In LTE systems, the downlink scheduler is an essential component for efficient radio resource utilization; hence, in the context of LTE simulation, the availability of good down-link scheduler models is very important. At the time this work started, the LTE module of the ns-3 simulator only supported two types of scheduler, namely Round Robin and Proportional Fair. To overcome this limitation, the authors implemented in ns-3 several well-known downlink LTE scheduler algorithms, namely maximum throughput, throughput to average, blind equal throughput, token bank fair queue and priority set. In this paper, they first describe in detail their design and implementation, and then discuss their validation done by comparison with the theoretical performance in some reference scenarios.