Complete partitioning allocation policies in a rain faded satellite environment

Celandroni N, Davoli F, Ferro E, Gotta A

Satellite networks  Fade countermeasures  Bandwidth allocation 

Two resource allocation methods, based on optimized adaptive complete bandwidth partitioning strategies, have been studied, simulated and compared between them and with a simple allocation scheme that does not apply any optimization criteria. The allocation methods are studied for a satellite network environment, where a number of earth stations (traffic stations) exchange multimedia traffic in weather conditions that may vary from clear sky up to heavy rain, with different levels of fade which affect the transmitted signals. In all the schemes presented, the call admission control (CAC) policy for real-time connections is administered locally in the traffic stations, while a master station is charged to manage the MF-TDMA (multi frequency-time division multiple access) bandwidth allocation policy. In the first control architecture (Optimized Centralized, OC) no explicit requests are issued by the traffic stations for bandwidth allocation; the master computes the allocations by optimizing a cost function which takes into account costs pertaining to the single stations. In the second scheme (Optimized Proportional, OP) the master optimizes the allocations according to explicit requests received. The third allocation policy (Simple Proportional, SP) allocates the bandwidth proportionally to the requests, without any optimization. This last scheme has been used simply to clearly show that a non-optimal allocation may have a low computational cost, but it may turn out to be less efficient than the others. Figures of merit such as loss, blocking and dropping probabilities are computed for the three methods, in order to evaluate the performance of each system in the same network conditions. Numerical results are provided for a specific network architecture in a real environment, based on the Italsat satellite national coverage payload characteristics.