2017/06/27 by Alessandro Brighente, Stefano Tomasin, Brighente, Alessandro +1
Engineering · #Advanced MIMO Systems Optimization #Telecommunications and Broadcasting Technologies #Millimeter-Wave Propagation and Modeling
paper · pdf · doi:10.48550/arxiv.1706.08745
We consider the problem of scheduling and power allocation for the downlink\nof a 5G cellular system operating in the millimeter wave (mmWave) band and\nserving two sets of users: fix-rate (FR) users typically seen in\ndevice-to-device (D2D) communications, and variable-rate (VR) users, or high\ndata rate services. The scheduling objective is the weighted sum-rate of both\nFR and VR users, and the constraints ensure that active FR users get the\nrequired rate. The weights of the objective function provide a trade-off\nbetween the number of served FR users and the resources allocated to VR users.\nFor mmWave channels the virtual channel matrix obtained by applying fixed\ndiscrete-Fourier transform (DFT) beamformers at both the transmitter and the\nreceiver is sparse. This results into a sparsity of the resulting multiple\naccess channel, which is exploited to simplify scheduling, first establishing\nan interference graph among users and then grouping users according to their\northogonality. The original scheduling problem is solved using a graph-coloring\nalgorithm on the interference graph in order to select sub-sets of orthogonal\nVR users. Two options are considered for FR users: either they are chosen\northogonal to VR users or non-orthogonal. A waterfilling algorithm is then used\nto allocate power to the FR users.\n