HIGH CAPACITY ADAPTIVE BASE-STATION … CAPACITY ADAPTIVE BASE-STATION ANTENNA SYSTEMS Anders G...

Ericsson Research ©2002 Ericsson ABISART´02, 4-6 March 2002, A Derneryd

HIGH CAPACITY ADAPTIVE BASE-STATIONANTENNA SYSTEMS

Anders G Derneryd

Ericsson ABAntenna Research Center

SE-431 84 Molndal, Sweden

Email: [email protected]


Outline

• Background• Adaptive Antenna Systems

GSM (Global Systems for Mobile Communications)GPRS (General Packet Radio Service)

EDGE ( (Enhanced Data Rates for Global Evolution)WCDMA (Wideband Code Division Multiple Access)

• Hardware realization• Conclusions


Background

Growth fromprevious year

• Increased mobilesubscribers growth

• To satisfy capacitydemand, new technologyis needed

• Conventional ways toincrease capacity

½ More radio spectrum: Regulatory limitations and high costs ! New terminals !

½ Cell splitting: High costs of acquring new sites & infastructure !

½ Higher degree of sectorization: Increased number of hand-offs !


Technology for Advanced Antenna Systems

Incr

ease

d implem

enta

tion co

mplex

ity an

d cost

Basic three-sector sites

Higher order sectorization

Fixed multi-beam antenna

Steered beam antenna


GSM Adaptive Antenna Concept

Array antenna

Interferer

Interferer

Desired

• Narrow beams are directed fromthe base-station towards themobile stations

• A beam can be (steered towardsthe desired mobile station or)selected from a set of fixed beams

• The beam for downlinktransmission is determined oninformation derived from the uplink,the direction of arrival (DOA)

Adaptive AntennaSystem

Reduced Interference

Tight FrequencyReuse Possible

Large CapacityIncrease


GSM Multi-Beam Adaptive Antenna System

Ericsson implementation

• Low complexity adaptive antenna system solution

• Non-coherent radio chains

• 8 fixed narrow interleaved beams per 120° sector

• RF level beamforming, with no calibration requirement

• Best beams selected for uplink combining

• Best beam selected for downlink transmission


GSM Capacity Booster, RBS 2205

Radio base-station 8-beam array antenna


Capacity Increase with GSM Adaptive Antenna

0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

Adaptive Ant. Sol. cells introduced in network [% of total number of cells]

Cap

acity

Gai

n [%

]

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Cap

acit

y in

crea

se (

%)

Adative antenna systems introduced in network (% of total number of cells)


GSM Adaptive Antenna Characteristics

• Tailored antenna beams reduce interference levels and enablea tighter frequency reuse pattern

• Live field trials show a capacity increase of more than 100% atsites using GSM adaptive antennas

• Substantial network capacity increase can be achieved byintroducing adaptive antennas in only a limited number of sites

Goal: Reduce Operator Infrastructure Cost


I

Q

(0,1,1)

(1,1,0)(1,0,1)

(0,0,0)

(0,0,1) (1,1,1)

(1,0,0)

(0,1,0)

I

Q

“1”

“0”

EDGE EDGE IntroducesIntroduces a Newa New Modulation Modulation

GPRS:GMSK Modulation

EDGE:8PSK Modulation

1 bit per symbol 3 bits per symbol


Basic Technical Parameters

GPRS EDGE

Modulation GMSK 8-PSK

Symbol rate 270 ksym/s 270 ksym/s

Modulation bit rate 270 kb/s 810 kb/s

Radio data rate per time slot 22.8 kb/s 69.2 kb/s

User data rate per time slot 20 kb/s 59.2 kb/s

User data rate @ 8 time slots 160 kb/s 473.6 kb/s

(including header bits) (182.4 kb/s1)) (553.6 kb/s1))

1) Usually specifed at 115 kbps and 384 kbps, respectively.


C/I Simulation Results for EDGE

−10 0 10 20 30 40 50 600

10

20

30

40

50

60

70

80

90

100

C.D

.F. [

%]

C/I [dB]

Sec, 35 usersSec, 50 usersAA, 35 users AA, 50 users AA, 65 users

• www-traffic model

• Link-adaptation inactive

• Same amount of traffic

• No protocol aspects considered

15 dB

C/I (dB)

CD

F (

%)


9.6 -14.4 kb/s

57.6 kb/s

115 kb/s

384 kb/s

GPRS

HSCSD

EDGE

CS

• No new license required

• Short time to market

• Low investment costs

• Capacity tripled

• Data rates tripled

EDGE Achievements


Interference Environments, TDMA vs CDMA

• TDMA- Inter cell interference

(co-channels in distinct reuse pattern directions)

• CDMA- Intra cell interference- Inter cell interference


WCDMA Downlink C/I Simulation

C/I (dB)

CD

F (

%)


Cylindrical vs. Planar Multi-Beam Antennas

−20 −10 0

30

210

60

240

90

270

120

300

150

330

180 0 −20 −10 0

30

210

60

240

90

270

120

300

150

330

180 0

d 1.15 d


Cylindrical Array Antenna Example


Cylindrical Omni-Directional Array Antenna

-20

-15

-10

-5

0

30

210

60

240

90

270

120

300

150

330

180 0

l 12 radiating columns

l 2 wavelength diameter

l 0.5 wavelength spacing

l all columns fed

l in-phase excitation


Cylindrical Multi-Beam Array Antenna

l 12 radiating columns

l 2 wavelength diameter

l 0.5 wavelength spacing

l 5 fed columns

l co-phasal excitation

−20 −10 0

30

210

60

240

90

270

120

300

150

330

180 0


Cylindrical Array Antenna Trade-Offs

l Radiation pattern types– Omni-directional beam for coverage and/or broadcast– Narrow multi-beams for capacity

l Cylinder radius and number of radiating elements– Radiation pattern ripple in azimuth with omni coverage– Number of directional beams in azimuth for capacity– Sidelobe level


Adaptive Base-Station Antenna SystemConclusions

l Less interference transmitted– Minimize interference spread in downlink

l Enable receiver interference suppression– Possibility to utilize spatial separation in uplink

l Adaptive antenna systems show substantial performance improvements

l Grow-on-site capacity increase in existing networks– No new additional sites– Site-by-site migration strategy

HIGH CAPACITY ADAPTIVE BASE-STATION … CAPACITY ADAPTIVE BASE-STATION ANTENNA SYSTEMS Anders G...

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