Methods for improving memory resource allocation at a base station of a wireless communications system, based on a virtual minimum spreading factor, may include computing a maximum traffic-to-pilot (T2P) power ratio for a UE, and sending a grant message to the UE specifying the maximum T2P power ratio. The base station may determine a largest minimum spreading factor (SF) for the UE based on the computed maximum T2P power ratio. The base station may allocate a memory buffer for storing minimum SF signal samples, receive one or more spread spectrum signals from the UE, and partially despread the received signals using the largest minimum SF, thereby preparing partially despread signal samples in the memory buffer. The base station may receive, from the UE, information about the actual SF used by the UE, and despread the partially despread signal samples stored in the memory buffer using the actual SF.