MMTP - Multimedia Multiplexing Transport Protocol

Multimedia data has special requirements that are hard to be met on mobile hosts due to potentially low bandwidth and disruptions due to host mobility . Such limited communication capabilities of mobile hosts can be offset by the simultaneous use of multiple link layer technologies. MMTP is a member of a suite of protocols that share the novel characteristic of aggregating bandwidth from multiple link-layer channels. The use of multiple channels t o transport user data provides five key benefits: (1) a fatter pipe, (2) a fast feedback path, (3) the retransmission of selected lost messages, witho ut delaying the playout of the data stream, (4) less sensitivity to minor b andwidth fluctuations on any one individual channel, and (5) smooth vertica l handoffs for active data streams. MMTP is a rate-based protocol designed for transferring multimedia data on mobile systems, and makes simultaneous use of every communication channel a vailable to send data at the required rate. Transmission in MMTP is governe d by two mechanisms. The first is a set of rate control protocols associate d with each outgoing channel. The second is a scheduling algorithm that pla ces incoming packets on the appropriate channel. MMTP is link-layer aware p rotocol that uses bandwidth estimation for congestion control, and relays t o the application information needed for rate adaptation. In this paper, we show that the quality of data transmission can be improved through the use of MMTP through experimental comparisons with data transmitted via UDP. We also demonstrate the economy of bandwidth: MMTP only sends packets that it estimates will arrive within the packet deadline, thus decreasing the numb er of late packets that will be discarded at the receiver.