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28
In the above equations,
k
is the user index and
R
k
is the minimum rate requirement for user
k
. c
k,n
is the channel assignment matrix (as was defined before) with a restriction that each subcarrier is
assigned to only one user. To formulate the problem as a convex optimization problem, the
received power for each user
k
, i.e. f
k
(r
k
), is required to be convex and the r
k,n
is relaxed to be a
real number within the interval [0,Mc
k,n
]. The authors apply the Lagrangian Relaxation technique
to solve this problem. Although the solution is tractable, it requires many iterations and is
computationally expensive O(>>N
2
).
The above was an overview of [28] and I will not go into the details because the proposed
algorithm is computationally expensive. Computationally expensive algorithms are inefficient
and consume more battery power on the mobile nodes. When designing resource allocation
schemes that will be used in a wireless system, we must keep in mind that the processing and
battery power of mobile nodes is limited. Hence we must carefully consider the tradeoff between
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This note was uploaded on 09/27/2009 for the course ECE 399 taught by Professor Prof during the Spring '09 term at University of Texas at Austin.
 Spring '09
 Prof

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