some wcdma tutorial

8/9/2019 Some WCDMA Tutorial

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What is Ec/Io (and Eb/No)?

If someone asks you "Which Signal Level for good call quality: -80 dbm or -0 d!m"

!e#are$ if you res%ond quickly$ you might end u% missing& 'his is because the correct ans#er is &&& it

de%ends( 'he Signal Strength is a very im%ortant and essential measure for any technology )*S+$ ,+.$/+'S$ L'$ etc&1& 2o#ever$ it is not the only one: let3s talk a little today about another magnitude$ equallyim%ortant: the Signal 4oise 5atio&

.lthough this ratio is of fundamental im%ortance to any cellular system$ is not #ell understood by many%rofessionals& 6n the o%%osite side$ %rofessionals #ith a good understanding of this ratio are able fore7am%le$ to correctly assess the 5 links$ and also to %erform more e7tensive o%timi9ations$ obtaining thebest %ossible %erformance of the system&

So$ let3s see a little about it

Eb and No

'o begin$ #e define the basic conce%ts of b and 4o& 'hey are basic for any digital communication system$and generally #e talk about it #hen #e deal #ith !it rror 5ate and also +odulation techniques&

Sim%ly %ut:

Eb: !it nergy&

o It re%resents the amount of energy %er bit&

No: 4oise S%ectral ensity&

o /nit: Watts29 )or mWatts291

Which brings us to the classic definition of b4o:

Eb/No: !it nergy on the S%ectral 4oise ensity&

o /nit: d!

It did not hel% much$ does it

o not #orry& Indeed$ only #ith the theoretical definition is still very difficult to see ho# this ratio is used$or ho# it can be measured&!ut okay$ let3s #alk a little further&

Okay, so how is Eb/No measured?

'o understand ho# this ratio can be measured$ let3s imagine a sim%le digital communication system&


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'he ratio b4o is measured at the receiver$ and serves to indicate ho# strong the signal is&

e%ending on the modulation technique used )!;S


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4ote: all the technology uses signal-interference ratio& or e7am%le$ in *S+$ #e use ,I&

.s #e are s%eaking of codes$ it becomes easier to understand the conce%ts by observing a sim%lifieddiagram of S%read S%ectrum +odulation&

In red$ in transmitter have a narro#band signal #ith data or voice modulated& 'his signal is s%read andtransmitted& .nd s%reads through the middle )air1& In the receiver$ the signal is des%read - using the same

sequence that #as s%read - and thus recovering the base narro#band signal&

'o %roceed$ #e must kno# some more definitions& 2o#ever$ this %oint is quite delicate$ as #e enter aconce%tual area #here #e have differences bet#een authors$ differences in translationscountries$ #heredifferences in technologies are a%%lied$ etc&&

Let3s try to define in a generic #ay$ and only the main&

No: S%ectral ensity of 4oise@

o 4oise generated by the 5 com%onents of the system$ the air$ among others&

Io: Interference is the !roadband@ Interfering co-channel$ including yourself setor&

E: is the signal )average1 energy - do not confuse it #ith the sinal )average1 %o#er&

b, c, s.&&: nergy are the %o#er %oints in time$ therefore related to the measure or 3length3 of

the time )the average %o#er is inde%endent of time 1&o 2ence it comes b$ c and s$ res%ectively relating to !it ,hi% and Symbol in different

times&

4ote: With these conce%ts$ several formulas can be derived #ith different numerators and denominators&or e7am%le$ s A b B k$ #here k A number of bits %er symbol& In =;S< modulation$ #here k A C$ s AC B b& .nd the derivations of formulas can reach far more com%le7 equations$ such as the definitions ofca%acity of an .W*4 channel$ and further deductions for equivalences )c4o$ b4t$ etc& &&&1& .gain$ it isnot our %ur%ose here today& We only mention a fe# conce%ts$ related&

'hen come back to the %ractical level - noting that theoretical a%%roaches can be done more easily later$after the basics are understood&

So let3s kee% today in ratios most common: b4o and cIo&

.s #e defined Eb/No is the .verage nergy of a bit signal$ on the S%ectral ensity of 4oise& It is %rimarilya %arameter related to the manufacturer for different bearers )based on the channel model1& !ut it canalso vary #ith the environment )urban$ rural$ suburban1$ s%eed$ diversity$ use of %o#er control$a%%lication ty%e$ etc&&


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.nd no# #e can begin to define Ec/Io$ one of the most im%ortant systems in ,+. and /+'S&

4ote: .n im%ortant observation is that often #hen #e refer to cIo$ #e are actually referring to c)Io D4o1& What ha%%ens is that for %ractical %ur%oses$ #e only have cIo$ because the interference is muchstronger and the noise can be neglected& 6ther#ise: for ,+. interference is like a noise$ then both canbe considered the same thing&

6kay$ let3s sto% #ith the issues and conce%ts$ and talk a little about the values of these indicators andtheir use in %ractice&

Eb/No Positie and Ec/Io Ne!atie?

In terms of values$ and talking logarithmicly$ if any ratio is less than E$ then the value is negative& Ifgreater than E$ %ositive&

We have cIo in the air$ #hich is s%read across the s%ectrum: then #e have negative value to the ratio ofenergy on the total noise )the energy is lo#er than the 'otal Interference1& It is measured at the in%ut ofreceiver )4ode!$ /$ etc1&

5egarding b4o$ it is in the baseband after des%reading and decoded only for one user - then #e have a%ositive amount of energy over the total noise& It is measured at the out%ut of receiver )4ode!$ /$ etc1&

Why shou"d we use Ec/Io?

. more natural question #ould be: #hy #e can not sim%ly use the Signal Strength measured by themobile as a guide for o%erations such as handover

'he ans#er is sim%le: the measured signal level corres%onds to the 'otal 5 %o#er - .ll cells that themobile sees&

So #e need another quick and sim%le measure that allo#s us to evaluate the contribution of each sectorindividually&

We used to measure the %ilot channel signal of each sector to assess the quality: if the level of the %ilot isgood$ then also are good levels for the traffic channels for our call in this sector& Like#ise$ if the %ilotchannel is degraded$ so #ill the other channels )including traffic1 be$ and it is best to avoid using thetraffic channels in this sector&

/+'S and ,+. systems$ #e have a %ilot channel$ some other control channels such as %aging$ andtraffic channels&

'he cIo varies #ith several factors$ such as the 'raffic Load and and 5 Scenario&

6f course$ the cIo is the final com%osition of all these factors simultaneously ),om%osite cIo1$ but it3seasier to understand talking about each one se%arately&

#han!e in Ec/Io accordin! to the $ector %ra&&ic 'oad

ach sector transmits a certain %o#er& Su%%ose in our e7am%le #e have a %ilot channel %o#er setting of CW$ and a %o#er of other control channels also fi7ed at C W&


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'o make it easier to understand$ #e calculate the cIo )%ilot channel %o#er to total %o#er1 of this sectorin a situation #here #e have no busy traffic channel )0 W1&

'hus #e have:

c A C W

Io A 0 D C D C A F W

Ec/Io A )CF1 A 0&G A -3 dB

4o# assume that several traffic channels are busy )eg use H W for traffic channels1& 'his is a situation oftraffic load$ #e3ll see ho# is cIo&

c A C W

Io A C D C D H A E0 W


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Ec/Io A )CE01 A 0&C A -7 dB

Conclusion: .s the traffic load in the sector increases$ the cIo #orsens&

#han!e in Ec/Io accordin! to the scenario

.ccording to the 5 scenario - a single server sector$ some or many servers sectors - #e can also takevarious measures to cIo&

,onsidering first a situation #ithout e7ternal interference$ #ith only one server sector )dominant1$ theratio cIo is about the same initially transmitted&

Ec/Io A )C81 A 0&CG A -6 dB

Whereas a signal coming from this sector in the mobile at level of -0 d!m )Io A -0 d!m1$ #e have c A-0 d!m D )- H db1 A -H d!m&

Let us no# consider another situation& Instead of one$ #e have five sectors signal arriving at the mobile)for sim%licity$ all #ith the same level of -0 d!m1&


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4o# have Io A -8 d!m )#hich is the sum of five signals of -0 d!m1& .nd the %o#er of our %ilot channelremains the same )c A -H d!m1&

'hus:Ec/Io A -H - )-81 A-13 dB

Conclusion: .s many more sectors serves the mobile$ the cIo #orsens&

'his situation #here #e have many overla%%ing sectors$ and #ith the same level of signal is kno#n as;ilot ;ollution - the mobile sees them all at once - each acting as interferer to each other&

'he solution in such cases is to eliminate un#anted signals$ by setting %o#er %arameters or %hysicalad?ustments )tilt$ a9imuth1$ leaving ?ust dominant signals #hich should e7ist at this %roblematic %lace&

Okay, and what are ty*ica" a"ues?

We have seen that for ,+. and /+'S systems$ the measurement of cIo #hich is very im%ortant in theanalysis$ es%ecially in handover decisions&

.nd no# also understand the measure cIo as the ratio of 3good3 energy over 3bad3 energy$ or 3cleaness3of signal&

!ut #hat are the %ractical values

'he value of cIo fluctuates )varies1$ as #ell as any #ireless signal& If the value starts to get too lo#$ youstart to have dro%%ed calls$ or can not connect& !ut #hat then is a good range of cIo for a sign


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In %ractical terms$ values of cIo for a good evaluation of the net#ork )in terms of this indicator1 aresho#n in the diagram belo#&

. com%osite cIo J - E0 db is a reasonable value to consider as good&

4ote: See #e are talking about negative values$ and considering them 3good3& In other #ords$ #e aresaying that energy is belo# the 4oise )and still have a good situation1&

'his is a characteristic of the system itself$ and cIo 3most negative3 or 3less negative3 is going to allo#assessment of the communication&

In situations #here cIo is very lo# )high negative number1$ and the signal level too )also high negativenumber1$ first #e need to #orry in enhancing the #eak signal&

.nother ty%ical situation: if the measured cIo is very lo#$ even if you have a good signal level$ you cannot connect$ or the call #ill dro% constantly&

I ho%e you3ve managed to understand ho# the cIo is im%ortant for ,+. and /+'S& 4ote$ ho#ever$that this matter is very com%le7$ and su%%lementary reading - books and internet - can further hel% youbecome an e7%ert on the sub?ect&

.ny#ay$ the content dis%layed serves as an e7cellent reference$ es%ecially if you3re not familiar #ith theconce%t of signal over noise for ,+. and /+'S&

+nd the $i!na" to Noise atio &or other techno"o!ies?

'he ratio cIo is the most commonly used to assess the condition of energy over interference$ but a%%liesonly in technologies that use codes )c1&

!ut the conce%ts understood here to ,+. and /+'S are very similar - a%%ly - for any technology$ eg*S+$ #here #e use the ,I&

.ny#ay$ this is a to%ic for another tutorial$ #e sa# today cIo&

#onc"usion

'oday #e had a brief introduction on the cIo ratio$ a measurement for decisions in ,+. and /+'S$ andused togheter #ith the measured Signal Strength&

We have seen that it re%resents the ratio of signal energy #ithin the duration of a chi% of the %ilotchannel$ on the S%ectral ensity of 4oise D Interference&

'his is a very im%ortant measure$ #hich someho# ignores the overall strength of the signal$ and focuseson ho# best to evaluate the %ilot channel signal is desired$ in relation to noise that interferes #ith it&


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5eturning to our original question: . strong signal level does not necessarily indicate an strong cIo: itde%ends on the level of interference&

What is %WP?

If you #ork #ith /+'S$3ve %robably heard someone talk about 5'W;& Its definition can be found in adictionary of acronyms$ such ashtt%:acronyms&thefreedictionary&com5'W;: 5eceived 'otal Wideband;o#er&

5e%resents a measure of /+'S technology: the total level of noise #ithin the /+'S frequency band of anycell&

5'W; is related to u%link interference$ and its monitoring hel%s control the call dro%s - mainly ,S& It alsohas im%ortance in the ca%acity management$ as it %rovides information for the ,ongestion ,ontrolregarding /%link Interference&

In /+'S$ the u%link interference may vary due to several factors$ such as the number of users in the cell$the Service$ ,onnection 'y%es and ,onditions of 5adio$ etc&&

.s our goal is to al#ays be as sim%le as %ossible$ #e #ill not delve in terms of formulas or conce%tsinvolved& We #ill then kno# the ty%ical values$ and kno# #hat must be done in case of %roblems&

%y*ica" a"ues

6k$ #e kno# that 5'W; can hel% us in checking the u%link interference$ then #e need to kno# its ty%icalvalues&

In a net#ork is not loaded$ normal$ acce%table 5'W; .verage value is generally around -E0F&G and -E0G&Gd!m&
http://acronyms.thefreedictionary.com/RTWPhttp://acronyms.thefreedictionary.com/RTWPhttp://acronyms.thefreedictionary.com/RTWP


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>alues around -G d!m indicate that the cell has some u%link interferers&

If the value is around -8G d!m$ the situation is ugly$ #ith strong u%link interferers&

/sually #e have 2igh$ Lo# and +edium measures of 5'W;& 2o#ever$ the ma7imum and minimum valuesare recommended only as au7iliary or reference$ since they may have been caused by a %eak of access$ oreven been forced to have a momentary value due to some algorithm i&e&&

'hus$ the value that hel%s us$ and has the most accurate information is the same +ean 5'W;(

or cases in #hich cell has t#o carriers$ the difference bet#een them 5'W; should not e7ceed H d!&


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ata should be collected for the sus%icious cell$ but also for its ad?acent cells$ allo#ing it to make atriangulation increasing the chances of locating the source of interference&

.nother #ay to locate the source of interference is to do a test in field& .n antenna guy must graduallychange the a9imuth of the antenna$ #hile another %rofessional do 5'W; measurements& 'hat is$ through

the information directing the antenna and the res%ective values of 5'W;$ you can dra# conclusions verygood&

It is obvious that changing the online system may not be a good %ractice$ and tests can be made #ith aagi antenna and a S%ectrum .naly9er&

>endors offer several #ays to measure 5'W;$ using the 6SS$ %erformance counters and logs&

#onc"usion

In this brief tutorial$ #e learn #hat is 5'W;$ and that the ideal ty%ical value is about -E0F&G d!m and

-E0G&G d!m&

.s the 5'W; is directly related to /%link Interference - and #e kno# that interference is the main cause of%erformance degradation - have concluded that im%roving 5'W;$ ie making is as close as %ossible to -E0Gd!m$ improving the Cll !rop "te#

I$%&"'(N' : Sei9ing the o%%ortunity$ see #hat #as stated at the start of this tutorial - dictionary - bydescribing 5'W;& 5emember that this site has been the sub?ect of a very interesting tutorial inthe 'i%sSection& If you have not visited this section of the %ortal yet $ I strongly recommend$ because ithas many issues that hel% in our gro#th in telecom and I' area&

What is etransmission, + and .+?

It3s very im%ortant to use solutions that im%rove the efficiency of the ado%ted model in any datacommunication system& If the transmission is 3Wireless3$ this need is even greater&

In this scenario #e have techniques that basically checks$ or verify if the information sent by thetransmitter correctly arrived in the receiver& In the follo#ing e7am%le$ #e have a %acket being sent fromthe transmitter to the receiver&
http://www.telecomhall.com/tips.aspxhttp://www.telecomhall.com/tips.aspx


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If the information arrived %ro%erly )com%lete1$ the receiver is ready to receive )and %rocess1 ne# data& Ifthe information arrived #ith some %roblem$ corru%ted$ the receiver must request that the transmitter sentthe %acket again )retransmission1&

Let3s understand a little more about these conce%ts increasingly used )and required1 in the currentsystems

Note: All telecomHall articles are originally written in Portuguese. Following we translate to English and

Spanish. As our time is short, maybe you find some typos sometimes we !ust use the automatic


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translator, with only a final and "#uic$" re%iew&. 'e apologi(e and we ha%e an understanding of our effort.

)f you want to contribute translating * correcting of these languages, or e%en creating and publishing your

tutorials, please contact us: contact.

Error Checking and Correction

We start talking about errors& rrors are %ossible$ and mainly due to the transmission link& In fact$ #e caneven 3e7%ect3 errors #hen it comes to Wireless ata 'ransmission&

If #e have errors$ #e need to take some action& In our case$ #e can divide it into t#o ste%s: errorchecking and error correction&

rror checking is required to allo# the receiver to verify that the information that arrived is correct or not&

6ne of the most common methods of error checking is the ,5,$ or 3,yclic 5edundancy ,heck3$ #here bits),5,1 are added to a grou% of information bits& 'he ,5, bits are generated based on the contents of theinformation bits& If an error ha%%ens #ith the information bits$ the ,5, bits are used to verify and hel%recover the degraded information&

'he level of %rotection %rovided is determined by the ratio: number of ,5, bits by the number ofinformation bits& .bove a certain error level$ the %rocess is eliminated& ,5, %rotection is used %racticallyin all e7isting >oice and ata a%%lications&

'he follo#ing diagram sho#s a sim%lified demonstration of ho# the ,5, is used&

.nd the ,5, is directly connected to the rror ,orrection methods& 'here are various #ays of o#ardrror ,orrection ),1$ but the main idea is$ given a level of quality in the link$ try to get the lo#estnumber of required retransmissions&

+inimi9ing the number of retransmissions #e ended u% having a more efficient data flo# result$ including- mainly - the 3'hrough%ut3&
http://www.telecomhall.com/contact.aspxhttp://www.telecomhall.com/contact.aspx


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In sim%lified #ay: the ,5, lets you kno# if a %ackage arrived 36oice for e7am%le$ is a service #here retransmission does not a%%ly& If a %iece of information is lost$ and isretransmitted$ the conversation becomes intelligible&

6n the other hand$ data services %ractically rely on retransmission$ since most have - or allo#s - a certaintolerance to delays M some more$ some less& With the e7ce%tion only for 35eal 'ime3 services&

!ut it is also im%ortant to take into account that the greater the number of needed retransmissions$ lo#erthe data transmission rate that is effectively reached: If the information have to be retransmitted severaltimes$ it #ill take long for the receiver to obtain the com%lete - final - information&


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ARQ

'ill no# #e talked in a generic #ay about data retransmissions$ error checking and correction& Let3s no#see some real and %ractical schemes&

'he sim%lest #ay )or more common1 control using #hat #e described above is kno#n as .5=$ or3.utomatic 5e%eat 5equest3&

In .5=$ #hen #e have a 3bad3 %ackage$ the system sim%ly discards it$ and asks for a retransmission )ofthe same %ackage1& .nd for this$ it sends a feedback message to the transmitter&

'hese feedback messages are messages that the receiver uses to inform #hether the transmission #assuccessful or not: 3.,


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!ut see that if there #ere no retransmissions$ the %erformance of the data flo# #ould be much better& Inthe e7am%le belo#$ com%ared #ith the %revious$ #e transmit more information - times in the same timeinterval&

/nfortunately #e don3t have much to do about the link conditions& 6r better$ #e are able to im%rove thelinks %erformance$ for e7am%le #ith configuration %arameters o%timi9ation$ but #e3ll al#ays be sub?ect toface adverse conditions& In this case$ our only #ay out is to try to minimi9e retransmissions&

.nd that3s #here arise other techniques or more 3enhanced3 schemes for retransmission& 'he main one is2.5=&

Hybrid ARQ (HARQ)

'he 2.5= is the use of conventional .5= along #ith an rror ,orrection technique called 3Soft ,ombining3$#hich no longer discards the received bad data )#ith error1&

With the 3Soft ,ombining3 data %ackets that are not %ro%erly decoded are not discarded anymore& 'hereceived signal is stored in a 3buffer3$ and #ill be combined #ith ne7t retransmission&

'hat is$ t#o or more %ackets received$ each one #ith insufficient S45 to allo# individual decoding can becombined in such a #ay that the total signal can be decoded(

'he follo#ing image e7%lains this %rocedure& 'he transmitter sends a %ackage NEO& 'he %ackage NEOarrives$ and is 36


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'he transmission continues$ and is sent a %ackage NCO& 'he %ackage NCO arrives$ but let3s consider no#that it arrives #ith errors& If the %ackage NCO arrives #ith errors$ the receiver sends a 34.,


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!ut if the combination of these t#o %ackages still does not give us the com%lete information$ the %rocessmust continue - and another 34.,


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2ere #e can see the follo#ing: along #ith the received %ackage NC&CO$ the receiver also has %ackages NCOand NC&EO$ that have not been dro%%ed and are stored in the buffer&

In our e7am%le$ #e see that the %ackage arrived C times 3#rong3& .nd #hat is the limit of theseretransmissions /% to F& I$ #e can have u% to F retransmission in each %rocess& 'his is the ma7imumnumber su%%orted by 3buffer3&

Different HARQ Schemes

*oing back a little in the case of ,onventional .5=$ #henever #e send a %ackage and it arrives #ith%roblems$ it is discarded&

'aking the above e7am%le$ #hen #e send the %ackage NCO$ and it arrives #ith errors$ it is discarded& .ndthis same %ackage NCO is sent again&

What ha%%ens is that #e no longer have the conce%t of 3%ackage version3 - NC&EO$ NC&CO$ etc& We do nothave the 3redundancy3 version$ or the gain #e get in 2.5= %rocessing&

'o understand this$ #e need to kno# that information is divided as follo#s:

+)nformation -edundancy -edundancy

When #e transmit the %acket NCO #e are transmitting this:


When retransmit the same %ackage NCO #e are retransmiting it again:



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What #e have seen so far clarifies the conce%ts involved& In %ractice$ in retransmission$ this ty%e of;rotocol is called 3Sto% .nd Wait3 )there are other kinds of similar %rotocols1&

What #ould be: send the information and sto%& Wait for the res%onse to send other information& Send$#ait for res%onse& Send$ #ait for res%onse &&&

4o( 4ot so in %ractice& In %ractice$ #e #ork #ith a number of 3%rocesses3$ #hich may vary for e7am%lefrom F$ H or 8& 'he follo#ing image illustrates this more clearly&


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*ther ty$es of HARQ

4e# schemes are constantly being develo%ed and used$ as the ty%e III 2.5=$ #hich uses self-decodable%ackages&

!ut enter these variations$ terminology and considerations$ is not the sco%e of our tutorial$ #hich #assim%ly to introduce the conce%t of 5etransmission$ .5= and 2.5=&

!ased on the key conce%ts illustrated here today$ you can e7tend your studies the #ay you #ant$ ho#ever#e believe that the most im%ortant thing #as achieved M understand ho# it #orks and #hat are all thecited conce%ts&

+A,A A$$let

!elo#$ you can see ho# some retransmission schemes #ork& 'here are several .%%lets available$ for themany %ossibilities ).5=$ 2.5=$ With Sliding Windo#s$ Selective$ etc1&

'he ne7t is a link for a R.>. .%%let that simulates a 3Selective 5e%eat ;rotocol transmission3&

htt%:media&%earsoncmg&coma#a#kurosenet#orkFa%%letsS5inde7&html
http://media.pearsoncmg.com/aw/aw_kurose_network_4/applets/SR/index.htmlhttp://media.pearsoncmg.com/aw/aw_kurose_network_4/applets/SR/index.html


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Conclusion

'his #as another tutorial on im%ortant issues for those #ho #ork #ith I' and 'elecom: data 'ransmissionand 5etransmission techniques$ .5= and 2.5=&

.5= is used for a%%lications that allo# a certain delay$ as Web !ro#sing and Streaming .udiovideo& It isused #idely in Wima7 and Wii communication systems& 2o#ever$ it cannot be used in >oice transmission$as for e7am%le in *S+&

2.5= for e7am%le is used in 2S;. and L'$ and therefore must be a #ell-understood conce%t for those

#ho #ork or #ant to #ork #ith these technologies&

We ho%e you en?oyed it& .nd until our ne7t tutorial&

What is # and +?

'o #ork #ith modern #ireless net#orks such as /+'S and L'$ it is essential that the telecom %rofessionalhas full understanding of its basic conce%ts$ such as those that control the call establishment andmaintenance$ #hether it is voice ),S1 or data );S1&


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In this scenario$ 5.! and 55, are t#o of the most im%ortant conce%ts because they are res%onsible for allthe negotiation involved in those calls&

In addition to 5.! and 55,$ #e still have some other terms directly involved in conte7t$ as 5!$ S5!$ '5!$among others& 'hese terms are also im%ortant conce%ts$ since #ithout them 5.! and 55, could not e7ist&

So lets try to understand today - the sim%lest %ossible #ay - #hat is the 55, and 5.! role in the calls ofthese mobile net#orks in %ractice& .s it become necessary$ #e #ill also talk about other conce%ts&






Introduction

'o start$ #e can divide a call into t#o %arts: the signaling )or control1 and data )or information1& .lreadyahead of key conce%ts$ #e can understand the 55, as res%onsible for the control$ and the 5.! asres%onsible for the information %art&

.s mentioned$ other au7iliary conce%ts are involved in calls$ but our goal today is to learn the most basicconce%ts - 55, and 5.!$ allo#ing us to evolve in our learning later&

6ddly enough$ even %rofessionals #ho already #ork #ith /+'S-W,+. and L' net#orks have trouble tofully understand the conce%ts of 55, and 5.!& .nd #ithout this initial understanding$ hardly they canevolve #ith clarity and efficiency in their daily #ork&

Without further introduction$ let3s go straight to the %oint and then try to understand once and for allthese so im%ortant conce%ts&

+na"o!y

.s al#ays$ and as usual the telecom2all$ let3s make an analogy that hel%s us to understand thefunctioning of the 55, and 5.! in %ractice&


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Let3s start imagining the follo#ing scenario: t#o %eo%le are cut off by a cliff& 6n the left side$ a %erson )E1#ant to buy some things that are for sale in a store )C1 or de%osit on the right side& In the right side$ inaddition to the de%osit$ #e also have a seller )1$ #hich #ill hel% the buyer to contact )negotiable1 #iththe de%osit&

.s additional or au7iliary ob?ects )F1$ #e have some iron bars #ith different si9es$ and some cars - somelike train #agon$ others like remote control cars&

In short$ #e have the situation outlined in the image belo#&

.nd so$ ho# this situation can be solved

Let3s continue #ith a %ossible solution: the buyer on the left #rite his request in a note$ tie on a smallstone that he found on the floor$ and send )E1 it to the seller on the other side& So$ the stone carry theinformation or initial request&


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'he seller receives the request$ but she need to send it to the de%osit$ in order for the sho%%ing to besent& She sends the request on a remote control car )E1$ #hich run a %reviously demarcated %ath to thede%osit&

Some time later$ the de%osit res%onse arrives to seller )E1$ #hich then checks to see #hether she #ill beable to send the data or not&

So that #e can %roceed #ith our call$ let3s consider a %ositive res%onse& 'hat is$ #hat the buyer is #illing$or the 3resources3 are available&

Seller reali9es that to fulfill the request$ and be able to send the %urchases$ she #ill need to build a 3%ath3)E1 bet#een the t#o ends of the cliff$ so the #agons could carry over #ith the ordersrecei%ts and%urchases& 'hen$ the seller uses some of its iron bars and creates a link bet#een the t#o sides&


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6nce established all the #ay bet#een those involved$ requests can be sent from both sides as #ell as the%urchases or any other information can be transferred by different %aths and #agonscars(

If you managed to understand ho# the above %roblem #as solved$ congratulations$ you ?ust understandho# the most common form of /+'S-W,+. and L' communication ha%%ens(

.lthough analogies are not %erfect$ it hel% us a lot to understand the com%le7 functioning of thesenet#orks$ es%ecially in relation to ne# conce%ts such as 55, and 5.!$ but also a very often used$ the3bearer3 T so much that it3s #orth talking a little bit about it&

What is earer?

If #e search the #ord 3bearer3 in the dictionary$ #e3ll find something like trasn%orter$ or carrier& In a sim%le#ay: one #ho carries or conveys something from some %oint to another %oint& In a restaurant$ #e cancom%are the 3bearer3 to a #aiter&


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!ut from the telecommunications %oint of vie#$ 3bearer3 is best understood as a 3%i%e3 that connects t#o ormore %oints in a communication system$ through #hich the data flo#s&

'echnically s%eaking$ it is a channel that carries >oice or ata$ a logical connection bet#een different%oints )nodes1 that ensures that the %ackets that are traveling have the same =oS attributes& 7%lainingbetter: for each 3bearer3 #e have several associated %arameters$ such as the ma7imum delay and %acketloss limit M and these attributes that make sure each %acket going in the same channel have the same=oS attributes&

0enera" "owchart - #, + and Others

4o# that #e kno# #hat is bearer$ let3s go back to the analogy %resented earlier$ but no# bringing it to thereal$ more technical side&

.ll that #e3ll talk can be summari9ed in a single figure$ having all the conce%ts seen today$ and that #ill bedetailed from no# on&

4ote: If you manage to understand the conce%ts that #ill be e7%lained in the figure belo#$ you #ill be#ith a great base for both W,+. and L' net#orks& 'his is because$ in order to facilitate #e use W,+.nomenclatures$ but the %rinci%le is %retty much the same in L'& Rust do the equivalent re%laces$ like4ode! for e4!&


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6n that ficticious scenario$ the seller is the /'5.4$ res%onsible for creating and maintaining thecommunication bet#een the / )buyer1 and ,4 )de%osit1 so that the =oS requirements of each are met&

/'5.4: /+'S 'errestrial 5adio .ccess 4et#ork

o 4ode!

o 54,

/: /ser qui%ment

,4: ,ore 4et#ork

o +S,: for s#itched voice services

o S*S4: for %acket-s#itched services

'he cliff is the /u Interface bet#een the / and the /'5.4$ and the road through the remote control car

goes until the de%osit is the Iu Interface$ bet#een the /'5.4 and ,4&

Sending requests and recei%ts is %art of signaling$ or the 55,& 'he shi%ment of %urchases is the data %art$or the 5.!& In our scenario$ the 55, are the 5ails$ and 5.! is the full service of sending data bet#een the/ and the ,4&

55,: 5adio 5esource ,ontrol

5.!: 5adio .ccess !earer


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4ote: the 55, is in Layer - control %lane$ #hile the 5.! occurs bet#een the / and ,4$ in the user%lane&

'he railcars are the 5!s$ and convey the information in the radio %ath& 'hese #agons define #hat ty%e ofthing #ill be trans%orted$ and in #hat quantity& Similarly$ the 5!s define #hat ty%e of data #ill in the 55,$#hich can be ata or Signaling& When the =oS attributes change$ then the 5bs associated #ith that 55,connection need to be reconfigured&

'he remote control cars are the Iu bearer$ and carry information on Iu Interface )bet#een the /'5.4 andthe ,41$ either ,S or ;S&

5!: 5adio !earer

Iu bearer: Iu !earer Interface

4ote: 5.! is the combination of 5! and Iu bearer&

.s e7am%les of 5.! for some services and different rates #e have:

'he ,onversational 5.! and the Interactive 5.! can be used together$ and in this case #e have a case of+ulti5.!&

'he 5! is a layer C connection bet#een the / and the 54,$ and can be used for Signalling and control/ser ata& When it is used for Signalling or ,ontrol +essages is called S5!& .nd #hen it is used for userdata is called '5!&

S5!: Signalling 5adio !earer ),ontrol ;lane1

'5!: 'raffic 5adio !earer )/ser ;lane1

4ote: in an o%timi9ed net#ork$ #e can find much of the traffic being handled by 2S;. bearers$ even+ulti5.!& 'his o%tion frees resources from , ),hannel lements1$ relieving the load on 5 )that canonly use these resources1& 2o#ever$ it should be done #ith caution$ because if im%ro%erly configured itcan degrade the ;erformance Indicators #ith !lockage ),ongestion1 and ailures&

.s you3ve %robably noticed$ #e3re talking about several ne# technical terms$ but these terms are #hatyou3ll find for e7am%le #hen reading /+'S or L' call flo#charts& !ut if you can understand at least in%art the conce%ts %resented today$ everything #ill be much easier&

Let us then take a look again on our figure$ and continue our analogy&


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.s #e sa#$ in telecom #e #ork #ith the conce%t of layers& .nd this #ay of seeing the net#ork brings usmany advantages$ mainly because #e #ere able to 3#ra%3 %hysical access& In this #ay$ any modification orre%lacement can be made #ith less com%le7ity&

We don3t need to tell you ho# much the radio %ath is com%le7$ continuously changing$ right 'hisstructure using beares ensures this sim%lification: the 54, and ,4 bother #ith =oS requirements in the%ath bet#een them )Iu Interface1@ and only the 54, have to #orry about meeting the com%le7 radio %ath=oS&

Sure$ but #hy #e have t#o ty%es of carriers - #agons and remote control cars 'he ans#er to this is inthe very characteristic of the t#o e7isting %aths& !eing the Iu a more robust interface$ and also because#e have ma?or changes in 5.!s during connections$ it is normal that these bearers are also different forthe %aths& it3s like using a F7F %icku% truck to climb a mountain$ and a race car to an as%halt race&


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5egardless the carriers$ #ith the 5.! the elements of the ,4 has the im%ression of a %hysical %ath to the/$ so don3t need to be #orrying about the com%le7 as%ects of radio communication&

or e7am%le$ a / can have 5.!s bet#een he and the 54,$ and these 5.!s may be changing$ as in thecase of soft handovers$ #hile the 54, has only E Iu bearer for this connection&

rom the %oint of vie# of the carriers$ the main task of the /'5.4 is managing these services on these

interfaces& She controls the /u interface$ and along #ith the ,4$ controls the %rovision of services in theIu interface&

5emember that in a communication bet#een the / and the ,4$ several other elements are involved$mainly to negotiate =oS requirements bet#een both %arties& 'hese requirements are ma%%ed in the 5.!s$that are visible to both )/ and ,41$ #here the /'5.4 is res%onsible for creating and maintaining these5.!s so that all of this is served in all as%ects&

. little bit more details&&&

. 55, connection e7ists #hen an / %erforms the call establishment %rocedure$ and get resources fromthe /'5.4& When a 55, connection is established$ the / #ill also get some S5!s& )If for some reasonthe initial request is not acce%ted$ the / can make a ne# request after some time1&

Since the S5! #as established bet#een the / and the ,4$ the 54, checks a series of information suchas the / identity$ #hat is the reason for the request and #hether the / is able to handle the requestedservice&

'he 54, that ma%s the requested 5.!s into 5!s$ to transfer bet#een the / and the /'5.4& In additionit is also check the attributes of the 5.!s: if they can be met by the available resources$ and even#hether to activate or reset radio channels )reconfiguration of lo#er layers services 1 based on thenumber of Signaling ,onnections and 5.!s to be transferred&

'his #ay$ it creates the im%ression that there is a %hysical %ath bet#een the / and the ,4& 5ememberingagain that no matter ho# many signaling and 5.!s connections there are bet#een the ue and the ,4 -there is only a single 55, connection used by the 54, to control and transfer bet#een the / and the/'5.4&

4o# that #e have seen a lot about 55, and 5.!$ let3s learn only a fe# more conce%ts today M after all$#e already have enough information %resented& Let3s talk about the .S and 4.S&

.S M .ccess Stratum is a grou% of s%ecific %rotocols of access net#ork

4.S M 464 .ccess Stratum: so$ are the other %rotocols$ or those that are not access net#ork

.t this %oint of vie#$ the .S %rovides the 5.! to the 4.S$ or information transfer service&


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'he / and ,4 need to communicate )eventsmessages1 #ith each other to %erform several %rocedures#ith many %ur%oses& .nd the 3language3 of this conversation bet#een them is called %rotocols&

'he %rotocols are then res%onsible for allo#ing this conversation bet#een the / and ,4$ and cause the,4 do not #orry about the method of access )be it *S+*;5S$ /'5.4$ L'1& In our case the 54, acts asa %rotocol - bet#een the /'5.4 and ,4&

.ccording to #hat #e learned today$ the 5.! is carried:

!et#een the / and the /'5.4: #ithin the 55, connection& 'he 55, ;rotocol is res%onsible for negotiating the

)logical1 channels of /u and Iu! interfaces$ and for the establishment of signaling dedicated channels as S5!s

and 5!s among these interfaces&

!et#een the 54, and the ,4: after being negotiated and ma%%ed$ in the 5.4.; %rotocol connection$ through

Iu interface ),S;S1&

o 5.4.;: 5adio .ccess 4et#ork .%%lication ;art

.s #e have seen above$ the 54, ma%s requested 5.!s into 5!s using current radio net#ork resourcesinformation$ and controls the services of lo#er layers& 'o o%timi9e the use of these resources$ as #ell asthe net#ork band and %hysical resource sharing bet#een different entities$ the /'5.4 can also %erformthe function of ,4 messages distribution&

or this$ the 55, ;rotocol trans%arently transfers messages from ,4 to the access net#ork through adirect transfer %rocedure& When this occurs$ a s%ecific indicator of ,4 is inserted in these messages$ andthe entities #ith the distribution function in 54, use this same indicator for direct messages to thea%%ro%riate ,4$ and vice versa&

!ut no# it started to get more com%le7$ and #e have already reached our goal today$ #hich #as to learnthe basics of 55, and 5.!&

verything #e ?ust talked about above can be seen again in the same figure belo#$ the same from thebeginning of the e7%lanations&


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# and + in 0$1?

6kay$ #e understand ho# 55, and 5.! #orks in /+'S-W,+. and L' net#orks& !ut in *S+$ does #ehave these conce%ts as #ell

.t first$ the ans#er is 46& 2o#ever$ #ith #hat #e learned today$ #e can make a com%arison #ith some*S+ 3equivalent3 %arameters&

We can com%are the S,,2 %hase and ',2 %hase of a *S+ call #ith 55, and 5.! in /+'S&

55, is the 5adio 5esource ,ontrol that #orks as ,ontrol ;lane in Layer & Is used %rimarily for Signaling in/+'S& 'hen #e can com%are #ith the signaling in *S+$ as the Immediate .ssignment %rocess for S,,2

resource allocation&

5.! is the radio access 3trans%orter3 that #orks as the /ser ;lane to %rovide data for the servicesrequested by the user& 'hen #e can com%are #ith the user %art in *S+$ as the ',2 .ssignment&

or each service requested by the user #e have only E 5.!& or e7am%le$ if the requested service is a>oice ,all ),S-.+51$ then E ,S 5.! #ill be generated and %rovided to the user& 'he same is true for ;S&

So our equivalence table #ould be:


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UMTS / LTE GSM

Control RRC Connection Immediate Assignment

User RAB Assignment (RNC-CN) Assignment (BSC-MSC)

# #onnection and + e2am*"e

'o com%lete for today$ let3s see )al#ays in sim%lified form1 a sim%le 55, connection and 5.!&

Whenever the / needs the /'5.4 resources$ he asks& So that these resources are allocated$ itestablishes a 55, connection #ith some S5!s&

In this case$ a 5.! connection is created to enable the transfer of user data& We remind you that the 5.!consists of 5! D Iu bearer& 'he 5.! is created by ,4$ #ith a s%ecific =oS request&

or a single /$ there may be multi%le 5.! for 4.S service ),S or ;S1&

!ut let3s ?ust stick to the initial %rocedure$ that is$ ho# is %erformed the 355, Setu%3 %rocedure$ from the/3s request&

'he follo#ing figure sho#s this more straightfor#ard&

'he 55, has al#ays ste%s:

E& 'he / requests a ne# connection in the /%link )P55, ,644,'I64 5=/S'Q1@

C& With sufficient resources available$ the 355, o#nlink ,644,'I64 S'/;3 message is sent$ including the

reason$ along #ith the S5! configuration@ )4ote: other#ise$ if the 55, connection cannot be established$ the

message sent is 355, ,644,'I64 S'/; 5R,'31&

& If all goes #ell$ the / sends the message in the /%link: P55, ,644,'I64 S'/; ,6+;L'Q&


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.nd after this$ the P+.S/5+4' ,64'56LQ message are being sent in the o#nlink$ for thecommunication continuity&

.fter the 55, connection is established$ the /'5.4 makes the checks bet#een the ,4 and the /$ fore7am%le the authentication and security o%erations&

.nd so$ the ,4 informs the 5.! to /'5.4 in accordance #ith requirements of the service requested by

the /& .s #e have seen$ 5.! occurs after the 55,$ and #ithout a 55, connection no 5.! may beestablished&

#onc"usion

We have seen today a sim%lified e7%lanation that covers a number of conce%ts involved in thecommunication of the most modern e7isting mobile net#orks$ %rimarily related to 55, and 5.!&

With this conce%tual base$ #e #ill continue to evolve in the ne7t tutorials #ith e7am%les that make theassimilation of these com%le7 conce%ts in a task far less e7haustive than normal&

We ho%e that you have en?oyed$ and #e count on your %artici%ation$ #hich can be for e7am%le suggestingne# to%ics$ or sharing our site #ith your friends& If %ossible$ leave also your comments ?ust belo#&

What is 1I1O?

4e# technologies are increasingly %resent in our lives$ evolving to#ards modern - and com%licated -net#orks(

'o enable this 35evolution3$ ne# techniques must be develo%ed$ and e7isting ones need to be im%roved&

2ere in telecom2all 3,ourse3 #e3ll talk about these techniques$ as al#ays trying to e7%lain each sub?ect inthe sim%lest %ossible #ay$ allo#ing to understand ho# these innovations may have become reality&

We begin today #ith: +I+6& 2ave you heard

ven if you already kno#$ #e invite you to read this brief summary #e %re%ared to you&






$I$O, 1I$O, $I1O

!efore #e talk s%ecifically about +I+6$ let3s kno#$ or remember #hat it also means SIS6$ SI+6 and+IS6&


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.lthough it may sound like some sort of lock tongues$ in fact these letters corres%ond to different ty%es ofa radio channel use& 'hat is$ refer to the access modes of the radio channel$ any transmitting andreceiving system&

Let3s start #ith SIS6 - "Single In%ut$ Single 6ut%ut 3$ as this model more intuitive& .s the name im%lies$#e only have one in%ut in the radio channel$ and only one out%ut&

In the figure belo# is easier to understand: #e use a 'ransmitter )'U1 to transmit data through a singleantenna$ and receive it in the 5eceiver )5U1$ also through a single antenna&

When the system has multi%le in%uts and only one out%ut$ #e have +IS6 - 3+ulti%le In%ut$ Single 6ut%ut3&

In this case #e have multi%le entries$ and only one out%ut&

4ote: in %ractice$ #e can have more than one antenna& Rust to sim%lify the demonstration #e #ill limitourselves to a ma7imum of t#o antennas in the illustrations&

5emember #e are talking about the radio channel$ the figure belo# hel%s to better understand thisnomenclature&


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So %retty much o%%osed to +IS6$ #e also have SI+6 - 3Single In%ut$ +ulti%le 6ut%ut3&

1I1O

6nce this nomenclature is understood$ #e can talk about +I+6&

.s mentioned$ although in %ractice #e may have multi%le antennas at the transmitter and multi%leantennas at the receiver$ #e3re re%resenting our system #ith only t#o antennas on each side&

.t first glance$ and com%aring #ith the %revious access$ +I+6 seems to be sim%le$ but unfortunately it3snot&


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Its o%eration is much more com%le7 than the others: #e no# have multi%le in%uts and multi%le out%uts&'he biggest challenge is ho# to recover the original information correctly

See illustration of a more realistic scenario$ sho#ing #hat ha%%ens in %ractice&

.lthough more com%le7$ it brings is a huge %erformance gain$ or s%ectrum use efficiency$ as discussedbelo#&

.nd again$ the #ay +I+6 #orks$ #ith its variations$ is very com%le7& We #ill try to sho# here ?ust sim%lyho# it #orks$ that is$ as is %ossible&

. good analogy to learn the conce%t of +I+6 is to imagine that #e have t#o 3mouths3 and use the t#omouths to ask someone:

32o# old are you3

4ote that #e use 3four3 #ords& .s #e have t#o mouths$ #e can use one to say 32o# old3 and and another -at the same time - to 3are you3&

With t#o mouths talking at the same time$ if the other %erson3s ears are #ell cleaned$ and it3s a smart%erson$ heshe3ll be able to understand&

'hat is$ #e s%eak 3four #ords3 in the 3same time3 that #e #ould s%eak 3t#o #ords3&

What does this mean In terms of data$ assume that each #ord has E00


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Sim%ly %ut$ this is #hat makes +I+6 %ossible$ and enables attaining high rates of 00 to H00 +b%s(

'hus$ +I+6 is used to im%rove #ireless access in a large number of a%%lications& Several access standardssuch as L'$ Wi+a7$ 2S;. and Wii use this gain to achieve the significant im%rovements that each onehas&

.nd no# #e have a conce%t that seems to be against everything #e learned: +I+6 is based oninterference at line of sight )L6S1$ ie$ the signal %ath bet#een the station and mobile&

'o +I+6 %resent some advantage$ #e need a good diversity in the signal&


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In other #ords$ anything that interferes #ith the signal %ath such as buildings$ cars$ %eo%le$ etc&& areactually contributing to the overall system efficiency$ and effectiveness of +I+6 a%%lications&

'he diversity of the signal - that doesn3t take a direct %ath bet#een the transmitter - once vie#ed as a%roblem$ is no# making it %ossible for the data streams to be combined and recovered(

.s seen in the analogy above$ +I+6 allo#s the sending of more than one stream of data on a singlechannel& It effectively doubles the s%eed that he have on that channel - considering the use of t#oantennas&

!ut okay$ ho# does it #ork

In the %ast$ S;3s$ or igital Signal ;rocessors #ere very hard to be develo%ed$ due to a lot of %astlimitations& ,urrently ho#ever$ S; develo%ment have evolved a lot - and are still evolving& 'his kind of%rocessors today are very %o#erful$ able to recover our transmitted signal #hen it arrives at the receiverat different time intervals&

'he S;3s then have the res%onsibility to take the data$ 3se%arate3 in different %arts$ send each %art viadifferent antennas$ at the same time$ at th same channel& .nd do the reverse %rocess at the receiver&


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'he result is obvious: #e are able to send a certain amount of data in half the time it #ould normally take&

ach antenna has its o#n stream of data$ both in transmission and rece%tion& In the end$ then #e havethe data received&

5emember$ the +ulti%ath varies according to location$ and this variation is very dynamic - difficult to%redict& Still$ the multi%ath makes it %ossible for the receiving antenna to differentiate bet#een data that

#as transmitted on the same channel at the same time&

O31

'hen enter the access via 6+ - 36rthogonal requency ivision +ulti%le7ing3& Let3s talk more about thisty%e of multi%le7ing access in another tutorial$ but 6+ is very im%ortant to +I+6 for ne# generationsof cellular technologies&

It is easier if #e make a com%arison&

In a single carrier systems have symbols )or 3%ieces of information31 transmitted over broadband$ each

transmitted sequentially$ and for a relatively short %eriod of time&

Symbols transmitted in *eries

Brodbnd


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*hort Symbol %eriod

In the 6+ symbols are transmitted in %arallel$ each using a relatively very narro# s%ectrum& 2o#ever$each symbol is transmitted by a much greater %eriod of time(

Symbols transmitted in %rllel

Nrro+ Bnd

ong Symbol %eriod

'his scenario re%resents an advantage in signal rece%tion$ since it is much easier for the receiver to checkeach of the symbols - even if they suffer some degradation - because they are transmitted over a muchlonger %eriod&

In #ideband transmission$ during the short time interval in #hich each symbol is transmitted$ #e mayhave %roblems #ith data loss$ making it difficult to recover information& If there is interference in thesignal$ a significant %art of it can be degraded and may end u% making it im%ossible to receive certainsymbols )%ieces of information1 correctly&


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,om%aring 6+ #ith a single carrier$ 6+ methodology have multi%le frequencies transmitted in%arallel - the symbols are transmitted in %arallel(

.nd each symbol is being transmitted over a much longer time %eriod& .nd even #hen #e have a %roblemof fading at some %oint #e3re %robably still able to retrieve information&

'hus$ #ith transmission of the symbols in %arallel and for a longer %eriod of time$ the greater the chancesof success at the rece%tion(

.nother ne# fact concerning #hat #e understand about transmission and rece%tion of data: the kno#nand common scenario for us is to have one antenna on the transmitter$ transmitting at a certainfrequency$ and another antenna on the receiver$ receiving at this this same frequency&

+I+6 introduces a ne# conce%t in terms of this kno#n o%eration$ and as #e have seen$ in terms ofs%ectral efficiency through the use of t#o or more antennas to transmit and t#o or more antennas toreceiving&

.nd %erha%s the most innovative conce%t: all the antennas transmit at the same frequency #ith different

data transmitted by each one(

Surely$ this is different from everything #e learned in school$ because #e learned that the frequencies #illcertainly interfere #ith each other$ and end u% losing all our data&

.ntennas o%erating in the same o%erating frequency and transmitting different data generatesinterference$ and interference generates losses

4o more& ortunately$ using ne# advanced technologies of S;3s #e can$ for the same frequency$ transmitdifferent data on different antennas - and simultaneously& .nd the receiving antennas$ #e can differentiatebet#een these streams of data&

It is not difficult to understand that this re%resents a huge advantage in terms of s%ectrum use efficiency&

If for e7am%le #e have t#o antennas$ #e double efficiency& If #e use more antennas$ tri%le or quadru%lethis efficiency& !ut it is obvious that the greater the number of antennas$ and the greater the com%le7ityof the system&

1I1O E2am*"e

In conclusion$ #e sho# an e7am%le of %ackets decoding by a +I+6 receiver&

5eturning to our initial e7am%le$ su%%ose a transmitter #ith t#o antennas& /sing the nomenclature 3hi?3 forthe channel 3h3 of the transmitter antenna 3i3 to receiver antenna 3?3&


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'hat is$ #hen a %acket 3%E3 is transmitted from the antenna of a transmitter$ the receiver receives 3hEEB%E3in its first antenna$ and also receives 3hECB%E3 in his second antenna& In other #ords$ the receiver receivesa vector #hose direction is determined by the channel&

!ut remember that our e7am%le has t#o transmitter antennas$ that is$ #hile #e can send another %acket3%C3 through its other antenna&

'he receiver receives 3hCE%C3 in its first antenna$ and 3hCC%C3 in his second antenna&


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With this$ #e have a vector at the receiver end$ defined by the sum of all vectors&

Sure$ but ho# the receiver can decode these t#o %ackages 6nce the t#o %ackages are sent concurrently$they re%resent interference to each other& 'o decode a %acket$ the receiver %ro?ects on a directionorthogonal to the interference of another %ackage&

'o eliminate the interference of the %ackage 3%C3$ and so be able to decode the %acket 3%E3$ the receiver%ro?ects on a direction orthogonal to it )%ackage 3%C31&


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Similarly$ to decode the %acket 3%C3$ the receiver eliminates interference from the other %ackage 3%E3$%ro?ecting a direction orthogonal to the interference of it&

'hen$ #ith t#o antennas can decode t#o com%eting %ackages( ollo#ing the same reasoning$ #e canunderstand that the +I+6 decoding allo#s com%etitors and ho# many %ackets as the number ofantennas&


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,onclusion

'oday #e had a brief introduction to +I+6$ #hich as mentioned$ is much more com%le7 than sho#n$because #e are ?ust doing an introduction to even allo# you to understand its basic o%eration&

2o#ever$ the benefits it %ays back the efforts of its com%le7ity&

2o%e you en?oyed$ and if you liked$ %lease share the telecom2all #ith your friends& !elo# you have a fe#quick #ays to do this&

What is ake eceier?

2ave you ever heard of "5ake 5eceiver" Surely you3ve heard of 5eceiver )5eceiver in nglish1$ and you%robably have heard of 5ake )5ake in nglish1&

With the %ictures bello#$ can you imagine #hat a 5ake 5eceiver can be


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6k$ if the analogy does not hel% much$ let3s go&

In a #ireless communication system$ the signal can reach the receiver via multi%le distinct %ath#ays&

In each %ath$ the signal can be blocked$ reflected$ diffracted and refracted& 'he signal of this many routesreach receivers faded& 'he 5ake receiver is used to correct this effect$ selecting the correct strongersignals$ bringing great hel% in ,+. and W,+. systems&

6kay$ but #hat is the 5ake 5eceiver$ and ho# it does it

3e&inition

'he 5ake 5eceiver is nothing more than a radio$ #hose goal is to try to minimi9e the effects of the signalfading due to multi%ath suffers #hen he travels& In fact$ #e can understand a set of 5ake 5eceiver sub-radios$ each lagged slightly$ to allo# the individual com%onents of the multi%ath can be tuned %ro%erly&

ach of these com%onents is decoded com%letely inde%endently$ but are combined in the final& It is as if#e took the original signal$ and adicionVssemos other co%ies of the original signal reaching the receiver#ith different am%litudes and arrival times& If the receiver kno#s the am%litude and arrival time of each ofthese com%onents$ it is %ossible to estimate the channel$ allo#ing the addition of com%onents&

ach of these sub-radios 5ake 5eceiver is called inger& ach finger is res%onsible for collecting the energyof bit or symbol$ hence the analogy #ith the groomer that #e use in the garden$ #here each branch of therake collecting t#igs and leaves(

'o ease some of the understanding$ imagine t#o signal com%onents arriving at the mobile unit as seen inthe %revious figure$ #ith a lag t among them&


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'he main advantage of 5ake 5eceiver is that it im%roves the S45 )or b 4o1& 4aturally$ thisim%rovement is observed in larger environments #ith many multi%aths than in environments #ithoutobstruction&

In sim%lified form: #e have a better signal than #e #ould have #ithout using 5ake 5eceiver( 'his isalready a sufficient argument$ isn3t it

3isadanta!es and 'imitations

'he main disadvantage of 5ake 5eceiver is not necessarily technical$ and is not as %roblematic& 'hisdisadvantage is %rimarily because the cost of the receivers& When #e insert one more radio receiver$ #eneed more s%ace and also increase com%le7ity& ,onsequently$ #e increase costs&

'he greater the number of multi%ath com%onents su%%orted by the receiver$ the more com%le7 is thealgorithm& .s #e al#ays do here$ #e #ill not be deducting formulas involved$ but the com%le7ity increasesalmost e7%onentially&

.nd in the real #orld$ the amount of multi%ath com%onents that arrive at the receiver is quite large$ there

is not a 3limit3& verything #ill de%end on the environment&

'he threshold number of fingers in a mobile unit is determined by each technology standard$ #hich fore7am%le in ,+. is H$ corres%onding to the ma7imum number of channels to direct traffic that can be%rocessed by the mobile unit at once ).ctive Set1&

2o#ever$ in cellular environments$ most of the ,+. mobile units need only actually of demodulators)W,+. uses F1& +ore than that #ould be a #aste of resources$ and an additional cost to manufacturethe %hone&

$earcher


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In a 5.4$ , resources are managed by both the 54, and 4ode!& 'he 4ode! re%orts its , ca%acity tothe 54,& 'he 54, determines #hether to admit a ne# service based on the number of ,s that need tobe consumed and controls , resources during , congestion& 'his ensures the %ro%er use of ,resources& 'he 4ode! dynamically manages , resources and ra%idly ad?usts the number of ,s that canbe consumed based on the actual service rate& 'his increases , resource usage&

. %ro%er use of , resources increases the number of /s that can be admitted and im%roves the servicequality of the admitted /s&

!asic ,hannel lement ,once%ts

, is a basic unit that measures the channel demodulation ca%abilities of a 4ode!& ,s are classified intou%link )/L1 ,s and do#nlink )L1 ,s&

E& 6ne /L , needs to be consumed by a /L EC&C kbits voice service )S A HF1 %lus &F kbitssignaling&

C& 6ne L , needs to be consumed by a L EC&C kbits voice service )S A EC81 %lus &F kbitssignaling&

If only &F kbits signaling traffic is carried on a ,2 or 2S;. channel$ one , still needs to be consumed&'he number of ,s that need to be consumed by services of other ty%es can be calculated by analogy&'he number of /L and L ,s su%%orted by a 4ode! is determined by the 4ode! hard#are ca%abilitiesand the licensed , ca%acity& 'he number of /L and L ,s su%%orted by the 4ode! hard#are is calledthe %hysical , ca%acity& 'he licensed , ca%acity may differ from the %hysical , ca%acity& 'he smallerdetermines the number of ,s that can be used by an o%erator&, is a conce%t of the 4ode! side& 6n the 54, side$ it is called 4ode! credit& 'he 54, %erforms admissionand congestion control based on the 4ode! credit& In the /L$ the number of 4ode credit resources is t#icethat of ,s& In the L$ the number of 4ode! credit resources equals that of ,s&
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5ules for ,alculating , ,onsum%tion

'he 54, determines the number of ,s required for a service based on the S that matches the servicerate& When an 5.! connection is set u% or released for a service$ , resources must be allocated or takenback and the number of ,s must be deducted or added accordingly& ifferent rules for calculating ,resource consum%tion a%%ly to channels or services of different ty%es&

, resources reserved by the 4ode! for common and 2S;. channels are sho#n in gray&

, resources that need to be consumed by 5 and 2S/;. services are sho#n in %ink&

,ommon ,hannels , ,onsum%tion

, resources required on the /L and L common channels are reserved by the 4ode!& 'herefore$ they donot occu%y the licensed , ca%acity& 'hese ,s do not need to be considered in the calculation of ,consum%tion&

2S;. ,hannels , ,onsum%tion

Similarly$ the 4ode! reserves , resources for the high-s%eed do#nlink shared channel )2S-S,21 andthe related control channels if 2S;. is used& 'hese ,s also do not need to be considered in thecalculation of , consum%tion&4ote that the signaling of an 2S;. / that is not %erforming an 5 service occu%ies one ,2 and

needs to consume one L ,& If the S5! over 2S;. function is enabled$ the signaling of an 2S;.service does not consume additional , resources& or an 2S;. / that is %erforming an 5 service$ itssignaling and the 5 service occu%y the same ,2& 'herefore$ only the ,s consumed on 5 trafficchannels need to be calculated&
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5 Service , ,onsum%tion

or an 5 service$ the 54, determines the number of ,s and 4ode! credit resources that need to beconsumed based on the S that matches the ma7imum bit rate )+!51 of the service&

irection 5ate

)kbits1

S 4umber of ,s

,onsumed

,orres%onding ,redits

,onsumed

/L &F CGH E C

E&H HF E C

8 HF E C

EH HF E C

C C E&G

HF EH H

EC8 8 G E0

EFF 8 G E0

CGH F E0 C0

8F F E0 C0

L &F CGH E E

E&H EC8 E E

8 EC8 E E

EH EC8 E E

C HF E E

HF C C C

EC8 EH F F

EFF EH F F

CGH 8 8 8

8F 8 8 8

2S/;. Service , ,onsum%tion

or an 2S/;. service$ the 54, determines the number of ,s and 4ode! credit resources that need to beconsumed based on the S that matches the service rate& 'he 54, determines the S based on a certainrate in the follo#ing #ays:

If the /L enhanced LC function is disabled and the 4ode! indicates in a %rivate information element

)I1 that dynamic , resource management has been enabled in the cell$ the 54, calculates the S basedon the larger of the bit rate of one 5L, ;/ and the guaranteed bit rate )*!51&


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o If the /L enhanced LC function is disabled$ the 5L, ;/ si9e is fi7ed& 'he bit rate of one 5L, ;/ is

determined by the 5L, ;/ si9e and transmission time interval )''I1&

If the /L enhanced LC function is enabled and the 4ode! indicates in a %rivate I that dynamic ,

resource management has been enabled in the cell$ the 54, calculates the S based on the larger of thebit rate of the smallest 5L, ;/ and the *!5&

o If the /L enhanced LC function is enabled$ the 5L, ;/ si9e is fle7ible& 'he bit rate of the smallest

5L, ;/ is determined by the minimum 5L, ;/ si9e and the ''I& 'he minimum 5L, ;/ si9e can bes%ecified by the 5lc;du+a7Si9eor/lLCnhance %arameter&

If the 4ode! re%orts that dynamic , resource management has been disabled$ the 54, calculates

the S based on the +!5&

If the 4ode! does not re%ort #hether dynamic , resource management has been enabled$ the 54,

calculates the S based on the value of the 2su%a,e,onsumeSelection %arameter and #hether the /Lenhanced LC function is enabled&

o If 2su%a,e,onsumeSelection is set to +!5$ the 54, calculates the S based on the +!5&

o If 2su%a,e,onsumeSelection is set to *!5:

If the /L enhanced LC function is disabled$ the 54, calculates the S based on the larger of the bit

rate of one 5L, ;/ and the *!5&

If the /L enhanced LC function is enabled$ the 54, calculates the S based on the larger of the bit

rate of the smallest 5L, ;/ and the *!5&

.fter determining the S$ the 54, searches the , consum%tion ma%%ing listed belo#

irection 5ate

)kbits1

S 4umber of ,s

,onsumed

,orres%onding

,redits ,onsumed

/L 8 HF E C

EH HF E C

C C E C

HF C E C

EC8 EH C F

EFF EH C F

CGH 8 F 8

8F F 8 EH

H08 F 8 EH

EFG0 CSF EH C

C0F8 CSC C HF

C80 CSC C HF

GKH0 CSCDCSF F8 H

, ,onsum%tion of F-Way 5eceive iversity

'he use of F-#ay receive diversity does not affect L , consum%tion but doubles /L , consum%tion&'he use of F-#ay receive diversity can be configured by resource grou%& /L , consum%tion of a resourcegrou% doubles if the resource grou% is configured #ith F-#ay receive diversity& , consum%tion of ancommon resource grou% remains unchanged&e7am%les of , ,onsum%tion

/ .$ #hich %erforms a /L HF kbits and L 8F kbits service on the ,2$ consumes three /L ,s

and eight L ,s&

/ !$ #hich %erforms a /L HF kbits and L E0CF kbits service on the ,2 and 2S-S,2

res%ectively$ consumes three /L ,s and one L , if the L signaling radio bearer )S5!1 is carried onthe ,2&


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/ ,$ #hich %erforms a /L H08 kbits and L E0CF kbits service on the -,2 and 2S-S,2

res%ectively and at the same time %erforms an .+5 s%eech service$ consumes nine /L ,s and one L,&

First to create an idea for channel elements:

". band ,hannel lement is the resource base required in the 4ode-! to ;rovide for one voice channel

ca%acity$ the control %lane$ including the control %lane signaling$ com%ressed mode$ the transmit diversity

and softer handover&

actors affecting ,a%acity in W,+. /L and L$ sorted by descending level of Im%ortance as ollo#s:

- /L: 4o& , su%%ort on each 4ode !$ interference$ 4ode ! sensivity$ &&

- L: 4o& , su%%ort on each 4ode ! Iub interface ca%acity$ %o#er L$ 6>S$ &&&

'hus$ , can be vie#ed as a license for each 4ode! ca%acity )not more1&

ach service #ill need some different , /L and L$ such as:

.+5 EC&C k: /%link E$ do#nlink E

,S ;S HF


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60 Er"an! conert to 3+%+ (1b*s)

,onvert erl to data )+b%s1&&& you nee to do the follo#:

or e7am%le you has EFKC&8KCG erl and you #ant to convert in +b%s

+b%s A )rl B HF1 E0CF+b%s A )EFKC&8KCG B HF1E0CF A C +b%s

'raffic )erl1BEC&C kbitsec&BH008 A


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Z 2igh S%eed o#nlink Shared ,hannel )2S-S,21: . do#nlink channel shared bet#een /s by allocationof individual codes$ from a common %ool of codes assigned for the channel&

!edicted trnsport chnnel t)pes re0

Z edicated ,hannel ),21: . channel dedicated to one / used in u%link or do#nlink&

&IC( C(NNE*

. general classification of logical channels is into t#o grou%s@ ,ontrol ,hannels )for the transfer of control%lane information1 and 'raffic ,hannels )for the transfer of user %lane information1&

1 Control Chnnels0

Z !roadcast ,ontrol ,hannel )!,,21: . do#nlink channel for broadcasting system control information&

Z ;aging ,ontrol ,hannel );,,21: . do#nlink channel that transfers %aging information& 'his channel isused #hen the net#ork does not kno# the location cell of the /$ or$ the / is in the cell connected state)utilising / slee% mode %rocedures1&

Z ,ommon ,ontrol ,hannel ),,,21: !i-directional channel for transmitting control information bet#eennet#ork and /s& 'his channel is commonly used by the /s having no 55, connection #ith the net#ork

and by the /s using common trans%ort channels #hen accessing a ne# cell after cell reselection&

Z edicated ,ontrol ,hannel ),,21: . %oint-to-%oint bi-directional channel that transmits dedicatedcontrol information bet#een a / and the net#ork& 'his channel is established through 55, connectionsetu% %rocedure&

Z Shared ,hannel ,ontrol ,hannel )S2,,21: !i-directional channel that transmits control information foru%link and do#nlink shared channels bet#een net#ork and /s& 'his channel is for ' only&

2 'ric Chnnels0

Z edicated 'raffic ,hannel )',21: . edicated 'raffic ,hannel )',21 is a %oint-to-%oint channel$dedicated to one /$ for the transfer of user information& . ',2 can e7ist in both u%link and do#nlink&Z ,ommon 'raffic ,hannel ),',21: . %oint-to-multi%oint unidirectional channel for transfer of dedicateduser information for all or a grou% of s%ecified /s&

UTRA Channels

/'5. radio interface has logical channels$ #hich are ma%%ed to trans%ort channels$ #hich are againma%%ed to %hysical channels& Logical to 'rans%ort channel conversion ha%%ens in +edium .ccess ,ontrol)+.,1 layer$ #hich is a lo#er sublayer in ata Link Layer )Layer C1&

ogicl Chnnels0

!roadcast ,ontrol ,hannel )!,,21$ o#nlink )L1;aging ,ontrol ,hannel );,,21$ Ledicated ,ontrol ,hannel ),,21$ /LL,ommon ,ontrol ,hannel ),,,21$ /LLedicated 'raffic ,hannel )',21$ /LL,ommon 'raffic ,hannel ),',21$ /nidirectional )one to many1

'rnsport Chnnels0

edicated 'rans%ort ,hannel ),21$ /LL$ ma%%ed to ,,2 and ',2!roadcast ,hannel )!,21$ L$ ma%%ed to !,,2or#ard .ccess ,hannel ).,21$ L$ ma%%ed to !,,2$ ,,,2$ ,',2$ ,,2 and ',2;aging ,hannel );,21$ L$ ma%%ed to ;,,25andom .ccess ,hannel )5.,21$ /L$ ma%%ed to ,,,2$ ,,2 and ',2/%link ,ommon ;acket ,hannel ),;,21$ /L$ ma%%ed to ,,2 and ',2o#nlink Shared ,hannel )S,21$ L$ ma%%ed to ,,2 and ',2


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%h)sicl Chnnels0

;rimary ,ommon ,ontrol ;hysical ,hannel );,,;,21$ ma%%ed to !,2Secondary ,ommon ,ontrol ;hysical ,hannel )S,,;,21$ ma%%ed to .,2$ ;,2;hysical 5andom .ccess ,hannel );5.,21$ ma%%ed to 5.,2edicated ;hysical ata ,hannel );,21$ ma%%ed to ,2edicated ;hysical ,ontrol ,hannel );,,21$ ma%%ed to ,2

;hysical o#nlink Shared ,hannel );S,21$ ma%%ed to S,2;hysical ,ommon ;acket ,hannel );,;,21$ ma%%ed to ,;,2Synchroni9ation ,hannel )S,21,ommon ;ilot ,hannel ),;I,21.cquisition Indicator ,hannel ).I,21;aging Indication ,hannel );I,21,;,2 Status Indication ,hannel ),SI,21,ollision etection,hannel .ssignment Indication ,hannel ),,.-I,21


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60 # e*ortin! Eents55, 5e%orting events or 2andover events are sent from 5!S or / to trigger the different handover%rocedures in the 54,& 'he generation of handover events de%ends on the different 5 %arameters andthresholds&

vent E.: . ;rimary ,;I,2 enters the re%orting range@ addition of a radio link&vent E!: . %rimary ,;I,2 leaves the re%orting range@ removal of a radio link&vent E,: . non-active %rimary ,;I,2 becomes better than an active %rimary ,;I,2@ re%lacement of the#orst cell in .S&event E: ,hange of best cellevent E: . ;rimary ,;I,2 becomes better than an absolute thresholdevent E: . ;rimary ,;I,2 becomes #orse than an absolute thresholdevent E*: ,hange of best cell )'1event E2: 'imeslot IS,; belo# a certain threshold )'1event EI: 'imeslot IS,; above a certain threshold )'1

vent Ca: ,hange of best frequencyvent Cb: 'he estimated quality of the currently used frequency is belo# a certain threshold and theestimated quality of a non-used frequency is above a certain threshold@ handover to inter-freq neighborsvent Cc: 'he estimated quality of a non-used frequency is above a certain thresholdvent Cd: 'he estimated quality of the currently used frequency is belo# a certain threshold@ start

com%ressed mode to measure inter-freq W,+. or *S+ neighbors&vent Ce: 'he estimated quality of a non-used frequency is belo# a certain thresholdvent Cf: 'he estimated quality of the currently used frequency is above a certain threshold@ sto%com%ressed mode Y sto% measure inter-freq W,+. or *S+ neighbors

vent a: 'he estimated quality of the currently used /'5.4 frequency is belo# a certain threshold andthe estimated quality of the other system is above a certain threshold@ handover to *S+ neighborsvent b: 'he estimated quality of other system is belo# a certain thresholdvent c: 'he estimated quality of other system is above a certain thresholdvent d: ,hange of best cell in other system

event F .: 'rans%ort ,hannel 'raffic >olume becomes larger than an absolute thresholdevent F !: 'rans%ort ,hannel 'raffic >olume becomes smaller than an absolute threshold

event G.: . %redefined number of bad ,5,s is e7ceeded

event H.: 'he / '7 %o#er becomes larger than an absolute threshold@ start com%ressed modeevent H!: 'he / '7 %o#er becomes less than an absolute threshold@ sto% com%ressed modeevent H,: 'he / '7 %o#er reaches its minimum valueevent H: 'he / '7 %o#er reaches its ma7imum valueevent H: 'he / 5SSI reaches the /3s dynamic receiver rangeevent H: 'he / 57-'7 time difference for a 5L included in the active set becomes larger than an absolutethresholdevent H*: 'he / 57-'7 time difference for a 5L included in the active set becomes less than an absolutethreshold

vent Ka: 'he / %osition changes more than an absolute thresholdvent Kb: S4-S4 measurement changes more than an absolute thresholdvent Kc: *;S time and S4 time have drifted a%art more than an absolute threshold

Iu 5ti"i7ation &or oer IP inter&ace in .uaweiIu! !and#idth /tili9ing 5atio )/LL1 A E00 XB)Iu! 5eal /LL 'raffic1)Iu! /LL ,onfigured!and#idth1

or 2ua#ei vendor$ the 4ode! measures the used /LL band#idth on the %hysical %ort every Gs for EGmand then caculates the averaging value&So the Iu! !W /tili9ing 5atio )/LL1 for 4ode equal:


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/L:N)>S&I;/l.vg/sed&ED>S&I;/l.vg/sed&CD>S&I;/l.vg/sed&D>S&I;/l.vg/sed&F1)>S&I;/l'otal&ED>S&I;/l'otal&CD>S&I;/l'otal&D>S&I;/l'otal&F1O 7 E00X

L:N)>S&I;L.vg/sed&ED>S&I;L.vg/sed&CD>S&I;L.vg/sed&D>S&I;L.vg/sed&F1)>S&I;L'otal&ED>S&I;L'otal&CD>S&I;L'otal&D>S&I;L'otal&F1O 7 E00X

$o&t-and-$o&ter-.andoer-in-W#31+

Slide C:E& Soft 2andover ,once%ts M efinitionC& +acro diversity& .dvantagesF& isadvantagesG& Soft 2andover ventsH& Soft 2andover vent 'riggering and related %arametersK& Soft 2andover actor )5atio1

Slide :efinition E: Soft handover refers to the %rocess that allo#s a +obile connection to be served

simultaneously by several cells$ adding and dro%%ing them as needed& 'his feature is %ossible in W,+.because all cells use the same frequency and are se%arated only by codes& efinition C: Soft handovermeans that the radio links are added and removed in a #ay that the / al#ays kee%s at least one radiolink to the /'5.4& Soft handover is %erformed by means of macro diversity$ #hich refers to the conditionthat several radio links are active at the same time&

Slide G:+acro-diversity: =: What is the difference bet#een S26 and macro-diversity .:4ote the difference inthese conce%ts: a S26 is a %rocedure& 6nce it is %erformed$ the result is a macro-diversity situation&Signals are transmitted over the air interface on the same frequency$ from several base stations se%aratedby considerable distances& 'his scheme is called the soft handover )S261& In a S26 all the %artici%atingbase stations use the same frequency$ and the result is a macro-diversity situation& In macro-diversity themobileQs transmission is received by at least t#o base stations$ and similarly the do#nlink signal is sent byat least t#o base stations&

Slide H:+acro-diversity in the L: In the do#nlink the / can receive$ at most$ as many macro- diversitycom%onents as it has fingers in its 5.


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escri%tion: 6n the L$ the / can combine the different received signals to increase the reliability ofdemodulation& !y combining the signals from different links$ the effective SI5 increases$ #hich reducesthe transmit %o#er even #hen com%ared to the %o#er required over the best link only& 'his is termed softcombining gain&

Slide E0:6n the /L$ if macro-diversity gain is observed$ the same is not al#ays true for the soft combining gain& Ifthe cells in soft handover do not belong to the same 4ode !$ it is not %ossible to combine the signals

before they are demodulated& Instead$ all the demodulated frames are sent to the 54,$ #hich decides#hich one to use& 'his %rocess still %rovides a gain com%ared to a single link$ since it increases the%robability of having at least one link #ithout error& 'his is the selection gain$ also a macro-diversity gain&

Slide EE:Soft handover advantages: It increases the reliability of transmission 5educes the transmit %o#errequirement for each link used& / at the boundary among several cells uses the minimum transmit %o#eron either link

Soft handover dra#backs: Since information must be sent over multi%le links$ that re%etition decreasesthe efficiency of resource utili9ation& +ore transmitted signals may mean more energy in the air$ #hichmeans more interference to the radio environment in the do#nlink direction& 'he control %rocedure in the/'5.4 has to be very clever indeed to meet the conflicting demands of mobility and lo# interferencelevels& S26 branches should be added to a connection only #hen the estimated resulting total interferencelevel is less than it #ould be #ithout the S26&

Slide EC:*ain in o#nlink transmission %o#er due to Soft 2andover;ositive value A gain$ 4egative value A loss *ain in 'U ;o#er 5elative %ath Loss bet#een t#o 4ode ! cellsor large signal value difference #e can see that transmission %o#er even is raised$ because of signalingerrors on do#nlink )%o#er control commands1& !est results are achieved #hen signal levels from t#o4ode !Qs has equal values *ainA C&G d! When the signals of t#o cells are more than F&G d! a%art$ it startsto have negative im%act&

Slide E:*ain in u%link transmission %o#er due to Soft 2andover ;ositive value A gain$ 4egative value A loss *ainin 'U ;o#er 5elative %ath Loss bet#een t#o 4ode ! cells !est results are achieved #hen signal levels fromt#o 4ode !Qs has equal values When the signal of t#o cells are more than G d! a%art$ it starts to havenegative im%act& or large signal value difference #e can see that transmission %o#er even is raised$because of signaling errors on do#nlink )%o#er control commands1&

Slide EF:'y%ical handover %arameters Windo# to add Windo# to dro% EM d! CMG d!

Slide EG:ffect of [4o Soft 2andover\ Without S26$ a communicating base station #ould have to transmit at ahigher %o#er level to reach the /$ #hich #ould %robably increase the overall system interference level&.dditionally$ if a / is in S26$ the connection is not lost altogether if one branch gets shado#ed&

Slide EH:Soft 2andover ]one )6verla% ]one1: . S26 is ty%ically em%loyed in cell boundary areas #here cells haveoverla%& It has many desirable %ro%erties& In the cell edges$ a / can collect more signal energy if it is inS26 than if it has only a single link to a base station&

Slide EK:Softer handover softer handover is a s%ecial case of soft handover #here the radio links that are addedand removed belong to the same 4ode ! )i&e& the site of co-located base stations from #hich several

sector-cells are served& . softer 26 is a 26 bet#een t#o sectors of a 4ode !& rom a /Qs %oint of vie#$ itis ?ust another S26& 'he difference is only meaningful to the net#ork$ as a softer 26 is an internal%rocedure for a 4ode ! )a /'5.4 base station has the curious name 4ode !1$ #hich saves thetransmission ca%acity bet#een 4ode !s and the 54, )a /'5.4 base station controller1& 'he u%link softer26 branches can be combined #ithin the 4ode !$ #hich is a faster %rocedure$ and uses less of the fi7edinfrastructureQs trans%ort resources than most other ty%es of 26s in W,+. systems

Slide E8:Soft 2andover in 2S;.E& 6nly on the control channel)5Q1 and not on the dedicated channelC& 'he 2S-S,2 does not su%%ort soft handovers


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Slide E:Soft 2andover ,ombining +ethods:uring soft handover$ a mobile simultaneously communicates #ith t#o )C-#ay S261 or more cellsbelonging to different 4ode !s of the same 54, )intra-54,1 or different 54,s )inter-54,1& '#o active%o#er control loo%s %artici%ate in soft handover$ one for each !S& In the softer handover situation$ a

mobile is controlled by at least t#o sectors under one !S$ the 54, is not involved and there is only oneactive %o#er control loo%& In /L$ the combining is done in 4ode ! itself and not the 54,&

Slide C0:,ombining method in L:In the do#nlink )L1$ the mobile receives both signals for ma7imal ratio combining& +a7imum ratiocombining is assumed to be a%%lied in the mobile terminal& 'herefore$ to a user inside the soft handover9one$ the received b I0 are the sum of the b I0 from all the !Ss in the active set& In the do#nlink$ #emodel macro diversity to sum together the signal received from active !Ss& 'hus$ #e reali9e ma7imal ratiocombining by summing measured SI5 values ,ombining method in the u%link 'he mobile code channel isdetected by both !Ss )C-#ay S261$ and is routed to the 54, for selection combining&In the u%link$ selection combining among active !Ss takes %lace to use the frame #ith the highest averageSI5 for statistics collecting %ur%oses$ #hile the other frames get discarded&

Slide CC:

Intra-frequency re%ortingevents for the mode: E.& . %rimary ,;I,2 enters the re%orting range& E!&. %rimary ,;I,2 leaves the re%orting range& E,& . non-active %rimary ,;I,2 becomes better than anactive %rimary ,;I,2& E& ,hange of best cell& Sim%lest #ay to define S26 vent: .ny +odifications tothe active sets is referred as soft handover vent&

Slide C:vent E.: Serving )!est ,ell1 M N4!5 D ,I6 )4!51O ^A d! Where@ 2ystforE. A 0I4'5.5L'265E.,S4>;AH J ) d!1 +eans: If the difference bet#een source and neighbour cell is lessthan or equal to d! for a set time N'5I*'I+E.AC0O$ then the neighbour #ill be added to the activeset& ,I6 ,onsideration: 'his %arameter can be defined at cell level and %er 4eighbour relation& D ve valueof ,I6 #ill hel% trigger the Soft 2andover event E . earlier than if #e have the ,I6A0& - ve value of ,I6#ill introduce delay in the Soft 2andover event E . &

Slide CF:d! 4!5 cell ! #hich is in monitored set is going to enter the re%orting 5ange& 'he re%orting range is d! do#n belo# the best cell . in active set & 5e%orting 5ange ;lot for E.

Slide CG:vent E!: Serving )!est1 M NServing )old1 D ,I6 )old1O_A H d! Where@ 2ystforE! A 0I4'5.5L'265E!,S4>;AEC J )Hd!1 +eans: If the difference bet#een best cell and C nd or rd bestcell in active set is greater than or equal to H d! for a set time N'5I*'I+E!AHF0O$ then the C nd or rdbest cell #ill be removed from the active set& ,I6 ,onsideration: 'his %arameter can be defined at celllevel and %er 4eighbour relation& - ve value of ,I6 #ill hel% trigger the Soft 2andover event E ! earlierthan if #e have the ,I6A0& D ve value of ,I6 #ill introduce delay in the Soft 2andover event E . &

Slide CH:Hd! 5e%orting 5ange ;lot for E! 4!5 cell ! #hich is in .ctive set is going to leave the re%orting 5ange&'he re%orting range is H d! d

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