Green wireless communication with relays

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  • I need a Matlab code that simulates IEEE 802.11 physical transmission in order to study how intermediate nodes receive the signal or interference. It's for my project. Any document about the subject is welcome. Thank you in advance.
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Green wireless communication with relays

  1. 1. Green Wireless Communication with Relays Aniruddha Chandra Electronics & Communication Engineering Department, National Institute of Technology, Durgapur. aniruddha.chandra@ieee.orgBangalore, India 01 August, 2012
  2. 2. Green Communication = Energy Efficient Communication A new timely ideaA. Chandra - Green wireless communication with relays 2/31
  3. 3. Outline Energy Efficiency – Why? Energy Efficiency – How? Basics of Relaying Case StudyA. Chandra - Green wireless communication with relays 3/31
  4. 4. Outline Energy Efficiency – Why? Energy Efficiency – How? Basics of Relaying Case StudyA. Chandra - Green wireless communication with relays 4/31
  5. 5. Energy Efficiency Why?  Traditional perspective: - Reduced Tx power → reduced reliability. - To maintain QoS, Tx rate should be reduced.  Ecological perspective: - Reduce greenhouse gas emission.  Economical perspective: - Reduce OPEX cost.A. Chandra - Green wireless communication with relays 5/31
  6. 6. Energy Efficiency Traditional Perspective  Value BW most: - Ever increasing subscriber base. - Strict spectrum regulations. - R&D focus on BW efficient radio access techniques. - These complex techniques demand more processing power. A typical MIMO-OFDM Tx Rx cktA. Chandra - Green wireless communication with relays 6/31
  7. 7. Energy Efficiency Traditional Perspective  What about energy? - Battery powered mobile terminals → limited energy. - Limited energy → limited reliable data rate. BER vs. SNR curves (M = 16) BW efficiency vs. power efficiencyA. Chandra - Green wireless communication with relays 7/31
  8. 8. Energy Efficiency Ecological Perspective  2007 statistics on environmental impact: - A cellular network ~ Energy for 1,70,000 homes. - 3% of the energy consumption. - 2% of CO2 emission. - The figures are going to triple by 2020. Objects in Mirror are Close than they AppearA. Chandra - Green wireless communication with relays 8/31
  9. 9. Energy Efficiency Sources of Greenhouse Gas Emission  Operation of radio access network: - RF transmission. - Fossil fuel powered BS. - Charging of devices.  Device/ equipment production.  Backbone network operation. A. Fehske et al. “The global footprint of mobile communications: the ecological and economic perspective,” IEEE Commun. Magz., 49 (8), 55-62, 2011.A. Chandra - Green wireless communication with relays 9/31
  10. 10. Energy Efficiency Economical Perspective  Decreasing revenue: - Vodafone annual ARPU decreased from € 30 (2000) to € 16 (2009).  Increasing fuel cost: - Diesel cost has doubled since 2008.A. Chandra - Green wireless communication with relays 10/31
  11. 11. Energy Efficiency Energy Consumption  Cost components:  Energy components: - Feeder network. - RF conversion. - Climate control (e.g., air conditioning). Energy components for BSA. Chandra - Green wireless communication with relays 11/31
  12. 12. Energy Efficiency Energy Cost Calculation  Revenue generated: Cell site - No. of subscribers per cell site ~ 800. BS - ARPU ~ 3$ / month. Subscriber Subscriber - Monthly revenue ~ 800 x 3$ = 2400 $.  Cost for energy: - Energy cost ~ 0.20 $/ kWh. Power plant - Power requirement per BS ~ 1.7 kW. - Cost per month ~ 30 (days) x 24 (hours) x 1.7 x 0.20 $ = 244 $.  10% of total revenue (even before tax, interest, depreciation)!A. Chandra - Green wireless communication with relays 12/31
  13. 13. Outline Energy Efficiency – Why? Energy Efficiency – How? Basics of Relaying Case StudyA. Chandra - Green wireless communication with relays 13/31
  14. 14. Energy Efficiency Energy Savings in Base Stations  Improvements in PA: - Linear PAs → 90% wastage. - DPD, Doherty, GaN based PA.  Power saving mode: - Sleep mode, discontinuous Tx/ Rx.  Optimization: - BS placement, cell size. Z. Hasan et al. “Green cellular networks: a survey, some research issues and challenges,” IEEE Commun. Surveys Tuts., 13 (4), 524-40, 2011. V. Mancuso et al. “Reducing costs and pollution in cellular networks,” IEEE Commun. Magz., 49 (8), 55-62, 2011.A. Chandra - Green wireless communication with relays 14/31
  15. 15. Energy Efficiency Energy Savings in Base Stations  Renewable energy: - Sustainable bio-fuel. - Solar energy. - Wind energy.  New BS architecture: - Short, low power RF cable between Amp. & Ant. - Feeder less site. Solar powered BS (Italy)  Reduce no. of BS? C. Lubritto et al. “Energy and environmental aspects of mobile communication systems,” Energy, 36 (2), 1109-14, 2011.A. Chandra - Green wireless communication with relays 15/31
  16. 16. Energy Efficiency New Communication Strategies  MIMO / beamforming: - Diversity. - More sectors per cell site.  Cognitive radio: - Find unused spectrum, BW traded off for power.  Use a third node: - Reduce effective transmission distance.A. Chandra - Green wireless communication with relays 16/31
  17. 17. Outline Energy Efficiency – Why? Energy Efficiency – How? Basics of Relaying Case StudyA. Chandra - Green wireless communication with relays 17/31
  18. 18. Basics of Relaying What is a Relay?  A simple repeater: Receive, boost, and re-send a signal.  Cellular network: Different node, carrier owned infrastructure, tree topology. IEEE 802.16j (mobile multihop relay). Sensor network: Identical node, subscriber equipment, mesh topology. IEEE 802.15.5 (WPAN mesh)/ 802.11s (WLAN mesh). Relay #1 Relay Station (RS) Source Relay #2 Destination Base Station Mobile Terminal (BS) (MT) Cellular network Sensor networkA. Chandra - Green wireless communication with relays 18/31
  19. 19. Basics of Relaying Why Use a Relay? RS-MS link  Save Tx energy: Cooperative BS-RS MT #1 transmission link Coverage/ radio - Reduced transmission distance. RS #1 range extension RS #2 Traditional direct  Performance improvement: MT #2 transmission BS - Enhance QoS, capacity, range. RS #3 MT #3 - Load balancing. Capacity enhancement through replacing low rate, unreliable links with multiple high rate, reliable links  CapEx benefit: Traditional service boundary - Temporary coverage, gradual rollout. A. Chandra, C. Bose, and M. K. Bose, “Wireless relays for next generation broadband networks,” IEEE Potentials, vol. 30, no. 2, pp. 39-43, Mar.-Apr. 2011.A. Chandra - Green wireless communication with relays 19/31
  20. 20. Basics of Relaying Direct Path vs. Relayed Path 1st time slot × × Relay Relay 2nd time slot Source Destination Source × Destination Co-operative Strategies 1st time slot Relay Relay 2nd time slot Source Destination Source Destination K. J. Ray Liu, A. K. Sadek, W. Su, and A. Kwasinski, Cooperative Communications and Networking, Cambridge University Press, 2009.A. Chandra - Green wireless communication with relays 20/31
  21. 21. Basics of Relaying Decoding at Relay  Amplify and forward: Relay - Relays act as analog repeaters. Source Destination  Decode and forward: Relay - Relays act as digital regenerative repeaters. Source Destination  Compress and forward: Relay - Relays quantize and compress. Source DestinationA. Chandra - Green wireless communication with relays 21/31
  22. 22. Basics of Relaying Resource Allocation  Persistent transmission: - Relays always forward a processed version of their received signals.  Selective relaying: - Relays autonomously decide whether or not to forward.  Incremental relaying: - Relays provide redundancy only when explicitly requested by destination. H. Katiyar, A. Rastogi, and R. Agarwal, “Cooperative communication: A review,” IETE Tech. Review, vol. 28, no. 5, pp. 409-417, Sep.-Oct. 2011.A. Chandra - Green wireless communication with relays 22/31
  23. 23. Outline Energy Efficiency – Why? Energy Efficiency – How? Basics of Relaying Case StudyA. Chandra - Green wireless communication with relays 23/31
  24. 24. Relay Placement Collinear Model Relayed Path Direct Path (Reference level) 42.2 m (Optimum location) Source Relay DestinationA. Chandra - Green wireless communication with relays 24/31
  25. 25. Relay Placement Non-linear ModelA. Chandra - Green wireless communication with relays 25/31
  26. 26. Relay Placement Non-linear Model ? Source Destination RelayA. Chandra - Green wireless communication with relays 26/31
  27. 27. Relay Placement Energy Ratio Source Destination RelayA. Chandra - Green wireless communication with relays 27/31
  28. 28. Relay Placement Open Problems  Relay - To use or not to use: - Always cooperate, or use relay only when the direct link fails?  Relay selection: - If there are many relay nodes, how many and which ones to select?  Other issues: - Multiple antennas at relay, distributed STC etc.A. Chandra - Green wireless communication with relays 28/31
  29. 29. Summary  Value energy.  Various means to reduce energy consumption.  Use of wireless relays is one of them.  A single collinear relay may save upto 35% energy.  For non-linear setup, an energy efficient region may be found to place the relay.  Many open problems, we need you!A. Chandra - Green wireless communication with relays 29/31
  30. 30. Read More About It Green Communication 1. G. Y. Li et al., “Energy efficient wireless communications: Tutorial, survey, and open issues,” IEEE Wireless Commun. Magz., 18 (6), 28-35, 2011. Modelling Energy Consumption 1. S. Cui et al., “Energy-efficiency of MIMO and cooperative MIMO techniques in sensor networks,” IEEE JSAC, 22 (6), 1089-98, 2004. 2. G. G. de Oliveira Brante et al., “Energy efficiency analysis of some cooperative and non-cooperative transmission schemes in wireless sensor networks,” IEEE TCOM, 59 (10), 2671-77, 2011.A. Chandra - Green wireless communication with relays 30/31
  31. 31. Thank You! Questions? aniruddha.chandra@ieee.orgA. Chandra - Green wireless communication with relays 31/31

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