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Scheduling Algorithms in LTE and Future Cellular Networks
1) The document discusses scheduling algorithms in LTE and future cellular networks. It provides an overview of key concepts like OFDMA, MIMO, small cells, and the essential elements of LTE including resource blocks and transport channels. 2) It describes important scheduling algorithms used in LTE like proportional fair, round robin, best CQI, and algorithms that consider QoS. The objectives and benefits of different algorithms are explained. 3) Future cellular networks will require capabilities like very high data rates, low latency, and support for applications involving AI, M2M communication, and cloud computing. 5G networks will need to meet requirements like low power consumption and worldwide connectivity.
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Scheduling Algorithms in LTE and Future Cellular Networks
- 1. Scheduling Algorithm inLTE and Future Cellular Networks Prof.Satheesh Monikandan.B Indian Naval Academy, Ezhimala (Indian Navy, Ministry of Defence) sathy24@gmail.com National Level STTP on Green Communication Network and Simulation of Wireless Networks using NS-3 S.A.Engineering College, Chennai 02 Dec 2019
- 2. 2 Cellular Network Technologies Adaptedfrom LTE:The Future of Mobile Broadband Technology, White paper@2009 10 meters 100 meters BB Data N/w’s
- 3. 3 4G MOBILE BBTECHNOLOGY • IP solutions • Voice, Data and Multimedia • Anytime, Anywhere • High Data Rates • Faster BB Connections • Streamed Audio and Video • Video Messaging and Telephony • Mobile TV and Online Gaming
- 4. 4 LTE and FutureCellular Networks • 2008 onwards (3GPP ETSI Release 8) • All-IP network • No circuit switching, voice is simply IP data • High Quality of Service (QoS) • High Throughput • Currently 46 bands with 3GPP - Release 12 • Heterogeneous systems • Smartphones
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- 7. 7 3GPP LTE Architecture Adaptedfrom www.computer.org, Fengyuan Ren et al., IEEE Transactions on Mobile Computing, Vol.12, No.2, pp.2412-2426, 2013.
- 8. 8 OFDMA in LTEDownlink Adapted from Concepts of 3GPP LTE Long Term Evolution @ Nokia Siemens Networks
- 9. 9 Key Technological concepts •The MIMO Concept • Invented at Bell Labs in 1990 • Multiple Antennas • High capacity with more antennas • The Small Cell Concept • Cell Splitting • Deployment of low power Base Stations (Hotspot) • Microcells, Picocells, Femtocells (100mW – 5W) • High (Indoor cellular) capacity in a small area
- 10. 10 LTE Networks • MIMOwith OFDMA in the downlink and SCFDMA in the uplink • High levels of spectral efficiency • End user data rates exceeding 100 Mbps • Improvements in capacity • Reductions in latency less than 10 ms • Bandwidths from 1.4 MHz to 20 MHz • FDD and TDD operation
- 11. 11 DL FRAME STRUCTURE- FDD Adapted from Concepts of 3GPP LTE Long Term Evolution @ Nokia Siemens Networks
- 12. 12 LTE DL TransportChannels • Broadcast Channel (BCH) • Broadcast Control Channel(BCCH) • Downlink Shared Channel (DLSCH) • Paging Channel (PCH) • Paging Control Channel (PCCH) • Multicast Channel (MCH) • Multicast Control Channel (MCCH)
- 13. 13 DL PHYSICAL MAPPING Adaptedfrom Concepts of 3GPP LTE Long Term Evolution @ Nokia Siemens Networks
- 14. 14 Scheduling Algorithm inLTE Networks • Controlling and optimizing the network radio resources, Resource Blocks (RBs) for the Uplink (UL) and Downlink (DL) • Method to distribute the available RBs to the User Equipments (UEs) for data transmission as per QoS demands • Minimize the operational time and improves the network utilization efficiency • Works from eNB for Radio Resource Management (RRM)
- 15. 15 LTE RESOURCE BLOCK(RB) - Simplified Adapted from www.researchgate.com
- 16. 16 LTE DL RESOURCEBLOCK - Detailed Adapted from www.pngkey.com
- 17. 17 LTE UL andDL Adapted from www.wirelessdictionary.com
- 18. 18 Scheduling Algorithm inLTE Networks • Channel Independent Scheduling • Dynamic Scheduling based on channel conditions • Works in Medium Access Control (MAC) layer Adapted from www.eventhelix.com
- 19. 19 MAC PROTOCOL STACK- Simplified Adapted from www.teletopix.org
- 20. 20 MAC PROTOCOL STACK- Detailed Adapted from www.tutorialspoint.com
- 21. 21 MAC TRANSPORT BLOCK(TB) - Detailed Adapted from www.tutorialspoint.com
- 22. 22 Important Scheduling Algorithms inLTE Networks • Scheduling decisions within 1 ms TTI / Subframe period • Time to encapsulate the upper layer data into a frame • Data flows from MAC layer to PHY layer through Transport Blocks (TBs) • Signal strength determined by Channel Quality Indicator (CQI) values • Throughput determined by the CQI and Modulation and Coding Scheme (MCS) adapted
- 23. 23 MODEL OF MACPACKET SCHEDULER (PS) Adapted from www.researchgate.com
- 24. 24 MAC PS –Detailed 1 Adapted from www.researchgate.com
- 25. 25 MAC PS –Detailed 2 Adapted from www.slideplayer.com
- 26. 26 MAC PS –Detailed 3 Adapted from www.link.springer.com, Adesh, N.D. & Renuka, A. Wireless Netw (2019) 25: 3149.
- 27. 27 MAC PS –Detailed 4 Adapted from www.eventhelix.com
- 28. 28 Traffic Types Handledby Scheduling Algorithms Best Effort (BE) / Non-Real Time (NRT) Real-Time (RT) • VoIP / Video
- 29. 29 Important Scheduling Algorithms inLTE Networks Round Robin (RR) Scheduler – Available RBs are shared among the UEs cyclically without any periority Proportional Fair (PF) Scheduler – Aims to increase the fairness – Calculate a scheduling priority metric – Schedule the UE when its instantaneous channel quality is high relative to its average channel quality over a period of time
- 30. 30 Important Scheduling Algorithms inLTE Networks Best Channel Quality Indicator (BCQI) Scheduler – Aims to increase the overall network throughput – Allocate / schedule RBs to the UEs when the channel quality is high • Blind Equal Throughput (BET) Scheduler – Aims to offer equal amount of throughput to all UEs – Allocate / schedule RBs to the UEs based on their past average throughput achieved
- 31. 31 Important Scheduling Algorithms inLTE Networks QoS Unaware Schedulers • QoS Aware Schedulers – Mainly for RT traffic – Employs in Time Domain (TD) and Frequency Domain (FD) – Priority is based on Guaranteed Bit Rate (GBR) and Non-GBR (NGBR) services
- 32. 32 Important Scheduling Algorithms inLTE Networks Channel / QoS Aware Schedulers – Priority Set Scheduler – Aims to provide a Target Bit Rare (TBR) to all UEs – Combines the operation of BET with high priority and PF with low priority in scheduling decisions • Channel Aware / QoS Unaware Schedulers – Maximum Throughput (MT) Scheduler – Allocates / schedule the RBs to the UEs based on their largest instantaneous throughput
- 33. 33 Important Scheduling Algorithms inLTE Networks QoS Class Identifier (QCI) based Scheduler Adapted from www.journals.plos.org, Maharazu Mamman et al., PloS ONE Vol.14, Issue.1, (2019).
- 34. 34 MAC-PS DL PROCESSING Adaptedfrom www.journals.plos.org, Maharazu Mamman et al., PloS ONE Vol.14, Issue.1, (2019).
- 35. 35 DL DATA FLOWPROCESSING Adapted from www.researchgate.com
- 36. 36 QoS Performance Metricsof Scheduling Algorithms Throughput – User Throughput & Cell Throughput Fairness / Fairness Index (FI) • Packet Delay (PD) / Latency • Packet Loss Rate (PLR) / Block Error Rate (BLER) • Buffer Occupancy (BO) • Blocking Probabiligy (BP) • Spectral Efficiency (SE) • System Capacity • Coverage
- 37. 37 Objectives of Scheduling Algorithms Trade-offbetween Throughput and PD Trade-off between Throughput and Fairness • Better Throughput at cell-edges
- 38. 38 Benefits of LTESystems • Provides a global ecosystem with inherent mobility • Offers easier access and use with greater security and privacy • Improves speed and latency • Delivers enhanced real-time video and multimedia for a better overall experience • Creates a platform to build and deploy the products and services of today and tomorrow • Reduces cost per bit through improved spectral efficiency
- 39. 39 Applications of FutureCellular Networks • Virtual Presence • Tele-Medicine • Tele-geoprocessing (GIS & GPS) • Crisis management • Online Interactive Education • Artificial Intelligence • Machine to Machine (M2M) Communication • 5G Networks
- 40. 40 5G Future Network Requirements •Very low battery power consumption • Worldwide wireless web (WWWW) • Low infrastructure deployment costs • Very high data rate • Better coverage at cell edges • Multiple data transfer paths • IPV6 address and accessability • Cloud Computing
- 41. 41 LTE / LTE-Advanced(LTE-A) Network Architecture Adapted from www.researchgate.com
- 42. 42 Multicarrier Protocol Structure ofLTE-A Adapted from Rosalyn Ryan, WIMAX / LTE : 4G Wireless Broadband Networks
- 43. 43 MAC STRUCTURE OFLTE / LTE-Advanced (LTE-A) Adapted from Antti Toskala and Harri Holma, LTE-Advanced: 3GPP Solution for IMT-Advanced, John Wiley & Sons (2012).
- 44. 44 M2M Communication Packet Flow Adaptedfrom www.researchgate.com
- 45. 45 5G Converged Architecture Adaptedfrom www.researchgate.com
- 46. 46 LTE-A Cloud Computing Adaptedfrom www.link.springer.com, Ben-Jye Chang et al., Wireless Netw (2016), 22:2579
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- 48. 48 Thank You ForYour Patient Listening.