Jitter, Delay, Throughput, and Packet Loss for QoS

I. Introduction

Nowadays, internet has been regarded as important thing in human life since 1996 when web page commercialized for the first time. In 1996 until 2002, web page showed static text content which did not need a huge bandwidth, but for sure at that time, our internet bandwidth was not as big as present.

Since 2002 until present, web page has been evolved and shows many contents even the multimedia contents like video and audio. As we know that video / audio contents need a huge bandwidth when transmitted. When it's transmitted in a crowded bandwidth, we will find delay issue and I trust that you ever been experienced about buffering process.

So, in multimedia transmission we need to make sure that our transmission media is qualified on QoS parameters. The indicators of QoS are jitter, delay, throughput, and packet loss. When our transmission media has a tolerated jitter, delay, throughput, and packet loss number, so we can know that our transmitted audio/video will be run smoothly.

II. What is Jitter, Delay, Throughput, and Packet Loss

1. Jitter

Jitter is the difference delay time of packets transmission between origin and destination because the time it takes for packets to be send is not the same as the period in which the will arrive at the receiver side. It's caused by many factors like the traffic on origin is less than destination so, on destination side will has many queue and makes jitter number becomes bigger. For better understanding, you may see this below picture :

In this image above, you can notice that one of the packets encounters some delay on his way and it is received little later than it was assumed. Audio/Video packets in networks have very changeable packet inter-arrival intervals because they are usually smaller than normal data packets and are therefore more numerous with bigger chance to get some delay.

2. Delay

Delay is a pending time on transmission process in one period for transmitting a packet from origin to destination. Delay can be categorized as :

• Packetization Delay, a delay which is happening on origin side because origin side needs time for transforming a data into IP packet data and ready to be sent.
• Queueing Delay, a delay which is caused of queueing process in router to handle all packet transmission from various sources.
• Propagation Delay, a delay which is caused by transmission media like copper cable, fiber optic cable, and radio. The worse propagation delay is on radio transmission because there are so many obstacles so some packets are failed to be sent and source / origin needs to resend the packet.

3. Throughput

Many sources write that throughput is a rate of how many something can be processed in one period. It means, how many packets data can be processed / transferred in one periode, for example : total data/second. Typically, throughputs are measured in Kbps, Mbps and Gbps.

4. Packet Loss

Packet loss is the failure of packet transmission to arrive at their destination. In TCP/IP protocol, when packet loss occurred, destination will ask to the source to resend the loss packet but it's causing a delay because the same packet will be sent twice or more. But, in UDP protocol, the loss packet will be ignored and causing improper display on destination site like this picture below :

The causes of packet loss include inadequate signal strength at the destination, natural or human-made interference, excessive system noise, hardware failure, software corruption or overburdened network nodes. Often more than one of these factors is involved.

III. Conclusion

Video/audio transmission like VoIP (Voice over IP), Video Streaming, and Video Call, highly depends with jitter, delay, throughput, and packet loss factors. Big throughput number impacts smaller number of jitter. delay, and packet loss. The smaller jitter, delay, and packet loss number indicate that the optimal Quality of Service (QoS) condition. But, computer network environment is too complicated and there are so many of factors which can decrease the QoS. One of factors can be involved or all of them in the same time.