)

• Up to 24 SDCCH channels for a BCCH TRX, • Up to 32 SDCCH channels for a non-BCCH TRX• Only supported by Ultrasite & Flexi BTS

Dynamic SDCCH must be activated in the BSC before Increased Dynamic SDCCH Capacity can be activated.

TRXSIG of 64kbps is required for the feature

Increased Dynamic SDCCH AllocationBSS21113


Alternative to dynamic SDCCH allocation (for call setup case)

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

Parameters (SEG Level)

newEstabCausesSupport (NECI) Y/N Enables feature is general

Parameters (BSC level)

ordinaryCallOnFacch (EOF) Y/N Enables ordinary call set up on FACCHemerCallOnFacch (EEF) Y/N Enables emergency call set up on FACCHreestablishOnFacch (ERF) Y/N Enables call reestablishment on FACCHpagingAnsOnFacch (EPF) Y/N Enables answer to paging call setup on FACCH

FACCH Call Set Up


Mobile terminating call -> MSC performs paging

MS identifies paging message with the IMSI/TMSIMS listens to own paging group only

SEG-BTS parameters

MSC parameters

Repaging Interval (INT) 0.5s…10s Time between consecutive pagingattempts

Repaging Attempts (AT) 0…5 Number of paging repetitions

Buffering

BTS stores up to 8 paging messages of the MSC in page group bufferBTS sends paging messages to MS according noOfMultiframesBetweenPaging

Paging Channel (PCH) Parameters

MO Class

Abbreviated Name

Range And Step

Description Default value

BSC - MML Name

BTS noOfMFramesBetweenPaging

2...9, step 1

Defines the number of multiframes between two transmissions of the same paging message to the MSs of the same paging group.

4 MFR


Mobile sends channel requests to BTS separated by random time intervals in case of no answer!

Parameters

Random time interval between consecutive retransmissions

t = S + random [0,.. numberOfSlotsSpreadTrans – 1] RACH slots

S depends on numberOfSlotsSpreadTranssignalling channel mapping (CCCH + SDCCH combined or not in one multi frame)

numberOfSlotsSpreadTrans = 10

signalling channel mapping = not combined S = 58

Therefore t = 58..to..67 RACH slots

time channel requests

RACH Parameters

MO Class

Abbreviated Name

Range And Step Description Default value

BSC - MML Name

BTS maxNumberRetransmission

1,2,4,7 Maximum number of retransmissions on the RACH that the MS can perform.

4 RET

BTS nbrOfSlotsSpreadTrans

MML Range: 3..12, 14, 16, 20, 25, 32, 50

The number of TDMA frames over which retransmission is spread on the RACH (random access channel)

10 SLO


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 for AGCH

noOfBlocksForAccessGrant (AG) 0..7 possible number, if CCCH and SDCCH are not combined1..7 possible number, if CBCH is used in non combined configuration0..2 possible number, if CCCH and SDCCH are combined

Preference of AGCH messages on PCH

noOfBlocksForAccessGrant 0 PCH can be used only, if no paging messages have to be send

= 0 AGCH messages have higher priority than PCH ones

Number of paging groups

N = (number of CCCH blocks – noOfBlocksForAccessGrant) * noOfMultiframesBetweenPaging

AGCH Parameters


Chs 1% 2% 3% 5% Chs 1% 2% 3% 5%

1 0 .01 0 .02 0 .03 0 .05 21 12 .80 14 .00 14 .90 16 .20

2 0 .15 0 .22 0 .28 0 .38 22 13 .70 14 .90 15 .80 17 .10

3 0 .46 0 .60 0 .72 0 .90 23 14 .50 15 .80 16 .70 18 .10

4 0 .87 1 .09 1 .26 1 .52 24 15 .30 16 .60 17 .60 19 .00

5 1 .36 1 .66 1 .88 2 .22 25 16 .10 17 .50 18 .50 20 .00

6 1 .91 2 .28 2 .54 2 .96 26 17 .00 18 .40 19 .40 20 .90

7 2 .50 2 .94 3 .25 3 .75 27 17 .80 19 .30 20 .30 21 .90

8 3 .13 3 .63 3 .99 4 .54 28 18 .60 20 .20 21 .20 22 .90

9 3 .78 4 .34 4 .75 5 .37 29 19 .50 21 .00 22 .10 23 .80

10 4 .46 5 .08 5 .53 6 .22 30 20 .30 21 .90 23 .10 24 .80

11 5 .16 5 .84 6 .33 7 .08 31 21 .20 22 .80 24 .00 25 .80

12 5 .88 6 .61 7 .14 7 .95 32 22 .00 23 .70 24 .90 26 .70

13 6 .61 7 .40 7 .97 8 .83 33 22 .90 24 .60 25 .80 27 .70

14 7 .35 8 .20 8 .80 9 .73 34 23 .80 25 .50 26 .80 28 .70

15 8 .11 9 .01 9 .65 10 .60 35 24 .60 26 .40 27 .70 29 .70

16 8 .88 9 .83 10 .50 11 .50 36 25 .50 27 .30 28 .60 30 .70

17 9 .65 10 .70 11 .40 12 .50 37 26 .40 28 .30 29 .60 31 .60

18 10 .40 11 .50 12 .20 13 .40 38 27 .30 29 .20 30 .50 32 .60

19 11 .20 12 .30 13 .10 14 .30 39 28 .10 30 .10 31 .50 33 .60

20 12 .00 13 .20 14 .00 15 .20 40 29 .00 31 .00 32 .40 34 .60

Erlang B TableFor reference in upcoming calculations


Combined CCCH / SDCCH configuration

noOfBlocksForAccessGrant = 1 2 CCCH blocks for PCH

3 MSs paged per paging message 3 pages per block2 blocks per multi frame 3 * 2 = 6 pages per multiframe

Number of pages per hour 3600 s / 0.235 s * 6 = 91915

Avg of 2 pages required per MS 91915 / 2 = 45957 MSs per hour

BTS 3 MS

Paging_Request

BTS 3 MS

Paging_Request

Paging CapacityExample


Cell with 325 subscribers1 call per subscriber once in a hour1 location update (LU) per subscriber once in 2 hours

Duration of call assignment = 4 s 4 s / 3600 s = 1.11 mErl on SDCCH per subscriber325 subscribers 325 * 1.11 mErl = 0.3607 Erl on SDCCH

Reservation time for LU = 5s 5 s / 7200 s = 0.69 mErl on SDCCH per subscriber325 subscribers 0.2242 Erl on SDCCH

Total SDCCH traffic 0.3607 Erl + 0.2242 Erl = 0.5849 ErlBlocking probability = 1% 4 SDCCHs required SDCCH combined with

CCCH can be used (MBCCHC)

SDCCH Signalling CapacityExample with call Establishment & Location Update


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 0.5849 + 0.325 Erl = 0.9099 Erl

Blocking probability = 1% 5 SDCCHs required not combined with CCCH (MBCCH)

SDCCH Signalling CapacityExample including SMS


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

bsIdentityCode Setting of BSIC

NCC 0..7, distinguishes between PLMNsBCC 0..7, distinguishes between clusters

BSIC + frequency channel unique identity of adjacent cell

f1f2

f3

f1

f1

bcc = 1

bcc = 2

bcc = 3

Base Station Identity Code


Training Sequence Code (TSC) 0…7

Defined on TRX level Used to determine signal distortion and bit error rate

trainingsequence

encrypted bitsencrypted bits3 31

stealing flag stealing flag

57 bits 57 bits26 bits

1

tail bits tail bits

Burst on TCH

data± difference =difference

expected bursttraining sequence ??

received burst

correlation

data* data*training sequence*

data*

Training Sequence Code


200 kHz

890 915 935 960

1 2 3 4 124123 1 2 3 4 124123

duplex distance

Absolute radio frequency carrier number ARFCN

uplink direction downlink direction

Example: GSM 900

Defining Frequency carrier number


Frequency to be used by TRX (must be unique within a BTS)

initialFrequency (FREQ) 1…1023 Setting of ARFCNs

GSM 800: 128 .. 251 GSM 900: 1..124 and 975..1023, 0 GSM 1800: 512..885 GSM 1900: 512..810

f1f2

f3f4

f5f6

f7

f1f2

f3f4

f5f6

f7

f1f2

f3f4

f5f6

f7

Frequency Reuse


Defining BA list

bCCHAllocationList ID 1…2000 Indicates ARFCN values given by BCCHallocation list

frequencyBandinUse 800, 900, 1800, 1900, Multi

Frequency list of ARFCN in the BAL

Idle mode MS listens on BCCH

idleStateBCCHAllocation (IDLE) 0,1…2000 0 = MS gets frequency information fromadjacent cells defined for the BTS1..2000 = MS gets frequency information fromthe defined BCCH allocation list

Dedicated mode MS listens on SACCH

measurementBCCHAllocation (ACT) ADJ = MS gets frequency information fromadjacent cells defined for the BTSIDLE = active MS uses same BCCH freq list as

idle MS

Frequency Information for MS


Frequency

Time

F1

F2

F3

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

Frequency hopping techniques

hoppingMode (HOP) BB,RF,NBB = base band hopping (1)RF = RF hopping (2)N = no frequency hopping at all (0)

Principle of Frequency Hopping


Baseband Hopping

TRX 1

TRX 2

TRX 3

0 1 72 Timeslot

TRX 4

BCCH

f 1

f 2

f 3

f 4

HSN1 (BB hopping group 1 and RF hopping)Timeslot 0 hops over TRXs 2-4 onlyBCCH does not hop

HSN2 (BB hopping group 2)Timeslots 1-7 hop over all TRXs

TRXs do not hopPhysical channels moved from one TRX to another

Hopping sequencehoppingSequenceNumber (HSN) 0..63

0 = cyclic hopping1..63 = pseudorandom hopping

Base Band Hopping


RF HoppingStandard technique

TRX 1

TRX 2

TRX 3

0 1 72 Timeslot

TRX 4

BCCH f1 – no hopping

f2,f3..fn – hopping accordingmobile allocation list One hopping sequencenumber only

All TRXs hop except TRX1 (provides BCCH)Up to 63 frequencies available defined by mobile allocation list -> better hopping gain

mobileAllocationList Setting of ARFCN values usedMobileAllocation (MAL) 0,1...2000 0 = BTS detached from any list

1..2000 = indicates list which shall be used


Standard technique

9 hopping hopping frequencies MAI = 0..8But 3 frequencies available for every TRX only

Freeform hopping

For every sector samemobile allocation listhopping sequence numberframe number (frame synchronization)

For every sector differentstarting points for hopping sequencepossible by mobile allocation index offset

maioOffset (MO) 0..62

setting of MAIO

9 hopping hopping frequencies MAI = 0..89 frequencies available for every TRX

RF HoppingFreeform Hopping

MAIO Offset MAI

TRX-1 (BCCH) -

TRX-2 0

TRX-3 1

TRX-4 2

TRX-5 (BCCH) -

TRX-6 3

TRX-7 4

TRX-8 5

TRX-9 (BCCH) -

TRX-10 6

TRX-11 7

TRX-12 8

Sector-3 6

Sector-1 0

Sector-2 3


Freeform hopping

• Not adequate for MA list with consecutive ARFCN values• Avoids co-channel interference but not adjacent channel interference

Flexible MAIO management

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

maioStep (MS) 1..62

maioOffset = 0, 6, 12 for sector 1, 2, 3maioStep = 218 frequencies required (2 * number of hopping TRXs)

RF HoppingFlexible MAIO Management

MAIO Offset

MAIO Step MAI

TRX-1 (BCCH) -

TRX-2 0

TRX-3 2

TRX-4 4

TRX-5 (BCCH) -

TRX-6 6

TRX-7 8

TRX-8 10

TRX-9 (BCCH) -

TRX-10 12

TRX-11 14

TRX-12 16

Sector-3 2

0

6

12

Sector-1 2

Sector-2 2


BCCH

Band allocation:

MA listConsecutive ARFCN

Only BCCH frequency planning requiredOnly BCCH frequency planning required

Flexible MAIO managementMAIO Offset + MAIO Step

BCCH

Band allocation:

MA listNon-adjacent ARFCN

Freeform hoppingMAIO Offset

MA list and BCCH frequency planning requiredMA list and BCCH frequency planning required

RF Hopping (Tight Frequency Reuse)


Changing Frequency Plan

BSIC / TSCFrequenciesFrequency hopping settingIntelligent underlay overlay TRX settings

• Plan downloaded to BSC/BTSs via MML or GUI• File-based plan provisioning• Immediate Plan activation method

Engineering

Bsspar1 s14 chapter 02_radio_resource_administration_v1.1