Contents

1 Buffering (jitter hiding)

• Error-correction/congestion-avoiding techniques which are based on ARQ protocols sometimes produce a high jitter (variation of the latency).
• Other times, the jitter is a direct consequence of the variation of the transmission bit-rates (most current transmission technologies use store-and-forward strategies and relatively large packets).
• The simplest and most used technique to provide a seamless playback is by using a buffer at the receiver, which delays the reproduction of the stream a reasonable amount of time.
• Example: YouTube.

2 Redundancy piggybacking

• Jitter (i.e., buffering time) can be minimized if some kind of information redundancy is introduced, avoiding the ARQ solution.
• Example:

3 Interpolation + Interleaving (increase quality in error-prone environments)

• Another technique for avoiding ARQ.
• Most transmission errors produce a random alteration in a contiguous sequence of symbols (burst errors).
• By interlaving the information before the transmission we spread the errors along the time (reducing the length of the bursts). Signal interpolation is easier if the burst errors are shorter.
• Example:

4 Buffer minimization

• Simulcasting and scalable video coding can help to minimize buffering times because receivers can modulate the bit-rate transmission of the senders.
• In the case of using multiple description coding, the buffer will not underflow whenever at least one description is received.

5 Content-aware routing

• Multimedia traffic is time-sensitive.
• Routers could prioritize multimedia data in order to minimize the latency and/or maximize the bit-rate of this information.
• Unfortunately, this implies data-labeling and important changes in the current tarification system.