From always on to always available Energy saving possibilities and potential Dr. Pål Frenger, Ericsson Research
Outline Why RAN energy performance? HetNet Energy efficiency P. Frenger, Y, Jading, and J. Turk A Case Study on Estimating Future Radio Network Energy Consumption and CO 2 Emissions, PIMRC 2013. Vodafone case study P. Frenger, Y, Jading, and J. Turk A Case Study on Estimating Future Radio Network Energy Consumption and CO 2 Emissions, PIMRC 2013. Multi-RAT energy efficiency P. Frenger and M. Ericson Assessment of Alternatives for Reducing Energy Consumption in Multi-RAT Scenarios, VTC-Spring-2014. Antenna muting P. Frenger, H. Koorapaty, and J.-C. Guey, Evaluation of Control Channel Performance with Adaptive Radio Unit Activation in LTE, VTC-Spring-2012 P. Skillermark and P. Frenger, Enhancing Energy Efficiency in LTE with Antenna Muting, VTC-Spring-2012. Ericsson Confidential 2014-06-17 Page 2
Why RAN Energy Performance? Perspectives and Players Operators Vendors Governments Economic Reduce OPEX and CAPEX Premium Brand Capture Energy Spend Premium Brand Sustainable growth Environmental Reach CO 2 reduction targets Take responsibility for our 2% Walk the talk Drive energy and climate transition Engineering Subscriber growth in off-grid areas Enable new power solutions Less is more Size, weight, enable new deployments etc. Energy efficiency Same answer, different questions Ericsson Confidential 2014-06-17 Page 3
L. Falconetti, P. Frenger, H. Kallin, and T. Rimhagen, Energy Efficiency in Heterogeneous Networks, in Proc. IEEE GreenComm Online Conference 2012.
Energy efficiency in HetNets Introducing HetNets with Energy Efficiency functionality. improves end user performance and decrease power consumption. Functionality micro cell wake-up > micro cell initiated based on uplink activity detection > macro cell initiated based on traffic load in the macro in addition we introduce > micro DTX in all base stations when there is no data to send
P. Frenger, Y, Jading, and J. Turk A Case Study on Estimating Future Radio Network Energy Consumption and CO 2 Emissions, PIMRC 2013
Paper overview Vodafone CO 2 target: Reduce CO 2 emissions by 50% against the 2006/07 baseline by March 2020 for mature markets Analysis of the current Vfe network: RBS energy consumption modeling Traffic Future RBS power consumption from 2013 to 2020 Generic models (based on the European EARTH project) CO 2 and kwh impact of different scenarios RBS modernization LTE introduction and network densification Ericsson Confidential 2014-06-17 Page 7
Current Network: Energy consumption model 12 x 105 Macro Micro Site energy consumption model based on RBS type Site Climate 2G RBS 10 8 Pico Nrof GSM 900 / 1800 TRXs PSU 3G RBS 6 Nrof UMTS 2100 / 900 carriers Average traffic load 4 Model accuracy verified with energy measurements Very close match 2 0-4 -2 0 2 4 6 8 10 x 10 5 1 2G site power 1 3G site power 1 Site power 0.9 0.9 0.9 0.8 0.8 0.8 0.7 0.7 0.7 0.6 0.6 0.6 0.5 0.5 0.5 0.4 0.4 0.4 0.3 0.3 0.3 0.2 0.2 0.2 0.1 0.1 0.1 0 0 500 1000 1500 2000 2500 3000 3500 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 0 0 1000 2000 3000 4000 5000 6000 7000 Ericsson Confidential 2014-06-17 Page 8 This model is used to estimate future energy consumption and CO 2 emissions
Future RBS Power models The EARTH project derived 3 different classes of power models EARTH Class 1: State-of-the-art RBS produced 2010 EARTH Class 2: State-of-the-art RBS produced 2012 EARTH Class 3: RBS with EARTH improvements For each of the above classes EARTH derived RBS power models for RBS type: Macro, Micro, Pico, Femto, RRH Output power: ranging from 20 to 49 dbm Number of TX antennas: 1, 2, or 4 Bandwidth: 1.4 MHz to 20 MHz EARTH Class 2 model EARTH Class 3 model Ericsson Confidential 2014-06-17 Page 9
Average power [W] Example: Future WCDMA Macro Installed base example: RBS 3202 Most common WCDMA macro in the current network RF power class 20W (1/1/1), the average consumption is 1200 W Compare with equivalent EARTH power model Macro, 5 MHz, 1 Tx, 20 W RF power, 3 sector/site, average RF load 20% 1400 Assumed evolution of power consumption for a typical 3G site 1200 20W (1/1/1) configuration 1000 800 600 EARTH Class 1 400 EARTH Class 2 200 EARTH Class 3 0 RBS 3202 2012 2013 2014 2015 2016 2017 2018 2019 2020 Ericsson Confidential 2014-06-17 Page 10
Average power [W] Example: Future LTE Macro Example: Macro, 10 MHz, 2 Tx, 40 W RF power, 3 sector/site, average RF load 20% 1100 1000 900 EARTH Class 1 Assumed evolution of power consumption for a typical 4G site 800 700 600 EARTH Class 2 500 EARTH Class 3 400 300 200 100 0 2012 2013 2014 2015 2016 2017 2018 2019 2020 Ericsson Confidential 2014-06-17 Page 11
LTE Introduction Assumptions Urban: 340m ISD All existing macro sites get LTE 800MHz, 10MHz 100% existing macro sites also get LTE 2.6GHz, 20MHz 15 picos per macro at 2.6GHz, 5MHz Number of macro-sites in different environments Urban (7%) Suburban: 1000m ISD All existing macro sites get LTE 800MHz, 10MHz 20% existing macro sites also get LTE 2.6GHz, 20MHz 10 picos per macro at 2.6GHz, 5MHz Rural All existing macro sites get LTE 800MHz, 10MHz No new macro sites Rural (60%) Sub-Urban (33%) Ericsson Confidential 2014-06-17 Page 12
LTE Introduction Network status 2020 Macro LTE 800 (18%) Number of new LTE RBSs Relative Energy Consumtion Pico LTE 2600 (5%) Macro LTE 2600 (12%) Macro LTE 2600 (3%) Pico LTE 2600 (79%) Macro LTE 800 (83%) Macro LTE800 will dominate energy consumption Psi-omni coverage will save more than pico-sleep or LTE2600 cell sleep Note: EARTH power models for picos are probably a bit too low Main conclusion holds also with 3GPP power models ( 4 times larger for small cells) Ericsson Confidential 2014-06-17 Page 13
Network Electricity Consumption (100% = 2012) Modernization and LTE Rollout Network Electricity 110 100 90 80 0% Scenario B: Continious Upgrades (random order) Legacy Electricity -4% LTE Electricity -10% -16% -24% 70 60 50 40 30 20 10-33% -42% -51% -61% 0 2012 2013 2014 2015 2016 2017 2018 2019 2020 Year Assumptions: Existing RBSs are modernized in random order LTE rollout (including densification) starts 2013 and ends 2020 Ericsson Confidential 2014-06-17 Page 14
Summary Significant CO 2 and cost reductions are possible in absolute terms; while deploying LTE; while densifying the network to handle the expected traffic increase; if old equipment is swapped at the same pace as new equipment is installed Small cells not likely to drive total NW energy consumption Covers < 5% of the area Consumes < 1/10 th the energy compared to a macro Offloads the macro cells (the net effect is often an energy decrease) More capacity EE features perform better (more DTX, cell sleep etc) Key message: Replacing an old macro RBS today reduces energy consumption 50% Additional node-level energy reduction of 70% possible (proven by EARTH) Ericsson Confidential 2014-06-17 Page 15
P. Frenger and M. Ericson Assessment of Alternatives for Reducing Energy Consumption in Multi-RAT Scenarios, VTC-Spring-2014
Purpose More RATs, more MIMO, more bands What about energy? Are multi-rat RBSs more energy efficient? Consumption of a multi-rat RBS vs. multiple single RAT RBS:s? How much power reduction can be achieved with PA sharing? Can we reduce the cost of providing coverage for multiple RATs Ericsson Confidential 2014-06-17 Page 17 GSM 900 WCDMA GSM 900 900 GSM 900 WCDMA GSM 900 900 GSM 900 GSM 900 900 GSM 1800 GSM 1800 1800 2100 WCDMA 2100 2100 2100 WCDMA 2100 2100 LTE LTE 2600 LTE 2600 800 LTE LTE LTE 2600 2600 800 LTE LTE 2600 LTE 2600 800 LTE LTE 2600 LTE 2600 800 LTE LTE 2600 LTE 2600 800 LTE LTE 2600 LTE 2600 800 LTE LTE 2600 LTE 2600 800 LTE LTE 2600 LTE 2600 800 LTE LTE 2600 LTE 2600 2600 LTE LTE LTE 2600 2600 2600 LTE LTE 2600 LTE 2600 2600 LTE LTE 2600 LTE 2600 2600 LTE LTE 2600 LTE 2600 2600 LTE LTE 2600 LTE 2600 2600 LTE LTE 2600 LTE 2600 2600 LTE LTE 2600 LTE 2600 2600 Macro with 66 Power amplifiers?
EARTH Power models Power consumption models of a 3-sector site for Macro 20W, 5MHz Macro 40W, 10MHz Micro 5W, 5MHz The -1 transmit power is the EARTH sleep mode Relative large difference between an RBS of year 2010 and 2012 Ericsson Confidential 2014-06-17 Page 18
Results: Single RAT vs. multi-rat Compare: Separate single RAT RBS configuration Combined multi-rat RBS Traffic Scenario 1: Most relevant 2015 traffic profile Same traffic load in HS and LTE HS RU 1 HS RU 2 LTE RU 1 LTE RU 2 HS + LTE RU 1 HS + LTE RU 1 Methodology 1. Apply system simulations to EARTH power models 2. Apply EARTH traffic profile (load per environment) over time 3. Average over time and over all environment distributions to get a total power consumption per km 2 over a country See EARTH D6.4 [1] for more info Antenna 1 (Port 0 and 1) Case A: Separate single-rat RUs - HS: 5MHz, 2x2, 20W - LTE: 5MHz, 2x2, 20W Antenna 2 (Port 0 and 1) Antenna 1 (Port 0 and 1) Case B: Combined multi-rat RUs - HS+LTE: 10MHz, 2x2, 40W Ericsson Confidential 2014-06-17 Page 19
Single-RAT vs. multi-rat (E 3 F) Ericsson Confidential 2014-06-17 Page 20
Results: Load Balancing Compare with and without load balancing Move all traffic to HS (if possible) and utilize LTE DTX due to MBSFN HS RU 1 HS RU 2 LTE RU 1 LTE RU 2 If not possible, both HS and LTE RU operate as normal (case A) Traffic Scenario 1 & 3: Most relevant 2015 & extreme traffic profiles Same traffic in HS and LTE But HS will carry double traffic if load balancing Antenna 1 (Port 0 and 1) Case A: Separate single-rat RUs - HS: 5MHz, 2x2, 20W - LTE: 5MHz, 2x2, 20W Antenna 2 (Port 0 and 1) Ericsson Confidential 2014-06-17 Page 21
Load Instantaneous power [W] Load balancing LTE RE and power using MBSFN Minimum LTE Resource Element usage Assuming 6 MBSFN sub-frames Minimum LTE power consumption With (red) and without (blue) EARTH improved DTX 0.7 700 0.6 600 0.5 500 0.4 400 0.3 300 0.2 200 0.1 100 0 0 1 2 3 4 5 6 7 8 9 10 time [ms] 0 0 1 2 3 4 5 6 7 8 9 10 time [ms] Ericsson Confidential 2014-06-17 Page 22
Average power consumption [W/km 2 ] Average power consumption [W/km 2 ] Load balancing Summary power consumption Traffic scenario 1 (2015), RBS from 2012 Averge pow er consumption over all EARTH environments for traffic scenario #1 HS and LTE pow er consumption for single RAT RUs compared to load balancing betw een RUs 800 Traffic scenario 3 (2020), RBS from 2012 Averge pow er consumption over all EARTH environments for traffic scenario #3 HS and LTE pow er consumption for single RAT RUs compared to load balancing betw een RUs 900 700 779 W 800 810 W 600 500-29% 551 W 700 600-24% 613 W 400 500 400 300 300 200 200 100 100 0 No Load balancing Load balancing 0 No Load balancing Load balancing The upper bound energy consumption gain with load balancing is 25-30% Slightly lower gain for traffic scenario 3 since fewer HS cells can handle the extra traffic load Note that KPIs such as user bit rate is not considered here Ericsson Confidential 2014-06-17 Page 23
Conclusions The traffic load dependency of the power consumption is low 1.4% extra power consumption due to traffic load assuming EARTH reference scenario and most relevant traffic scenario for 2015 PA sharing can reduce power consumption in a multi-rat RBS with 40% On par with e.g. psi-omni (/// rural EE coverage solution for WCDMA) HS and LTE Load balancing can reduce power consumption 25-30% Upper bound, depending on traffic scenario Ericsson Confidential 2014-06-17 Page 24
P. Frenger, H. Koorapaty, and J.-C. Guey, Evaluation of Control Channel Performance with Adaptive Radio Unit Activation in LTE, VTC-Spring-2012 P. Skillermark and P. Frenger, Enhancing Energy Efficiency in LTE with Antenna Muting, VTC- Spring-2012
LTE Antenna Muting or Merging Muting: Deep fading Merging: Full antenna correlation Port 0 Port 1 Port 2 Port 3 (a) Logical and physical antenna port muting (b) Logical antenna port merging and physical antenna port muting Ericsson Confidential 2014-06-17 Page 26
Link Simulation Assumptions Parameter Carrier Frequency System bandwidth Duplex Value 2.6 GHz 5 MHz FDD PDCCH coding (uncoded bits / coded bits) 20 / 72 PDSCH modulation 16-QAM (2 2) QPSK (4 2) PDSCH coding rate 0.4385 Doppler spread PDSCH Transmission format 5 Hz LTE Tx-diversity Channel model Vehicular A Ericsson Confidential 2014-06-17 Page 27
Throughput (b/s) PDSCH Throughput, 2x2 6 x 106 5 EVA MEDIUM, 2x2 system.port_to_tx_weights = [1 0;0 1] system.port_to_tx_weights = [1 0;0 0] system.port_to_tx_weights = [1.41421356237309 0;0 0] system.port_to_tx_weights = [1 1;0 0] 4 3 2 1 0-4 -2 0 2 4 6 8 10 12 SINR (db) Ericsson Confidential 2014-06-17 Page 28
BLER PCFICH, 2x2 10 0 10-1 PCFICH, EVA MEDIUM, 2x2 system.port_to_tx_weights = [1 0;0 1] system.port_to_tx_weights = [1 0;0 0] system.port_to_tx_weights = [1.41421356237309 0;0 0] system.port_to_tx_weights = [1 1;0 0] 10-2 10-3 10-4 10-5 Ericsson Confidential 2014-06-17 Page 29-4 -2 0 2 4 6 8 10 SINR (db)
System Simulation Assumptions Traffic Models User distribution Indoors with uniform distribution User speed 3 km/h Traffic model File transfer (file size 0.5 MB) Radio Network and Deployment Models Deployment Hexagonal grid with wrap-around, 3 sectors/site, 21 sectors in total Inter-site distance 500 m Distance attenuation (L) L(d) = +10 log 10 (d) with = 3.76, = 15.3 Indoor penetration loss 20 db Shadow fading Log-normal, 8 db standard deviation Small-scale fading 3GPP SCM urban macro 15 [7] LTE System Model Spectrum allocation FDD, 10 MHz downlink at 2 GHz carrier frequency Base station output power 46 dbm (40 W) Number of base station transmit antennas 1, 2, or 4 Number of UE receive antennas 2 UE receiver MMSE Scheduling Proportional fair in time and frequency domains Transmission scheme Code-book based precoding with rank adaptatio, LTE Rel-8 codebook Modulation and coding schemes QPSK, 16QAM, 64QAM; Turbo coding according to LTE Rel-8 standard Ericsson Confidential 2014-06-17 Page 30
Cell Power Consumption Cell Power model 700 Macro, 10 MHz, 40W, 4TX 650 600 550 500 450 400 350 300 250 4 PA active 3 PA active 2 PA active 1 PA active 200 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Pout/Pmax Ericsson Confidential 2014-06-17 Page 31
P/A [kw/km 2 ] Power per area unit 10 8 6 4 4 Tx: all active 4 Tx: adaptive 2 2 Tx: all active 2 Tx: adaptive 1 Tx 0 0 20 40 60 80 100 120 System throughput [Mbps/km 2 ] Ericsson Confidential 2014-06-17 Page 32
Resource utilization Resource Utilization 1 0.8 0.6 4 Tx: all active 4 Tx: adaptive 2 Tx: all active 2 Tx: adaptive 1 Tx 0.4 0.2 0 0 20 40 60 80 100 120 System throughput [Mbps/km 2 ] Ericsson Confidential 2014-06-17 Page 33
Mean user bitrate [Mbps] Mean User Bit-rate 50 40 30 4 Tx: all active 4 Tx: adaptive 2 Tx: all active 2 Tx: adaptive 1 Tx 20 10 Ericsson Confidential 2014-06-17 Page 34 0 0 20 40 60 80 100 120 System throughput [Mbps/km 2 ]
User bitrate percentiles (5 95) [Mbps] User Bit-rate Percentiles 50 40 30 20 10 Ericsson Confidential 2014-06-17 Page 35 0 0 20 40 60 80 100 120 System throughput [Mbps/km 2 ]
DL Control channels in LTE Rel-8 PBCH: Physical Broadcast Channel Carries the MIB PDSCH: Physical Downlink Shared Channel Carries the SIBs PDCCH: Physical Downlink Control Channel Needed for decoding of PDSCH PCFICH: Physical Control Format Indicator Channel Needed for PDCCH decoding PHICH: Physical Hybrid ARQ Indicator Channel ACK/NACK feedback related to uplink data Ericsson Confidential 2014-06-17 Page 36
Conclusions (I) System level performance for antenna muting. Results for 1TX, 2TX and 4TX presented Detailed models of UE pre-coder selection and feedback Energy consumption reduced with 31-47% at low load Insignificant reduction of user bit-rates Ericsson Confidential 2014-06-17 Page 37
Conclusions (II) Merging logical antenna ports is better than muting them All DL control channels are robust towards merging PDSCH degradation is only 1-2 db PCFICH, PDCCH, PHICH, and PBCH degrades 2-3 db Performance loss with merging is perfectly acceptable at low traffic load Merging could be the default operation mode whenever maximum capacity or maximum peak rate is not required System level study shows around 30% gain for 2TX and 50% gain for 4TX Ericsson Confidential 2014-06-17 Page 38