network planning & optimisation 4 nov 2009

Soc Classification level

Presentation / Author / Date1 © Nokia Siemens Networks

Network planning & optimisation Technical sharing sessionJonathan Tam

Network planning & optimisation expert

4 Nov 2009



Agenda

1. Antenna separation recommendation

2. 2G-3G interworking

3. HSPA implementation strategy

4. Capacity management

5. Inbuilding coverage

6. Any other topics








6. Any other topics



Antenna separation recommendation

• Horizontal spacing is the distance between antenna centre lines

• Vertical spacing is the gap between antennas




RF Filters to allow even closer separation of antennas may be

Considered.

• The antenna separation is typically greater than 0.5m and provided the relative angle is greater than 90Deg a filter is not required. With angles less than 90Deg and panel separation less than 0.5m, a 900MHz GSM bandpass filter may be required in the GSM base station antenna feeders for each polarisation




• For the instance of a dual band GSM panel mounted in close proximity to a 3G antenna, and the GSM dual band antenna is a 2 port type with BTS combining within the equipment shelter, it is not necessary to install a 900MHz band pass filter. The 1800MHz band pass filter is still required. This is because the 900/1800 dual band combiner has sufficient isolation performance for 900MHz.








6. Any other topics



2G-3G interworking

Main objectives:

1. 3G capable UEs should camp on 3G as long as radio conditions allow. 2G network is only used by 3G capable UEs when 3G coverage becomes weaker.

2. Consistent 2G-3G interworking in Idle & Connected mode to allow smooth intersystem reselection or handover for 3G capable UEs

• In idle mode� Ping pong degrades not only customer experience but also increases signalling load

due to location update unnecessarily.

� A safe margin for 2G-3G interworking should be made available to stop ping pong

• In connected mode� Handover should be executed without causing additional drop calls

� Coverage related ISHO thresholds can be made differently for voice and PS calls

� ISHO threshold should be set in line with idle mode parameters

• Load balancing� Load & service based HO can be used to offload 3G traffic onto 2G



2G-3G interworking

• 3G parameters Sintrasearch, Sintersearch and SsearchRAT are compared

with Squal (CPICH Ec/No -Qqualmin) in S-criteria for cell re-selection



2G-3G interworking

>-8

-8..-10-10..-14

<-14



2G-3G interworking

• 2G parameters Qsearch_I, Qsearch_P, FDD_Qmin and FDD_Qoffset are

used for 2G>3G cell reselection



2G-3G interworking• In connected mode, FMCS & FMCG parameters are used to trigger ISHO due to DL

DPCH power, UL Qual, UE Tx power, CPICH RSCP & CPICH EcNo. Different sets of

FMCS can be FMCG can be applied to RT, NRT and HSDPA services.



2G-3G interworking

Lessons learnt from other networks:

1. Poor 3G>2G ISHO success rate

• Mainly due to high congestion on 2G TCH

• Mismatch or missing datafill in MSS or SGSN

Solutions: 2G TRS expansion, 2G load balancing, Half rate, consistency check

2. UEs camp on 2G even though well in 3G coverage area

• Missing neighbours

• Incorrect 2G Idle mode parameter

Solutions: Neighbour size audit, 2G parameter consistency check

3. 3G PS data calls switch to 2G GPRS or EDGE very frequently

• Too conservative ISHO thresholds for PS service

Solutions: Fine-tune ISHO thresholds, disable HSDPA ISHO








6. Any other topics



HSPA implementation

HSPA implementation

• A number of HSPA upgrade steps available to meet different levels of mobile broadband requirement

Step Description Max

Mbps per

user

BTS

throughput

Mbps

Simult

HSDPA users

3 (2010 target) Second carrier deployment in RU20 21.1 21.1 - 63.3 72 - 216

Layering features Depending Depending

on scheduler on scheduler

2 (2009 target) Second carrier deployment in RU10 14.4 14.4 - 43.2 64 - 192

Layering features Depending Depending

Node B capacity expansion on scheduler on scheduler

1 (Intermediate) 15 channel codes 10.8 10.8 - 32.4 48 - 144

Shared or dedicated scheduler

Now 5-10 channel codes 3.6 - 7.2 10.8 48

Shared scheduler 1

2

3

4



HSPA implementation

When to upgrade from 1+1+1 to 2+2+2 second carrier?

• for higher HSDPA throughput (dedicated HSPA carrier)

– More available HSDPA codes from dedicated second carrier for HSDPA

– More cleaner frequency & better CQI

• for improved voice performance (dedicated HSPA carrier)

– HSDPA move to second carrier. DL interference becomes lesser for voice services

• for extremely high demand of HSPA traffic (shared HSPA/R99 carrier)– Both layers to be HSPA enabled to provide maximum HSPA traffic



HSPA implementation

When to upgrade from 1+1+1 to 2+2+2 second carrier?

• When HSDPA code availability becomes smaller



Dedicated HSPA layer for 2+2+2 HSPA implementation

• High HSDPA/HSUPA throughput due to clean frequency

• DRRC F1->F2 (HSPA capable terminals) is done to clean frequency, Idle mode users directed/kept always on F1 and F2 cell_FACH, cell_PCHusers stay on F2, typically all HSPA terminals stay in cell_PCH instead in idle mode so those can be kept in F2

• Continuous R99 layer with SHOs (supports high speed mobility for voice)

• Voice call performance on F1 improves due to all HSPA traffic moved to F2 -> less interference

• When HSDPA/HSPA supporting terminal penetration increases the HSPA layer supports more and more traffic without interfering R99 layer

F2: HSPA

F1:R99

GSM

F2: HSPA

F1:R99

GSM



Shared HSPA/R99 carrier for 2+2+2 HSPA implementation

• Extremely high HSPA capacity as HSPA on both layers

• Both layers support HSPA and R99 so only #HSPA users need to be balanced (F2 higher HSPA usage layer => F1 primarily for voice and R99 users)

• Stable HSPA throughput for mobile wireless broadband user

F2: HSPA + R99

F1: HSPA + R99

GSM



Key optimisaiton achievements

• NSN Sumatra optimisation taskforce delivered the following key achievements

– Significant improvement in HSDPA accessibility

– Significant improvement in AMR & PS DCR

– A reduction of 1918 CEs used during peak hours for the whole NSNSumatra area – a decrease of 12.5% of total 15498 CEs used after optimisation. At the same time, 3G AMR traffic has increased by 200% for Batam while 3G voice & data traffic remains steady for other cities.



Key optimisaiton achievements

• NSN Sumatra optimisation taskforce was setup in June 2009

– Dedicated optimisation team for Batam, Medan & Palembang

– Key optimisation activites were carried out as follows








6. Any other topics



Capacity management

After HSDPA launch and active marketing HSDPA data volume grew 5 times in just 2 weeks from 2500Gb to 12500Gb and doubled during next 3 and half months (ten times growth in 4 months)

Reasons for data growth

1. High data rates

2. Flat rate pricing

3. Simple installation

4. Laptops penetration

13 TB/day

10 TB/day

Mobile broadband traffic grows exponentially…



Capacity management

Proactive capacity monitoring is important to identify potential bottlenecks especially in RAN.



Capacity management

No

>48 simultaneous users exceeded

Possibility to reduce the

usage?

Yes

Yes

More throughput

needed

NoNo

Iub capacity for HSDPA supports higher throughput

Yes

Possibility to reduce the R99

usage?

No

Yes

No

Upgrade the Iub

#available SF 16 codes supports new

scheduler

Yes


usage?

No No

YesUpgrade to 2nd

carrier

BTS CE capacity supports addition of

schedulers

Add more schedulers

Yes


usage?

No No

Upgrade

the BTS

Throughput limited by BTS

power, CQI or user location?

Upgrade the BTS power

Possibility to optimise the throughput

Yes No

Yes



Capacity management

Upgrade 2+2+2 to maximise data usage through the monitoring of :

• HSDPA code availability

• Simultaneous HSDPA users

Capacity upgrade for other NE or interface through the monitoring of:• CE usage

• Iub reservation & utilisation

• ATM CID usage

• IuPS load

• RNC/DMPG load

• etc



Capacity management: Iub

Below is comparison of RNC CAC reservation (per BTS per hour) relation to actual usage for the case (hours & BTSs) of no HSDPA usage

As it can be seen the reserved capacity by the RNC CAC is not fully utilised by the R99 connections, from simple trend lining the utilisation is roughly

• In DL 1/3 from CAC reservation (but increasing trend of utilisation is visible when the reservation increases)

• In UL 1/4 from DL CAC reservation (but increasing trend of utilisation is visible when the reservation increases)

• Also the trend depends on traffic profile (share of traffic between CS and PS)

-10%

-5%

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

0% 10% 20% 30% 40% 50% 60% 70% 80%

RNC CAC Reservation %

Uti

lis

ati

on

DL

%

-5%

0%

5%

10%

15%

20%

25%

30%

35%

0% 10% 20% 30% 40% 50% 60% 70% 80%

RNC CAC Reservation %

Uti

lis

ati

on

UL

%



Capacity management: CID

Each AAL2 connection requires individual CID

• CCCH– CCCHs consists of FACH-u, FACH-c, PCH & RACH i.e. per cell 4

CIDs are needed

– 3 sector site requires therefore 3*4=12 CIDs for CCCH

• Normal call requires 2 CIDs:– SRB

– RB

• HSPA Call requires 3 CIDs:– SRB

– MAC-d Flow in DL

– UL Return Channel (HSUPA or R99)

• Multi-RAB Call requires one additional CID per additional RAB

One VCC can have 248 CIDs and lack of CIDs can cause call setup to fail due to TRANSMISSION








6. Any other topics



Inbuilding coverage

• 3G inbuilding coverage is best served by dedicated inbuilding solution for high rise building� 3G interference caused by reflections and defractions from building when directional

antenna transmitted from adjacent building.

� Providing dominant coverage is the most important principle in 3G coverage planning

� Utilising existing 2G DAS system and co-locate if possible

network planning & optimisation 4 nov 2009

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