Efficient and robust header compression for real-time services

When real-time multimedia is carried over bandwidth-limited channels using the IP, UDP, and RTP protocols, it is critical to minimize the overhead due to the resulting encapsulating headers. When the payload is small, such as is often the case for voice-over-IP (VoIP) applications, these headers can use a large percentage of the available bandwidth. The overhead can be especially undesirable in wireless environments, where bandwidth is often both scarce and expensive. Error rates in these environments can be very high, dictating the need for robustness as well. This paper describes an IP/UDP/RTP header compression scheme called ACE (adaptive header compression), which utilizes traditional header compression concepts, but adds several new mechanisms to achieve very good bandwidth efficiency. Robustness to errors and error bursts is also achieved.