We consider the uplink of a non-terrestrial network where a relay node is forwarding digitized signals via a rate limited error-prone forward link to the serving satellite. The focus of our investigations are the design of suitable low-bit resolution quantization schemes to limit the rate on the forward link and the optimization of the decoder processing at the satellite. To this end, we investigate Information Bottleneck (IB) based quantizer design with mutual information as fidelity criterion. The IB approach can be extended to consider also the error statistic of the forward link within the quantizer design. By numerical investigations we demonstrate the performance gains of this forward-aware IB quantizer in case of erroneous forward links. Furthermore, we investigate a lookup-table based decoder which is optimized for the end-to-end statistic including the access link, the quantizer and the forward link. This decoder implementation processes only discrete values using lookup-tables of small size. The numerical results show that the performance of 3-bit forward-aware IB quantizer in combination with a 3-bit discrete decoder implementation is close to the double-precision floating-point belief propagation decoder even for strongly errorprone forward links.