This is a running count of payload bytes received over the satellite interface, specifically excluding HDLC framing overhead. Comparing it against cdmipWanFpgaRxHdlcHeaderCount lets an admin see exactly how much of the satellite link's received capacity is going to actual data versus HDLC framing cost. For example, if payload bytes are only slightly larger than header bytes over a given period, it suggests many small frames are being sent, wasting a disproportionate share of the link on overhead.