B8 RNP Extension Frequency Hopping Ed01

8/9/2019 B8 RNP Extension Frequency Hopping Ed01

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Mobile Radio Network Planning 1 All rights reserved © 2004, Alcatel

RNP Extension: B8 Frequency Hopping

Prerequisites: Radio Network EngineeringFundamentals


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Mobile Radio Network Planning 2

RNP Extension: Frequency Hopping

All rights reserved © 2004, Alcatel

Overview

Frequency Hopping Basics

Simulation Results

Frequency Planning of Hopping Networks

Frequency Hopping Parameters


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Abbreviations

BCCH Broadcast Channel TCH Traffic Channel

FH Frequency Hopping

SFH Slow Frequency Hopping

BBH Base Band Hopping RFH Radio Frequency Hopping

MAI Mobile Allocation Index

MAIO Mobile Allocation Index Offset

HSN Hopping Sequence Number FN Frame Number


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FFH

FH

SFH

BBH RFH

Method of FH notation

FFH - Fast Frequency Hopping SFH - Slow Frequency Hopping

BBH - Base Band Hopping

RFH - Radio Frequency Hopping (Synthesized Hopping)


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FFH

Fast Frequency Hopping changes frequencies faster than thesymbol rate

GMSK modulation; payload on air interface =22 kbit/s

1 symbol is modeled with 3 bits

Symbol rate on air interface around 7ksymbol/s

For FFH, > 7000 hopps per second


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SFH

Slow Frequency Hopping is able to change its frequency everytimeslot

Considering one user, occupying every 8th TDMA timeslot, SFH isleading to 216.6 hopps per second:

One TDMA frame: 4.616 ms -> 1/0.004616s=216.6Hz

The frequency changes every 8 bursts but the system permits afrequency change at every burst; however there is no benefit for

the MS and for the network

Frequency Hopping used in GSM is specified in GSM 05.02 (ETSI

recommendation)


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BCCH and SFH

Frequency Hopping can be applied on each traffic channel and eachsignaling channel except the logical BCCH channel!

As the BCCH frequency is used for RXLEV measurements ofneighbour cells, this frequency must be on air all the time without

power reduction

DTX and PC are not allowed on BCCH frequency

FH is not allowed on the BCCH channel (timeslot 0 on BCCHfrequency)


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Basics of BBH


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Base Band Hopping

FFH

FH

SFH

BBH RFH


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Base Band Hopping (1)

The Frame Units create the TDMAframe structure

The Carrier Units modulate thebase band signal onto the carrier

frequency

In BBH the connections betweenFUs and CUs are changed, not

the carrier frequencies

FU 1

FU 2

FU 3

FU 4

CU 1

CU 2

CU 3

CU 4

Nhop NTRX within one cell≤


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TRX 1

TRX 2

TRX 3

TRX 4

BCCH

Base Band Hopping (2) As the CUs aren’t tuning their

transmit frequency, RTCs (Remotetunable cavity / combiner) can beused

Less pathloss then with WBCs(Wide band combiner)

The communications (users) arehopping over the different CUs(Carrier Units)

TS 0 of the BCCH TRX is alwaystransmitting on the BCCH

frequency. Other timeslots can use other

frequencies unless the BCCHfrequency is transmitted by anyother TRX at the same time


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Basics of RFH


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Radio Frequency Hopping

FFH

FH

SFH

BBH RFH


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FU 1

FU 2

FU 3

FU 4

CU 1

CU 2

CU 3

CU 4

Radio Frequency Hopping (1)

In RFH, each Frame Unit is connected to one CarrierUnit

Hopping is performed by changing the carrier frequencywithin the carrier unit by using a synthesizer (synthesizerhopping)

A drawback of the synthesizer hopping configuration is

that the BTS cannot be equipped with remote tunablecombiners (RTC), since the tunable filters cannotchange their frequency on a timeslot basis. Therefore awideband combiner (WBC) has to be used for theconnection between transmitter and antenna,

WBC: 5.05 dB insertion loss = 1.6 dB duplexer loss

+3.45 combiner loss RTC: 3.2 dB insertion loss (for max. 4 TRX

combination)

=> 1.85 dB increased downlink path loss for theWBC configuration


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Radio Frequency Hopping (2)

As the communication(user) is not hopping

between the CUs, but the

CU frequency itself is

hopping, there is no limit

for the number offrequencies used for

hopping except the

software release!

TRX 1

TRX 2

TRX 3

TRX 4

BCCH

Nhop ≥ NTRX possible and mostly used

the BCCH will be on air all the time (needed for MS measurements) and

doesn’t perform hopping at all


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Hopping modes (1)

Cyclic hopping:

HSN = 0 All BTS use a unique periodical hopping scheme

Random hopping:

HSN = 1...63

63 possible pseudo random hopping schemes to guaranteeuncorrelated hopping

HSN = Hopping Sequence Number


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Hopping modes (2)

Cyclic hopping

Random hopping

F1

F2

F3

F4

F2

F3F4

F1


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Comparison between Non Hopping and HoppingNetworks


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Improved FER: 1.4%→ 0.6%

Reduced Call Drop Rate: 3.2%→ 2.4%

Reduced Call Establishment Failure: 6.5%→ 5.5%

Increased HO rate: 10%...15%

Increased HO rate based on quality: 20%

Can be reduced by adjusting HO quality thresholds

Results from Field Trial in Jakarta

(Implementing BBH)

BUT


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Results from Field Trial in South Africa

(Implementing RFH)

Improved CSSR from Improved CDR from

Increased HO Rate due toquality from

During Optimization of HOsdue to quality, the HO rate due

to quality decrease again from

93.64% to 98.51%

1.72% to 1.32%

6% to 25%

25% to 7%

BUT

Implemented was 1x3 reuse with 37.5% RF load

Capacity increase in Bloemfontain was about 100%!!!


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21 cells, 19 with 2 TRX-es and 2 with one TRX, 18 frequencies available fortraffic carriers

Dropped call reduction

Increase of the received mean level

Possibility of using tighter schemes (like 1/3) providing higher capacitycompared with non-hopping network

No degradation of audio quality

Conclusions useful for radio planning:

The number of hopping frequencies must be 4 of larger.

Hopping frequencies must be separated as much as possible.

Reuse 1*3 (4 frequencies) 1*3 (6 frequencies) 2*6 (3 frequencies) No Hopping

CDR 2.7 2 2.2 2.5

HO Rate 4000 3900 3700 3000

RXQual Increased with 10 % Increased with 20 % Increased with 35 % -

Results from Telefonica Field Trial in Spain

(RFH)


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Results from Field Trial in Egypt - Ismailia (RFH)

10 sites, 21 cells with 2 TRX-es and 9 cells with 3 TRX-es

Effect of the RF Load can be noticed on the quality HO between

Reuse 3 and Reuse 1 Applying DL PC and DTX together can enhance RFH performance

N e t w o r k

E v o l u t i o nN o H o p p in g 1 * 3

1 * 3 w i th Pa r a m e te r

S e t t i ngs

O f f se t_ H o p p in g _ H O

L _ RX Q u a l (PC

m in i m u m th r e sh o l d )

1 * 1

1 * 1 w i th

Pa r a m e te r s

S e t t i ngs

O f fse t_ H o pp i n g _ H O

L_ RXQ u a l

(PC

m in im u m

t h r e s h o l d )

1 * 1 w i th

D L PC +

D L D TX

+ EFR

D L Q u a l i t yH O

1 5 0 0 0 2 7 0 0 0 1 9 0 0 0 1 8 0 0 0 1 3 0 0 0 1 0 0 0 0

C D R 1 . 3 1 .2 1 0 . 8 0 .7 0 .7

Q V o i c e

Q u a l i t y

( g o o d )

9 1 .2 % 9 4 % 9 4 % 9 2 .6 % 9 2 .7 % 9 3 .2 %


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Frequency Hopping Simulation Results


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Why Frequency Hopping?

There are two advantages when using Frequency Hopping

Frequency Diversity

Cyclic and random hopping take benefit

Improves the effectiveness of the GSM error correction algorithm bytaking advantage from interleaving

improve the effect of fading

Interferer Diversity

Only random hopping takes full benefit!

Averages the interference on the hopping carriers, thus highlyinterfered cells (before hopping) gain significantly


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Fading effects


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Fading

Caused by delay spread of original signal Multi path propagation

Time-dependent variations in heterogeneity of environment

Movement of receiver

Short-term fading, fast fading

This fading is characterised by phase summation andcancellation of signal components, which travel on multiplepaths. The variation is in the order of the consideredwavelength.

Their statistical behaviour is described by the Rayleigh

distribution (for non-LOS signals) and the Rice distribution (forLOS signals), respectively.

In GSM, it is already considered by the sensitivity values, whichtake the error correction capability into account.


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Fading

Mid-term fading, lognormal fading

Mid-term field strength variations caused by objects in the sizeof 10...100m (cars, trees, buildings). These variations are

lognormal distributed.

Long-term fading, slow fading

Long-term variations caused by large objects like largebuildings, forests, hills, earth curvature (> 100m). Like the mid-

term field strength variations, these variations are lognormal

distributed

Fading Effect consists in quality degradation


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Frequency Diversity


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Frequency Diversity (1)

Especially SlowMoving Mobiles

suffer from fading

(fading time can

be long)

Fading means ashort breakdown

of the received

power due to

environmentalconditions-70

-60

-50

-40

-30

-20

-10

0

0 . 1

2 . 8

5 . 4

8 . 0

1 0

. 6

1 3

. 2

1 5

. 9

1 8

. 5

2 1

. 1

2 3

. 7

2 6

. 3

2 9

. 0

3 1

. 6

3 4

. 2

3 6

. 8

3 9

. 4

4 2

. 1

4 4

. 7

4 7

. 3

4 9

. 9

Distance [m]

R e c e i v e d P o w e

r [ d B m ]

Lognormal fading

Raleygh fading

fading notches


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Frequency Diversity (2)

Hopping over several frequencies, does not reduce the number offrames being destroyed by fading notches, but reduces the time of

being in a fading notch!

With FH the probability to get into a fadingnotch is higher, but the average duration of a

notch is shorter!

Note: The example is based on the assumption of cylic hopping

no fading notch

f1

f3

f4

Hopping over

f1,f2,f3,f4 fading notch

f2


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Frequency Diversity (3) - Interleaving and its

benefit

456 bit 456 bit

TDMA Time

Slot:

3 3 3 3 3 3

………...

…. …. …. …. …. ….2

260 bit Data with redundancy for error correction

TIMEBurst (partly) destroyed by

fading, but only 12.5% of 456

bit affected -> high chance for

successful error correction!

Interleaving depth: 8

used frequency: f2 f3 f4 f1 f3 f4f1

Note: Only f1 suffers from

fading in this example

Creating burst structure


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Frequency Diversity (4) - Interleaving and its

benefit

GSM collects 20 ms of speech data before packing it into the 260bits (456 bits include 260 data bits plus redundancy) Without hopping, several consecutive bursts (456 bits) would be

affected by fading

This would affect most of the 8 sub-blocks of the 456 bit, leading to

low chance of successful error correction. With hopping, in the regular case less consecutive blocks are

affected, leading to a good chance of error correction

As RXQUAL does not take interleaving into account, but the BERbefore de-interleaving, the FH benefit is not visible in RXQUAL!

RXQUAL is even worse, as the BER during “good quality time” ishigher.


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Interference Diversity


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Interferer Diversity (1)

Interferer Diversity means the averaging of the interferencewithin the frequency group

Each frequency within a frequency group suffers frommore or less interference

The overall interference to one communication is thereforethe average of the single frequency interferences of thefrequency group

Note: The overall interference within the network does not

change, but the standard deviation is reduced


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Reducing the network wide C/I standard deviation by FH

Uncorrelated hopping is assumed in the example Random Hopping (HSN 1..63)!

C/IThr

C/IThr

C/I

σσ

C/Iwithout SFH with SFH

1 2 3 4 5 6 7

8

1 2 3 4 5 6 7

8

One MS call which

changes the frequencyseveral times within the

frequency group (e.g. 8

times)


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If the average C/I in the network is below the required C/Ithr , the quality

gets worse when using frequency hopping

C/IThr

C/IThr

C/I

σσ

C/Iwithout SFH with SFH

1 2 3 4 5 6 7

8

1 2 3 4 5 6 7

8

Uncorrelated hopping is assumed in the example Random Hopping (HSN 1..63)!

One MS call whichchanges the frequency

several times within the

frequency group (e.g. 8

times)


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If the standard deviation is quite high some mobiles sufferfrom a C/I smaller then the required C/Ithr

When using FH, the C/I values are average values from thecorrespondent frequency hopping group

Due to this averaging, the C/I standard deviation gets smaller

Now also the “bad” calls have acceptable conditions


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Summary of frequency and interference

diversity

F1F2

MS1BS1

C1

I2

I1

MS2

F2

P F1

F1,F2,F3

F1

F2

M S1BS1 M S2

F2,F3,F1

P

Inter ferenceDivers i t y

F requency

Divers i t y

N oHopping

FrequencyHopping

I1

I2


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BBH

Advantages

The timeslots 1 to 7 of the BCCH frequency are allowed toperform frequency hopping

Combination of “intelligent” frequency planning with thebenefit of frequency hopping

Disadvantages

Frequency hopping performs best with at least 4 hoppingfrequencies Cells must have at least 4 TRXs!


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RFH

Advantages

Hopping over more frequencies than installed TRXspossible

NHOP ≥ NTRX

More benefit from Interferer Diversity

The more frequencies are used, the higher the “averaging effect”

Disadvantages

No hopping at all on the BCCH TRX!


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Comparison BBH vs. RFH (1) BBH is better than RFH

Interference point of view BBH intelligence integrated in the frequency plan

RFH not (so much) intelligence in the frequency plan (especially in 1*1). Thedrawback is the increased level of interference (cf. A955 simulations)

Strategy for operator for hopping mode selection:

prefer BBH instead of RFH if the available BW is sufficient migrate from BBH to RFH only

when the point comes to deploy a new TRX in the BBH network

without any violations


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Comparison of hopping schemes 1 x 3, 1 x 1 and BBH

(Network Design point of view)R e u s e

s c h e m e

B e n e f i t s D r a w b a c k s

1 x 3 A l l o w a r e - u s e o f t h eh o p p i n g f r e q u e n c i e s ( f o r t h e

m i c r o c e l l s ) .

E a s e t h e t r a n s i t i o nb e t w e e n h o p p i n g a r e a a n d

n o n - h o p p i n g a r e a .

F r o m i n t e r f e r e n c er e d u c t i o n p . o . v . N e e d a g o o d

d e s i g n o f t h e n e t w o r k ( s a m e

h e i g h t o f t h e s i t e s , r e g u l a r

a z i m u t h o f t h e a n t e n n a s , f l a t

a r e a , c a r e f u l t i l t t u n i n g ) t o b e

f u l l y e f f i c i e n t .

R e q u i r e h o p p i n g o n an u m b e r o f f r e q u e n c i e s

m u l t i p l e o f 3 .

1 x 1 F r o m i n t e r f e r e n c e

r e d u c t i o n p . o . v . , t h e

r e q u i r e m e n t t o h a v e s a m e

a n t e n n a h e i g h t a n d a c a r e f u l

t i l t t u n i n g i s e v e n h i g h e r a s f o r

1 x 3 , w h e r e a s t h e r e i s n o

r e q u i r e m e n t f o r s a m e a z i m u t h

G o o d c e l l p l a n n i n gr e q u i r e d , l i t t l e c o v e r a g e

o v e r l a p a l l o w e d .

N o r e - u t i l i z a t i o n o f t h eh o p p i n g f r e q u e n c i e s

p o s s i b l e ( f o r e x a m p l e f o r

m i c r o c e l l s ) .

M o r e d i f f i c u l t t r a n s i t i o nb e t w e e n h o p p i n g a r e a a n d

n o n - h o p p i n g a r e a .B B H

M i n i m u m i n t e r f e r e n c e +

b e n e f i t s o f i n t e r f e r e r a n d

f r e q u e n c y d i v e r s i t y

F e w e r c o n s t r a i n t s o n t h en e t w o r k d e s i g n : a n t e n n a

h e i g h t + a z i m u t h , t i l t t u n i n g

a r e n o t c r i t i c a l f a c t o r s

a n y m o r e

H i g h e r e f f o r t f o r f r e q u e n c yp l a n n i n g


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FH field trial

Field trial performed in TMN Network in Portugal 2003

The result is a comparison between RFH 1x1, BBH and RFH 1x3

TMN Network configuration

Hardware 19 BSCs with 1400 cells

dual band network azimuths with regular patterns

Frequency policy GSM 900: 21 freq. for BCCH; 18 freq. TCH with RFH 1x1

DCS 1800: 14 freq. for BCCH; 16 freq. TCH with RFH 1x1


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FH field trial - reasons for FH modifications

Network had a high RFLoad - due to high number of TRX per cell

(urban areas)

RxQual in hopping TRX was worse than RxQual in BCCH (fromdrive tests)

Band % cells with more TRX than recommended

GSM900 45% of cells have more TRX than recommended (for RFLoad < 12%)

DCS1800 85% of cells have more TRX than recommended (for RFLoad < 12%)

BCCH/ Hop % bad RxQual

BCCH (RxQual > 4) 10.4%

Hopping (RxQual > 5) 13.0%


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FH field trial - 1x1 vs 1x3

Motivation for 1x3: network has a regular pattern

QoS Results

Drive tests results

Conclusion: reduction of Quality HO

increase of Level HO

no significant modification for other QoS indicators or in QVoicemeasurements

I n d i c a t o r 1 x1 1 x3

Better cell HO 90,000

47%

90,000

47%

Q uality HO 47,500

24%

44,000

23%

Level HO 50 000

27%

53,000

28%

Bad RxQual - b efore Bad RxQual - after

16.7% 15.2%


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FH field trial - BBH

Motivation:

TCH TRX using 1x1 have RxQual worse than BCCH more frequencies for BCCH

Using the BCCH band reduces the network RFLoad

Call Drops on the BCCH frequencies, due to interference can be

reduced by hopping BBH combines the benefits of

intelligent frequency planning

frequency hopping

BBH was applied only for one BSC


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FH field trial - BBH Results QoS results

Drive tests

results

QoS indicators

1x1 Baseband

hopping

Obs

SDCCH drop 1.2% 0.8% Significant improvement

RTCH assign fail 0.6% 0.4% Significant improvement,showing c learly a reduction of

interference

Call-drop 1.1% 0.9% Significant improvement

Handover

success rate

96.2% 96.4% Improvement more visible in

some other BSCs

HO causes Better-cell: 43%

Qual HO: 34%

Level HO: 19%

Better-cell: 41%

Qual HO: 32%

Level HO: 22%

Reduction of Qual HO with BBH

Interference

bands

(% in band 900)

54% 61% Improvement is visible with BBH

HO/call 0.64 0.58 Reduc tion with BBH even morevisible in other BSCs: shows

improvement in Voice Quality

Hopping 1x1 Baseband

HoppingVQ – good 88.9% 90.8%

VQ – suffic ient 6.7% 6.8%

VQ – bad 4.4% 2.6%


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FH field trial - BBH Conclusion

Clear reduction of network interference: real reduction of

SDDCH drop

RTCH assign fail

Call Drop

Reduction of HO/call

QVoice measurements showed improvement

Due to good results, BBH was generalized for entire network (19BSCs):

SDCCH drop: 1.1% -> 0.8%

RTCH assign fail: 0.5% -> 0.3% Call-drop: 1.2% -> 1.0%

HO Success Rate 96.8% -> 97.5%

Call Success Rate: 97.2% -> 97.9%


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Hard Blocking / Soft Blocking


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Hard blocking

Hard blocking is determined by the amount of availablechannels

This type of blocking occurs in conventional traffic systems,with a low interference probability

The blocking is defined by the blocking probability, e.g.Pblock=2%

With hard blocking, mobiles will not get access to the network,since all channels are in use (100% traffic load)


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The maximum capacity in a system is defined as the limit, where either the

hard blocking or the soft blocking limit is reached

Soft blocking

Soft blocking occurs due to high interference or due to an

unacceptable call drop rate This type of blocking occurs in a network design with a low reuse

cluster size, resulting in a high level of interference

The soft blocking limit can be defined by the traffic load, at which the

quality in the network becomes unacceptable e.g. when 10% of themobiles will suffer from a C/I < C/IThr or when the call drop rate

reaches 5%

With increasing traffic load, the capacity will be limited due to softblocking before the hard blocking limit is reached (traffic load


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DTX Discontinuous Transmission PC Power Control

Usage of Power Control and DTX

DTX and PC (used only by TCH carriers) reduce interference

Capacity increase possible with remaing QoS figures

In non hopping systems, "bad" communications take much advantage from PC and DTX

"good" communications do not see any improvement

In hopping systems, due to interferer diversity, allcommunications will experience an improvement

Hopping networks with ARCS < 9 are limited by softblocking

Any interference reducing feature is more effective in such asystem

PC and DTX in UL and DL are recommended especially for hoppingnetworks!


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Simulation Results

RNP E t i F H i


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FH Performance Simulation - Description

The next slides present the results of a hopping performance

investigation done with the Alcatel Radio Network Planning Tool A9155

Two different approaches are used to determine the softblockinglimit:

Softblocking defined by the traffic load at which 10 % of themobiles suffer from an C/I < C/Ithr

Softblocking defined by the traffic load at which the call droprate reaches 5 %

RNP E t i F H i


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Considering softblocking based on C/I

? What is the achievable capacity when 10% of all MS sufferfrom a C/I < C/Ithr ?

Parameters: BW=36, (hard)blocking=2%, 8 TCH per TRX

Considering DTX, PC, HO, GSM signal processing:

BUT: Call drop rate for the design rises up to 16%!

Configuration

Capacity (Erl/Site) 86.4 71.1 49.8

Gain comp. to +74% +42% +0%

‘C/I’ Simulation (1)

RNP E tension Freq enc Hopping


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ARCS >= 12:

Hard blockingrelated

ARCS = 9:

Hardblocking =

Softblocking

ARCS < 9:Soft blocking

related

C: 45ErlD: 20Erl

A: 49.8Erl

E: 86.4Erl=+74%

16% Call dropB: 71.1Erl=+42%

0

50

100

150

200

250

3 6 9 12

ARCS

E r l a n

g p e r

3 s e c

t o r s

i t e

Hard Block.

Soft Block/No Hopping

Soft Block/Hopping




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‘C/I’ Simulation (3) Nonhopping:

The hardblocking limit would be reached at ARCS of 12(traffic load=100%)

Hopping: The hardblocking limit still can be reached at a ARCS of 9,

meaning that the C/I or the call drop rate is still below the

threshold (traffic load=100%) If the ARCS is 3 and the traffic load has reached 30% of the

theoretical available hardware capacity, we can see, that thesoftblocking limit with a "too" bad quality can be reached

The increased call drop rate is also based on the fact, that

the used PC and HO algorithm were very simple HO is based on distance only, thus with an according quality

based emergency HO the call drop rate can further bereduced.



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The simulation does not take into account real

topography,morphology etc. 4*3 and 3*3: capacity can be calculated manually, soft block not

reached

49.8 Erl/3 sector site = 16.63 Erl/sector *3 sectors/site

16.63 Erl : from Erl table with 24 (3*8) channels and GOS=2% 1*3 case: capacity can not be calculated manually, soft blocking is

reached (hardblocking would lead to 3*84.1=252 Erl per site for 12

(TRX) *8 slots = 96 channels per sector at 2%block)

But due to the soft block (interference), the real capacity is lower

Simplification: No signalling considered



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Bandwidth=constant in the example

Idea of fractional loading:

Since at a ARCS of 3 the softblocking limit is reached andonly 30% of a HW will be used, it is certainly not

cost effective to install all the HW if 70% of the hardware

is unused. Thus the amount of TRX is lower then theamount of hopping frequencies

Fractional reuse (ARCS, FARCS) only possible with RFH

Summary: Optimum in terms of capacity could be achievedwith an ARCS of 1x3



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‘Call drop’ Simulation (1)

Considering Softblocking based on Call Drop Rate of 5% or

hardblocking limit is reached What is the capacity when 5% of all calls will drop?

More suitable definition of softblocking for an operatorcompared to the "C/I" criteria

Same simulation conditions as in previous example Best results are achieved with the reuse scheme

But: no quality based handover considered in simulation

Reduced call drop rate in reality can be expected



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0

10

2030

40

50

60

70

80

Configuration

E

r l a n g p e r s i t e

‘Call drop’ Simulation (2)

Best solution when taking

into account the call droprate as the softblocking limit

is achieved with ARCS of 9.

The hardblocking limit stillcould be reached: Capacity

increase here: 42%, but

when taking into account

the BCCH with an ARCS of

12, only 30% can be

achieved.Max. Capacity with softblocking based on call drop rate of 5%



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Conclusion on Simulations System simulations show:

"C/I" simulation: best result with the scheme, but with

an increased amount of call drops "Call drop" simulation: reuse scheme is the optimum

Therefore for a first introduction, NTRX=NHop should be used,aiming at an ARCS of 9 for the TCH

30% capacity increase, taking into account a BCCH with ARCS of 12 in a typical scenario

Further reduction of the ARCS has to be evaluated in a secondstep with NTRX


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Frequency Planning in Hopping Networks


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Frequency Planning in Hopping Networks

Introduction



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q y pp g


A9155 FH planning strategy

AFP - Automatic Frequency Planning Several frequencies can be assigned to one carrier

1*1 and 1*3 fractional reuse supported

HSN and MAIO allocation done automatically

Absolute calculated interference value is taken into account duringfrequency assignment

Aim: Minimize the cost! The cost includes violation of channelseparation, interference etc.



67/130


q y pp g


Required number of Frequencies

Investigations show, that most benefit is taken from FH when

hopping over at least 4 frequencies!

TU3

TU50

6

7

8

910

11

12

13

14

15

1 2 3 4 5 6 7 8 9 10 11 12

number of frequencies in hopping sequence

r e q u

i r e

d C / I ( d B )

TU3

TU50

For slow moving mobiles, the benefit of FH is much bigger!

Remark: TU3 = Typical Urban Environment with an average mobile speed of 3 km/h

TU50 = Typical Urban Environment with an average mobile speed of 50 km/h


68/130



Fractional Reuse



69/130


Reuse Cluster Size Definition for FH

The classical definition of the Reuse Cluster Size is:

The definition of the Reuse Cluster Size for RFH conditions is:

cell per TRX of amount Average

Bandwidth ARCS =

cell per sFrequencieof amount Average

Bandwidth

FARCS =

FARCS = Fractional Average Reuse Cluster Size



70/130


Examples for ARCS

ARCS

27 frequencies for TCH TRXs

3 TCH TRXs in average per cell

9

3

27

/#

===

cellTRX

B ARCS Example: Group planning with 9

frequency groups, 3

frequencies each

A1

A3

A2 B1 B2

B3

A1 A2

A3

B2

B3

B1

C2

C3

C1B2B1

B3

A1 A2

A3



71/130


Examples of FARCS (1)

FARCS

27 frequencies for TCH TRXs 3 hopping groups with 9

frequencies each

1 hopping group per cell

39

27

/#===

cell f

BFARCS

REUSE 1*3

Example:

3 frequency groups, 9 frequencies

each

A

C

B A B

C

A B

C

B

C

A

B

C

AB A

C

A B

C



72/130


Examples of FARCS (2)

FARCS

27 frequencies for TCH TRXs 1 hopping group with 27

frequencies

same hopping group on each

cell

127

27

/#===

cell f

BFARCS

REUSE 1*1

Example:

1 frequency group including all

27 frequencies

A

A

A A A

A

A A

A

A

A

A

A

A

A A A

A

A A

A


73/130



Creating Hopping Groups



74/130


The GSM Hopping Sequence Generator

External Parameters which can be modified by operator

MA Mobile Allocation MAI Mobile Allocation Index

MAIO Mobile Allocation Index Offset

FHS Frequency Hopping Sequence

HSN Hopping Sequence Number Internal Parameters which cannot be modified

T1, T1R, T2, T3 GSM internal timers

FN Frame Number



75/130


MA

MAI ARFCN

1

2

3

0

4

... ...

2

5

12

7

6

MA - Mobile Allocation

The MA is the look up table that is

giving the relation between thedifferent MAI numbers and the

corresponding ARFCN.

Range:The look up table has N lines.

N is the number of

frequencies used in the

hopping sequence (hopping

group)



76/130


Selection of hopping channels acc. to MA

Overall speech quality improved in relation with frequency

management During the channel assignment procedure, the BSC will take into

account the MA of the channels before allocating the resource

The MA gives the number of frequencies over which the targetchannel hops: the bigger it is, the better the quality can be expected

Hence, the BSC will select preferably the channels with the biggestMA



77/130


MAI - Mobile Allocation Index

The MAI is an index number, which allows to determine the correct

line in the MA look up table to find the corresponding ARFCN. Range: 0 .. N-1

Note: N is the number of frequencies used in the hopping sequence.



78/130


MAIO - Mobile Allocation Index Offset

The MAIO is selectable for each timeslot and each TRX separately

The MAIO is constant on the TRX but it changes between the FU Due to the fact, that normally for each timeslot within one TRX the

same FHS is used, there is no need to change the MAIO from

timeslot to timeslot. Therefore the MAIO is constant on the TRX.

It is a number that is added to the calculated MAI to avoid intra-sitecollisions due to co or adjacent channel usage.

Range: 0 .. N-1 (max. 63)



79/130


MAIO - BBH Example (1)

TS 0 TS 1 TS 2 TS 3 TS 4 TS 4 TS 5 TS 6 TS 7

FU 1 BCCH TCH TCH TCH TCH TCH TCH TCH TCH

fhs_id, maio freq 1, 0 1, 0 1, 0 1, 0 1, 0 1, 0 1, 0 1, 0

FU 2 TCH SD/8 TCH TCH TCH TCH TCH TCH TCH

fhs_id, maio 2, 0 1, 1 1, 1 1, 1 1, 1 1, 1 1, 1 1, 1 1, 1FU 3 TCH TCH TCH TCH TCH TCH TCH TCH TCH

fhs_id, maio 2, 1 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2

FU 4 TCH TCH TCH TCH TCH TCH TCH TCH TCH

fhs_id, maio 2, 2 1, 3 1, 3 1, 3 1, 3 1, 3 1, 3 1, 3 1, 3



80/130


MA

MAI ARFCN

1

2

3

0

F2

F3

F4

F1E.g. MAI = 1 calculated

MAIO=2

F4 is used

MAIO - Example (2)

E.g. a TRX has the MAIO 2

Frequencies used on this TRX: f1, f2, f3 ,f4 The frequency hopping generator creates the MAI sequence

3,0,1,2,1,1,3,0,2,…

The hopping sequence will be:

f2, f3, f4,f1,f4,f4,f2,f3,f1,...



81/130


FHS - Frequency Hopping Sequence

The FHS is the set of frequencies (max. 63) to be used in the

hopping sequence (frequency hopping group). It is given by theoperator and can be different for each timeslot and each TRX of

each cell

TS 0 TS 1 TS 2 TS 3 TS 4 TS 4 TS 5 TS 6 TS 7

FU 1 bc/ sd4

or

bcch

TCH TCH TCH TCH TCH TCH TCH TCH

fhs_id, maio freq 1, 0 1, 0 1, 0 1, 0 1, 0 1, 0 1, 0 1, 0

FU 2 TCH SD/8 TCH TCH TCH TCH TCH TCH TCH

fhs_id, maio 2, 0 1, 1 1, 1 1, 1 1, 1 1, 1 1, 1 1, 1 1, 1


fhs_id, maio 2, 1 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2 1, 2


fhs_id, maio 2, 2 1, 3 1, 3 1, 3 1, 3 1, 3 1, 3 1, 3 1, 3

FHS_ID = 1: all associated frequencies of the BTS are used

FHS_ID = 2: all associated frequencies of the BTS except BCCH frequency are used

(BCCH in TS 0 have to stay on its fixed frequency)



82/130


Extended Frequency Hopping Sequence

Since release B5.1, FHS can be extended up to 63 frequencies

SDCCH and TCH (Traffic channels) can hop on up to 63 frequenciesin a cell

As the GSM standard does not allow CBCH (Common BroadcastChannel used for SMS-CB) to hop on such a high number of

frequencies, the operator can configure the frequency hopping

system in two different ways, depending on his decision to make the

CBCH hop or not



83/130


SMS-CB with/without hopping CBCH

Hopping CBCH

All FHS (Frequency Hopping Sequence) of the differentchannels (CBCH, SDCCH, TCH) have an upper limit of 16

frequencies (for both bands)

Non-hopping CBCH (or if there is no SMS-CB)

in GSM 900: SDCCH and TCH can hop on up to 63 frequencies.In GSM 1800, the GSM standard limits the number of

frequencies which can be used for SDCCH channels to an

upper limit which depends on the span in the cell. The span

represents the shift between the higher frequency used in the

cell and the lower frequency



84/130


Non hopping SMS-CB with hopping TCH’s

The maximum number of frequencies in the hopping sequence for

GSM 1800 cells is defined in the table below

Span in the cell Max number of frequencies in the FHS

up to 22.5 MHz 63

from 22.5 up to 25.5 MHz 28

from 25.5 up 51 MHz 21

from 51 up 75 MHz 17



85/130


HSN - Hopping Sequence Number

The HSN is one of 4 input parameters to the GSM hopping

sequence generator algorithm (see GSM Rec: 05.02). Range: 0 .. 63

HSN = 0 means cyclic hopping!

The values 1 to 63 are so called Pseudo Random HoppingSequence Numbers. Their usage forces the hopping sequence

generator algorithm to determine MAIs randomly. Due to the fact,

that only the GSM internal timers T1R, T2 and T3 are additional

input to this algorithm, their period is also the period of the hopping

sequence



86/130


T1, T1R, T2, T3 - GSM internal timers

Ranges of the timers:

T1: 0 .. 2047 T1R: 0 .. 63(T1R = T1 modulo 64)

T2: 0 .. 25

T3: 0 .. 50

T2 and T3 are triggered every 8 timeslots (1 TDMA Frame). Whenboth timers switch back to 0, T1 (and T1R) is triggered (that is every

26*51= 1326 TDMA Frames).

In the GSM hopping sequence algorithm the timers T1R, T2 and T3are used. This is leading to a period of 64*26*51-1 = 84863 for the

MAI sequence (hopping sequence)



87/130


Note: Duration of one TS 577 µs

FN - Frame Number

It is incremented after every TDMA frame (8 timeslots)

At each FN increment, timers T1, T1R, T2, T3 are impacted,however only T1R, T2, T3 determine the periodicity of the MAI

sequence (hopping sequence)

FN periodicity is 26*51*2048-1 = 2 715 647 TDMA frames

Each frame has a duration of apporx. 4.62 ms

The absolute time from FN 0 to next time FN 0 is accordingly:2 715 647 * (8*577 µs) = 3h 28min 53 s



88/130


Hopping Sequence Generation - Diagram

With the before shown parameters,the used absolute frequency can

be determined

MA MAIO HSN T1 T2 T3

Algorithm specified inGSM Rec. 05.02

ARFCN = MA(MAI)

Press for demonstration



89/130


The Period of the Hopping Sequence

Timer T1R is only increased, when T2 and T3 switch back to zero at

the same time (every 1326 TDMA frames)! The total period of the 3 timers T1R, T2, T3 (=duration of FHS):

64*26*51-1 = 84863 TDMA frames 6min 32sec

This means, that even if we select the same HSN on two different(not synchronised I.e no common master clock) sites, they have a

probability of

1/84863 = 1.18*10-6

to use the same frame number.

If they have different frame numbers, the order of the used hopping

frequencies is uncorrelated



90/130


New understanding of reuse

A reuse of A X B means, that A sites belong to the same reusecluster and B frequency groups are used on this site.

A

A

A

A

AA

A

C

B

A

CB

Re-use 1x3 Re-use 1x1



91/130


Co-cell / co-site constraints max RF load

Co-cell constraint 2 channels spacing (ETSI recommends 3, but

with Alcatel EVOLIUM capabilities this value can be set to 2) Co-site constraint 2 channels spacing

As on the same site the minimum distance between two frequenciesis 2, only every second frequency of a band of consecutive

frequencies can be used

This is leading to a effective usage of the spectrum resources ofmaximum 50%

These 50% are the so called maximum RF load on the site



92/130


Max RF Load

The max RF load within a cell can be calculated according the

following formula:

This maximum RF load is only achieved, if all TRXs within the cellare fully loaded!

If the TRXs are only fractional loaded, the effective RF load is muchlower!

CellsFrequencie

CellTRX load RF

/#

/#max =



93/130


%7.1612

2.max ==load RF

%504

2.max ==load RF

Max RF Load - Examples

3 sector site, 12 hopping frequencies, 2 hopping TRX per sector

1*1 reuse:

1*3 reuse:

These values (16.7% and 50%) are the theoretical maximum

achivable RF loads for the two cases.This is due to the fact, that a consecutive frequency band isassumed and thus due to inter cell constraint of 2 channelsspacing only every second frequency can be used at the sametime



94/130


Real RF Load

The real RF load within a cell can be calculated according the

following formula:

Only active timeslots contributes to the RF Load

Average number of active timeslots are given by the traffic capacity,in Erlang

RF Load can be reduced due to the features “BCCH TRX Marking(since B5.2) or “TRX Prioritized Preference Quality Control (since

B6.2)

8*)/#(

/A#

CellsFrequencie

Celltimeslotsctiveload RF real =


R l RF L d E l


95/130


3 sector site, 12 hopping frequencies, 2 hopping TRX per sector

BCCH TRX Marking is used, therefore BCCH carrier is preffered tobe filled by traffic 3 TRX -> 14.896 Erlang, 2% blocking probability 14.896 timeslots active during the busy hour. The remaining 7.104

timeslots guarantee a blocking probability of 2%

The average timeslots active on hopping carrier is then14.896 timeslots - 6 timeslots on first carrier = 8.896 active timeslots 1*1

reuse:

1*1 reuse:

1*3 reuse

%26.912*8

896.8==load RF real

%8.274*8

896.8==load RF real

Real RF Load - Examples



96/130


Real RF-load Proposed max. values:

Reuse

scheme

Service target Real RF load

marginal service quality (theoretical upper limit for

synchronized hopping)

50 %1 x 3

service quality comparable to conventional systems30 % … 35 %

marginal service quality (theoretical upper limit for

synchronized hopping)

16.6 %1 x 1

service quality comparable to conventional systems 10 %


Real RF Load with Directed Retry and Fast


97/130


Real RF Load with Directed Retry and Fast

Traffic Handover

The efficiency of TRX is increased by these features

The same number of timeslots can carry a higher amount of trafficwith the same blocking probability

The interference in the network is increased

Therefore the Real RF Load has to be reduced whenthese features are used

It is preferred to use these kind of features, even it lead to a reducedRF Load instead of having a high RF Load without these features


I t it t i t


98/130


Inter site constraints

The maximum RF load is just a theoretical value, up to which we canavoid violating the co-cell and co-site constraints

The real RF load of a cell (e.g. the traffic in Erlang handled by thehopping carriers) is the real indicator for the interferer potential of the

cell

With increasing number of used hopping TS, the probability ofhaving a collission with a used TS of another cell using the samehopping frequencies is increasing


Traffic / Interference relation Examples


99/130


Traffic / Interference relation - Examples Which scenario interferes most to your communication (yellow)?

Scenario 1 Scenario 2 Scenario 3

TRX1

TRX2

TRX3

TRX4

TS 0 1 2 3 4 5 6 7

TRX1

TRX2

TRX3

TRX4

TS 0 1 2 3 4 5 6 7

TRX1

TRX2

TRX3

TRX4

TS 0 1 2 3 4 5 6 7

TRX1

TRX2

TRX3

TRX4

TS 0 1 2 3 4 5 6 7

TRX1

TRX2

TRX3

TRX4

TS 0 1 2 3 4 5 6 7

TRX1

TRX2

TRX3

TRX4

TS 0 1 2 3 4 5 6 7

Assumptions: Cells not syncronized, cells using same hopping frequencies, BCCH not included

I n t e

r f e r e r

S e r v e r


Creating Hopping sequences


100/130


Creating Hopping sequences The following slides show, how new frequency hopping groups can

be generated and how the MAIO is assigned to the different TRXs

within the cell

Keep in mind the two GSM constraints

2 channels spacing between the frequencies on air at the sametime within one cell (only Alcatel EVOLIUM equipment)

2 channels spacing between the frequencies on air at the sametime within one site

Assumptions: 12 consecutive frequencies available (1..12) excluding BCCH frequencies



101/130


Fractional

Reuse 1*2, 1*3,

1*x


1*3 reuse (1)


102/130


1 3 reuse (1) Before we create new groups, we have

to keep two things in mind:

The RF-load of 50% is not possiblewith consecutive frequencies in the

FHS

50% RF-load is only possible when

all odd or all even frequencies areon air at the same time sameamount of odd and even

frequencies in each group

1 4 7 10

2 5 8 11

3 6 9 12

Cell A

Cell B

Cell C

Group A: 1,4,7,10

Group B: 2,5,8,11

Group C: 3,6,9,12


1*3 reuse (2)


103/130


1 3 reuse (2)

To avoid violating the GSM constarints, MAIOs have to be definedfor each TRX of the site.

1 4 7 10 1 4 7

2 5 8 11 2 5 8

3 6 9 12 3 6 9

Cell A

Cell B

Cell C

MAI = 0

….

….

….

Frequency used by TRX 1

Frequency used by TRX 2

MAIO settings:

Group A: 0,2

Group B: 1,3

Group C: 0,2


1*3 reuse (3)


104/130


1 3 reuse (3) In a hopping group with 4 frequencies, the MAIs 0 to 3 are possible to

be generated by the hopping sequence generator

1 4 7 10 1 4 7

2 5 8 11 2 5 8

3 6 9 12 3 6 9

Cell A

Cell B

Cell C

1 4 7 10 1 4 7

2 5 8 11 2 5 8

3 6 9 12 3 6 9

Cell A

Cell B

Cell C

1 4 7 10 1 4 7

2 5 8 11 2 5 8

3 6 9 12 3 6 9

Cell A

Cell B

Cell C

1 4 7 10 1 4 7

2 5 8 11 2 5 8

3 6 9 12 3 6 9

Cell A

Cell B

Cell C

MAI = 0

MAI = 3MAI = 1

MAI = 2

Assumption:

MAIOs are as defined

before

Group A: 0,2

Group B: 1,3

Group C: 0,2


1*3 reuse (4)


105/130


1 3 reuse (4)

For each frequency group we have an own MA table

With the group allocation from before, we get:

MAI ARFCN

MA - Group B

1

2

3

2

5

8

11

0

MAI ARFCN

MA - Group A

1

2

3

1

4

7

10

0

MAI ARFCN

MA - Group C

1

2

3

3

6

9

12

0


1*2 reuse (1)


106/130


1 2 reuse (1) On a two sector site we may have only 2 frequency groups and

therefore only an 1*2 reuse.

In a first step we allocate the frequencies according to the allocationscheme known from the 1*3 reuse

Group A

Group B 2 4 6 8 10 12

1 3 5 7 9 11

Problem: For max. possible RF load, all odd or even must be

on air at the same time. This is not possible in this case, as

all odd frequencies are in group A and all even in group B


1*2 reuse (2)


107/130


1 2 reuse (2)

To have an equal distribution between odd and even frequencieswithin one frequency group, we change every second frequency

Group A

Group B 2 4 6 8 10 12

1 3 5 7 9 11 Group A

Group B 2 3 6 7 10 11

1 4 5 8 9 12

To be done: MAIO assignment!


1*2 reuse (3)


108/130


1 2 reuse (3)

To assign MAIOs we assume the FN 0, and circle as manyfrequencies as TRXs are using this group. The circeled frequencies

must fulfil the GSM intra site and intra cell constraint

1 4 5 8

2 3 6 7

Cell A

Cell B

9

10 11

12MAIO TRX 1

MAIO TRX 2

MAIO TRX 3


1*4 - Exercise


109/130


The frequencies 1..24 are available (excluding BCCH freq.)

4 sectors on the site 3 TRXs are hopping in each cell

Cells are syncronized in terms of FN

Create Hopping Groups and assign MAIOs!



110/130


Fractional Reuse

1*1


Reuse 1*1 - 3 sector site


111/130


In the reuse 1 case, we use all available frequencies (1..12) on eachcell of the site

Intra site collisions are only avoided by the MAIO assignment

1 2 3 4

1 2 3 4

Cell A

Cell B

5

5 6

6 7 8 9 10 11 12

7 8 9 10 11 12

1 2 3 4Cell C 5 6 7 8 9 10 11 12

... .... ... ..........

..........................

MAIO of TRX 1

MAIO of TRX 2


Reuse 1*1 - 2 sector site


112/130


On a 2 sector site with 12 frequencies of course 3 TRXs per cell arepossible

61 2 3 4

1 2 3 4

5

5 6

7 8 9 1011 12

7 8 9 10 11 12

Cell A

Cell B

MAIO of TRX 1

MAIO of TRX 2

MAIO of TRX 3


Reuse 1*1 - Exercise


113/130


The frequencies 1..24 are available

4 sectors on the site

4 TRXs are hopping in each cell

Cells are syncronized in terms of FN

Create Hopping Groups and assign MAIOs!


Summary: 1*2/1*3/1*4/…

1 4C ll A

Only

necessary if


114/130


1

2

Cell A

Cell B

.......

.......

.......

.......

.......

3

...

Cell C

Cell ...

1 4

2 3

Cell A

Cell B

.......

.......

.......

.......

.......

1

2

Cell A

Cell B

3

...

Cell C

Cell ...

....... .......

.......

.......

.......

.......

MAIO TRX 1

MAIO TRX 2

MAIO TRX 3

MAIO0 2 3 4 51

Cell A

Cell B

Cell C

Cell D

.......

T R X 1

T R X 2

T R X 3

T R X . . . .

0

1

0

1

2

3

2

3

4

5

4

............ ..... .......

..... .......

.......

.......

.......

necessary, if

the number of

frequency

groups id

even“Rotate” the

frequencies

through the

cells

AssignMAIOs

according to

the standard

scheme for

Reuse 1*X


Summary: 1*1


115/130


1 2 3 4

1 2 3 4

Cell A

Cell B

5

5 6

6 7 8 9 10 11 12

7 8 9 10 11 12

1 2 3 4Cell C 5 6 7 8 9 10 11 12

... .... ... ..........

..........................

MAIO of TRX 1

MAIO of TRX 2

Cell A

Cell B

Cell C

.....

.......

T R X 1

T R X 2

T R X 3

T R X . . . .

0

2

4

x+2

x+4

2x+4

....

....

2x+2

.......

..... .......

..... .......

.......

.......

.......

x

....

....

“Rotate” the

MAIOs

through the cells

Standard MAIOassignment for

Reuse 1*1


FH parameter relation to Hardware - 1*3


116/130


FN

(T1R, T2, T3)

(0 … 84863)

HSN

(0 … 63)

Frequency Hopping

Sequence A

(e.g. 1,4,7,10)

Sector 1

Frequency Hopping

Sequence B

(e.g. 2,5,8,11)

Sector 2

Frequency Hopping

Sequence C

(e.g. 3,6,9,12)

Sector 3

MAIO (e.g. 2)

Hopping TRX 2

Site Cells TRXs

MAIO (e.g. 0)

Hopping TRX 1

MAIO (e.g. 1)

Hopping TRX 1

MAIO (e.g. 3)

Hopping TRX 2

MAIO (e.g. 2)

Hopping TRX 2

MAIO (e.g. 0)

Hopping TRX 1


FH parameter relation to Hardware - 1*1


117/130


FN

(T1R, T2, T3)(0 … 84864)

HSN

(0 … 63)

Sector 1

Frequency Hopping

Sequence

(e.g. 1,2,3,4,5,

6,7,8,10,11,12)

Sector 2

Sector 3

Site Cells TRXs

MAIO (e.g. 6)

Hopping TRX 2

MAIO (e.g. 0)

Hopping TRX 1

MAIO (e.g. 2)

Hopping TRX 1

MAIO (e.g. 8)

Hopping TRX 2

MAIO (e.g. 10)

Hopping TRX 2

MAIO (e.g. 4)

Hopping TRX 1


Alcatel BTS - Hopping concepts


118/130


A910 (M4M) - Evolium Micro BTS

RFH possible for each non BCCH TRX

(max. 4 TRX within one sector)

A9110-E (M5M) Micro Base Station

BBH

RFH for each non BCCH TRX

A9100 - Evolium Macro BTS

BBH

RFH for each non BCCH TRX


Implementation of Frequency Plan to theOMC R


119/130


OMC-R Directly using OMC-R

Frequencies are implemented manually in the OMC-R Used for small networks

Using External Tools

A9156 RNO or Excel edit of PRC files (for small changes)

Particularly A9155 RNP offers its A9155 PRC Generator Module toupload the frequency plan to the OMC-R (for massive changes)

Number of Cells Time Estimation using

OMC-R

Time Estimation using

external tool

10 1h22' 1h22'

100 4h24' 4h26'

500 17h50' 17h58'1000 34h38' 34h55'

2000 68h14' 68h49'


120/130



Frequency Hopping Parameters


BSS and CAE parameters


121/130


In the hopping case, RXQUAL does not reflect the real quality in the

network as explained before

To overcome this problem, Offsets are applied to RXQUALdedendent parameters

Offset_Hopping_PC influences

L_RXQUAL_UL_P

L_RXQUAL_DL_P

Offset_Hopping_HO influences

L_RXQUAL_UL_H

L_RXQUAL_DL_H


Default Parameters for SFH


122/130


Find hereafter the parameters which are different within hopping

networks

Offset_Hopping_PC = 1.0

Offset_Hopping_HO = 1.0

HO_INTRACELL_ALLOWED = DISABLED

Note: Resolution of Offset_Hopping_XX is 0.1 since B6.2


Quality indicator for FH (1)


123/130


The RXQUAL calculation takes only the BER before de-interleaving into account

The benefit of FH is not visible in RXQUAL

The higher probability to get into a fading notch (but for ashorter time) is leading to a worse RXQUAL then without

hopping, except the non hopping frequency would be in afading notch at this location

FER - Frame Erasure Rate

is counted after de-interleaving

takes higher error correction possibilities due to FH intoaccount


Quality indicator for FH (2)


124/130


Principle of quality indicator calculation within the mobile

DEMOD DECODER

ENCODER

Frame Erasure DecisionVoice

Decoder

RXQUALFrame Erasure Rate

FER

Deinterleave

Error

correct.

Inside the mobile station Air

-


Influence of FH on RXQUAL


125/130


- 1 1 0

- 1 0 6

- 1 0 2

RXQUAL_DL = f (RXLEV_DL)

0

1

2

3

4

5

6

7

- 9 8

- 9 4

- 9 0

- 8 6

- 8 2

- 7 8

- 7 4

- 7 0

- 6 6

- 6 2

- 5 8

- 5 4

- 5 0

Without Hopping

With Hopping

R X Q U A L

RXLEV [dBm]

Subjective speech quality isgood with RXQUAL=5

approximately:

RXQUAL(FH)

=

RXQUAL(no FH) + 1

Offset_Hopping_PC and

Offset_Hopping_HO are

introduced for correcting this

“error”.Resolution : 0.1

Min value : 0; Max value : 7


FH implementation via OMC-R (1)


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One of the tasks of the OMC-R is the management of relationshipsbetween a cell and its neighbouring cells in the network

In the OMC-R it is done by the logical configuration management

For example, it enables you to:

Radio configuration including frequency allocation, frequencyhopping schemes, TRX and logical channel configuration

PC/HO parameters

Import/Export…


FH impl. via OMC-R (2) B8 TRX configuration


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Selecting hopping mode and MAIO


FH impl. via OMC-R 1353-RA (3) B8 Frequency Allocation and FHS definition


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q y

Selecting HSNSelecting

cell

hopping

type


FH Summary Main benefits of frequency hopping are:


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q y pp g

frequency diversity

interference diversity

BBH is recommended since combines an intelligent frequency planand frequency hopping benefits

RFH

used when the capacity increase is not possible with BBH

fractional reuse allows cluster reduction

key parameters ARE real traffic load

the level of interference

should be used in well planned and optimized networks quality can be improved while using it with DTX and PC


What about Your network?


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How to start?

Frequency Band and its subdivision

Special Cells (micro-cells, concentric cells…)

Hopping useful?BBH or RFH?

Problems (RF load, interference…)/Solutions

Open Discussion

Documents

B8 RNP Extension Frequency Hopping Ed01