03 - 2006-02-10_Digitel - Radio Features

No Slide TitleDigitel/Alcatel – Radio Features
2006, February 10th
Alcatel Features for improving
Lower Mobile Tx Power
Traffic is not symmetric
Lower complexity at Mobile’s receiver
gain in capacity
HSDPA
This slide gives a rough idea of the gains provided by the different features.
These gains depend on many parameters such as traffic volumes, environments, cell size, number of carriers…
On this slide you can see that TMA is best suited for coverage improvements while 4 ways Rx diversity provides huge gains for both coverage and capacity.
Adding carriers is a poor coverage feature but the most powerful capacity enhancement feature (around 90% gain).
All rights reserved © 2006, Alcatel
Digitel 3G Workshop / February 2006
Uplink Feature
Impact on link budget
Reduces global Noise Figure
4.3dB on link budget for 3dB feeder loss
2.3dB on link budget for 1dB feeder loss
Usage recommended
Typical reduction of the
required number of sites:
TMA impacts Link Budget curve but not Traffic curve
Tower Mounted Amplifier
As per slide
0.4
0.8
1
12
14
16
18
Impact on Downlink Capacity TMA increases propagation losses to be supported by the Downlink + increased traffic in the cell
Tower Mounted Amplifier
- Noise figure reduction
- Feeder loss compensation
As per slide
Uplink Feature
4 Rx-Div
Introduction of diversity schemes to reduce fading effect
Upgrade from default 2-RX diversity to 4-RX diversity brings up to 2.5 dB* gain on receive Eb/N0
Antenna
Cross -
Polarisation
Eb/No Reduction in 4 Rx-Div compared to default 2 Rx-Div:
Results from Link Level simulations
4 Ways Receive Diversity
Vehicular A3km/h: 3 dB
Vehicular A50km/h: 2.5 dB
1 rx antenna
2 rx antennas
3 rx antennas
4 rx antennas
BER
1 rx antenna
2 rx antennas
3 rx antennas
4 rx antennas
Uplink coverage gain depends on the traffic density!
4RX div impacts Link Budget curve AND Traffic curve
Typical reduction of the required
number of sites:
0.6
6
7
8
9
4 Rx-Div helps to reduce Rx Eb/No provides capacity gain in Uplink
a gain of 50% can be achieved
However, as for TMA, it increases propagation losses to be supported by DL + it increases traffic in the cell accelerates Downlink Limitation
- Rx Eb/No reduction
- Cell load reduction
Uplink & Downlink Feature
21dBi Antenna : obtained thanks to a high efficiency feed network
Broadband: 1710-2170 Dual Pol: ±45°
HPBW: 65° VBW: 4.1°
21dBi Antenna
Antenna Performance:
21dBi Antenna
21dBi Antenna
21dBi antenna impacts Link Budget curve but not traffic curve
Link Budget Curves
Over 18dBi
21dBi Antenna
Possible Issue:
In Practice:
Multi-path propagation smoothes the signal strength variations
426.bin
21dBi Antenna
19dBi Antenna
21dBi Antenna
21dBi Antenna
21dBi Antenna
21dBi-19dBi
Most effective way to increase system capacity
Gain depends on Node-B configuration, propagation losses...
Carrier Adding
Compute an “optimised” Cell Range finding the appropriate number of carriers
Carrier added when
DL cell load is met
DL max Power is met
DL Node-B Power for a given radius
P < Pmax ?
Cell Range, Node-B Power, Mobiles Power per service, Cell loads
Add a carrier
Carriers Carrier Max ?
Main Design Process
Value added: 3 different processes can be applied depending on needs or if working together with Uplink or alone.
Traffic model involved in every process.
Exemple of use: DL node-B power for a given radius: for capacity analysis. You have a cell range as input, you want to derive the required site capacity to support both coverage and capacity . If power overruns max available power, add a carrier…
Uplink Coverage:
Link Budget curve stays the same, traffic curve depends on # of carriers
Uplink Capacity:
Adding a carrier means:
reducing power per carrier
Downlink Capacity:
Capacity is not doubled when doubling # of carriers because of power reduction per carrier
Gain depends on the Node-B configuration (features implemented), propagation losses...
Carrier Adding
Carrier Adding
Downlink Feature
High Power Amplifier
Power Issues
Power is the limitation in DL for both coverage and capacity
In Multi-Carrier configuration, Node-B Power further divided:
Always the concern about having enough TX power at Node-B
HPA: sometimes seen as a solution to increase capacity
Unfortunately, no easy relation between Power and Capacity
MPA
Impact of Node B power on DL capacity
Commonly Agreed: HPA brings low gain when Allowable Propagation Loss is low
200
400
600
800
1000
0
149
139
129
119
109
99
For High propagation losses, HPA may have some interest
10 W
20 W
40 W
6.5 W
10 W
20 W
40 W
6.5 W
For average propagation losses, it becomes interesting for the 3rd carrier
10 W
20 W
40 W
6.5 W
Adding carrier on 20 W MPA leads to some capacity loss per carrier:
S111 -> S222: 10%
S222 -> S333: 12%
S111 -> S333: 21%
For High propagation losses, it becomes mandatory for the 3rd carrier
10 W
20 W
40 W
6.5 W
Adding carrier on 20 W MPA leads to some capacity loss per carrier:
S111 -> S222: 22%
S222 -> S333: 20%
S111 -> S333: 37%
Example for mono-service NRT 128kbit/s and fixed inter-site distances
Better gains for Rural than for Urban
Betters gains for 2 or 3 carriers configurations
Dense Urban
Max Power per carrier
Conclusion
I. DL Capacity Evaluation must be performed considering UL limitation. Both links have to be balanced
II. Limited Interest for HPA when the APL are low:
In DU and U, and where High Data Rates are offered in UL
III. Growing Interest for HPA when the APL get higher:
In SU and RU environments
Where low data rate services offered in UL
Where coverage enhancement features offered in UL (TMA, 4Rx-div)
IV. HPA may be useful in some areas. Not the only means to increase power/carrier
Downlink Feature
TEU
Tx
The transmit antenna diversity techniques consist in using several transmit antennas, broadcasting decorrelated complementary signals
2 modes :
TSTD - Time Switch Transmit Diversity
(Synchronization channel only)
Transmit Diversity
TX Power is doubled by adding a power amplifier (PA or TEU)
Required Eb/No is reduced thanks to diversity technique
Higher reduction for closed-loop TxDiv (for low speed mobiles) than for open loop
Higher gain in low multi-path diversity environment
Transmit Diversity
Performance enhancement
Performance gain of TX diversity feature comes from two main enhancements:
TEU
Tx
ANRU
Without Tx diversity
Target Tx Eb/N0 (dB)
Target Tx Eb/N0 (dB)
Transmit Diversity
Capacity Gain
As for HPA, depends on cell range and attenuation
As for HPA, higher gain when more carriers are used
“Pure Diversity” Gain:
High difference between multi-path environments:
low to medium gain in Vehicular A (macro-cells)
significant gain in Pedestrian A (micro-cells)
Better gain in closed loop mode (for low speed mobiles) than for open loop
Impact on Downlink Capacity Combined effect of power increase and Eb/No reduction
Transmit Diversity
Capacity Gain
DL Tx-Div Open loop
DL Capacity gain due to Tx-Div open loop, typically 10% compared to 3x1 configuration without Tx-Div
DL Tx-Div Closed loop
DL Capacity gain due to Tx-Div closed loop, typically 20% compared to 3x1 configuration without Tx-Div
Typical UL Cell Range
Downlink Feature
MP
TEU
Mix-TEU Configuration
Power is the limitation in DL for both coverage and capacity
In Multi-Carrier configuration, Node-B Power further divided:
Alternative solution to HPA and Tx-Div: Mix-TEU
MPA
f1 20W
Downlink Feature
Low Cost Configuration
Downlink:
Only one TEU is needed (one power amplifier): low cost
The signal is split between the 3-sectored antennas : less power per sector antenna available
On downlink, OTSR is equivalent to an omni-directional site : the downlink capacity per site is reduced regarding a 3-sectored antenna
3 cells Uplink
1 cell Downlink
Each antenna transmits the same signal
This leads to destructive interference in the overlap sector area
The OTSR antenna radiation pattern is degraded compared to an omni-directional antenna
This degradation depends on the distance between antennas
However multi-path effect will lower the degradation due to destructive interference
Omni-Transmit Sectored-Receive
Compared to a 3-sectored site, the Downlink capacity is around 2.5 lower.
20
40
60
80
100
0
2.5
2
1.5
1
0.5
0
DL OTSR
DL Tri-sectored
Remote part hosted in a Mini or Micro cabinet
Connection between remote and local part is optical or electrical (max ~20 km)
Max 12 Remote RF Head
Remote RF Heads
Standard Node B:
Remote RF Head solution:
Optical fibre/
Micro Node-B
1 sector, 3 carriers in just 34 liters
Up to 3 sectors (Master/slave conf.)
10 W output power at antenna connector
64 AMR channels, up to 1.5 Mbit/s data rate
Optional integrated antenna
Micro Node-B
When stringent installation constraints
Efficiently address traffic hotspots
High Capacity
Downlink Feature
HSDPA
AMC
Adaptive
Modulation
&Coding
HARQ
Multi User Detection
4 ways Tx-Div
Conclusion
Alcatel solution includes a wide range of features to enhance UMTS coverage and capacity
Each feature should be used for specific needs and conditions
There is a need for accurate Design and Planning to assess the gains brought by these features in different situations
The smart scheduling of these features can allow drastic CAPEX savings: This is part of Deployment strategy
www.alcatel.com
0.2
0.6
0
10
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4
2
0
0.4
0.8
1
12
14
16
18
0.6
6
7
8
9
2 carriers due to lower transmit power par carrier
Typical uplink
coverage-limited cell
1e-006
1e-005
0.0001
0.001
0.01
0.1
1
-2
0
2
4
6
8
10
BER
1 rx antenna
2 rx antennas
3 rx antennas
4 rx antennas

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