Estimation of carrier and channel parameters for land-mobile satellite channels

Information about the channel state is particularly useful for adapting transmission parameters to different fading conditions. With slowly fading channels, the signal-to-noise ratio (SNR) is the most significant figure of merit to obtain the required goals in terms of availability and throughput. Using mobile satellite links, however, the situation may change within the round-trip time. Therefore, not just SNR estimates have to be delivered to the transmitter station in the context of an adaptive coding and modulation strategy, but also some additional information about the signal-to-interference ratio (SIR) and, perhaps more important, the Doppler spread of the mobile link, which determines the amount of variation in time. Assuming a channel determined by correlated Rician fading, an appropriate estimation framework for carrier frequency and phase, SNR, SIR, and Doppler spread will be discussed in the current paper. The signal model reflects in principle the conditions on a time-selective land-mobile satellite link, whereas frequency selectivity - as it is typical for multipath propagation - is considered to be negligible.