Ahmed N. Zaki and Abraham O. Fapojuwo Dept. of Electrical and Computer Engineering

1. A novel radio resource management approach for QoS Provisioning in multi-service Multi-slot OFDMA Systems Ahmed N. Zaki and Abraham O. Fapojuwo Dept. of Electrical and Computer Engineering The University of Calgary, Calgary, AB, Canada WCNC 2008

2. Outline • Introduction • System model • Optimal scheduling • Suboptimal scheduling • Simulation • Conclusion

3. introduction • In this paper, we consider the Radio Resource Management (RRM) in the downlink on OFDMA system • RRM is the Problem of distributing • different resources • Multi-user

4. introduction • The general approach taken by all the past papers • Formulate the RRM problem • It can be optimally solved from the mathematical programming theory • In the rest of thist paper will propose a suboptimal algorithm

5. introduction • Assumptions • To allocate enough resource to each user • Each user will be satisfy a constant data rate • RT services are allocated a constant number of bits every frame • Thus, each NRT services will depend on many parameters

6. introduction • Assumptions • Due to frequency selective fading, each user may have a different SNR for the different subcarriers • BS invokes the scheduling once during each frame

7. System model • The total available bandwidth divided into K subchannels • A frame length of W seconds • there are T available time slots per subchannel in the current frame • There are M different modulation/conding • There are N users that will be allocate resource

8. System model • let β denote the number of bits that can be transmitted in one time slot on any subchannel • A logical subchannel is a physical subchannel that can only be used with one modulation/coding combination • Hence, the total number of logical subchannels G = K M. • The number of data units transmitted on a logical subchannel ( Sg )

9. System model • Xg,nequals the number of time slots allocated to the nth user on the gth logical subchannel

10. Optimal scheduling

11. a 5 2 D1 8 S 3 6 b 7 4 D2 c 8 Suboptimal scheduling _baseidea • Network flow

12. a 5 2 D1 8 S 3 6 b 7 4 D2 c 8 Suboptimal scheduling _baseidea • Network flow

13. a 5 2 D1 8 S 3 6 b 7 4 D2 c 8 Suboptimal scheduling _baseidea • Network flow 2 5 2 0 3 3 3 3 3

14. Suboptimal scheduling _example modulation user 16 -5 Subchannel 10 slot 2 slot 0 slot 1 a -10 80 byte 64 8 slot -5 16 -5 -5 10 slot 7 slot 2 b 120 byte 64 -10 12 slot 16 -5 3 10 slot 0 slot 30 byte c -10 64 3 slot

15. Simulation • The simulated system consists of a single cell • The channel consists of 4 subchannels • The available modulation schemes are QPSK, 16-QAM and 64-QAM • The frame length is 10 msec • Each subchannel has 7 time slots

16. Simulation

17. Simulation

18. Conclusion • This paper proposed a novel approach for OFDMA radio resource management • Simulations show that the proposed approach enhances the system performance

19. Thank You !