Cooperative Strategies for Satellite Access

This chapter has presented the possible adoption of cooperation strategies in satellite access, focusing on two case studies showing an uplink and downlink mobile satellite scenario. The use of these different techniques and methodologies in various applications scenarios, can led to the achievement of improvement of the system performance in terms of Bit Error Rate and Packet Error Rate. In particular, in the uplink scenario, the introduction of the Coded-Cooperation for DVB-RCS terminals working in a land vehicular scenario, allows improving considerably, for increasing Eb / N0 values, the system performance compared with the non-cooperative system, especially if a codeword partitioning scheme maximising the level of randomness in the distribution of the sub-blocks among different users is adopted. In the best simulated scenario, if it is considered a Codeword Error Rate value of 10−5 , the system performance is, however, still roughly 3.8 dB away from the reference (AWGN with erasure rate equal to NLOS share) case, leaving significant room for further optimisation of the system. However, a trade-off between the number of cooperative users, the resulting system complexity and the achievable performance is necessary. Moreover, also the adoption of a Selective Forwarding cooperation in a DVB-RCS land-vehicular scenario, allows improving sensibly the system performance in the considered environments, depending on the number of users involved in the cooperation process. The simulation results have shown that, considering 4 cooperators which cooperate with 2 active users, a cooperation gain equal to 1.4 dB can be achieved with respect to the case of absence of cooperation. As what concerns, instead, the downlink scenario the idea was to build a cooperation among a set of mobile terminals, in a way that the signal received by each single device is the result of the composition of more replicas of the same signal sent by other cooperating devices. Link cooperation, in this case, enables the reception of satellite services from handheld terminals when a cluster of cooperating users is present.