A processor device processes data samples of a radio signal in a mobile communication system. A fast flow process is executed for all samples and a batch process is executed at intervals on a subset of the samples. The device has a processor for executing the flow process via a local buffer memory, a memory interface to a system memory, and a memory controller for controlling storing of the data samples in the buffer memory. The processor establishes whether data samples in the local buffer memory are part of the subset, and if not, invalidates them after executing the flow process. The memory controller provides free memory space in the local buffer by transferring data samples which are not invalidated from the local buffer memory to the system memory, and by invalidating processed samples. Advantageously the local buffer may be relatively small, while the amount of data transferred to the system memory is limited.