**Acknowledgement**

16 Will-be-set-by-IN-TECH

The CDFs of *T* for ESA, SG, max C/I, and Round Robin (RR) with five users are plotted in Fig. 11. Note that max C/I is a special case of SG in which, for each TTI, resources are allocated only to the user with the best channel condition. On the other hand, RR refers to a base-line scheduling scheme, whereby each user is scheduled one at a time in a round robin fashion. Under such a scheme, the respective channel quality of the users are not used during the scheduling. The corresponding values of *E***<sup>Γ</sup>** [*T*] for ESA, SG, max C/I, and RR are 10.6, 8.8, 2.8, and 1.9 bits per TTI respectively. The prominent steps in the CDFs for RR and max C/I are due to the coarse quantization resulting from allocation of resources to only one user in each TTI. It can be seen that RR has the lowest bit rate as it does not take into account user channel

<sup>103</sup> <sup>104</sup> <sup>0</sup>

TBS per TTI (in bits)

**Figure 11.** CDF of the aggregate bit rate in TBS per TTI for ESA, max C/I, and Round Robin (RR) with

In this chapter, the issue of allocating resources to multiple users simultaneously in HSDPA has been examined via a number of optimization methods. The problem formulation based on the channel feedback scheme specified in the WCDMA standard has been presented. Simulation results have shown that both the global optimal and the simulated annealing-based methods can provide a substantial throughput improvement over a more simple greedy algorithm. It has been observed that the method based on simulated annealing can achieve a bit rate that is very close to that of the global optimal, with a much lower

ESA SG max C/I RR

conditions.

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five users. ([14]©IET)

**7. Conclusion**

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5 users

1

This work was supported in part by the Natural Sciences and Engineering Research Council (NSERC) of Canada under Grant OGP0001731, by the UBC PMC-Sierra Professorship in Networking and Communications and by a Marie Curie International Incoming Fellowship PIIF-GA-2008-221380.
