What is a Jitter Buffer?

Network Jitter is a common feature faced by a network, even though most people are unaware of it. You’ll understand network jitter when you understand how information is transferred through various networks. You might send information as a whole from one computer to another (one end to another), but the information is transmitted in data packets through the internet. These data packs are transmitted over a period at regular intervals. A jitter happens when a delay in sending the data packets over your network connection occurs. There might be several reasons for the delay, such as network congestion or route changes.

In VoIP, the network you’ll come across a jitter buffer. It is the shared data area that collects, stores, and sends voice packets to the voice processor at regular intervals. Variations in the arrival time of the packet (jitter) occur due to timing drift, route changes, or network congestion, as mentioned before. The jitter buffer located at the receiving end of the voice connection purposefully delays the packet arrivals to ensure a clear connection with minimal sound distortion at the user end.

Types of Jitter Buffer

A jitter buffer can be static or dynamic. A static jitter buffer is usually hardware-centred, and the manufacturer configures it. Also known as fixed jitter buffer, it adds a fixed delay to voice packets. It is possible to configure the delay period for the static jitter buffer.

But a dynamic jitter buffer is software-based and is configured by the network administrator to adjust to any changes in a particular network’s delay. It is also known as an adaptive jitter buffer and can adapt based on delays in the network. You can configure the range of this delay time to ensure minimal distortion.

Minimum Delay and Maximum Delay

Two parameters are employed to limit the range of the delay. While receiving an RTP packet, if the packet delay is less than the minimum, it is called an underflow event. On the other hand, if the packet delay is greater than the maximum, it is an overflow event. Both scenarios will lead to packet loss and audio loss.

You can use maximum and minimum delays when the jitter buffer is fixed or static. If it is adaptive or dynamic, it will adjust itself according to the network latency, and an adaptive jitter buffer is usually recommended.

How to measure network jitter?

Single endpoint – if your network controls only one of the endpoints (single-ended), you can measure jitter by measuring the mean RTT or round-trip time and a minimum RTT of a sequence of voice packets.

Double endpoint – if your network controls more than one endpoint (double-ended path), you can measure jitter instantaneously by measuring the variation between the intervals in transmitting and receiving the packet. Jitter is the mean difference between the instantly measured jitter and the average instant jitter throughout the transmission period of the data packets.

How to fix network jitter?

Troubleshooting network jitter can be challenging as it is unpredictable. Set up your network correctly the first time to keep jitter to a minimum. You can reduce network jotter by ensuring a quality connection, sufficient bandwidth, and predictable latency.

Click here to learn more about network jitter, latency, and packet loss.