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CDN - An opportunistic Scheduling Scheduling Scheme with a Minimum Date-Rate Guarantees for OFDMA

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CDN - An opportunistic Scheduling Scheduling Scheme with a Minimum Date-Rate Guarantees for OFDMA

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CDN - An opportunistic Scheduling Scheduling Scheme with a Minimum Date-Rate Guarantees for OFDMA

  1. 1. An Opportunistic Scheduling Scheme with Minimum Data-Rate Guarantees for OFDMA George Suveti Cellular Data Networks
  2. 2. OFDM & OFDMA OFDM Orthogonal frequency-division multiplexing (OFDM) is a method of encoding digital data on multiple carrier frequencies. OFDM has developed into a popular scheme for wideband digital communication, used in applications such as digital television and audio broadcasting, DSL Internet access, wireless networks, powerline networks, and 4G mobile communications. OFDMA Orthogonal Frequency-Division Multiple Access (OFDMA) is a multi-user version of the popular orthogonal frequency-division multiplexing (OFDM) digital modulation scheme. Multiple access is achieved in OFDMA by assigning subsets of subcarriers to individual users. This allows simultaneous low data rate transmission from several users.
  3. 3. OFDM & OFDMA
  4. 4. RELATED WORK Opportunistic scheduling In order to provide higher system capacity in a multiuser wireless environment by taking advantage of instantaneous channel variations and giving transmission priority to the users with better channel conditions. This is referred to as multiuser diversity and is the basis of opportunistic scheduling (OS). OS schemes adopt a cross-layer approach to medium access control (MAC) packet scheduling by making use of the channel state information (CSI) of each user, retrieved at the physical layer. Techniques of opportunistic scheduling: - schedule the users with better channel quality for transmission - Round Robin, independently of the channel conditions form of - proportional fair algorithms, aims at assuring a degree of fairness on a long term scale 
 (e.g. choose for transmission, at each time-slot, the user with the highest ratio between its instantaneous channel capacity and its average data rate.
  5. 5. Goal To design a scheduling algorithm for a heterogeneous traffic OFDMA-based system that will guarantee a minimum average (on a system-set time scale) data-rate for each user, based on classes-of-service, while using opportunistic scheduling in order to maximize the system spectral efficiency. The algorithm considers the variations of the channel quality for each user as compared to the average value over the considered time window, and try to schedule for transmission, at each time-slot, the users that have greater than average channel quality. SCHEDULING ALGORITHM
  6. 6. SCHEDULING ALGORITHM
  7. 7. SIMULATION RESULTS
  8. 8. SIMULATION RESULTS
  9. 9. SIMULATION RESULTS
  10. 10. CONCLUSIONS The proposed algorithm, by leveraging multiuser diversity, outperforms classic OS schemes due to its ability to provide minimum data-rate guarantees for different
 classes of service, while at the same time provides a high system throughput. The hardness of the constraints as well as the level of the introduced delays can be controlled by modifying the size of the time window over which scheduling is performed. The inverse proportional relationship between the level of the data-rate guarantees and the system throughput(or spectral efficiency) has been evidenced. Further work Extend the heuristic in order to take into account queue information and thus provide delay guarantees.
  • MostafaAlalimi

    Dec. 14, 2016

CDN - An opportunistic Scheduling Scheduling Scheme with a Minimum Date-Rate Guarantees for OFDMA

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