Low-Earth Orbit (LEO) satellite systems are intended to have an important part of the future generation of mobile telecommunication systems. They aim to provide different services to various populations of users. Each class of users requires a certain Quality of Service (QoS) and thus a given part of the shared channel resource. In this paper, LEO satellite systems based on an earth-fixed cell concept are considered, and different channel allocation strategies with handover queuing are discussed. Two channel allocation techniques have been investigated : fixed and dynamic channel allocation FCA and DCA. Moreover, in order to reduce the handover failure probability, we have assumed that handover attempts can be queued. An analytical model has been derived in the FCA case considering handover queuing and different categories of users. Implementation aspects for the DCA scheme have been discussed in comparison with FCA results.