Repeater in the CDMA network

Repeaters in CDMA network

• Dr. Joseph Shapira

PROPRIETARY AND CONFIDENTIAL1

Parameters affecting capacity• Power (FL) limit• Effect - Blocking• Measure - Power-per-user, blocking rate• Interference (RL) limit• Measure – noise rise ( may have an access limit set by the

system)• Effect - Access failures, dropped calls, coverage reduction

(“breathing”)• Measure – (RL) access failures/ dropped calls rates• Excess SHO• Draws power from multiple cells – limits FL power• Increases overhead communications• Draws channel cards


Capacity Measurements• Measure – Power per WC (Power per user).• This is an average measurement, that assumes the

same user distribution and data flow per user.• P/WC is sensitive to coverage, and has to be corrected

for change of coverage, if channel changes are measured (diversity)

• Pilot power allocation % affects TCH power and capacity

• Measure - Blocking rate• A valid measure only for full load (saturation)• Disrupted by anti-saturation means (e.g. AOC)• Noise Rise – (may have a limit by the system)


CDMA optimization parameters

•Improve the channel – reduce Eb/Nt required margin

– Receive diversity– Transmit diversity

•Reduce link loss variations– Distributed antennas– Repeaters

•Reduce SHO overhead– Increase the transmission-

loss slope– Balance FWD and RVS links– Access Control

•Balance the loads– Intersector – Intercell

•Optimize the service •Dynamic optimization is the next frontier


Time Delay Transmit Diversity (TDTD)


Residential area

70% increase in capacity

(2.3 dB gain)

Performance Comparison - Sector 21Z

-0.1

0.4

0.9

1.4

1.9

2.4

2.9

3.4

3.9

4.4

4.9

200 300 400 500 600 700 800

Minutes of Use

P b

lock

ing

[%

]

w/o TDTD

w TDTD - Before Tilt

Performance Comparison - Sector 21X

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

700 900 1100 1300 1500 1700 1900

Minutes of Use

P b

loc

kin

g

[%]

w/o TDTD

w TDTD

Highway traffic

25% increase in capacity

( 1 dB gain)

Blocking probability

2%

2%

Indoors Penetration enhancementby a repeater across-the-street, with

Transmit Diversity plus TTLNA


-10 -5 0 5 10 15 20 250

0.5

1

1.5

2

2.5

3

-25 -20 -15 -10 -5 0 5 10 150

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

RSSI {with TD – w/o TD } [dB] Distribution Handset Tx Power {with TD – w/o TD} [dB] Distribution

-4dB5dB

Network Optimization/ Capacity Maximization Process

•Improve the channel – reduce Eb/Io required margin


•Reduce link loss variations– Distributed access– Repeaters




•Optimize the service •Dynamic optimization is the next frontier






•Reduce SHO overhead– Antenna control– Balance FWD and RVS links– Access Control


•Optimize service •Dynamic optimization is the next frontier


Number of Sectors involved in a callA Major Metropolitan Market, US


Site # X Site # Y

2.12.2

1.5

3.4

2.3

2.2

Power Inefficiency factor


Site # X Site # Y

[Simple+2*CTrfCode+ChnSrHO+2.25*CTrfCode+ChnSHO] / [Simple+CTrfCode+ChnSrHO+CTrfCode+ChnSHO]

20 - 30%

The Smart ClusterAdd-On Dynamic Optimization

Cluster size - 10 to 15 cells


SensorsOptimization

Effectors

Communication Communication

Objectives

Mobile unitsBTS RF stateRepeatersAntenna stateSwitch – performance parameters

RET and RBC AntennasRepeater gainBTS pilot levelNeighbor listSearch window

Additional parameters

Repeater usage for Maximizing Capacity

1. Hot spots2. Indoor illumination from outdoor3. Indoor distribution (DAS)4. Increase transmission slope/ reduce SHO5. Load balancing6. Add diversity


Types of Repeaters

1. Embedded2. Border extension3. Remote4. Cascaded


RR3

D3

D2

1

2

3

RR2

RR1

D1 RCRR3

D3

D2

1

2

3

RR2

RR1

D1 RC

Forward Link

•Relays all donor transmission ( plus other interfering sources)

•No automatic balancing RVS/FWD•Has to be controlled for coverage (gain) and saturation (AMLC)•Reduces RSU (repeater-served-users) per-user power•Increases PiCH/TCH ratio for RSU (TCH is power-controlled)

RFDFF GTy


Impact of Repeaters on the Network - FL

• Net gain (yF) determines coverage

• Excess gain causes oscillations/spurii• AMLC reduces coverage, causes imbalance and reduces capacity• Amplifying other sources may lead to AMLC• Instability of the BS-Repeater (BSR) link (e.g. directive antenna nodding,

fiber loss change with temperature, etc.) changes coverage• Overlap with donor’s coverage adds multiple fingers to the MS receiver,

introduces interference (excess fingers) and diversity• Repeater delay requires broadening of the search window (significant in

fiber and selective repeaters)


Impact of repeater on network - RL

•Effective cell noise factor

•Repeater adds RL noise•Reduces donors’ coverage, • or donor’s capacity.•Trade-off repeater coverage• vs. donor coverage/ capacity

RCCE yFFF


RCCE yFFF

GRR

FR

GBFB

BTS Repeater

Tr

n

TD

RC RR

Tc

RC0

m

GRR

FR

GBFB

BTS Repeater

Tr

n

TD

RC RR

Tc

RC0

m

RL Impact of repeater on network – cont.

• No Rx diversity – increases MTX and BTS load, and reduces coverage

• Loads the donor noise and reduces its coverage and/ or capacity

• Overlap introduces diversity. Excess fingers introduce interference

• Change in BSR link gain causes change in coverage for both repeater and donor

• Imbalance FL-RL (excess offset) causes the P.C. open loop to be noisy, and loss of capacity. Imbalance exceeding about close loop range breaks the P.C. loop and drops RSUs


Fixed Coverage vs. Fixed Capacity

• A Excess noise rise for fixed capacity (loss of coverage)

• B Loss of capacity for fixed noise rise• A B


0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-10 -8 -6 -4 -2 0 2 4 6 8

Apparent repeater noise figure

Do

no

r ca

pac

ity

rela

tive

to

no

min

al

(max

. lo

ad f

acto

r vs

. no

min

al)

8

9

10

11

12

13

14

15

16

17

18

-10 -8 -6 -4 -2 0 2 4 6 8

Apparent repeater noise figure

No

ise

rise

[d

B]

Coverage of repeaters

• Embedded Border Remote


-10.00

-8.00

-6.00

-4.00

-2.00

0.00

2.00

4.00

6.00

8.00

10.00

Distance from BTS (normalized)

Prs

/Ps

[dB

]

-10.00

-8.00

-6.00

-4.00

-2.00

0.00

2.00

4.00

6.00

8.00

10.00

0.46

0.52

0.58

0.64 0.

7

0.76

0.82

0.88

0.94

1

1.06

1.12

1.18

1.24 1.

3


Prs

/Ps

[dB

]

-15.00

-13.00

-11.00

-9.00

-7.00

-5.00

-3.00

-1.00

1.00

3.00

5.00


Prs

/Ps

[dB

]Cell border

Repeater Controls

• Gain, RL• Power, RL• Gain, FL• Power, FL• AMLC – Automatic Level Control• Frequency filtering• Switching (advanced option)• BS-Repeater Link Gain• Antenna controls


Basic Repeaters

• Definition: Fixed frequency band/selective, fixed gain independent in FWD/RVS, has maximum power protection (e.g. AMLC), provides alarms and monitoring, no AISG provisioning (maybe external), no diversities, simple RF F1-F1 (no dedicated conduit), no watermarking, no multi-hop, includes a wireless modem

• Parameters: FWD Gain, RVS Gain, RVS Tx Power, FWD Power, AMLC Level and Status, Wireless Modem parameters forwarding (Ec/Io, RSSI, FER, Tx PWR)

• Optimization: Setting procedures (FWD, RVS, Noise Rise, Pilot PWR %, balancing), search window, neighbor list

• Parameters such as # carriers, traffic load, carriers' loading, BTS allowed shrinkage, enter into setting and optimization as constraints

• Incorporate repeaters in the optimization tool with shared BTS-Repeater coverage, combined traffic, macro-diversity and interference, all above setting considerations.


Advanced Repeaters

1. Repeater performance2. Enhanced performance3. Enhanced features4. Network Parameters Readout


Advanced Repeaters

Repeater performance1. Stability2. Robustness3. Installation – parameter setting4. Alarm functions5. Link balancing 6. Traffic, coverage, overhead


Enhanced performance

• Interference cancellation1. Adaptive angular interference cancellation

(adaptive donor antenna)Filter-out other donors or interfering sources

2. Adaptive feedback cancellationReduces coupling between donor and service antennas, allowing for tighter installation on the tower


Enhanced features

1. Frequency filtersInter-systems and sub-bands

2. Antenna control (RET/ RBC)Control of repeater service antenna

3. Diversity FWD/RVS True or pseudo-diversity (PSD/TDD)

4. Multi-carrier/ multi functionMulti-systems with separate controls

5. BTS-Repeater (backhaul) link stabilization


Network Parameters Readout

1. Traffic load through repeaterLimited effectiveness. The noise rise is affected by the total donor+repeater load

2. Tagging repeater – “Water-marking” RSUsFrequency or delay modulation of repeater RL. Requires detection by BTS

3. Wireless Modem parameters’ monitoring4. Switch parameters pre-filtering and processing


Cascaded (multi-hop) repeaters• Repeaters are cascaded to increase coverage1. Along roads • maximal area/ length2. Within an area/ campus • mixed large/ small areas3. Within buildings• limited area, complex coverage • Distribution (backhaul):• Star• Cascade


Star/ Cascade

• Star• Each repeater may be controlled independently• The aggregate apparent noise factor counts. Optimal

setting – same net gain to each. • Cascade• The gain setting of each repeater influence the rest of

the chain. The coverage is successively smaller. Optimal setting – same net gain (y) to all repeaters but the first (preferably y=1). Control the chain by the net gain of the first.


RCR1 R2 R3 R4

Total range

RCR1 R2 R3 R4

Total range

Setting

• Roads/ area• Maximizes for y=1. Repeaters and donor are planned

and optimized together.

• Indoors• Low net gain (y <<1). Small coverage. Minor impact on

donor coverage. Loosely interdependent optimization of donor and repeater chain.


Network planning with repeaters

• Optimizing the repeaters’ location and their parameters’ setting is crucial for any further control and optimization of the network.

• Major parameters:• Repeater RL/FL power, gain, dynamic range (per

location and purpose)• Repeater location• height, beam-width, direction and tilt of dservice

antenna• Backhaul link


Optimization with Repeaters• Change repeater coverage vs. donor coverage

– Hot spot – Repeater coverage should exceed high density area– Border – affects pilot pollution/ SHO extent– Remote – rural coverage vs. core coverage

• Change repeater antenna orientation/ tilt– Hot spot – controls overlap with donor (capacity, performance)– Border – controls pilot pollution/ SHO extent– Remote – controls Repeater coverage area

• Frequency Filters and service antenna control– Controls load distribution/ service destination

• Switch– Switch off dormant coverage and reduce noise


Enhancement Tools CDMA wireless modem in the repeater

1. Reports repeater status2. Relays commands to the repeater3. Automatic FL/RL links balancing

By reading the offset parameter of the modem P.C. and controlling repeater gains

4. Location • (e.g. by differentiating time-of-flight to

modem and to subscriber)5. Identifies PNs through repeater

Support reduction of interference from other sources


Thank you• Contact• Dr. Joseph Shapira• Comm&Sens Ltd• +972 4 8251653• +972 54 6607088• Jshapira@comm-and-

sens.com


Repeater in the CDMA network

Technology

Transcript of Repeater in the CDMA network