RTC (Real Time Communications) refer to any method of telecommunications wherein all users have the capability to exchange information in an instant way, or with a reasonable latency. In line with this, the term ‘real time’ is often synonymous to the term ‘live’.
RTC can happen in two types of modes: Half Duplex and Full Duplex.
Half Duplex RTC – data may be transmitted in two directions using a single circuit or carrier. However, it is not done at the same time.
Full Duplex RTC – data may be transmitted in two directions at the same time through a single circuit or carrier. This type of Real Time Communications typically points to peer-to-peer communications. It is quite different to multicast or broadcast communications.
In Real Time Communications, one thing is certain. There is always a path directly available in between the source, as well as the destination. Though the link may not include a number of intermediate notes, data travels from a source to the destination without the need to be stored anywhere. On the other hand, time-shifting communications generally involve a certain form of data storage in between the source and the destination.
Real Time Communications also involves:
- Conventional sense of Telephony
- Cellular and Mobile technology
- Multi way or two way amateur radio
- Instant Messaging (IM)
- IP or VoIP (Internet Phone or Voice over Internet Phone)
- Live video conferencing communications
- Live teleconferencing communications
- Robotic telepresence
For example, when messages are left through email on a blog, or on bulletin board, you are actually sending communications using the time shifting mode, and not in the real time mode. This means that there is latency, or a significant delay in between the transmission, as well as the receipt of the information between the source and the destination.
What RTC Offers?
- In Real Time communication, it is very important that the data arrives at the destination in a reliable manner. Aside from getting there fast, RTC works on making sure that a reliable quality of data is being sent accordingly. Therefore, it often employs the use of elastic applications, which are very useful to an enterprise.
- Of course, arriving in a timely manner is very important in real time communications. To accomplish this, messages may be given priority and delivered according to need.
Types of RTC Traffic:
- Asynchronous / Aperiodic Messages :
This type of messages generally does not have deadlines. Best effort in delivery is the main focus and small delays are maintained. This type of traffic is often characterized by an average delivery time.
- Synchronous Periodic Flow:
They are generally consumed and produced in a steady, continuous basis, while some are following a certain schedule.
They may require certain performance guarantees
They may also be generated often by periodic tasks, such as fixed rate flows (isochronous flow), or by message length, inter packet spacing and reception deadline.
They may also be generated through sporadic tasks, characterized by variable rate flows, maximum burst size and average throughput.
Factors that Affect Delay:
- Sender Queuing Delay:
This happens when the network is not yet ready to receive a packet as soon as it becomes available. As a result, data may be queued if it is produced faster than the speed that the network can deliver it.
- Receiver Queuing Delay:
This happens when the application itself becomes unready to accept data packets from the network. As a result, data may be delivered in bursts.
- Network Queuing Delay:
This happens due to bottleneck and cross traffic links
- Network Transit Time:
This is often referred to as fixed propagation delay