From always on to always available Energy saving possibilities and potential. Dr. Pål Frenger, Ericsson Research

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1 From always on to always available Energy saving possibilities and potential Dr. Pål Frenger, Ericsson Research

2 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 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 Multi-RAT energy efficiency P. Frenger and M. Ericson Assessment of Alternatives for Reducing Energy Consumption in Multi-RAT Scenarios, VTC-Spring 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 Ericsson Confidential Page 2

3 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 Page 3

4 L. Falconetti, P. Frenger, H. Kallin, and T. Rimhagen, Energy Efficiency in Heterogeneous Networks, in Proc. IEEE GreenComm Online Conference 2012.

5 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

6 P. Frenger, Y, Jading, and J. Turk A Case Study on Estimating Future Radio Network Energy Consumption and CO 2 Emissions, PIMRC 2013

7 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 Page 7

8 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 x G site power 1 3G site power 1 Site power Ericsson Confidential Page 8 This model is used to estimate future energy consumption and CO 2 emissions

9 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 Page 9

10 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 W (1/1/1) configuration EARTH Class EARTH Class EARTH Class 3 0 RBS Ericsson Confidential Page 10

11 Average power [W] Example: Future LTE Macro Example: Macro, 10 MHz, 2 Tx, 40 W RF power, 3 sector/site, average RF load 20% EARTH Class 1 Assumed evolution of power consumption for a typical 4G site EARTH Class EARTH Class Ericsson Confidential Page 11

12 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 Page 12

13 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 Page 13

14 Network Electricity Consumption (100% = 2012) Modernization and LTE Rollout Network Electricity % Scenario B: Continious Upgrades (random order) Legacy Electricity -4% LTE Electricity -10% -16% -24% % -42% -51% -61% Year Assumptions: Existing RBSs are modernized in random order LTE rollout (including densification) starts 2013 and ends 2020 Ericsson Confidential Page 14

15 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 Page 15

16 P. Frenger and M. Ericson Assessment of Alternatives for Reducing Energy Consumption in Multi-RAT Scenarios, VTC-Spring-2014

17 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 Page 17 GSM 900 WCDMA GSM GSM 900 WCDMA GSM GSM 900 GSM GSM 1800 GSM WCDMA WCDMA LTE LTE 2600 LTE LTE LTE LTE LTE LTE 2600 LTE LTE LTE 2600 LTE LTE LTE 2600 LTE LTE LTE 2600 LTE LTE LTE 2600 LTE LTE LTE 2600 LTE LTE LTE 2600 LTE LTE LTE LTE LTE LTE 2600 LTE LTE LTE 2600 LTE LTE LTE 2600 LTE LTE LTE 2600 LTE LTE LTE 2600 LTE LTE LTE 2600 LTE Macro with 66 Power amplifiers?

18 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 Page 18

19 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 Page 19

20 Single-RAT vs. multi-rat (E 3 F) Ericsson Confidential Page 20

21 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 Page 21

22 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 time [ms] time [ms] Ericsson Confidential Page 22

23 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 W W % 551 W % 613 W 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 Page 23

24 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 Page 24

25 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

26 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 Page 26

27 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 Doppler spread PDSCH Transmission format 5 Hz LTE Tx-diversity Channel model Vehicular A Ericsson Confidential Page 27

28 Throughput (b/s) PDSCH Throughput, 2x2 6 x 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 = [ ;0 0] system.port_to_tx_weights = [1 1;0 0] SINR (db) Ericsson Confidential Page 28

29 BLER PCFICH, 2x 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 = [ ;0 0] system.port_to_tx_weights = [1 1;0 0] Ericsson Confidential Page SINR (db)

30 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 Page 30

31 Cell Power Consumption Cell Power model 700 Macro, 10 MHz, 40W, 4TX PA active 3 PA active 2 PA active 1 PA active Pout/Pmax Ericsson Confidential Page 31

32 P/A [kw/km 2 ] Power per area unit Tx: all active 4 Tx: adaptive 2 2 Tx: all active 2 Tx: adaptive 1 Tx System throughput [Mbps/km 2 ] Ericsson Confidential Page 32

33 Resource utilization Resource Utilization Tx: all active 4 Tx: adaptive 2 Tx: all active 2 Tx: adaptive 1 Tx System throughput [Mbps/km 2 ] Ericsson Confidential Page 33

34 Mean user bitrate [Mbps] Mean User Bit-rate Tx: all active 4 Tx: adaptive 2 Tx: all active 2 Tx: adaptive 1 Tx Ericsson Confidential Page System throughput [Mbps/km 2 ]

35 User bitrate percentiles (5 95) [Mbps] User Bit-rate Percentiles Ericsson Confidential Page System throughput [Mbps/km 2 ]

36 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 Page 36

37 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 Page 37

38 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 Page 38

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