A broadcast transmission system transmits data packets from a server to a client over a unidirectional broadcast network. The system transmits both full-length data packets, which have uncompressed headers, and reduced-length data packets, which have compressed headers derived from associated uncompressed headers. The server compresses the data packets by compressing the packet header. Compressed packet headers contain fewer header fields than their associated uncompressed headers. The server transmits a series of intermixed full-length and reduced-length packets to the client. As the packets are received, the client determines whether the packets are full-length or reduced-length. If the packet is full-length, the client stores the uncompressed header in a header table. If the packet is reduced-length, the client rebuilds the compressed header from its corresponding uncompressed headers in the header table.