agilent - concepts of hsdpa - q&a

7/30/2019 Agilent - Concepts of HSDPA - Q&A

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Concepts of HSDPA: Bringing Higher Speed to W-CDMA eSeminar

Agilent Technologies 2005

Concepts of HSDPA: Bringing Higher Speed to W-CDMAeSeminar

Question and Answer (Live Only) February 22nd

. 2005

Presentation Title

Concepts of HSDPA: Bringing Higher Speed to W-CDMAeSeminar

Question Answer

How can we get a copy of Agilent'seSeminar presentation Concepts of HSDPA:Bringing Higher Speed to W-CDMAeSeminar?

The presentation file (pdf) for the eSeminar can bedownloaded from the eSeminar URL:http://seminar2.techonline.com/s/agilent_feb2405 (once in thepresentation, click on Additional Resources). This pdf file does

not have speaker notes. Instead, we recommend theapplication note Concepts of HSDPA, the self-paced trainingmodule based on the same material, and the application noteHSDPA RF Measurements for User Equipment, that are nowavailable in the URL: www.agilent.com/find/HSDPA

Note: The e-Seminar presentation is based on material fromthe application note Concepts of HSDPA and the applicationnote HSDPA RF Measurements for User Equipment. Thosetwo application notes (and the self-paced training module onConcepts of HSDPA available in the same URL:www.agilent.com/find/HSDPA) provide more detailedexplanations than the e-Seminar.

Is there a system similar to HSDPA forUMTS? HSDPA is part of the UMTS system.

Is HSDPA technology used in the uplinktoo?

The improvements in data rate and spectrum efficiency thatHSDPA offers are only for the downlink. The bulk of the workto implement HSDPA technology is on the Node-B scheduling,but the UE still needs to be modified to decode the newdownlink shared channels and to transmit the new uplinkcontrol feedback channel, the HS-DPCCH.

What is Node-B? Node-B is one of those unfortunate committee terms thatstuck. It refers to a specific element in the network which issynonymous with the GSM BTS - Base Transceiver Station.

So, HSDPA will enable throughput up to 14Mbps per cell?

The 14 Mbps data rate is only theoretical. The capacity anddownlink throughput improvements of HSDPA depend on the

cell size and channel conditions. During the first HSDPAimplementation (Release 5), it is expected that the capacity willbe up to 1.5 Mbps (approximately 30% greater than standardW-CDMA) for macro cells. The gain in capacity is bigger formicro cells and pico cells (maybe 3 Mbps for micro cells andlarger than that for pico cells). The actual throughput to theusers will depend on the number of users. The gain incapacity and throughput will be bigger in future releases ofHSDPA, with enhancements in the receiver architecture, etc.


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Why is it that throughput changes with cellsize? Why is it that pico cells have higherpotential for throughput?

This is because micro and pico cells have a higher geometryfactor (cell power vs. interference power). So, it is likely thatthe high effective code rates and 16QAM that result in higherthroughput will only be used in isolated micro and pico cellscenarios since the advantages of higher modulation typesand high effective code rates only become useful when thegeometry factor is very high e.g. >10 dB. Macro cells typicallyoperate at 0 dB meaning 16QAM adds no value.

Regarding the fact that 16QAM might onlybeing used in exceptionally good channels,is this something that will occur frequently inpractice, or is this more to market the higherpeak throughput?

It is likely that 16QAM will only be used in isolated micro andpico cell scenarios since the advantages of higher modulationtypes only becomes useful when the geometry factor (cellpower vs. interference power) is very high e.g. >10 dB. Macrocells typically operate at 0 dB meaning 16QAM adds no value.

How does the spectral efficiency of HSDPAcompare to the spectral efficiency ofcdma2000 1xEV/DO Release 0 andRelease A?

In the first instance there is little to choose between them. In apractical deployment the different technologies will bedifferentiated by the quality of their adaptive coding schemesand the specific channel conditions which is much harder toquantify than abstract spectral efficiency under artificiallycontrolled conditions. The only accurate answer would be todeploy two systems side by side and observe the dynamics.Since this is rarely done in practice, the debate about which isthe most efficient system gets lost in the differences between

the scenarios used to promote one system against another.Even comparing two different implementations of the samesystem in the same scenario could produce very differentefficiency results.

Please compare HSDPA with 1xEV-DV andWiFi.

HSDPA and 1xEV-DV are fundamentally the same technology,with the physical layer designed to be appropriate to the chiprate, spreading codes, and bandwidth of the respectivesystems. Both use Hybrid ARQ, and adaptive modulation andcoding. These are similar to DO, though slight difference existin how ACK/NACK is structured and expected from the UE. Allthree systems require extremely fast response to an ACK of apacket and spooling the next packet to another UE.The cellular and WiFi technologies play in slightly different

space, with a fair amount of overlap. WiFi generally is highdata rates, short distance, typically hot spots. The billing forthese is fragmented when compared to cellular. Cellulartechnololgies have matured to the point that there is wide areacoverage, common billing, and automatic roaming whenneeded. So, the major differentiator is the business end ofgetting coverage, a reasonable bill, and known pricing.Mobility can be an issue, favoring cellular, but consider thatsecondary to portability.

How does the number of voice users affectHSDPA throughput and the number ofHSDPA users?

HSDPA uses whatever capacity is left after the standard W-CDMA channels used for voice and circuit switched data areoccupied. So, the higher the number of voice users, the lower

the total capacity left and the lower the overall throughput forHSDPA packet data users. There are no limits on the ratiobetween any of the services delivered by the cell. It could be100% voice, circuit-switched data or HSDPA. The cellcapacity will depend on the specific cell channel conditions.


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How many active users can there be per cellfor the HSDPA-enabled cell?

There is no theoretical maximum. As explained in the questionabove, the left-over capacity after resources are taken by voiceusers, etc, will be shared among all the high-speed data users.The resources allocated to each user will be determined by thescheduler.

Does the RNC or the Node-B decidewhether the data that the UE is asking forshould be delivered using HS-DSCH or thenormal DCH? What is that decision based

on?

The choice of using HSDPA or existing W-CDMA channels fordata communication will be decided at the time the session isstarted. It is likely the choice of physical channel will not bemade directly by the user but via a more abstract request for a

particular type of service. This gives flexibility to how thenetwork delivers the service. So, once a session is started itwill already have been determined if it is a standard DCH or anHS-DSCH connection. At a higher layer a decision would bemade as to which is appropriate, but it is not intended that theservice to supply a particular data stream to the UE wouldswitch from DCH to HS-DSCH.

Can one UE have a multi service sessionwhere the data is served by HSDPA andvoice by W-CDMA 12.2 codec? The UE willneed to have two receiver paths for this?

Simultaneous operation of voice and data is entirely possibleand would require the UE to simultaneously decode both an

AMR voice channel and an HSDPA channel. This requires twological receive paths, which should not be confused with twophysical receive paths.

How is the simultaneous voice and datascheduled in W-CDMA with HSDPA? Forexample, 1xEV-DO is dedicated to data,which presumably means that allocatingresources to simultaneous data and voicemay not be easy.

It is easier to optimize a radio channel for either voice or data.HSDPA was always developed as a combined data and voicesystem whereas 1x-EV-DO was always a data only channel.Because the channel bandwidth of cdma2000 is one third thatof W-CDMA there are many more frequency channels and it ispossible to dedicate frequency channels to data only. But forW-CDMA with only 12 frequency channels in the primary bandwith each operator having only two or three frequencychannels it is essential to share data and voice in the samefrequency channel. HSDPA was developed with this in mind.On the other hand, in 1xEV-DV, which also allows both voiceand data, if too much of the cell is used for voice, thescheduler doesn't have much freedom, and will not be asefficient. The simulations on 1xEV-DV for 50% voice and 50%data showed data services not very different from cdma2000alone. From that perspective, HSDPA gets the benefit of the3x wide channel and number of users.

How about scheduling dealing withsimultaneous voice and data? How difficultis that?

Sharing voice and data in one cell is covered in the questionabove. This question may be related to simultaneous voiceand data with one UE. If so, this is similar to the DTM (DualTransfer Mode) already developed for EDGE. From a radioperspective, it is easier to do simultaneous services on W-CDMA than it was on GSM since CDMA systems allowsimultaneous transmission of multiple channels at the same

frequency using different spreading codes whereas GSM-based systems require the use of time division multiplexing forsimultaneous transmission.


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Are there shared channels also available forRelease 99?

The new shared channels will be visible to R99 UE in Rel-5networks but R99 UE will just treat them like any other channelthat it is not interested in. So an R99 UE will just see theshared channels as orthogonal noise and not attempt todecode them. Only the HSDPA-capable UE will be able todecode and use the new channels. Handling of packet data inearlier releases such as via the common packet channel(CPCH) is less sophisticated.

How much more efficient is the packetscheduling in HSDPA compared to W-CDMA R5?

There are never exact figures available for comparisons sincethe assumptions made about the scenarios are rarelysufficiently controlled. HSDPA is clearly a big advance onprevious packet data services such as the CPCH in that it canhandle real time variations in channel conditions and offerlarge bandwidth to any UE that is capable of receiving it.

Is adaptive modulation a concept broughtfrom cdma2000 1xEV-DV?

The concept of adaptive modulation and coding is common toboth HSDPA and 1xEV-DV. The companies who developedthis concept had it adopted into both the 3GPP and 3GPP2standards.

Do the Transport block sizes change withnoisy environments?

Absolutely. This is the key. HSDPA has to work with theavailable cell capacity and the power available to any user isalmost fixed so the only remaining variable is to modify theamount of channel coding (and the modulation scheme) toensure a nominal 10% error rate at the UE.

Can you please explain how the largestnominal data rate is 13.976 Mbps?

The nominal data rate is the data rate within a subframe. It iscalculated by dividing the transport block size by the subframelength (2 ms). There are 254 transport block sizes from whichto choose in the FDD mode (see 25.321 Appendix A). Thelargest transport block size is 27952 bits. So, 27952 bits / 2ms=13.976 Mbps, which is the largest nominal data rate. Thistransport block size (and data rate) is only possible when 15HS-PDSCHs and 16 QAM are used. The effective code ratefor this combination is 0.97, which means that almost nopadding is added to the original data in the transport block, so

close-to-ideal channel conditions that can only be achieved inlab environments are required for correct decoding. This iswhy this data rate is a theoretical limit that will never be seen ina real network.

In order to support both QPSK and 16QAMmodulation schemes, the UE need be ableto do blind detection to decide whichmodulation is used in downlink. Is it correct?

No. Slot #0 in the HS-SCCH carries the physical channelinformation (HS-PDSCH modulation scheme and code set) forthe HS-DSCH. The HS-SCCH is transmitted two slots beforethe HS-PDSCH(s), so the UE has 1 slot (between reception ofHS-SCCH slot #0 and reception of the HS-PDSCHs) to decodethe HS-PDSCH(s) modulation scheme and code set.

While using 16QAM modulation to HSDPA

channels, I assume all other channels indownlink such as CPICH will also bemodulated with the same scheme. Is itcorrect?

No. The HS-PDSCHs are the only channels that can use 16

QAM. All the other W-CDMA and HS-SCCH downlink physicalchannels use QPSK. Modulation (symbol-mapping) andspreading are performed for each channel separately and thenall the channels are combined to create a composite IQwaveform in which the individual modulation formats are nolonger apparent.


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Why is there no 8PSK option in HSDPA? In practice, the 16QAM version is only useful in exceptionallygood channel conditions (isolated micro/pico cells). For mostscenarios, QPSK performs better than 16QAM in terms ofthroughput. An 8PSK version would just have been anintermediate option that would have added no significant value.The need even for 16QAM is debatable.

More information on why there is no 8PSKin HSDPA

During the investigation phase for HSDPA, 8PSK wasconsidered as one of the possible modulation schemes.However, it was finally left out. As it is right now, there are

already too many combinations of effective code rate andmodulation scheme to choose from to cover the differentchannel conditions: 254 transport block sizes, QPSK or16QAM and up to 15 HS-PDSCH, which results in almost 2000combinations of these three parameters. In practice, 16QAMversion is only useful in exceptionally good channel conditions(isolated micro/pico cells). For most scenarios, QPSK performsbetter than 16QAM in terms of throughput. An 8PSK versionwould just have been an intermediate option that would nothave added significant value.

Does the UE send CQI frame per frame oronly at the beginning of the session?

The CQI report can be sent every 2ms or longer (or evennever). The actual cycle is defined by the CQI feedback cycleparameter k that is signaled by higher layers (see 25.214section 6A.1.2)

What factors/parameters does the UE useto determine the CQI?

The UE can use whatever resources it has available althoughit is expected that the received CPICH quality will be thedominant factor in determining the downlink channel quality.

So CPICH Ec/Io determines CQI? This is one of the main factors but is not the only factor the UEcan use in deciding the channel quality.

How does UE calculate the CQI to send? The exact CQI derivation algorithm is not specified. Thefollowing is described in the specifications (25.214 section6.A.2): The CQI can take values from 0 to 30. There are CQImapping tables (25.214 Table 7A,..,E), depending on the UEcategory, that link the CQI values to certain coding and

modulation parameters. For a certain category, each CQIvalue corresponds to a certain transport block size, a certainnumber of HS-PDSCHs, either QPSK or 16 QAM modulation,and a reference power adjustment ? (except for CQI=0, whichdenotes out-of-range conditions). Higher CQI values denotebetter link conditions, so these CQI values typically correspondto larger transport block sizes, larger numbers of HS-PDSCHs,16QAM, and larger reference power adjustments.To derive the CQI value, the UE assumes a certain virtual IRbuffer size, which depends on the UE category. It alsoassumes that the RV used is 0 and a certain value for the totalreceived HS-PDSCH power, based on the power of thereceived CPICH during a 3-slot reference period ending one

slot before the CQI is sent, the measurement power offset Gsignalled by higher layers and on the reference poweradjustment ? (see 25.214 6.A.2 for more details).The transport block size, number of HS-PDSCHs, and themodulation scheme define the effective coding and modulationof the HS-DSCH. The UE reports the maximum CQI valuefrom the table for its UE category that corresponds to codingconfigurations that should provide BLER equal or lower than0.1, assuming a certain buffer size, redundancy version=0, andtotal received HS-PDSCH power. For example, if a CQI value


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of 15 is reported, the UE is telling the BTS that it should beable to receive and decode any configurations correspondingto CQI values 15 or lower with a BLER better than 0.1, underthe aforementioned assumptions and present channelconditions. The exact CQI derivation procedure is notdescribed in the specifications, but basically the idea is that thealgorithm has to be able to link received channel conditionsbased on the received CPICH C/I levels to one of the 30 HS-DSCH coding configurations in the CQI tables, that wouldprovide BLER closest to and lower than 10%.

What is BLER? BLER - Block Error Ratio

It seems that a BLER of 10% to determinethe CQI value is high, which requires RLC/TCP retransmit rates that are high. Incdma2000 systems we optimized for 5%which is a good power and throughput tradeoff. When HSPDA is consideredretransmissions are much moreexpensive

The 10% figure is used as a calibration reference point for theUE CQI parameter. The Node-B is free to transmit using abetter or worse figure by altering the chosen transport formatfrom that indicated by the UE. The choice of 10% as areference point has been determined through detailedsimulation that takes into account the specific protocols used inHSDPA which are not identical to cdma2000.

What is puncturing? Puncturing is a technique used to reduce the number of bits ina data stream. It is usual to add redundancy and errorcorrection to user data to create a longer more robusttransmission. Puncturing reverses this by removing some ofthe encoded data. However, due to the encoding process, thedata bits removed do not usually correspond exactly with theuser data bits so it is possible during the decoding process torecreate the original data stream - although with less marginfor error. The objective of puncturing in general is to match thebits after the encoding to a smaller number of bits fortransmission. In HSDPA, the data is typically punctured (ratematched) in two different stages: first to match the bits at theoutput of the turbo encoder to the virtual IR buffer size (this

size is equivalent to the IR buffer size reserved in the UE tocombine the bits received during different transmissions for thesame data block) and then to match the bits within the virtualIR buffer to the different redundancy versions or RVs (this iscalled RV selection).


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I am assuming that when IR is used, thesame modulation scheme and transportblock size is used. Correct?

Also, will this IR mechanism cause bufferoverflow?

For a retransmission, the transport block size always stays thesame because we are resending the same transport block ofdata. However, if incremental redundancy is used, the BTScan decide to change the modulation scheme and the numberof HS-PDSCHs depending on the information reported by theCQI. If they do not change, the puncturing scheme orredundancy version (RV) can change. So, a retransmission issent depending on the ACK/NACK report, and the modulationand number of codes can change depending on the CQIreport. The virtual IR buffer size (number of bits after the firstrate matching stage) has to stay the same to ensure that thereis no buffer overflow. During testing of the HARQ IRfunctionality (Demodulation of HS-DSCH test) the channelcoding is fixed (fixed reference channels or FRCs are used) tosimplify testing, and only the RV (or puncturing scheme)changes for a retransmission.

Based on the response to the previousquestion, how will the scheduler decidebetween sending same data with differentpuncturing scheme or just to discard and trya new modulation scheme?

The MAC-layer scheduler functionality interacts with the HARQfunctionality and the AMC functionality in the Node-B to makethis decision. There are no rules for how to make the trade-off.This is considered a commercial issue.

Does inter-TTI apply to both uplink anddownlink?

Yes. The same transmission pattern targeted to a specific UEon the downlink is repeated on the UE's uplink ACK/NACKfield. Note: The uplink CQI report is sent every 2 ms, 4 ms, 8ms, etc, as scheduled by higher layers, so it is independentfrom the donwlink transmission pattern.

Do you have a primary number for howmuch memory is needed for IR?

The parameter 'Total number of soft channel bits' defined foreach HSDPA UE category is equivalent to the total IR buffersize (for all HARQ processes combined) required in the UE, soit tells you the memory requirements for each UE category.

What are the main bottle necks forthroughput? Sorted in descending order.

1. Simultaneously decoding the CQI and ACK/NACK data fromevery UE and predicting which UE to communicate with in the

next subframe and picking the hardest transport format thatensures an ACK in order to optimize throughput2. Everything else seems rather simple...

Will the UL rate of ACK/NACK limit thedownlink throughput?

The HSDPA system is designed to support a 2ms TTI whichrequires continuous transmission of ACK/NACK and CQI dataon the HS-DPCCH which enables the optimum choice to bemade by the Node-B for the next transport format in order tooptimize throughput. However the HS-DPCCH uses a highspreading factor of 256. So compared to the downlink, whichuses at least 16 times that capacity for a single HS-PDSCHchannel, the uplink HS-DPCCH does not use up much of thechannel bandwidth and is not the limiting factor on throughput.

Is the HS-DSCH involved in the softhandover?

No


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How does the handover works from cell tocell when the UE is in the middle of a call?

Due to the complexity of the Node-B scheduling and HARQprocess, HSDPA does not use soft handover. The criteria forhard handover to another cell will be similar to the criteria usedfor other services which use a variety of UE and networkmeasurements to determine the optimum cell for the UE to becommunicating with. An overview of these procedures can befound in 25.303 "Interlayer procedures in Connected Mode".

Is handover or cell reselection possiblebetween W-CDMA and HSDPA?

Maintaining a data session when moving from HSDPA tostandard W-CDMA or GPRS will require a handover which will

be a challenge for the network but is still well within theintended scope of the standards and is an expected usemodel.

Does HSDPA require hardware changes orcan it be achieved solely by a newsoftware?

The answer depends on the capability of the equipment. Froman RF point of view, many Node-B can be software upgradedfor HSDPA but may require upgraded backhaul into theswitched network to cope with the higher data rates. For theUE the intention is that the RF is no harder than R99 due tothe new lower maximum power requirement, so in theory a UEcould be software upgraded if it had sufficient memory tohandle buffering etc.

Does the UE need a higher minimum C/N

ratio compared to R5 UE?

For an equivalent coding gain (which translates to data rate),

an HSDPA channel would have the same C/N requirement asany other W-CDMA channel. Standard W-CDMA channelshave fixed coding gains and therefore fixed C/N requirements,so they have to be power controlled in order to raise thechannel to a sufficient level to be decoded successfully.HSDPA is designed to provide a large range of differenttransport formats that have a huge variation in coding gain sothat they can be matched to the current channel conditions forthe UE being transmitted to without relying on power control.So HSDPA is less dependent on C/N ratios than standard W-CDMA channels.

Please compare Baseband chip complexity

for HSDPA vs. W-CDMA - gates, power etc.

Estimate in terms of number of gates is difficult, but for the UE

it is not a major hit, perhaps 20%. If you look at the number ofsimultaneous channels needed to support W-CDMA, and thenadd HSDPA to that, it is a minor addition. The challenge for theNode-B is much higher due to the need to do real timescheduling with multiple UE.

Does HSDPA have any impact on the UEstates?

HSDPA has a significant impact on the UE states. The overallarchitecture can be found in 25.308.

Is the equalizer necessary for the receptionof HSDPA in the UE?

An equalizer is not required to meet the Release 5performance targets. Release 6 is adding new performancetargets that will require more advanced receiver designs whichmay incorporate an equalizer.

What is the implementation stage of

HSDPA? Are terminals able to use HSDPAavailable? If not, what is the implementationschedule?

Many companies are trialing HSDPA UE in test networks

today. Serious deployment in not likely before 2006. Widedeployment will probably be approximately one to two yearsafter the initial HSDPA launches by different operators in thedifferent regions, so approximately in the 2007-2009timeframe.

Does HSDPA work only on FDD or TDDtoo?

HSDPA is also available to TDD although it has received lessattention and lags behind the maturity of the FDDspecifications.


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Why are the radio interfaces Uu, etc calledso?

The interface names and overall UTRAN description can befound in 25.401. There was no doubt some reasoning behindthe naming but as is often the case, temporary names usedduring standards development tend to stick around. Theequivalent interface for GSM is Um. The infamous Abisinterface is simply a variation on the original A interface withthe "bis" added to indicate a second instance. And then wehave Node-B. Whatever happened to Node A?

Are there any changes in networkplanning/optimization by including HSDPA ?

Not as such although the higher data rates require use ofmicro and pico cells.

My understanding is you can not disablephysical layer re-transmission in HSDPA. Inyour opinion, is it suitable for real-timeservices such as VoIP?

HSDPA only offers high speed data rates for the downlink, so itis not suitable for symmetric services. In addition, since thelatency can vary and is not guaranteed, VoIP is not a suitableapplication for HSDPA.

Is HSDPA suitable for any kind of broadcastmode, e.g. MBMS (MultimediaBroadcast/Multicast Service)

HSDPA is a point to point service and is very unsuitable as abroadcast medium.

What will be optimal for HSDPA: UDP/TCPetc ?

HSDPA should work well with any packet data protocolcarrying a service with significant downlink asymmetry butwould not be a good choice for a service that required

symmetric or continuous throughput.What is the new lower UE maximum outputpower requirement and why is it introduced?

The bursted HS-DPCCH increases the uplink peak-to-averagepower ratio by up to approximately 1 dB (depending on thebeta factors or relative power ratios among the uplinkchannels). The UE Maximum Output Power specification hasbeen relaxed for uplink transmissions that include the HS-DPCCH to take into account the increase in peak-to-averagepower ratio. This allows an R99 capable UE Power Amplifierto accommodate HSDPA.

Are the Node-B power requirementschanged, too?

The Node-B power requirements have not changed.

What is FRC? FRC - Fixed Reference Channel. It is very similar to theReference Measurement Channels that already exist. Thename fixed comes from the fact that the channels are notmodified with respect to modulation type or coding unlike in areal network. The reason these variable reference channelswere not used to define performance is that it would haverequired the test equipment performance to have been part ofthe answer which was not helpful.

Is BER reported? No. Only ACK/NACK are reported from which the system candetermine an average BLER.


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Why the limit for BLER is 10%? For W-CDMA, it is only 0.1% BER (not BLER).

In general BER/BLER requirements vary depending on theservice and ability to retransmit data packets. HSDPA isdesigned to operate near a 10% packet error rate. This worksdue to a highly efficient MAC-hs scheduling and retransmissionprotocol in the Node-B rather than the RNC. Existing R99packet data has a much longer retransmission latency whichleads to favor using lower BLER (around 1%).Note that the values above are typical operation values, butnot test requirements limits. The specific requirements dependon the specific test and test conditions. The 0.1% (0.001) BERrequirement is specific to the W-CDMA receiver characteristicstests. Other W-CDMA performance requirements use differentBLER requirements from 10% to 0.1% depending on the testparameters (fading profile, etc). For example, the requirementfor the receiver Maximum Input Level for 16 QAM test is athroughput of 700 kbps using FRC H-Set 1 (16QAM) with anominal average information bit rate of 777 kbps. Thisrepresents a BLER of 10% (0.1). No AWGN and no fadingare used for this test. However, for the Demodulation of HS-DSCH test, which is tested with AWGN and different fadingprofiles, the throughput requirements translate into BLERvalues that vary all considerably from 20% to almost 100% forsome of the 16 QAM configurations and test parameters.

Release 6 adds enhanced requirements for receivers withreceive diversity and the BLER requirements are lower(meaning more demanding) for those. In general, it is notpossible to make a straight comparison between the W-CDMABER requirements and the HSDPA BLER requirementswithout describing the service.

Does HSDPA require better UE receiverRMS phase noise and quadratureaccuracy?

Since 16QAM will only be used during good channel conditions(high C/N at the receiver), it should not require better UEreceiver RMS phase noise. A new HSDPA receiver test hasbeen added to the specifications to verify reception of 16QAMdownlink channels. This new test only verifies reception atmaximum input level, so it is not particularly sensitive to issueslike phase noise. Quadrature error is implementation specific.

Direct digital IF receiver architectures can minimize this errorconsiderably. If analog IQ demodulation is used, 16QAM canpose tighter requirements, since IQ quadrature error amongmany other errors- is part of the error budget that the UE hasto handle.

Is there a test to check HSPDA effects onvoice users?

All of the HSDPA tests use Fixed Reference Channels, each ofwhich includes a non-HSDPA 12.2 kbps ReferenceMeasurement Channel. In typical network operation, the non-HSDPA channel would not be present. But the intention was toinclude this signal so that the load that HSDPA puts on the UEis in addition to maintaining, for instance, a voice call or lowrate data call.

Regarding the Reporting of CQI tests, is itthe median or the mean that is used? Themean is a more valuable statistical term...Right?

The median (50% distribution) is the correct and intended termand is used in preference to the mean to remove the impact ofoutlying CQI reports that reflect the behavior of the radiochannel.


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Regarding the UE test Reporting of CQIunder AWGN propagation conditions, why isthe median CQI used and not just the CQIsent by the UE?

This test is trying to calibrate the UE's CQI accuracy byaveraging over a long period. The procedure for the Reportingof CQI tests starts with the system simulator (SS) sendingdownlink data blocks with the HS-DSCH configured with acertain configuration (arbitrarily chosen to be the codingconfiguration corresponding to CQI=16) and then the SScollecting 2000 CQI reports. The median-CQI is calculatedfrom those (and the variance is also calculated for theReporting of CQI under AWGN propagations conditions test).The median-CQI is then used to configure the HS-DSCH (themedian-CQI is the best CQI value to use, since it is expectedto be the CQI value, or be very close to the value, thatoccurred most frequently), and downlink data blocks are sentwith this configuration until the SS collects 1000 CQI reports.So, for this test, there isn't a close CQI feedback loop (thepreviously received CQI is not directly used to modify the nextHS-DSCH configuration in real-time). The test procedurecontinues and is different for the AWGN and the fadingpropagation conditions test. You can find a more detailedexplanation of the procedure in our application note: HSDPARF Measurements for User Equipment in the following URL:www.agilent.com/find/HSDPA.

What test support is available for HSDPA

BTS testing?

There are several BTS platforms available depending on the

application or the design/verification stage: ADS2003 offers aTestModel 5 behavioral downlink source to simulate BTStransmitter testing (EVM). The E4438C ESG vector signalgenerator also offers Test Model 5 as a pre-configured setupwhich can be used as a reference signal for BTS transmittertesting. The PSA series spectrum analyzers with the HSDPApersonality (option 210) , the E4406A vector signal analyzer,with the HSDPA personality (option 210) and the 89600 seriesvector signal analyzers with the 3G personality (B7N) all offercode domain analysis and modulation quality measurementsfor downlink (and uplink) signals with HSDPA channels. ForBTS receiver test, Signal Studio for HSDPA over W-CDMAcombined with the E4438C ESG can generate HSDPA uplink

signals with different ACK/NACK and CQI patterns, to testACK/NACK and CQI detection at the BTS receiver.

Does ADS 2004A have HSDPA simulationcapabilities in terms of simulating the wholedownlink?

No. ADS2004A has a behavioral uplink source and uplinkreceiver, but it does not have a downlink source (other thanTest Model 5 used for BTS testing) and a downlink receiverneeded to simulate the whole downlink.

Does the Agilent test setup allow collectionof latency statistics for information data bits?

Not directly. There are no specific latency measurementsdefined. In a real environment the size and latency of eachdata packet will vary but the only easily measureable statisticis the long term throughput. An example of differing latencywould be a hard transport format that resulted in lots of

retransmission vs. an easier transport format that had thesame throughput with no retransmission. The latter is clearlydesirable from a latency perspective but actual performancewill be based on the quality of the Node-B schedulingalgorithms which may or may not differentiate between thesetwo scenarios.


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Given that the nature of data traffic over thenetwork is changing to include much moremultimedia IP traffic, throughput is only oneof two key performance parameters. Theother is latency. Can statistics on thelatency of information bit frames (i.e.. meanlatency and variance) and/or Ack/Nackretransmission/IR statistics be collected forvarious RF conditions?

This is similar to the question above. The analysis ofretransmission statistics under specific RF conditions wouldprimarily be a measure of the quality of the AMC process ofthe Node-B for which there are no requirements rather than ameasure of the UE. Such logging and analysis would have tobe provided by the Node-B itself and is out of scope of thecurrent 3GPP spefications.

Could you briefly describe the AniteSATprotocol testing and RF tests can becombined with protocol testing?

The Anite Test System provides functional verification ofHSDPA UEs, with full upgradeability to a complete Release 5development test system. The system comprises multiple testunits with an industry-standard PC controller. The test units areconnected to the PC controller via a LAN interface. TheHSDPA Test Unit is comprised of an Agilent 8960 wirelesscommunications test set and an Anite Add-On module.Multiple test units provide support for simulation of multiplecells and to allow handover procedures to be tested. The RFpaths are combined via a straightforward powersplitter/combiner. Introduction of other channel impairmentssuch as co-channel or adjacent channel interferers can bedone externally using a directional coupler or power

splitter/combiner.The Anite HSDPA Test Solution includes both MAC and RLCfunctionality in accordance with 3GPP specifications TS25.321and TS25.322 respectively. The following components of theMAC architecture are implemented:MAC-hs - manages flow control, scheduling and prioritycontrol, per-user HARQ processes and transportformat/resource combination selection. Manages transmissionof RLC PDUs via HS-DSCH transport channels in conjunctionwith associated signaling channels (I.e. an uplink HS-DPCCHand downlink HS-SCCH)MAC-d - implements transport channel switching, C/Tmultiplexing and flow control with transport channel routing to

MAC-hsRLC entities can be activated in transparent mode,unacknowledged mode or full acknowledged mode and routedto logical channels as needed.The following W-CDMA downlink physical channels can beactivated: P-SCH & S-SCH, CPICH, AICH, PICH, P-CCPCH,S-CCPCH, DPCH. In addition, up to four HS-SCCHs and upto two HS-DSCH, each with up to 15 HS-PDSCHs can beactivated.The Anite HSDPA Test System can be controlled in a numberof ways:A C/C++ programmable API. This allows the test system userto write test programs or simulation scenarios in C/C++ using

Anites full Programmers Toolset (PT) for W-CDMA & HSDPA.In addition to the functions of the test system itself, theprogrammer has access to the underlying facilities of the hostcomputer such as file and I/O systems. This, for example,allows programs to control external equipment, to control theUE under test or to store and retrieve large amounts of testdata.A graphical user interface (GUI) that allows channels to beactivated and deactivated. Test configurations can also bestored and reloaded. It allows for creation of complex cell or


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network simulations.It also supports a number of data source routing options. Datacan be supplied for transmission at the upper interface of RLC(I.e. at the radio bearer level), at the upper interface of MAC(I.e. at the logical channel level) or directly at the physical layervia transport channel access points. At the API level, thedynamic real-time data can be supplied at the RLC and MAClevels, or built-in data sequence generators can be chosen.The built-in data sequence generators can be selected asfollows:Pseudo-random sequence PN-9, continuous or reseeded

every TTI (when used as a physical layer source) or at thestart of every PDU (when used as an RLC or MAC source)Pseudo-random sequence PN-15, continuous or reseeded

every TTI (when used as a physical layer source) or at thestart of every PDU (when used as an RLC or MAC source)All ones (1111) or All zeros (0000)Two ones/two zeros (11001100), four ones/four zeros

(1111000) or eight ones/eight zeros (1111111100000000)

Will the Test Protocol solution based on the8960 be validated for PTCRB (PVG) andGCF certification schemes?

The Anite protocol test solution that uses the 8960 as part ofits test system is validated by PTCRB (PVG) and GCF. TheGS-8800 plus UMTS RF Conformance System incorporatingthe 8960 is being validated by GCF.

What about HSDPA-capability in the Agilent8960 wireless communications test set?

The 8960 now supports HSDPA (as of September 05).

Please give me the list of Specificationsdocuments that we can look at for HSDPA.

You can find them at the end of the Application Note Conceptsof HSDPA (www.agilent.com/find/HSDPA).

Are there some good references (book etc.)for understanding HSDPA?

We have some material (Agilent application notes and self-paced training) in our HSDPA website:www.agilent.com/find/HSDPA

agilent - concepts of hsdpa - q&a

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