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  1. 1. Bader Al-Manthari, Nidal Nasser, and Hossam Hassanein,“Downlink Scheduling With Economic Considerations for Future Wireless Networks,” IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, Vol. 58, No. 2, FEBRUARY 2009. Advisor:Yeong-Sung Lin Student:Chiu-Han Hsiao Department of Information Management National Taiwan University Taipei, Taiwan, R. O. C.
  2. 2. Outline  Introduction  Background Study Problem Description and System Model Centralized Downlink Packet Scheduler (CDPS) Performance Evaluation Experiment Result Conclusion 2010/05/18 OPLAB 2
  3. 3. Introduction(1/2)  3G Universal Mobile Telecommunication System (UMTS)(2Mbps)  High-Speed Downlink Packet Access (HSDPA) (3.5G) can theoretically support up to 14.4 Mbps, which is seven times higher than the data rate offered by UMTS  A key component of radio-resource management (RRM) is packet scheduling, which is responsible for distributing the shared radio resources among the mobile users  we propose a novel centralized downlink packet scheduler (CDPS) scheme to be implemented at the base stations of future wireless cellular systems 2010/05/18 OPLAB 3
  4. 4. Introduction(2/2) CDPS utilizes an opportunity cost function that allows service providers to control its degree of fairness and hence control the system capacity CDPS is designed to balance between the requirements of connections (e.g., throughput, fairness, etc.) and the requirements of service providers (e.g., revenues) CDPS can be configured to reduce to the maximum carrier-to-interference ratio (Max CIR) and proportional fairness (PF) schemes 2010/05/18 OPLAB 4
  5. 5. Background Study 2010/05/18 OPLAB 5
  6. 6. Multiple Access Methods Multiple users share the available spectrum 2010/05/18 OPLAB 6
  7. 7. What is “IMT-2000” IMT-2000 (Internet Mobile Telecommunications- 2000) is the personalized global multi-media service, which unifies all the various mobile telephone system specs Services – global roaming service – multimedia communications This is “ 3rd Generation Mobile Communication System” 2010/05/18 OPLAB 7
  8. 8. IMT-2000 ITU (International Telecommunication Union) IMT-2000 • Year 2000 Ready • Operate at 2000 MHz • Provide 2000K bps Data Rate 3G Data Rate Requirement • Vehicular -- 144 Kbps • Pedestrian --- 384 Kbps • Indoor --- 2Mbps 2010/05/18 OPLAB 8
  9. 9. IMT-2000 Evolution 2010/05/18 OPLAB 9
  10. 10. IMT-2000 Evolution W-CDMA PDC ARIB (W-CDMA) (FDD) Wideband Multicarrier UTRA (W-CDMA) CDMA Multicode TD-CDMA GSM GPRS (TDD) EDGE 136 HS AMPS IS-54 IS-136 UWC-136 136+ cdmaOne • AMPS: Advanced Mobile Phone System cdma2000 (IS-95) • GSM: Global Systems for Mobile Comm. • GPRS: General Packet Radio Service IS-95B • PDC: Personal (or Pacific) Digital Comm. • EDGE: Enhanced Data rates for GSM • IEEE Spectrum, Aug. 1999 (Modified) (or global) Evolution OPLAB • UTRA: UMTS Terrestrial Radio Access 10 2010/05/18
  11. 11. IMT-2000 Terrestrial RTT Standardization  CDMA2000 (North America) – Based on Qualcom cdmaOne – Support multi-carrier (MC) – Use IS-41 to accomplish the core network compatibility  TD-SCDMA (Mainland) – 大唐電信 and Siemens – TDD-based – Requirement : time synchronization – Limit coverage area of BS  WCDMA/UMTS (Japan and Europe) – NTT DoCoMo develops WCDMA – Core network is based on GSM system – UTRA (UMTS Terrestrial Radio) proposed by Europe is similar as WCDMA 2010/05/18 OPLAB 11
  12. 12. Network Upgrade Comparison: CDMA2000 1x vs. GPRS / W-CDMA SGSN: Serving GPRS Support Node GGSN: Gateway GPRS Support Node OPLAB 12 2010/05/18 MSC: Mobile Switching Center
  13. 13. New Terms WCDMA/UMTS Terms – BTS → Node B (NB) – BSC → RNC (Radio Network Controller) • New job : RRM (Radio Resource Management) Radio Bearers Channels – Logical Channel – Transport Channel – Physical Channel Data forwarding direction – Uplink (reverse link) – Downlink (forward link) 2010/05/18 OPLAB 13
  14. 14. 3G Frequency Allocation in Taiwan E E MHz 845 870 890 825 1885MHz 2025MHz 2110MHz 2200MHz ITU IMT-2000 ITU IMT-2000 A A B C D BCD A BC D 2010 2025 15 20 60 MHz 20 35 45 25 35 50 1975 2110 2165 1915 3G 執照 頻寬 頻帶 (MHz) A 2 x 15 MHz + 5 MHz 1920 ~ 1935, 2110 ~2125, 1915 ~ 1920 B 2 x 10 MHz + 5 MHz 1935 ~ 1945, 2125 ~ 2135, 2010 ~ 2015 C 2 x 15 MHz + 5 MHz 1945 ~ 1960, 2135 ~ 2150, 2015 ~ 2020 D 2 x 15 MHz + 5 MHz 1960 ~ 1975, 2150 ~ 2165, 202 0 ~ 2025 E 2 x 20 MHz 825 ~ 845, 870 ~ 890 Apple - iPhone - 技術規格.htm 2010/05/18 OPLAB 14
  15. 15. WCDMA Standards 3GPP – www.3gpp.org WCDMA – FDD mode – TDD mode Release – R98 (1998) – R99 (200003 freeze) --- WCDMA – R4 (200103 freeze) – R5 (2002 freeze) --- HSDPA – R6 (2003 freeze) --- HSUPA – R7 (2007 freeze) – R8 (2008 freeze) --- LTE – R9 (ongoing) – R10 (ongoing) LTE: Long Term Evolution 2010/05/18 OPLAB 15
  16. 16. History (1/2) Release 98 (1998) – This and earlier releases specify pre-3G GSM networks Release 99 (2000 Q1) – Specified the first UMTS 3G networks, incorporating a CDMA air interface – USIM : mutual authentication (AKA) Release 4 (2001 Q2) – Originally called the Release 2000 - added features including an All-IP Core Network Release 5 (2002 Q1) – Introduced IMS and HSDPA Release 6 (2004 Q4 ) – Integrated operation with WLAN networks and adds HSUPA, MBMS, enhancements to IMS such as Push to Talk over Cellular (PoC) 2010/05/18 OPLAB 16
  17. 17. History (2/2) Release 7 (2007 Q4) – Focuses on decreasing latency, improvements to QoS and real- time applications such as VoIP – also focus on HSPA+ (High Speed Packet Access Evolution), MIMO, SIM high-speed protocol and contactless front-end interface (Near Field Communication enabling operators to deliver contactless services like mobile payments), EDGE Evolution. Release 8 (In progress, not ready before Mar 2009) – LTE, All-IP Network (SAE). It constitutes UMTS as an entirely IP based fourth-generation network. Release 9 (In progress, expected to be frozen in Dec 2009 ) – SAES Enhancements, WiMAX and LTE/UMTS Interoperability Release 10 (In progress) – LTE-Advanced 2010/05/18 OPLAB 17
  18. 18. 3GPP Development Progress Functionality IMS phase 1, HSDPA, LCR TDD, Wideband AMR, UTRA FDD/TDD UTRA FDD IP transport Release nn Release modes, USIM, repeater function, in UTRAN OFDM? AMR speech 700MHz support MIMO? codec, MMS, for GERAN Release 66 Release EDCH? LCS, IMS further CAMEL etc. Release 55 HSUPA, Release MBMS, Phase? WLAN/UMTS Release 44 Release Interworking , IMS phase 2 Release 1999 Release 1999 1999 - 12 2001 - 03 2002 - 03/06 2003/12 Time 2010/05/18 OPLAB 18
  19. 19. 3GPP’s Evolution/Revolution Towards 4G Enchanced New IMT - 2000 IMT - 2000 Mobile Access 2001/11/04 2002/06/24 2003/09/26 2005/01/04 R8 3GPP R4 3GPP R5 3GPP R6 3GPP R7 (WCDMA) 3GPP R5 3GPP R6 3GPP R7 LTE (+HSDPA (+HSDPA) (+HSUPA) (+MIMO) (+MIMO) OFDMA ) Systems 3GPP R4 3GPP R5 3GPP R6 3GPP R7 3GPP R8 Data Rate (peak) Forward 2 Mbps > 10 Mbps > 10 Mbps > 20 Mbps 100 Mbps Link Reverse 384 Kbps 384 Kbps > 2 Mbps > 5 Mbps 20 Mbps Link OPLAB 19 2010/05/18
  20. 20. Radio Resource Management CDPS is proposed 2010/05/18 OPLAB 20
  21. 21. Channel quality condition for scheduling decisions 2010/05/18 OPLAB 21
  22. 22. Packet Scheduler Model 2010/05/18 OPLAB 22
  23. 23. System Formulation we emphasize recent scheduling schemes for data (non–real-time) services in future wireless cellular networks the base station simultaneously serves n connections n ≥ 1 and selects one or more connections for transmission in a frame of some fixed time duration These PDUs are stored in the transmission queue of the corresponding connection in a first-in–first-out fashion 2010/05/18 OPLAB 23
  24. 24. Utility Function The user’s i (1 ≤ i ≤ n) preferences at time t as perceived by the service provider can be expressed by a utility function Ui(Xi1(t),Xi2(t), . . . , Xim(t)), – where n is the total number of users’ connections in the system, – Xi1(t), . . . , Xim−1(t) are the chosen quantitative measures of the user connection’s preferences in this system such as the average throughput, current data rate, average delay, etc., – Xim(t) is a fairness measure that represents how fair the scheduling scheme is to the user connection, and m is the maximum number of chosen quantitative measures. We assume that the utility function is additive 2010/05/18 OPLAB 24
  25. 25. Objective Function OCi(t) is the opportunity cost of serving connection i at time t, and K is a predefined constant value 2010/05/18 OPLAB 25
  26. 26. Cobb–Douglas Utility Function for Downlink Scheduling Cobb-Douglas生產函數:簡稱C-D生產函 數 最簡單之形式如:Q = AKαLβ 式中Q:產出量,K:資本使用量,L勞 動使用量,A、α 及β表固定常數,其數 值可由實際統計資料估計出 2010/05/18 OPLAB 26
  27. 27. Cobb–Douglas生產函數 1.若α +β>1,則此生產為遞增的規模報酬;即 若所有生產要素按相同比例增加,則產量增 加的比例大於生產因素增加的比例。如:Q = 20K0.7L0.6 2.若α +β=1,則此生產為固定的規模報酬;即 產量增加的比例等於生產因素增加的比例。 例:Q = 50K0.4L0.6 3.若α +β<1,則此生產為遞減的規模報酬;即 產量增加的比例小於生產因素增加的比例。 例:Q = 100K0.5L0.3 2010/05/18 OPLAB 27
  28. 28. Definitions of Xi1(t) and Xi2(t) Assuming m = 2 in our formulation of CDPS, the Cobb–Douglas utility function is expressed as Ui(X1,X2) = X1c ·X2d – where c, d ≥ 0. Let X1 be any performance metric that the service provider wants to optimize, such as the average connection throughput or average delay. Let X2 be a fairness measure that increases as the connection’s or system’s perception of fairness increases, which results in an increase in U 2010/05/18 OPLAB 28
  29. 29. Definitions of Xi1(t) and Xi2(t) To maximize the system’s overall utility, we need to achieve the highest possible values of Xi1(t) and Xi2(t) for all connections. However, it is not possible to achieve high values of both Xi1(t) and Xi2(t) for all connections because of the tradeoff between capacity and fairness 2010/05/18 OPLAB 29
  30. 30. Definitions of Xi1(t) and Xi2(t) Given these two definitions, the fairness measure for connection i at time t, αi(t) can be defined Si(t) is the average throughput for connection i up to time t maxj Sj(t) is the maximum average throughput achieved among all connections up to time t. the fairness measure for connection i is the ratio of its average throughput to the maximum throughput achieved among all the connections in the system. We call this measure the “relative fairness.” 2010/05/18 OPLAB 30
  31. 31. Definitions of Xi1(t) and Xi2(t) The opportunity cost of serving connection i at time t (i.e., the opportunity cost of fairness) is defined as where Ri(t) is the current data rate for connection i at time t, which depends on its channel condition, maxj Rj(t) is the maximum current data rate of all connections at time t 2010/05/18 OPLAB 31
  32. 32. Definitions of Xi1(t) and Xi2(t)  c: the Cobb–Douglas utility function’s constant, where c ≥ 0. The value of this constant determines the weight on Xi1(t) in the Cobb–Douglas utility function  d: the Cobb–Douglas utility function’s constant, where d ≥ 1. The value of this constant determines the weight on Xi2(t) in the Cobb–Douglas utility function.  We restrict the value of this constant to an odd integer because our defined Xi2(t) in the adopted Cobb–Douglas utility function is a negative function  d must be odd 2010/05/18 OPLAB 32
  33. 33. Definitions of Xi1(t) and Xi2(t) Xi1(t) = Ri(t): the current data rate of connection i at time t The utility of connection i being served increases as Ri(t) increases. It should be noted that other performance metrics could be used. However, we use the current data rate as the first component in the Cobb– Douglas utility function to increase the system capacity and, hence, achieve the efficiency objective 2010/05/18 OPLAB 33
  34. 34. Definitions of Xi1(t) and Xi2(t) Xi2(t) = f(αi(t), γi(t)) = 1 − γi −ln(αi(t)) γi > 1: the fairness measure, which is a function of the relative fairness that we defined to increase fairness in the system 2010/05/18 OPLAB 34
  35. 35. Definitions of Xi1(t) and Xi2(t) The parameter γi is used to control the shape of Xi2(t) and , hence, the level of fairness in the system γi can be set to different values for different connections to allow the service provider to maintain different levels of fairness for different connections depending on the type of traffic they have, the amount of money they are expected to pay, their loyalty, etc. 2010/05/18 OPLAB 35
  36. 36. Definitions of Xi1(t) and Xi2(t) Objective function Connection Selection 2010/05/18 OPLAB 36
  37. 37. Experiment Environment Setting Simulation Model 2010/05/18 OPLAB 37
  38. 38. Simulation Parameters 2010/05/18 OPLAB 38
  39. 39. Test Environments Case I: Ped A (Fig 5~12) – The mobile users in the Ped A environment move at a fixed speed of 3 km/h, which is the recommended value by the 3GPP Case II: fixed differentiated channel conditions (Fig 13, 14) – The fixed channel environment is created to evaluate the performance of the CDPS under different fixed channel conditions (as opposed to Ped A in which the channel conditions of users vary with time, according to the models specified by the 3GPP) 2010/05/18 OPLAB 39
  40. 40. 2010/05/18 OPLAB 40 Fig. 5. Cell throughput. Fig. 6. Cell throughput with different values of K.
  41. 41. Fig. 7. Distribution of connection average throughputs. 2010/05/18 OPLAB 41
  42. 42. Fig. 8. Distribution of connection average throughputs with different values of K. 2010/05/18 OPLAB 42
  43. 43. Fig. 9. User satisfaction with minimum throughput of 128 Kbps 2010/05/18 OPLAB 43
  44. 44. Fig. 10. User satisfaction with minimum throughput of 128 Kbps with different values of K. 2010/05/18 OPLAB 44
  45. 45. Fig. 11. User satisfaction with minimum throughput of 356 Kbps 2010/05/18 OPLAB 45
  46. 46. Fig. 12. User satisfaction with minimum throughput of 356 Kbps with different values of K. 2010/05/18 OPLAB 46
  47. 47. Fixed Differentiated Channel Conditions Seven values are used for the SNR: −7, −4, −1, 2, 5, 8, and 11 dB For each SNR value, there are ten connections (a total of 70 connections in the cell) 2010/05/18 OPLAB 47
  48. 48. Fig. 13. Average connection throughput for connections with different SNR2010/05/18 values. OPLAB 48
  49. 49. Fig. 14. Percentage of packet loss for connections with different SNR values. 2010/05/18 OPLAB 49
  50. 50. Conclusions we have proposed a CDPS scheme for future wireless cellular systems that is based on a utility function to represent the satisfactions of the mobile users as perceived by the service provider Our scheme also utilizes an opportunity cost function to represent the satisfactions of the service provider CDPS can simultaneously meet four design objectives, that is, efficiency, fairness, users’ satisfactions, and flexibility 2010/05/18 OPLAB 50
  51. 51. Comments How does it work on real-time traffic or another service types? – X1c may be delay or delay jitter. – Objective function have to be modified. How is the uplink data flow? What is the business model for a operator to get maximum revenues? Strategy? 2010/05/18 OPLAB 51
  52. 52. Thank you

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