Optimal Downlink Scheduling and Power Allocation with Reconfiguration Delay

We consider a downlink scheduling problem in which the base station needs to serve a set of users. We consider a time-slotted system in which in each time-slot, the scheduler assigns service to a user. Whenever the scheduler changes the service from one user to the other, the base station has to switch it's configuration from that of the previous user to that of the current user. This incurs a delay, called “Reconfiguration delay”. In this paper, we study the problem of scheduling in downlink with reconfiguration delay. Our objective is to design scheduling policies that optimally trade-off the average delay of data bits with the average transmission power. We consider an indpendent and identically distributed (IID) fading channel in which the channel gain in each time-slot varies according to a distribution. Also, the channel gain for each downlink user is independent of each other and follows the same distribution. We obtain an lower bound to the average power of transmission for any arrival rate vector in the stability region. For the case of constant channel state, we show that the outer bound is achievable using a variable frame drift + penalty policy. We also study the trade-off problem for the case of multiple channel states via simulations for two different scheduling policies.

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