A Dynamic Region based Limited Feedback Scheme for Efficient Power Allocation in OFDM Systems

Abstract

This letter proposes a dynamic region based limited feedback scheme for efficient power allocation in orthogonal frequency division multiplexing (OFDM) systems. At the receiver, after obtaining the channel gains of all subcarriers by channel estimation, the maximum and the minimum channel gains can be determined easily. Using the maximum and the minimum channel gains, the proposed scheme divides the range of the channel gains into multiple regions adaptively. Each region is assigned with a unique index. Then each subcarrier will be allocated with the index of the region that its channel gain belongs to. The index information of all subcarriers can be denoted by a code from a predetermined codebook. Along with the maximum and the minimum channel gains, only the codes will be fed back. The feedback information will be used to estimate the channel gains of all subcarriers at the transmitter. The simulation results show that the proposed scheme can improve both the accuracy of feedback channel gain information and the spectral efficiency with less feedback information overhead.

Iterative Eigenvalue Decomposition and Multipath-Grouping Tx/Rx Joint Beamforming for Millimeter-Wave Communication

“…Fig. 2 shows a simple example, which is a surface of z = −(x − 1) 2 − (y − 1) 2 . With the alternating optimization method, like IEVD, the optimal solution can be quickly achieved.…”

“…As in MMWC the propagation distance may be tens of meters for WLAN or hundreds of meters for mobile communications, the difference of path distances may be several or even tens of meters. Hence, a frequency-selective steering channel model is suitable for MMWC 2 , which has been used in [10], [25] and can be expressed as…”