Bsspar1 s14 chapter 02_radio_resource_administration_v1.1

1 © Nokia Siemens Networks
BSSPAR1: Chapter 2
Radio 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)
0
1
3
4
5
7
6
0
1
2
3
4
5
7
6
0
1
2
3
4
5
200 kHz
Physical channel
e.g. allocated to one
subscriber with FR voice
and no frequency hopping
frequency
time
TDMA frame
2
2 2 2
Basic TDMA Structure

0 1 2 49 500 1 2 24 25
0 2047
0 1 2 48 49 50
0 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 Station
Subsystem
Logical Channels
for transport of specific content
Physical Channels
transport medium
MS
mapping
Physical channel parameters
ARFCN
Time slot number
Frequency 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
Common
Channels
Dedicated
Channels
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
t
f
t t
T T T T
t t
T
t
T
f
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
Downlink
-
Uplink
BCCH CCCH
f s f s
CCCH CCCH
SDCCH 0
SDCCH 1
SDCCH 2
SDCCH 3
SACCH
0/2 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
SACCH
2/0 SACCH
3/1
SDCCH 0
SDCCH 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
Downlink
-
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
(BCCH +CCCH/9)

f
f
i = idle TDMA frame
f
iii
iii
SDCCH 0
SDCCH 1
SDCCH 2
SDCCH 3
SDCCH 4
SDCCH 5
SDCCH 6
SDCCH 7
SDCCH 1
SDCCH 2
SDCCH 3
SDCCH 4
SDCCH 5
SDCCH 6
SDCCH 7
SDCCH 0
Downlink
Uplink
SACCH
0/4 SACCH
1/5
SACCH
2/6 SACCH
3/7
SACCH
6/2 SACCH
7/3
SACCH
4/0SACCH
5/1
1 51
1 51
(SDCCH/8 +SACCH/C4)

Channel configuration defined by parameter channelType
TCHF (0) = full rate traffic channel
TCHH (1) = half rate traffic channel
TCHD (2) = dual rate traffic channel
SDCCH (3) = standalone (SDCCH/8)
MBCCH (4) = broadcast control channel
MBCCHC (5) = BCCH + SDCCH/4
MBCCB (7) = BCCH + SDCCH/3 with CBCH
SDCCB (8) = SDCCH/7 with CBCH
NOTUSED (9) = timeslot has no radio definition or Abis allocation
ERACH (10) = random access channel of extended area
EGTCH (14) = EGPRS packed data traffic channel for extended area
LRTCH (15) = long reach traffic channel
Channel Mapping
Parameter 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/RTSL
Parameter 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 Allocation
BSS21113

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 FACCH
emerCallOnFacch (EEF) Y/N Enables emergency call set up on FACCH
reestablishOnFacch (ERF) Y/N Enables call reestablishment on FACCH
pagingAnsOnFacch (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/TMSI
MS listens to own paging group only
SEG-BTS parameters
MSC parameters
Repaging Interval (INT) 0.5s…10s Time between consecutive paging
attempts
Repaging Attempts (AT) 0…5 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
Paging Channel (PCH) Parameters
MO
Class
Abbreviated
Name
Range
And Step
Description Default
value
BSC - MML
Name
BTS noOfMFramesB
etweenPaging
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 numberOfSlotsSpreadTrans
signalling 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 maxNumberRetra
nsmission
1,2,4,7 Maximum number of retransmissions on the RACH
that the MS can perform.
4 RET
BTS nbrOfSlotsSpread
Trans
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 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
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 Table
For reference in upcoming calculations

Combined CCCH / SDCCH configuration
noOfBlocksForAccessGrant = 1  2 CCCH blocks for PCH
3 MSs paged per paging message  3 pages per block
2 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 Capacity
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 = 4 s  4 s / 3600 s = 1.11 mErl on SDCCH per
subscriber
325 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 subscriber
325 subscribers  0.2242 Erl on SDCCH
Total SDCCH traffic  0.3607 Erl + 0.2242 Erl = 0.5849 Erl
Blocking probability = 1%  4 SDCCHs required  SDCCH combined
with CCCH can be used (MBCCHC)
SDCCH Signalling Capacity
Example 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 Capacity
Example 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 PLMNs
BCC 0..7, distinguishes between clusters
BSIC + frequency channel  unique identity of adjacent cell
f1
f2
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
training
sequence
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 burst
training 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
f1
f2
f3
f4
f5
f6
f7
f1
f2
f3
f4
f5
f6
f7
f1
f2
f3
f4
f5
f6
f7
Frequency Reuse

Defining BA list
bCCHAllocationList ID 1…2000 Indicates ARFCN values given by BCCH
allocation 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 from
adjacent cells defined for the BTS
1..2000 = MS gets frequency information from
the defined BCCH allocation list
Dedicated mode  MS listens on SACCH
measurementBCCHAllocation (ACT) ADJ = MS gets frequency information from
adjacent cells defined for the BTS
IDLE = 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,N
BB = 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
BC
CH
f 1
f 2
f 3
f 4
HSN1 (BB hopping group 1 and RF hopping)
Timeslot 0 hops over TRXs 2-4 only
BCCH does not hop
HSN2 (BB hopping group 2)
Timeslots 1-7 hop over all TRXs
TRXs do not hop
Physical channels moved from one TRX to another
Hopping sequence
hoppingSequenceNumber (HSN) 0..63
0 = cyclic hopping
1..63 = pseudorandom hopping
Base Band Hopping

RF Hopping
Standard technique
TRX 1
TRX 2
TRX 3
0 1 72 Timeslot
TRX 4
BC
CH f1 – no hopping
f2,f3..fn – hopping according
mobile allocation list
One hopping sequence
number 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..8
But 3 frequencies available for every TRX only
Freeform hopping
For every sector same
mobile allocation list
hopping sequence number
frame number (frame synchronization)
For every sector different
starting points for hopping sequence
possible by mobile allocation index offset
maioOffset (MO) 0..62
setting of MAIO
9 hopping hopping frequencies MAI = 0..8
9 frequencies available for every TRX
RF Hopping
Freeform 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, 3
maioStep = 2
18 frequencies required (2 * number of hopping TRXs)
RF Hopping
Flexible 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 list
Consecutive ARFCN
Only BCCH frequency planning required
Only BCCH frequency planning required
Flexible MAIO management
MAIO Offset + MAIO Step
BCCH
Band allocation:
MA list
Non-adjacent ARFCN
Freeform hopping
MAIO Offset
MA list and BCCH frequency planning required
MA list and BCCH frequency planning required
RF Hopping (Tight Frequency Reuse)

Changing Frequency Plan
BSIC / TSC
Frequencies
Frequency hopping setting
Intelligent underlay overlay TRX settings
• Plan downloaded to BSC/BTSs via MML or GUI
• File-based plan provisioning
• Immediate Plan activation method

Bsspar1 s14 chapter 02_radio_resource_administration_v1.1

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