Effects of joint macrocell and residential picocell deployment on the network energy efficiency Holger Claussen Bell Laboratories, UK

Effects of joint macrocell and residential picocell deployment on the network energy efficiency

Holger Claussen

Bell Laboratories, UK

2 | June 2008 All Rights Reserved © Alcatel-Lucent 2008

Problem Overview

Increasing costs of energy and international focus on climate change issues have resulted in high interest in improving the efficiency telecommunications industry

Telecommunications is a large consumer of energy

(e.g. Telecom Italia uses 1% of Italy’s total energy consumption)

This results in significant CO2 emissions which

contributes to climate change, and

will result in increased costs due to carbon taxation.

Question:How can we contribute to reducing the energy consumption?

(a) Directly by improving the efficiency of cellular

networks

(b) Indirectly by reducing the need for travel

•Example: rising oil prices in recent years•source: http://seekingalpha.com/article/78326-oil-price-chart-since-1990


Agenda

1. Direct effects of improving efficiency of cellular networks Mixed macro-pico cell topology

Network power consumption with today’s technology

Potential Macrocell improvements

Potential Picocell improvements

Future network power consumption

2. Indirect effects of improving networks Teleworking

Teleconferencing to reduce travel

3. Comparison of direct and indirect effects & conclusions


1 Direct effects of improving efficiency of cellular networks


Reduce the power required to operate our networks: Mixed macro-pico cell topology

The concept Use home-BS deployed by the

user to supplement macro-cellcoverage

Use the users internet connectionas backhaul

Allow public access for home-BS

This results in no costs for the cell deployment, the site, electricity, and backhaul forthe operator

Objective of this investigation Analyse the impact of such a mixed

deployment on the total energy consumption and CO2 emissions of the network


Scenario assumptions

Assumptions for user demand and distribution Wellington, NZ + Suburbs (10x10km)

Population: 200000 (Wellington 160k, region 420k)

Mobile users: 190000 (95% of population) Population NZ = 3.7M, Vodafone: 1.9M, Telecom NZ: 1.6M

Usage: 740 min/user/month = 24 min/user/day = 8 calls/day (3 min)

Homes: 65000 assuming 3 persons per home

Demand is based on real measurements, extrapolated to the considered operator

market shares of 10%, 20%, 30% and 40%Assumptions on emission and energy costs: Electricity Emission factor = 0.50063 kg CO2 / kWh Electricity price = 86.3 Euro / MWh Carbon emission trading value = 21 Euros/tonne CO2


Joint macro- and picocell deploymentHome-cell deployment: random in homes that have the distribution of the evening traffic cell coverage area: 100x100m up to 8 active users Power consumption: 15W

Macro-cell deployment: Macrocells take care of the remaining users Shared bandwidth: Supported active users per macrocell depends on their requested data rate. Different numbers of supported active users are

considered: 30 (high speed data) to 240 users (voice) per macro-cell This results in a VERY ROUGH approximation of the required number of macro-BS User-distribution: max(dist_business, dist_evening) users_covered_by_HBS Power consumption: 2500 W for a 3 sector, 1 carrier base station (480 W power amplifier, 2020W base & control).

A small fraction of randomly deployed home base stations can achieve a significant user

coverage!

0 0.2 0.4 0.6 0.8 10

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

fraction of customers with picocells

frac

tion

of

use

r co

vera

ge

100% market share40% market share30% market share20% market share10% market share

0 0.2 0.4 0.6 0.8 10

10

20

30

40

50

60

70

fraction of customers with HBS

requ

ired

num

ber

of m

acro

cells

(6

0 u

sers

per

ma

croc

ell)

40% market share30% market share20% market share10% market share

With increasing home base station coverage, fewer macrocells are required to provide full

user coverage

By deploying picocells, the required number of

macrocells is reduced to achieve the same capacity


Energy consumption and CO2 emission of different deployment scenarios – Today

Challenge: Macrocell coverage becomes less energy

efficient compared to picocell coverage with increasing demand for high data rate services

Approach: A mixed deployment of macrocells for area

coverage and picocells for the main demand reduces the total network energy consumption and CO2 emission significantly.

Model Results – Wellington NZ: Maximum expected CO2 reduction from direct

effects (assuming 30 users/macrocell) would be up to approximately 2250 tons CO2 /year for covering the full population in Wellington

Total carbon reduction value: 47250 Euros/year (for full population coverage)

The total saved energy costs: 377000 Euros/year (for full population coverage)

Network energy consumption for operator with

40% market share (Today)

100% of energy costs paid by operator

97% of energy costs paid by end user

0 0.2 0.4 0.6 0.8 10

500

1000

1500

2000

2500

3000

3500


Ann

ual

ne

two

rk e

nerg

y co

nsu

mp

tion

[M

Wh/

a]

30 users/macrocell60 users/macrocell120 users/macrocell240 users/macrocellpicocell contribution

The highest energy savings can be achieved when a small fraction of the customers have picocells deployed

Picocell contribution

increases linearly


Macrocell improvements: Power Amplifier Efficiency improvements over time and their drivers

Source: Georg Fischer, Bell Labs Nuernberg


Macrocell Improvements: Efficiency improvements by change in architecture

Current architecture:

DigitalRF-Signal

Gen(Radio)

PA

Cable.Up to 2.5dB losses

(40% of the power!)

Diplexer

8-Element Antenna1dB Loss in divider network

(20% loss)PA,~60% of Power lost in Heat Connector

Cable,0.5dB Loss

(10%!)

Tower-Top-architectures:

Digital

RF-Signal Gen

(Radio)

PA,(MUCH smaller)

Diplexer

Antenna(single Element)

RF-Signal Gen

(Radio)Diplexer

RF-Signal Gen

(Radio)Diplexer

NO Cable Losses!

Ground - Tower

Ground - Tower

By Changing the architecture, min. 50% of the required RF-Power can be saved!

But: more power in parallel radios etc. required…Source: Florian Pivit, Bell Labs Ireland


Picocell improvements

Introduction of idle mode procedures In urban areas public picocell deployments can quickly result in high over provisioning of capacity (20% of customers with picocells can serve up to 80% of the total demand)

Switch off picocells temporarily in areas where sufficient capacity is

already provided by other picovells

Other possible areas for improvements

more efficient processing

Power saving states when only partially loaded

•not considered here


0 0.2 0.4 0.6 0.8 10

500

1000

1500

2000

2500


Ann

ual

ne

two

rk e

nerg

y co

nsu

mp

tion

[M

Wh/

a]

30 users/macrocell60 users/macrocell120 users/macrocell240 users/macrocellpicocell contribution

Assumptions: Macrocell efficiency is improved by 33%

by improved PAs and architectural improvements.

Picocells dynamically switch off when the area in which they are deployed already provides sufficient coverage and capacity.

Results: The improved efficiency results in a

significant further reduction of the total energy consumption, energy costs, and CO2 emissions.

Reductions of up to 70% compared to a macrocell network with today’s technology are feasible, for high data rate demand in urban areas (30 user/macrocell).

The benefits of a mixed macro- and picocell topology will increase further as both technologies mature.

Energy consumption and CO2 emission of different deployment scenarios – Future improved Technology

Network energy consumption for operator with

40% market share (Future improved Technologies)

100% of energy costs paid by operator

85% of energy costs paid by end user

Higher macrocell efficiency

Higher picocell efficiency

When picocells dynamically switch off based on demand, more than the optimum number of picocells can be deployed without significantly

increasing the energy consumption

Picocell contribution does not increase linearly

anymore


2 Indirect effects of improving communication systems: Teleworking Teleconferencing to reduce travel


Effects of teleworking

A reduction of approximately 6MWh in Energy usage can be achieved by telework per person compared to full time office work

The main savings result from reduced travel. The energy for heat and light is similar in all cases The reduction results in a value of 33.6 Euros under the carbon emission trading scheme

per year The average travel cost reduction per year is far greater at 698£ = 938 Euros (assuming

car travel with 7.1 l/100km and 0.169 kg CO2/km, and price of unleaded petrol 103.9 pence per litre)

At a national level, the effect of 5 million people working at home would save about 8 million tonnes of CO2, 1.4% of UK total CO2 emissions.

based on study by BT Laboratories


Teleworking Example: Wellington + Suburbs

Approximately 65% (130000) of the population are working. Assumption: New communication technologies would enable an increase of 10% (13000) of the working population to work from home. For Wellington this would result in a CO2 reduction of up to 20800 tons of CO2 per year. This would correspond to a carbon reduction value of 43680 Euros per year. The total travel cost reduction would be 12.2 x 106 Euros per year


Reduced travel due to Teleconferencing Example: Wellington International Airport

Wellington Airport (http://www.wellington-airport.co.nz/html/business/statistics.php)

110000 flights per year, approximately 95% are domestic, and 5% international

55% of flights (60500) are business related Assumption: A typical domestic flight distance is

800km and emits 11.61 kg CO2/km resulting in a total of 9.288 tons CO2 emission. Total emission of 57475 flights = 533828 tons CO2

Assumption: A typical international flight distance is 8000km and emits 23.39 kg CO2/km resulting in 187 tons. Total emission of 3025 flights = 565675 tons CO2

Per 1% reduction of business flights in Wellington would result in a reduction of 10950 tons of CO2 per year.

This would correspond to a carbon reduction value of 231000 Euros per year.

In addition the corresponding reduction in travel costs would be roughly 87 x 106 Euros (assuming: domestic flight = 150 Euros, International flight = 700 Euros)


3 Comparison of Direct and Indirect effects

& Conclusions


Comparison of direct and indirect effects of improved networksResults: Improving the efficiency of network equipment can directly reduce both OPEX and CO2 emissions Indirect CO2 and cost reduction as a result of improved networks can be far greater that the direct effects. Examples of indirect effects resulting from improved networks are:

increase in teleworking replacement of business trips by

teleconferencing

Opportunity: Teleworking and teleconferencing have an enormous potential to reduce both costs and CO2 emissions if the user experience is improved. Possible solutions are:

improve technology to provide the required higher data rates to homes and offices

reduce the data rates required for high quality video conferencing (e.g. by improving compression).

Potential CO2 reduction for Wellington per year

Potential cost reduction and carbon value for Wellington per year

Direct effects

Indirect effects


Conclusions

Direct effects: Architecture improvements A mixed macro- and picocell architecture can significantly reduce the energy consumption of cellular networks in urban areas where macrocells are capacity limited

Effect expected to increase in the future when both technologies mature

Attractive for operators since energy for picocells is paid for by the user

Indirect effects: Teleworking and reducing travel Improving telecommunication systems can reduce energy consumption indirectly by improving teleworking and video conferencing

Reducing travel has a very high impact on the energy consumption and emissions

Indirect effects have a much higher impact as direct effects.

Reducing the environmental impact can be achieved best by a combination of

(a) Improving the efficiency of eetworks

(b) Improving communication systems to promote teleworking and reduce travel


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Documents

Effects of joint macrocell and residential picocell deployment on the network energy efficiency Holger Claussen Bell Laboratories, UK