Module07 1xEV-DO RF Guidelines

7/27/2019 Module07 1xEV-DO RF Guidelines

1/103

Infrastructure for All-IP Broadband Mobile WirelessAccelerating Access Anywhere

Module 7: 1xEV-DO RF DesignGuidelines, Airlink Parameter Settings,

and Optimization

Jay Weitzen

Airvana Performance Engineering


2/103

Confidential & Proprietary 2

Module Objectives

To help you understand

1xEV-DO RF Design Guidelines and Link

Budgets

RF/Airlink Parameter Settings

Which Parameters to Set and which not to set

Optimizing 1xEV-DO networks

Which metrics to watch

Understand commonalities with 1xRTTdesign guidelines


3/103


Recommended Audience

RF engineering staff, proficient in IS-95/IS-

2000 CDMA RF engineering principles

Prerequisite Modules:

1xEV-DO Air Interface

1xEV-DO Signaling 1xEV-DO Hybrid Mode Operation


4/103


Reference Documents

Qualcomm 1xEV-DO master system

parameters, Document 80-H0562-1,

Airvana/Nortel RF design guidelines

IS-856 specification

Handbook of CDMA System DesignEngineering and Optimization, K. Kim,

Prentice Hall, 2000


5/103

Some General Thoughts Before Starting


6/103


Understand Your Users and Usage Patterns

Differences between fixed and mobility systems.

Dimensioning is different based on user profile.

Will users make 1xEV-DO their primary internet accesssource?

Reasonable usage plans tend to control networkusage.

All you can eat plans tend to encourage data hogswho consume disproportional levels of resources andcan load down a network.

Traffic shaping may not help control data hogs.

To the degree possible, try to discourage large scaleuploading (home web hosting).


7/103


Become Familiar Thinking in C/I vs. Ec/Io

1xEV-DO uses C/I because it is TDMA on

FL and HO is virtual fast sector switching.

1xRTT uses Ec/Io because every signal has

the potential to be used or interference in

true SHO system.

=+

=

1

1

iio

c

CWN

C

Io

E

=+

=

2

1

iio CWN

C

I

C


8/103


Converting Between C/I and Ec/Io

=

o

c

o

c

IE

I

E

I

C

1

+

=

IC

I

C

I

E

o

c

1

C/I dB vs Ec/Io

-20

-15

-10

-5

0

5

10

15

-18 -16 -14 -12 -10 -8 -6 -4 -2 0

Ec/Io (dB)

C/I dB


9/103


Understand 1xEV-DO Service Models and

Service Requirements

Fixed, nomadic and mobile users

Mobile users (phone-like devices) with completemobility

Portable PCMIA laptop devices

Fixed wireless access point devices

Minimum service offerings

Broadband replacement: 300-600 kbps downlink 20-40 kbps uplink (typical)

40 kbps reverse is minimum found to not impact TCP (ftp)

performance on forward link Mobility services 20 kbps uplink, 100-300 kbps

downlink


10/103


Types of 1xEV-DO Deployments

Overlay With existing IS-95/IS2000 System

Currently highly recommend 1x1 overlay with

1x to avoid adjacent channel interference andnear far issues.

Design will be constrained by 1xRTT design

Overlay with other Technology such as

TDMA or GSM

Stand Alone 1xEV-DO service


11/103


Guardbands are required between CDMA and non-CDMA signals

CDMA signals appear as a raised noise floor to other technologies receivers Non-CDMA signals appear as noise to CDMA receivers

No guard band is customarily used between frequency-adjacent CDMA

signals; there is a slight decrease in capacity due to adjacent-frequency

interference but it is negligible in normal operation

260 kHz

Guard Band

260 kHz

Guard Band

Frequency

Pow

er

1.77 MHz

1.25 MHz

CDMA Carrier

CDMA SIGNAL

Coexistence of CDMA With Other Systems


12/103


Sector Capacity Estimates

Initial capacity analysis

Estimated average forward link/ reverse link

throughput per sector (QC)

Expected Throughput with single diversity is

about 30% less than dual diversity

Uplink: 250Uplink: 270Uplink: 300+ kbps

Downlink: 600-

800kbps

Downlink: 700-900

kbps

Downlink: 900-

1200 kbps

MobileNomadic (pcmcia

card)

Fixed Stand Alone

Device


13/103


Understand the Differences Between Running a

Voice Network and Running a Data Network

User experience and annoyance measures are different

in voice and data networks.

Dropped call, while critical in voice is far less critical in a data

network because of buffering and reconnection.

New metrics are required and under development.

Example: A data drop which is an application timeout is

different than a call drop in a voice network. Erlang equivalent.

Even more critical as you begin to add real time applications.

RF performance staff need to learn about TCP/IP!


14/103


Understand Hybrid Mode Operation

Coupling between voice network and data

activity

See hybrid mode operation module


15/103


Manage and Adapt Your Backhaul Network

Backhaul is one of largest recurring costs

Avoid tendency to put it in and take it for

granted One E1 should suffice early in the deployment, add a

second E1 when your statistics indicate that you need it,on a selective cell basis

For mobility type of network 2 e1s should be max needed

Carefully monitor both network and backhaulperformance at the aggregation router to determine when

to add more backhaul Need to monitor average usage queue delay, and dropped

packets

Compare to 2 - E1 system for reference

Try to project in advance when second E1 will be required


16/103

RF Planning 1xEV-DO Networks


17/103


Access Terminal Parameter Assumptions

Parameter

Terminal Type Nomadic Mobile Fixed

Peak Transmit Power 200mW (23dBm) 200mW (23dBm) 200 mw (23 dBm)

Antenna Omni-directional, -1dBi Omni-directional, -1 dBi External 7/dBi

Cable Loss 0 dB 0 dB 2 dB

Diversity Dual Single/Dual Dual

Nominal Value Assumptions

Dual Diversity AT shown to provide approximately 2

+ dB improvement over no diversity Try to design for at least 20 kbps on reverse link @ 3

dB loading and at margin for no impact on forward

link using TCP. Be aware of PC->AT interference issues with data

cards


18/103


Base Station Parameter Assumptions

Parameter Nominal Value Assumptions

Max. Average PA output power 10-15W

Antenna Sectored, 17dBi, 65 deg. or 90 deg.Antenna Height >30 meters (dependent on morphology)

Cable Loss 0 to 3dB (dependent on implementation)

Effective AN Noise Figure 5dB


19/103


Base Station Antenna Configurations

Multi-sector or single sector operation.

Antenna configurations:

Dual horizontal space with vertical polarization, 10-20 spacing if predominant service models are fixed or

nomadic.

Dual polarization, +/- 45 degree for mobile applications Use 65 degree Beamwidth antennas for 3 sector

sites to control interference.

Target 2-3 db (max) cable loss.

Coaxial cable types and losses 7/8 for AGL =101ft.


20/103


General Comments on Link Budgets

1xEV-DO FL/RL link budgets are highly

asymmetric.

Reverse link performance tends to be limiting factor onoverall link budget

Reverse link budget is about 2 db higher than CDMA-

2000 voice reverse link budget (wherever there is voicecoverage there should be capable of 19.2 kbps for

1xEV-DO at margin )

Forward link is more interference sensitive thanCDMA-2000 because there is no true soft handoff


21/103


1xEV-DO Link Budget

Reverse Link Budget - Mobile User1x-EV-DO

Forward Link Budget - Mobile User1x-EV-DO

Data Rate [kbps] 38.4 19.2 9.6 Average Throughput (or Data rate) [bps] 87,802

Data Rate[dB-Hz] 45.8 42.8 39.8 Serving Time Fraction 14.3%

AT TX PO [Watts] 0.2 0.2 0.2 Average Burst Rate [bps] 614,000

AT TX PO [dBm] 23.0 23.0 23.0 Bandwidth [kHz] 1228.8

AT Antenna Gain [dBi] -1.0 -1.0 -1.0 Bandwidth [db-Hz] 60.9

Body Loss [dB] 3.0 3.0 3.0 BTS Tx Power [Watts] 15.0EIRP [Watts] 0.1 0.1 0.1 BTS Tx Power [dBm] 41.8

EIRP [dBm] 19.0 19.0 19.0 BTS Antenna Gain [dBi] 18.00

BTS Antenna Gain [dBi] 18.0 18.0 18.0 BTS Cable Loss [dB] 3.00

BTS Rx Cable Loss [dB] 3.0 3.0 3.0 BTS EIRP [dBm] 56.8

BTS Noise Figure 5 5 5 AT Rx Antenna Gain [dBi] -1.00

BTS Thermal Noise [dBM/Hz] -169.0 -169.0 -169.0 Body Loss [dB] 3.0

Target PER (%) 2% 2% 2% Noise Figure [dB] 9.0Eb/No per Antenna [dB] 3.84 4.98 6.62 Thermal Noise [dBm/Hz] -165.0

Traffic Loading Factor [dB] 3.00 3.00 3.00 Target PER (%) 2%

BTS Rx Sensitivity [dBm] -116.3 -118.2 -119.6 (Ior/No) req per Antenna (dB) 6.00

Confidence (Cell Edge) [%] 90% 90% 90% Multi-user Diversity Gain (dB) 0.00

Log Normal Shadow Std Dev [dB] 8.0 8.0 8.0 Rx Diversity Gain (dB) 4.70

Log Normal Shadow Margin [dB] -10.3 -10.3 -10.3 AT Receiver Sensitivity (dBm) -98.1

Soft Handoff Gain [dB] 4.1 4.1 4.1 Confidence (Cell Edge) [%] 90%Penetration Loss [dB] 8.0 8.0 8.0 Log Normal Shadow Std Dev [dB] 8.0

Differential Fade Margin [dB] 2.1 2.1 2.1 Log Normal Shadow Margin [dB] -10.3

Soft Handoff Gain [dB] 4.10

Building Penetration Loss [dB] 8.00

MAPL [dB] 134.1 135.9 137.3 MAPL [dB] 136.7


22/103


Designing to Minimize Interference Is Key in

1xEV-DO System Design

Forward link transmits at full power using

TDMA rather than multiple carriers as in

IS-95. Controlling forward link interference is even

more important than in IS-95 system due to

virtual SHO vs. true SHO.

MSM-5500 AT can track up to 6 pilots in

active set, but communicate with only 1 at atime.


23/103


Approximate Forward Rate vs. C/I (AWGN)

0 dB C/I: 2 equal

strength pilots

above noise

-3 dB C/I: 3

equal strengthpilots above noise

=+

=

2

1

iio CWN

C

I

CData rate[Kbps]C/I [dB]

38.4 -11.5

76.8 -9.5

153.6 -6.5

307.2 -3.0

614.4 -1.0

921.6 1.3

1228.8 3.0

1843.2 7.2

2457.6 10.5

Pilot add and

drop thresholds

designed to

guarantee 76.8

kbps Control

Channel


24/103


Forward Link Rate Distribution

1228.8

1843.2

2457.6

153.6

921.6614.4

307.2

2.4Mbps

2 Pilot

Interference

Limited Region

Range limited

Interference +

Noise Region or

3+ pilot Soft

Handoff

Interference

Limited Region

Single

Sector Data

Ratelimited by

Range


25/103


What Is Idle Slot Gain and How Does It Help?

When there is no data to send, the forward link

powers down by IdleSlotGain for duration of

data portion (not pilot or mac) of the slot Commonly provides up to 10 DB gain on lightly

loaded systems

When duty cycle increases, effective idle slot gaindecreases.

Maximum Idle Slot Gain is limited by RadioSpecifications (-10 dB for Nortel Radios)


26/103


Forward Link Design Rules:

Control Number of Strong Pilots

Ensure there is a dominant Pilot

Control the number of strong pilots visible

1 pilot: OK 2 pilots: soft or softer handoff, handoff diversity gain

3 pilots: soft or softer handoff, handoff diversity gain

4 pilots: 4 way handoff, problems possible

5 or more, performance problems likely


27/103


Margins: Key Element of the Link Budget:

Shadowing Margin: Standard is 6-10 dB based on st. dev. of lognormal

shadowing process, and reliability. Example with 8 dB

sigma, 10.23 dB provides 90% edge reliability and 95%cell coverage assuming Log normal Shadowing

Penetration Margin

Definition: Difference between reverse link transmitterpower out-doors at street level and inside a building

Depends on a number of factors including: buildingmaterials, location, type of building, reliability, etc.

Head and Body losses

Multi-Cell Diversity Gain (soft handoff gain)

between 2 and 4 dB on interior cells


28/103


Shadowing, Cell Edge Area Availability And

Probability Of Service

Overall probability of service is best close to the

BTS, and decreases with increasing distance

away from BTS

For overall 90% location probability within cellcoverage area, probability will be 75% at cell

edge

Result derived theoretically, confirmed in

modeling with propagation tools, andobserved from measurements

True if path loss variations are log-normally

distributed around predicted median values,

as in mobile environment

90%/75% is a commonly-used wireless

numerical coverage objective

Statistical View of

Cell Coverage

Area Availability:90% overall within area

75%at edge of area

90%

75%


29/103


Shadow Fading Margin

Cumulative Normal Distribution

Standard Deviation from Mean Signal Strength

0%

10%

20%

30%

40%

50%

60%

70%

80%90%

100%

-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3

Cumulative

Probability

0.1%

1%5%

10%

Standard

Deviation

-3.09

-2.32-1.65

-1.28

-0.84 20%

-0.52 30%

0.675 75%

0 50%0.52 70%

0.84 80%

1.28 90%

1.65 95%2.35 99%

3.09 99.9%

3.72 99.99%

4.27 99.999%

Cumulative Normal Distribution

Standard Deviation from Mean Signal Strength

0%

10%

20%

30%

40%

50%

60%

70%

80%90%

100%

-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3

Cumulative

Probability

0.1%

1%5%

10%

Standard

Deviation

-3.09

-2.32-1.65

-1.28

-0.84 20%

-0.52 30%

0.675 75%

0 50%0.52 70%

0.84 80%

1.28 90%

1.65 95%2.35 99%

3.09 99.9%

3.72 99.99%

4.27 99.999%

Cumulative

Probability

0.1%

1%5%

10%

Standard

Deviation

-3.09

-2.32-1.65

-1.28

-0.84 20%

-0.52 30%

0.675 75%

0 50%0.52 70%

0.84 80%

1.28 90%

1.65 95%2.35 99%

3.09 99.9%

3.72 99.99%

4.27 99.999%


30/103


For an in-building user, the actual signal level includes regular outdoor path

attenuation plus building penetration loss

Both outdoor and penetration losses have their own variabilities with their own

standard deviations

The users overall composite probability of service must include composite

median and standard deviation factors

COMPOSITE = ((OUTDOOR)2+(PENETRATION)2)1/2

LOSSCOMPOSITE = LOSSOUTDOOR+LOSSPENETRATION

Building

Outdoor Loss + Penetration Loss

Computing Composite Margins


31/103


Statistical techniques are effective

against situations that are difficult to

characterize analytically

Many analytical parameters, allhighly variable and complex

Building coverage is modeled using

existing outdoor path loss plus an

additional building penetration loss Median value estimated/sampled

Statistical distribution determined

Standard deviation estimated or

measured

Additional margin allowed in link

budget to offset assumed loss

Typical values are shown at left

Building penetration

Typical Penetration Losses, dBcompared to outdoor street level

EnvironmentType

(morphology)

MedianLoss,

dB

Std.Dev., dB

Urban Bldg. 15 8

Suburban Bldg. 10 8

Rural Bldg. 10 8

8 4Typical Vehicle

Dense Urban Bldg. 20 8

Vehicle penetration

Building Penetration Statistical Characterization


32/103


Commonly Used Penetration Margins

Vehicular, and Rural: 5-7 dB. Insures service inside avehicle at cell edge.

Suburban: 8-12 dB. Service within most (75%) locations

of typical residential dwelling at cell edge, not includingbasement. Propagation through roof and walls.

Urban: 12-18 dB. Coverage for above plus service within

most commercial buildings, may have to move near towindow for service, strongly function of location of mobilerelative to window and cell. Propagation through walls andwindows

Dense Urban: 18-25 dB. Coverage inside of steal and glasshigh rise building.


33/103


Adjustments to Composite Margin

Soft Handoff Gain

Only Applicable in interior sectors (not exterior)

Based on 8 dB log normal shadowing, equalsignal strength, 50% correlation

In 1xEV-DO is effectively a multi-sector shadow

diversity GainQC uses 4.1 dB

-2.1 dB reduction on average

Net 2.0 dB Soft Handoff/Shadow diversity Gain

C it P b bilit f S i C l l ti F d


34/103


Composite Probability of Service Calculating Fade

Margin For Link Budget

Example Case: Outdoor attenuation is 8 dB., and penetration loss is 8 dB. Desiredprobability of service is 75% at the cell edge

What is the composite ? How much fade margin is required?

Composite Probability of ServiceCalculating Required Fade Margin

EnvironmentType

(morphology)MedianLoss,

dB

Std.Dev.

, dB

Urban Bldg. 15 8

Suburban Bldg. 10 8

Rural Bldg. 10 8

8 4Typical Vehicle

Dense Urban Bldg. 20 8

BuildingPenetration

Out-Door

Std.Dev.

, dB

8

8

8

8

8

CompositeTotal

AreaAvailability

Target, %

90%/75% @edge

90%/75% @edge

90%/75% @edge

90%/75% @edge

90%/75% @edge

FadeMargin

dB

7.6

7.6

7.6

6.0

7.6

COMPOSITE = ((OUTDOOR)2+(PENETRATION)2)1/2= ((8)2+(8)2)1/2 =(64+64)1/2 =(128)1/2 = 11.31 dB

On cumulative normal distribution curve, 75%

probability is 0.675 above median.Fade Margin required =

(11.31) (0.675) = 7.63 dB.Cumulative Normal Distribution

Standard Deviations from

Median (Average) Signal Strength

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3

75%

.675

O l i 1 EV DO With IS 2000 V i


35/103


Overlaying 1xEV-DO With IS-2000 Voice

Networks

According to QC, wherever 1xRTT has

service at 9.6 kbps reverse link 1xEV-DO

should have 19.2 kbps at the same margin


36/103

Setting Airlink Parameters and

Configuration


37/103


A Word to The Wise

Almost every parameter can be set,

adjusted, tweaked and optimized, BUT

In most cases it is wise to use default parametersettings in the network unless there is a very

good reason not to

There are some parameters that must be set and

optimized, and we will focus on these


38/103


Default Parameter Settings

Most standard settings have been tested and simulated

many times.

Exceptions:

Some differences between settings for hybrid and non-hybrid

networks.

Some differences between settings for fixed vs. Nomadic/mobility.

Some tweaking of parameters may be warranted after carefulmeasurements of system parameters.

Often the effects of changing parameters will not be

obvious, and may not have an effect until the system loads. Performance of system when lightly loaded will be

different than when heavily loaded.


39/103


Some General System Parameters

Maximum number of channel elements per BTS:

96 pooled for entire BTS (3-6 needed for access

channel, up to 90 available for traffic) Maximum number of connections/sector: 48

(theoretically 63, but limited by implementation)

Control channel data rate: 78.6 kbps

Access channel data rate: 9.6 kbps


40/103


Setting Handoff Parameters

Use QC recommended defaults.

Pilot add and drop, corresponds to C/I

necessary to support forward rate of 76.8 CCHrate.

Decreasing will tie up extra resources (pilot add 7,pilot drop 9), without better performance.

Increasing pilot_add will open holes in the network,or prevent effective handoff.

Parameters are communicated on sessionConfig message.


41/103


Neighbor Set Strategies

Make sure the neighbor set is accurate, not toomany or too few pilots

Set pilot add and drop thresholds to QCrecommended defaults

AT limited maximum number of neighbors is 20!

BTS limit 14 pilots with channel included BTS limit 19 pilots otherwise

Neighbor list is communicated in Sector

Parameters Message Do not set NeighborChannelIncluded unless

there is a good reason


42/103


Important Change in Neighbor Processing

Beginning with release 2.2 to speed up inter-RNC

transfer:

Pilots which are not neighbors will not be added to theactive set.

The RNC will treat them as pilots from a neighboring

RNC subnetwork. Getting the neighbor list right is even more

important.

From the AT view, it will look like the remainingset search window is 0, but do not do this because

you cannot transfer to a different RNC then.


43/103


Sector Parameters Message


44/103


PN Assignment & Pilot Increment Planning

PN assignments are similar to 1xRTT

planning.

The pilot PN offset is the PN offset in timeas a multiple of 64 chips defined per sector

to distinguish different sectors at the AT. Implementation Rule:

Two Nodes with the same PN cannot not be in

the neighbor list


45/103


PN Planning for Multi-Carrier Operation

! If multi-carrier, then all sector carriers in

this sector must have same PN. (see below)

! If a sector carrier is advertised in the carrierlist, it must be there, or AT may hang.

! Channel List message must have thechannels in the same order in multiple

sectors/BTS


46/103


Multi-Carrier Channel Hashing Algorithm


47/103


Setting Search Window Sizes

Airvana Rel 2.0 SW supports SearchParameterAttributesetting on a per RNC basis, and therefore, does not allowto have different SearchWindowActive,

SearchWindowNeighbor, and SearchWindowRemainingper sector. The only search window size that can be setdifferently per sector is NeighborSearchWindowSizewhich is in SectorParameter.

Use a default value for SearchWindowActive,SearchWindowNeighbor, SearchWindowRemaining,which works well for most situations.

NeighborSearchWindowSize can be set per sector if thedefault SearchWindowNeighbor is not suitable for thesituation of that sector.


48/103


Access Channel Parameters

Access channel rate is 9.6k

Access Parameter Message

Access Cycle Duration, OpenLoopAdjust,

ProbeInitialAdjust, ProbeNumStep,

PreambleLength, Apersistence

Attributes

CapsuleLengthMax, PowerStep, ProbeSeqMax,

ProbeBackoff, ProbeSeqBackoff


49/103


Access Probes

probe

probe

sequence

p

1 2 3 Np

1

persistence

s

p

1 2 3 Np

2

persistence

p

1 2 3 Np

Ns

persistence

Time

...

...


50/103


Setting Access Parameters

Set and optimize open loop adjust

May want to limit the number of probes in a

sequence

Care must be taken to insure that good

access is achieved without excessinterference to degrade reverse performance


51/103


Access Parameters Message


52/103


Open Loop Adjust

According to the access channel operation in IS-856 specification, the

access terminal shall send the i-th probe in the probe sequence at a

power level of the pilot channel given by X0+(i-1)PowerStep, where

X0 represents the access terminals open-loop mean output power of

the Pilot Channel and is given by X0 = - Mean RX Power (dBm) +

OpenLoopAdjust + ProbeInitialAdjust and the Mean RX Power is

estimated throughout the transmission of each probe.

OpenLoopAdjust is used to estimate the open-loop mean output powerfrom the average received forward channel pilot power from the sector.

The value of OpenLoopAdjust depends on the transmit power of the

sector and given by the following:

OpenLoopAdjust = -126 + Tx power in dBm.


53/103


Open Loop Adjust (Contd)

OpenLoopAdjust value needs to be fine tuned through field

measurement to be truly optimal.

If OpenLoopAdjust is set wrong, the connection setup will take a long

time since too many access probes are needed or the reverse linkcapacity will be reduced from excessive interference caused by access

probes.

If the average received power of the initial access probe is too high,

then it is needed to decrease the OpenLoopAdjust. If the average number of access probes is big, then it is needed to

increase the OpenLoopAdjust.

It is best to target the average number of access probes less than 2

while keeping the received power of the initial access probe less than 3

dB plus the nominal received power for a 9.6 Kbps packet.


54/103


OpenLoopAdjust

OpenLoopAdjust is a function of BTS TX power

is856SecElOpenLoopAdjust (0 255) = -(-126 + Tx

power in dBm)

How to know if OpenLoopAdjust is about right?

How many access probes do I receive? Try to target a bit

less than 2. Too little, say always 1 access probe OpenLoopAdjust is too

high

Too many, say on average 4 access probes OpenLoopAdjust

is too low

What is the relationship between Access Probe power

and Traffic Channel power

N b f P b S


55/103


Number of Probe Steps

Up to 15, but many systems use 8, (if it has

not acquired after going up 8x6=48 dB, it is

not going to Probe signal increases by ProbeStep each

time.

Each probe sequence is sent 3 times before

a failure is declared

S i DRC L h d G i


56/103


Setting DRC Length and Gain

a) DRCLength = 1

b) DRCLength = 2

c) DRCLength = 4

d) DRCLength = 8

DRC ChannelTransmission

Forward Traffic Channel SlotsWhere the Information in the

DRC Channel Transmission is

Used for New Physical LayerPacket Transmissions

DRC Channel

Transmission

Forward Traffic Channel Slots

Where the Information in theDRC Channel Transmission is

Used for New Physical Layer

Packet Transmissions

DRC Channel

Transmission


Where the Information in theDRC Channel Transmission is


DRC Channel

Transmission


Where the Information in the

DRC Channel Transmission is


One Slot

Higher DRC Length

Pros: Less power

Cons: Less accurate DRC

DRC L th d G i


57/103


DRC Length and Gain

Airvana Currently recommend DRC Length

of 4 and Gain 3 dB

Currently Recommend DRC Gating Off

T ffi Ch l A i t M


58/103


Traffic Channel Assignment Message


59/103

Optimizing Reverse Link Capacity and

Stability Parameters

What Constrains the Maximum Reverse Link


60/103


W C

Data Rate and Capacity?

Reverse sector capacity is ultimately limited by RL co-

channel interference, in cell and out of cell

Each additional user operating at a given data rate appears as noise

to the other users RAB algorithm insure that the RL remains stable

Pole capacity is the number of users or sector throughput if the

ATs could power up infinitely

The rate transmitted on the RL of an individual user is the

minimum of :

RAB and reverse rate ROT control loop

Maximum transmitter power available at AT

RRI based on max rate table

Reverse rate transition probability

Ri O Th l (ROT) d P l C it


61/103


Rise Over Thermal (ROT) and Pole Capacity

SNWFNS

RW

IoE

th

b

)1)(1( ++

=

Received signal quality as a function of vaf,number of users

and Received Signal Power S

If S is unconstrained, then the theoretical maximum number of

users is

( )1

1

1max +

+=

dWN

This is called the pole capacity and is not reachable. Most

systems operate at between 50 and 60 sometimes 75 %. At

which level the rise over thermal is between 3 and 4 dB

Reverse Link Capacity and Performance


62/103


p y

Parameters

RL frame error rate

RAB offset

RAB threshold

Max rate table

Reverse rate transition probabilities

S tti R Li k F E R t


63/103


Setting Reverse Link Frame Error Rate

Decreasing the RL FER will cause more

power to be transmitted by the AT to

maintain higher Eb/No and will decreasesector capacity.

Increasing RL FER will cause less power tobe transmitted by AT and will increase

sector capacity BUT

Do not increase RL FER above 1%, to avoid

TCP performance issues.

What is the RAB?


64/103


What is the RAB?

Total reverse link capacity is on the order of 270-350 kbps.

Reverse activity bit (RAB) is used to control the reverse link rate of

each user so that the reverse link capacity is maximized while

maintaining the stability of the reverse link.

Reverse link rate control algorithm is implemented in the BTS and the

rate control is performed per sector

The sector loading is used to control the reverse activity bit (RAB). If the

loading (defined as rise over thermal (ROT) value is greater/less than athreshold, the RAB is set/cleared, which in turn decreases/increases

reverse link rates of mobiles in the sector probabilistically.

One RAB is transmitted in every RABLength slots.

Different sectors can have different time offset in slots (RABOffset) whentransmitting RA bits. RABlength and RABoffset are settable per each

sector and are conveyed to the access terminal via traffic channel

assignment (TCA) message.

RAB Offset Planning


65/103


RAB-Offset Planning

For the operation of RAB, we need to set two values: RABLength and

RABOffset per sector. RABLength can be k*8 slots where k = 1,2,4,8.

Given RABLength (i.E. Given k), RABOffset can be k*n slots,

n=0,1,2...7.

Airvana recommends that RABLength be set to the IS-856 default

value of 32. Airvana recommends that RABLength be the same for all

sectors.

RAB offset planning, insures that sectors that are neighbors (withsignificant coverage overlap) do not change their reverse activity bit in

the same time (slot), which can cause large transients in transmitted

power on the reverse link and instabilities in the reverse link rate

control. RAB offsets for sectors in the same cell should be spaced by at least

(RABLength / 8) slots if possible. Neighbors with significant coverage

overlap or soft handoff also should be assigned different RAB offsets

What Is the Max Rate Table and How Is It Used?


66/103


What Is the Max Rate Table and How Is It Used?

Total reverse link capacity is on the order of 270-350 kbps depending on conditions.

Because the reverse link rate control is based onsoftware ROT measurements, there is someinaccuracy. RAB is not foolproof.

To insure RL stability, a second mechanism hasbeen put in place to control the reverse rates as afunction of the number of connected users.

Max rate table limits the maximum rate based onnumber of active users.

Assumes that users are always transmitting RL

data (which they are not) =1.

Setting Max Rate Table and RL Stability


67/103


Setting Max Rate Table and RL Stability

Configure max rate table along with the RAB/ROT control

system.

Set eROTth to 4 db

Use the following RateLimit table in R2.0

For 1-7 users set the rate to 153

For 7-48 users set the rate to 76.8

If too much offered RL capacity, then ROT will throttle

down

Call drop rate should be closely monitored. If there is high

call drop rate associated with high number of users, thenmay want to make RateLimit table more conservative.

Optimizing Max Rate and RL Capacity


68/103


Optimizing Max Rate and RL Capacity

Max rate table needs to be fine-tuned based on actual RF

environment

Max rate table should be made more conservative if call

drop rate under heavy load conditions increases

Rate table needs to be more conservative if:

Higher mobility

Smaller path exponent

Less shadow fading

Higher PilotAdd, PilotDrop thresholds

Rate table can be more aggressive if: Reverse capacity at heavy loads is well below pole capacity

Some tolerance for call drops in trade for more RL capacity

What Is RL Transition Probabilities and


69/103


How Do We Tune it?

Current Recommended Transition Probabilities


70/103


Current Recommended Transition Probabilities

Transition009k6_019k2 0x80




Transition153k6_076k8 0xFF




Note: These are different from the default parameters recommended inIS-856, and have been changed based on field results

After each hybrid mode Tune away, RL resets to 9.6 kbps and

transition starts again


71/103

RNC System Wide Parameters

Why Do We Need Drop and Fade Timers?


72/103


Why Do We Need Drop and Fade Timers?

Users may move out of coverage: when to

drop?

Efficient to release resources for users whoare inactive

Close down users at fringe to avoid excessRL interference from un-controlled AT

Setting Drop and Fade Timers


73/103


Setting Drop and Fade Timers

Set RLFadeTimer and FTCDesiredWait to

QC default of 5 seconds (time after which a

connection drops) Set AT SupervisionLost Timer to 5 seconds

On a Non-Hybrid network you may want toset these at 2 seconds.

Setting Inactivity (Dormancy) Timer


74/103


Setting Inactivity (Dormancy) Timer

CallCall CallCall

Active Intervals (Connections) Dormant Interval

Data

Limited number of Channel Elements (CEs) Connection management based on Inactivity timer

FastConnect reduces Connection setup time

Connection setup

Inactivity time

Connection

tear-down

Transmission

Tradeoffs in Inactivity Timer /


75/103


Increasing the Timer

Reduces the number of page attempts.

Reduces the number of connection attempts.

Reduces overall call process signaling. Provides an improved user experience since

fewer reconnects means less observed delay.

On the other hand:

May increase blocking probability in heavily loadedsector.

May effect max rate table calculations.

Increases use of CEs.

Optimizing Inactivity Timer


76/103


Optimizing Inactivity Timer

Make shorter if: (5 seconds)

Heavily loaded system with possibility of element or resource

blocking

Heavily loaded system effecting RL rate table and stability Distribution of dormancy times indicates high percentage of long

dormancies

Make longer if: (10 seconds)

System loading is relatively light

Give user better experience since fewer reconnects following

dormancy

Excessive paging and call processing

Distribution of dormancy times indicates high percentage of short

dormancies

Fade and Connection Drop Timers


77/103


Fade and Connection Drop Timers

FTCDesiredWait 50x100ms = 5 seconds

RLFadeTimer 50*100ms = 5 seconds

AT Supervision Timeout= 12 CC

cycles=5.12 seconds

These are driven by hybrid mode to

minimize probability of connection dropwhile in Hybrid Tuneaway

Should We Change Pilot Add and Drop?


78/103


Should We Change Pilot Add and Drop?

Use QC recommended defaults.

Decreasing will tie up extra resources (pilot add

7, pilot drop 9), without better performance. Pilot add, corresponds to forward rate of 76.8, pilot

drop, 38.4 kbps.

Increasing will open holes in the network, orprevent effective handoff.

Changing Delta will increase callprocessing


79/103

Optimizing 1xEV-DO Networks

Optimization Scenarios:


80/103


What Is Available to Optimize

Overlay of existing system (includingantennas and cables)

Using existing RF design Optimization and change options are limited

due to effects on legacy system

Greenfield deployment from start Everything is can be optimized

Entire RF design must be verified againstcustomer objectives


81/103

Steps in 1st time Optimization Process


82/103


Steps in 1 time Optimization Process

Check Pilots on correct sectors

Refine and Optimize Neighbor List

Adjust planning tool predictions based on drive testing Check RAB offset plan

Verify Number of Probes required and Open Loop Adjust

Verify Handoff Boundaries Compare handoff boundaries to predictions from

planning tool

Verify location and functionality of 1xRTT 1xEV-

DO handoff boundaries

Optimization Process (Contd)


83/103


Optimization Process (Cont d)

Characterize coverage Forward data rates

Reverse data rates

Call drop/data interruptions Call setup

Paging

Performance at penetration margin

Find absolute limits and islands of coverage (where user can hold up acall

Verify coverage over crucial areas

Freeways, major roads

Key customer identified coverage areas

Verify coverage at customer defined grade of service

> 150-300 kbps forward link, 19 kbps reverse link for mobility

> 600 kbps forward link, 19-40 kbps reverse link for fixed service

Optimization Process (End)


84/103


Optimization Process (End)

Adjust antenna down-tilt to control pilot pollution

and move handoff regions, if possible

Adjust system parameters based on drive testresults, and type of deployment

Fixed deployment versus mobility system

Repeat process to verify successful parameterchange

Execute customer specific acceptance tests

Continue to monitor network from EMS to verify

network performance

Optimization Tools


85/103


Optimization Tools

RF Planning tool

Airvana uses AirPlan-1xEV-DO a proprietary

combined planning and measurement integration tool

GPS Equipped Access Terminal Diagnostic Units

Tool for collecting and parsing data

Airvana uses QC CAIT Tool

Method for integrating results from 1,2,3

Airvana uses integrated Planning and Optimization

tool, AirPlan 1xEV-DO

EMS and Network Centered Data analysis Tools

Purchase at Least One CAIT Key per Market


86/103


y p

Only current option for Access Terminal

Diagnostic Monitor for 1xEV-DO

Couple with GPS and Planning tool tocharacterize your network (handoff

boundaries) etc. CAIT is intrusive during throughput tests!


87/103

10 Key Metrics to Monitor NetworkPerformance

10 Operational Metrics to Watch After Deployment


88/103


p p y

1. Call drop rates on RNC, slot, and per sector basis2. Number of users per sector, per slot, and per RNC

3. Session and connection setup success rates

4. Paging success rates5. Connection duration and dormancy duration

6. Aggregation router statistics on each back haul element

(usage, queuing delay, packet drop)7. FL and RL throughput on RNC, per slot, and per sector

8. Pre-RLP packet drop statistics

9. Forward and reverse handoff success rates10. CPU usage for RNC

Data Collection OMs


89/103


Start with Airvana/Nortel default DC

template

Will provide basic statistics RNC,SLOT, andper sector

Add some call control logs to get information

on drops, and call durations

Automate DC post processing

What to Watch For


90/103


Approach of metrics to engineering or MRS

limits

Change in parameters indicating change insystem operation and performance

Gradual increase in loading

What Is a Dropped Call and How Do We

Compute Dropped Call Rate?


91/103


Compute Dropped Call Rate?

A dropped call is an abnormal call termination caused byloss of signal supervision either: RtcLost

NoFtc

Because of Link Asymmetry, Ratio of RTCLost/NoFTCshould be very high (calls will drop on reverse link before

forward link).

Other Events that will Peg as Dropped Calls Hybrid Mode Tune away lasting more than 5 seconds

Inter RNC switch (drop then re-acquire on new RNC)

ctionsnatedConnenumANTermictionsnatedConnenumATTermi

cLostSloionCloseRtnumConnectFtcSlotionCloseNonumConnectRateDropCall

+

+=

What Is a Forward Sector Switch Failure and

How Do We Compute the Rate?


92/103


How Do We Compute the Rate?

ccessSHnumTotalSuFtcionCloseNonumConnect

FtcionCloseNonumConnectRateFailureDRCicCatestroph

+=

Two Types of Forward Sector Switch Failures:

Catastrophic (resulting in a drop) and non-

catastrophic (no drop)

FtcDesirechesFailednumDRCSwitccessSHOnumTotalSu

FtcDesiredchesFailednumDRCSwitchFailureSectorSwit

+=

What Is a Reverse Soft Handoff Failure, and How

Do We Compute the Rate?


93/103


Do We Compute the Rate?

All failed reverse soft handoffs result in

connection drops

Causes of Soft Handoff Failure RNC/Slot OM

Pegs

sSHOAttemptnumRevLink

SHOSuccenumRevLink-sSHOAttemptnumRevLinkRateFailureHandoffSoft =

numRevLinkSHOFailRncTimeout(slot)

numRevLinkSHOFailedTccTimeout(slot) (lost signal on target RN/DOM)

numRevLinkSHOFailedByRncResources(slot)

numRevLinkSHOFailedByRnSlot

numRevLinkSHOBlockedByRncResources(slot) (RNC was too busy to do the handoff)

numRevLinkSHOBlockedByRn(Slot) (one or more RN/DOMs did not have channel

elements

Paging Statistics


94/103


g g

How much paging activity is occurring:numPageMessagesToAT (slot)

Successful page is defined as changing fromdormant to active state when there is data at the

RNC

DtoAFailureRate = (numFailedRncInititatePages numPageReqsWhileTearingDown) / numRncInitiatedPages

DtoASuccessRate = numPagesSucceeded /

(numRncInitiatedPages numPageReqsWhileTearingDown)

Connection and Session Setup Information


95/103


p

RNC (slot) Session Setup Attempts (per Busy Hour) RNC (slot) Session Setup Success (per Busy Hour)

RNC (slot) Connection Setup Attempt (per Busy Hour)

RNC (slot) Connection Setup Success (per Busy Hour) RNC (slot) Connection Teardown (per Busy Hour)

Connection Setup Success Rate = numConnectionsOpened /(numConnectionRequestsFromAT + numFastConnectsAttempted -numConnReqsWhileSettingUp - numConnReqsWhileTearingDown -numConnReqsWhileOpen)

RNC (slot) Connection Teardown (per busy hour) =(numConnectionCloseFromAtNormal +

numConnectionCloseFromAtError +numConnectionCloseFromAtReserved) +(numConnectionCloseToAtNormal + numConnectionCloseToAtError

Note: A successful page causes a connection request from

the AT

How Many Connections and Sessions Are Active

and Dormant?


96/103


and Dormant?

Number of active connections (sessions):numActiveSessions (slot)

Total number of sessions:numCurrentSessionsEstablished (slot)

How to Measure Forward and Reverse

Throughput at RNC (Slot)


97/103


Throughput at RNC (Slot)

Forward Throughput RNC (Slot):

Reverse Throughput

While you are at it, monitor Pre-RLP DroppedPackets

Time

8*)Bytes(slotforwardRlpThroughputRLPForward

=

Time8*)Bytes(slotreverseRlpThroughputRLPReverse

=

Where to Get Sector Carrier Data


98/103


From the individual DOM/RN

Forward traffic per sector

Reverse traffic per sector

From RNC SectorCarrier OMs collected

at RNC RN/DOM logs

What to Look At Sector Carrier


99/103


Forward and Reverse Traffic From RN/DOM

Sector Carrier Data

totalAirlinkRsrcAllocatedCurSectorCarrier

numConnectionCloseNoFtcSC

numConnectionCloseRtcLostSC

numConnReqsANInitiatedSC

numConnReqsATInitiatedSC numSuccessfulOpensForANConnRequestSC

numSuccessfulOpensForATConnRequestSC

numFailedOpensforBlockedRNConnRequestSC

Looking at Sector Carrier Data


100/103


Do it graphically: it makes more sense to

understand trends

Monitoring CPU Usage


101/103


Where to get the data? Airvana-entity-utilization-MIB

RNC MOD numbers:Bio1/1/1 - 010101 - 65793

Bio1/2/1 - 010201 - 66049Rnsm1/3/1 - 010301 - 66305

Rnsm1/4/1 - 010401 - 66561

Rnsm1/5/1 - 010501 - 66817

Rnsm1/6/1 - 010601 - 67073

Sc1/7/1 - 010701 - 67329

Bio1/11/1 - 010b01 - 68353Bio1/12/1 - 010c01 - 68609

Rnsm1/13/1 - 010d01 - 68865

Rnsm1/14/1 - 010e01 - 69121

Rnsm1/15/1 - 010f01 - 69377

Rnsm1/16/1 - 011001 - 69633

DOM MOD numbers:BIOSC - 010301 - 66305

FLM - 010401 - 66561

RLM - 010402 - 66562

Call Duration and Dormancy


102/103


Collect RNC call control logs

For each UATI: parse for connection opened

and connection closed (call duration) For each UAT: parse for connection closed and

connection opened (dormancy duration)

Collect for all UATI and all calls;

Collect pdfs, mean and std


103/103

End of ModuleThank You

Accelerating Access Anywhere