The present invention provides systems and methods for boundary detection of protocol data units in a communication system. A protocol entity such as a header check sequence (HCS) validation circuit is used to compute header check sequences of protocol data units in a packet burst. If a given HCS is valid, then the payload of the respective protocol data unit may be used. However, if the given HCS is invalid, then a parallel sliding window is used to compute other possible HCSs to identify a protocol data unit boundary. Once the boundary is located, then the payload may be used. Even if a protocol data unit is invalid or a header is not found, other protocol data units in a packet burst may be used in accordance with aspects of the invention. Such operation reduces the number of retransmissions required due to invalid HCSs.