B. R. JI ANG ET AL.

Copyright © 2013 SciRes. CN

Table 5 shows the computational complexity of the

four algorithms. We can easily learn that the complexity

of ma x-rate algorith m is

O KN, and the complexity of

PF and Qos algo rithm a r e all

. For the proposed

algorithm , th e c ompl exity of initial allocation is

,

and the complexity of re-allocation scheme is

O KN,

Therefore, the overall complexity of proposed algorithm

is

O KNOKNO KN+= . It is observed that, the

proposed algorithm gains the quadratic complexity,

which is the same as that of PF and Qos algorithm. The

last column of Tabl e 5 explains that the max-rate algo-

rithm gets the lowest computational complexity, and the

other three algorithms have the same computational

complexity.

5. Conclusions

In this paper, we propose a two-step resource block allo-

cation algorithm for LTE downlink systems. The first

step of pro posed algorithm initiall y allocates AUs to each

user based on the proportional fairne ss sc he me. The n, t h e

proposed scheme re-allocates the AUs with the worst

channel condition of each user to improve the perfor-

mance restriction by those AUs. The algorithm can pro-

vide us with a higher data rate and a flexible allocation

scheme, and ensures the user's fairness. Simulation re-

sults show that the proposed algorithm provides higher

thro ughput and ens ures the fairness of each user.

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