CDMA System Parameters

I removed the 1.9GHz adjective to the title. The slides were really designed for800 MHz. I have added notes to some other slides indicating some differencesbetween 1900 and 800. (Sam Fernandez)

Applied System Engineering

Motorola Confidential Proprietary3/6/98 Page 1

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There are three categories of parameters.The first catagory are those whose changes are easily evaluated through fieldoptimization techniques. Handoff parameters and forward link ERP are included inthis list.The second category are those which require a calibrated laboratory evaluation toachieve the repeatability required in their evaluation.Power control parameters areincluded in this group.The final set of parameters are those that should, in most typical cases, never bechenged in the field.



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When the Pilot Ec/Io exceeds the T_add parameter, the mobile station will send aPILOT STRENGTH MEASUREMENT MESSAGE and transfer the pilot from theNeighbor set to the Candidate Set.



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T_add

T_drop

Pilot Stength

Ec/Io

(d

B)

Neighbor Set

Candidate Set

TimeHandoff Attempt Start

When the Pilot Ec/Io falls below T_Drop a timer, TT_Drop, is started. If the Pilot Ec/Io goes above T_Drop, the timer is stopped.When the timer expires, the Pilot is moved to the Neighbor Set.



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T_add

T_drop

Pilot Stength

Time

Ec/Io

(d

B)

Active or Candidate Set

Neighbor Set

TTdrop

The TTDrop timer, which we talked about on the previous slide is used to removePilots from the Active Set or Candidate Set to the Neighbor set.

When the candidate set is full and a new Pilot needs to be added via TAdd, thepilot closest to expiration is removed.

The Mobile Station sends a PSMM for active set pilots only. Candidates aresimply demoted to the neighbor list without any PSMM generation.



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T_add

T_drop

Pilot Stength

Time

Ec/Io

(d

B)

Active or Candidate Set

Neighbor Set

TTdrop



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T_add

T_drop

Pilot Stength

Time

Ec/

Io (d

B)

Neighbor Set

Candidate Set

Active Set

Neighbor Set

(1) (2) (3) (4) (5) (6) (7)

TComp is used to achieve hysterisis on a MAHO or Pilot Beacon Hard Handoff. Itinfluences the Pilot Shuffle algorithm.



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T_add

Active Pilot 1

Pilot Stength

Time

Ec/Io

(d

B)

T_CompActive Pilot 2

Pilot Po

Neighbour Set

Candidate Set

Handoff Attempt Start

This slide shows the impacts of selecting too high or too low of a value for thevarious parameters. We also show the impact of too high or too low a differencebetween TDrop and TAdd.Tadd ranges from -10 to -14 dB in our current systems. Tdrop ranges from a rangeof -11 to - 16 dB. One important aspect of these two parameters is the differencebetween the two settings. There will be more messaging/SHO transitions for a delta(TAdd-TDrop) of 1 as opposed to 2 dB. TTDrop ranges from 1 (1 second) to 4 (6seconds). This should be set as long as possible to slow down messaging and Ping-Pong effects. From field experience, TTDrop of 3 seems to require less cell sitelevel optimization, but results in about increase of 33% PSMMs and about 20%SHOs over a TTDrop setting of 4.For ease of deployment it is best to start with the same TAdd, TDrop, TTDropsettings on all cells. If care is not taken when making changes with respect tosurrounding cells the mobile can be left in a state of soft handoff Ping-Pong. Thiswill occur when TAdd is lower than TDrop. A better method is to first decreaseTTDrop in situations where pilots get stuck in the active set during rapidlychanging conditions. For non-urban/high rise canyon environments, TAdd modewith TAdd of -12 and TDrop of -13 with TTDrop of 3 is a good starting point.



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Too Low Too HighTAdd high rate of PSMM,

increase unneccssary handoffs,require more traffic channel

poor FER,may cause handoff delay,high MS Tx power at boundary.

TDrop increase cell size,use up more traffic channels.

reduce size of handoff zone,increase ping-pong handoff.

TDrop -TAdd

increase in messaging. increase use of Tch resources.

TTDrop increase ping-pong handoff. more three-way handoff.

TComp high rate of PSMM,require more traffic channels.

may cause delay handoff,poor FER.



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This slide is used to provide some background information on neighbor lists.------------------

A composite neighbor list is formed when in 2-way or 3-way SHO. This isaccomplished by merging neighbor lists in a round-robin fashion (with theyoungest active pilot last), eliminating all duplicates, and truncating the list to 20entries.

Recommendations to enter SHO with Remaining Set pilots are, generally, nothonored. Exceptions include the following: if the Remaining Set pilot is, in fact, atruncated neighbor; OR, if the if the pilot is included in the neighbor list of aprevious active pilot. A previous active pilotis any pilot that was dropped whichwas not succeeded by an add attempt (i.e. dropped pilots are remembered until anadd attempt occurs).

Neighbor List Updates (NLU) are sent for every add (either soft or softer).NLUs are sent also for a drop where the previous NLU involved truncation.



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There are two parameters which determine the power of the Access channel.

NomPwr is the Access Channel Nominal Transmit Power Offset. It is thecorrection factor the mobiles are to use in the open loop power estimate. It is sentto the mobile in the Access Parameters Message. Range -8 to 7 dB.InitPwr is the Initial Power for Access. It is the correction factor to be used bymobile stations in the open loop power estimate for the initial transmission on anaccess channel. Sent to the mobile in the Access Parameters Message, Range -16to 15 dB.______________

The equation for J-STD-8 is:Mean Tx (dBm) = - Mean Rx (dBm) - 76 + NomPwr (dB) + InitPwr (dB) - 16 x NOM_PWR_EXTThe Nom_Pwr_Ext flag provides an additional 16 dB of attenuation. It effectivelychanges the range of NomPwr from -8 to 7 dB to -24 to 7 dB.(Sam Fernandez)



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Initial Mean Output Power

Time

Tx po

wer

leve

l (dB

m)

Access Probe Sequence

V5.0. Changed recommended values. Sam Fernandez



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RPCMaxEbNo is theReverse Power Control Maximum Eb/No. Reverse powercontrol algorithm parameter which specifies maximum Eb/No the power controlthreshold is allowed to rise to. This data is used to derive the actual threshold usedby the algorithm. Range 2.0 - 14.9 dB, in 0.1 increments.The maximum threshold variable (RPCMaxEbNo) restricts any particular mobilefrom requiring too much Eb/No (power) to achieve its desired call quality.

V5.0. Recommended value was changed. Value for 13k is 12.9. I dont know thecorresponding table value.

I typically introduce additional material here to discuss the RPC closed loopmechanism with inner and outer loops and make the connections to the BTShardware (i.e. MCC and XCDR).



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This slide is used as a reference to show how the Pilot Power at the top of theframe is related tot the Sync and Paging channel powers through the digital gains.The recommended setting of 33dBm is for Pilot Power only.______________

Traffic channel gains are different for rate set 1 and 2. The gains are categorized asnon-changeable and so recommended values are not documented here. (SamFernandez)

I typically introduce additional information here reviewing in simple form the FPCmechanism (i.e. a stepping algorithm).



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PilotGain2

SchGain2=

PPilot (W)PSync (W)

PilotGain2

PchGain2=

PPilot (W)Ppaging (W )

This slide lists the parameters which will control cell radius. The discussion ofthese parameters is discussed on the following slides.



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This parameter defines the number of access channel frames that the mobiles are tosend preamble on when attempting to access the system.__________________

This discussion gives insight into the sizing of PamSz and its relationship to thecell radius. In R6, this parameter value was modified indirectly via the cell radiusfield.



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One Access Channel Slot

Access Channel Preamble Access Channel Message Capsule

1+PamSz frames

20 ms frame

This parameter defines the access channel preamble window size in PN chips. Thiscan be adjusted with field data to provide the minimum window size, allowing theaccess channel to provide maximum sensitivity (multiple searches).__________________

This discussion gives insight into the sizing of AchPamWinSz and its relationshipto the cell radius. In R6, this parameter value was modified indirectly via the cellradius field.



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As a general philosophy, access and traffic channel window sizes should be kept totheir minimum in order to allow maximum searcher performance (multiple scans)for both the BTS-MCCCE (channel element) and mobile station. In addition,smaller access windows allow for reduced preamble size which can increase thepaging throughput and paging response time by reducing the slot size.TchAcqWinSz should be as large or slightly larger then AchPamWinSz. Itimpacts only handoffs.TchPamWinSz - centers a smaller window based on information learned throughthe access channel acquisition process.



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Cell radius (km) window size(PN chips)

PamSz (frames)0.0 to 0.9 12 01.0 to 2.9 25 03.0 to 3.9 37 04.0 to 5.9 50 06.0 to 6.9 62 17.0 to 8.9 75 19.0 to 9.9 87 1

10.0 to 11.9 100 112.0 to 12.9 112 213.0 to 14.9 125 215.0 to 15.9 137 216.0 to 17.9 150 218.0 to 18.9 162 219.0 to 20.9 175 321.0 to 21.9 187 322.0 to 23.9 200 324.0 to 24.9 212 325.0 to 26.9 225 327.0 to 27.9 237 4

The Active pilot set search window size. This size is made large enough toincorporate 95% of the expected delay spread energy. This window size may alsoneed to be set on a per sector basis. This will be extremely difficult to do withoutknowing the delay spread environment for each sector. Just increasing all activepilot search window sizes would reduce the likelihood of missing pathlogical raysbut at the expense of increasing PN hypothesis search time. Increasing PNhypothesis search time would increase soft handoff delay.



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The Neighbor pilot set search window sizeis made large enough to account fordifferential time delay between the mobile and a potential handoff cell given in themobiles neighbor list. The worst case differential delay would be the case whenthe mobile is next to a serving site and tries to handoff to another distant site.The remaining pilot set search window size is similar to SrchWinN except the siteswill typically be further away. Our current infrastructure does not promoteremaining set pilots to the candidate set.



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Here are the equations used to calculate the table values:

(chips - 2) * 0.8138 = delay (micro-seconds)

(chips - 2)/2 * 244 m/1609.2 m/mi = distance (miles)(chips - 2) * 0.0758 = distance (miles)(chips - 2) * 0.122 = distance (kilometers)

The -2 is to compensate for time-of-flight (i.e. real world) delays. If you werestarting with a distance and calculating a window size, you would add two chips.



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SrchWin 0 1 2 3 4 5 6 7Window size (chips) 4 6 8 10 14 20 28 40Delay (us) 1.6 3.3 4.9 6.5 9.8 14.6 21.2 30.9distance (mi) 0.2 0.3 0.5 0.6 0.9 1.4 2.0 2.9SrchWin 8 9 10 11 12 13 14 15Window size (chips) 60 80 100 130 160 226 320 452Delay (us) 47.2 63.5 79.8 104.2 128.6 182.3 258.8 366.2distance (mi) 4.4 5.9 7.5 9.7 12.0 17.0 24.2 34.2

PilotInc is the Pilot PN Sequence Offset Index Increment. The mobile station usesthis field to determine how remaining set pilots should be searched. This data issent to the mobile station in the RF: Neighbor List Message and the RF: NeighborList Update Message.



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CDMA System Parameters

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