一种用于离散比特分配的改进注水算法

该文针对OFDM系统的离散比特分配问题，提出一种改进的注水算法。该算法的实现借助于文中定义的比特水线——分配给某个子载波的功率直接满足整数比特约束的注水线。先用最大信道增益子载波的比特水线进行离散比特分配，再调整分配结果以满足总发射功率约束。理论证明和分析显示，该算法能实现最优比特分配，运算复杂度仅与子载波数量有关。

An Improved Water-filling Algorithm for Discrete Bit Allocation

In this paper, an improved water-filling algorithm is proposed for the problem of Discrete Bit Allocation DBA in OFDM systems. The bit-water-level, defined in this paper as the water-filling level under which the power allocated to a certain sub-carrier satisfies the integer bit constraint, is used in the proposed algorithm. First, using the bit-water-levels of the sub-carrier with the maximal channel gain, bits and power are allocated to all the sub-carriers. Then, the allocation results are adapted to satisfy the total transmit power constraint. It is proved that the algorithm yields the optimal solution and its computational complexity depends only on the number of sub-carriers.