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A New Strategy to Improve the Efficiency of OBBP Allocation Algorithm

A New Strategy to Improve the Efficiency of OBBP Allocation Algorithm

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A New Strategy to Improve the Efficiency of OBBP Allocation Algorithm

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  1. A New Strategy to Improve the Efficiency of OBBP Allocation Algorithm Ghazal Rouhafzay Supervised by Assoc. Prof. Dr. Erhan A. İnce

  2. INTRODUCTION

  3. Mobile WiMAX based on IEEE 802.16e is a broad band wireless access technology which has been widely accepted as the best solution for wireless broad band services. OFDMA Instead of using a single wide-band carrier, multiple narrow-band parallel subcarriers are used Subchannels

  4. subchannels t Slot The minimum frequency-time resource unit Burst Several slots assigned to a Mobile Station Rectangular IEEE802.16e

  5. WiMAX Frame Structure

  6. Unused Slots 51 4 56 54 75

  7. Thesis Description • Implementing Orientation Based Burst Packing algorithm (OBBP) • Introducing a new packing strategy in the third stage of the OBBP frame packing algorithm (Modified OBBP) • Comparison Between OBBP MOBBP, eOCSA for randomly generated bursts • Comparison Between OBBP MOBBP, eOCSA for Hata channel model

  8. OFDM VS OFDMA

  9. Overlapped spectrum of subcarriers in OFDM Overlapping subcarriers Saving in Bandwidth

  10. Multi-user concept of OFDMA Subchannels OFDM Symbol n+1 OFDM Symbol n OFDM Symbol n+2

  11. Effect of ISI ISI is a form of distortion of a signalin whichonesymbol interferes with subsequent symbols. OFDM Symbol OFDM Symbol OFDM Symbol OFDM Symbol Inter Symbol Interference (ISI)

  12. Applying guard intervals 1 OFDM Symbol = L data symbols ISI between OFDM symbols are removed While > T=L OFDM SYMBOL Duration Data SYMBOL Duration T OFDM Symbol OFDM Symbol OFDM Symbol OFDM Symbol OFDM Symbol OFDM Symbol Guard Interval Guard Interval

  13. Applying Cyclic prefix Cyclic prefix OFDM Data Symbols Copy and paste the last v symbols

  14. Subchannelization schemes

  15. Subcarrier Types

  16. Subcarrier permutation modes Downlink The subcarriers are distributed over the entire spectrum Subcarriers are from adjacent frequencies

  17. DL-PUSC 2 symbol=28 4 pilot &24 data subcarriers

  18. DL-FUSC 1- Pilot subcarriers 48 data subcarriers

  19. BROADBAND WIRELESS CHANNEL

  20. Broadband Wireless Channel Transmitter Communication System Receiver Fading The variation of signal amplitude over frequency and time. Shadowing Pathloss

  21. Path loss Path loss means the reduction in power density of the signal as it passes through the wireless channel. Transmitter gain Receiver gain Frii’s formula Transmitted power, Received power at the receiver

  22. Cost hata channel model a=3.2 4.79

  23. OBBP VS MOBBP

  24. Orientation Based Burst Packing (OBBP) • Pre-packing Stage

  25. Pre-packing Stage

  26. ⨯14 B=

  27. Divisors =

  28. Constructing OF Matrix OF_Matrix=

  29. Burst Adaptation Removing bursts with OFs out of the frame range from the OF_Matrix. DL-Subframe 60 80

  30. Burst Adaptation 67 67 + 1

  31. Constructing RpMatrix Rp_Matrix

  32. Orientation Based Burst Packing (OBBP) • Main Packing Stage

  33. main packing Stage

  34. Packing set selection 4+6+7+9+10=36

  35. Packing set selection = {4, 6, 14, 18, 24, 32, 44, 50, 74, 76, 78} Descending Order = {78, 76, 74, 50, 44, 32, 24, 18, 14, 6, 4}

  36. Finding the optimal subset of bursts All elements in OF_Matrix with the values equal to 38 and 22 will be set to zero. {38, 22} {37, 16, 7} {39, 12, 7, 2} If the corresponding element in Rp Matrix is equal to 1 Else corresponding element in Rp Matrix will be reduced by 1

  37. 22 38

  38. Packing Set Arrangement Calculating sum of each group Rearranging them in descending order based on their sums.

  39. Packing Set Stuffing We start packing bursts from the bottom-right corner of the subframe.

  40. Orientation Based Burst Packing (OBBP) • Packing remaining bursts

  41. Packing remaining bursts Sorting remaining bursts in descending order Dividing unallocated slots into rectangles with its maximum possible dimension. Choosing the suitable rectangle for the burst Fitting the burst in the selected rectangle.

  42. 1 7 40 60 OBBP algorithm drops the burst MOBBP

  43. eOcsa

  44. SIMULATION RESULTS

  45. [77 63 21] Slots

  46. OBBP [77 63 21]

  47. MOBBP [77 63 21] 78 64