1. Introduction

One of the most important performance measures of a data network is the average delay required to deliver a packet from origin to destination. Furthermore, delay considerations strongly influence the choice and performance of network algorithms, such as routing and flow control. For these reasons, it is important to understand the nature and mechanism of delay and the manner in which it depends on the characteristics of the network.

This tutorial will delve into the origin of increased latency in communication networks, its impacts on various types of applications, and some recent efforts to reduce latency.

2. Origins of Network Latency

The following are the fundamental reasons for latency in communication networks:

Processing delay is the time the packet is correctly received at the head node of the link and the time the packet is assigned to an outgoing link queue for transmission. The processing delay is also independent of the amount of traffic handled by the corresponding node if computation power is not a limiting resource.

Queueing delay is the time between the moment the packet is assigned to a queue for transmission and the moment it starts being transmitted. During this time, the packet waits while other packets in the transmission queue are transmitted.

Transmission delay is the time between the moments that the first and last bits of the packet are transmitted.

Propagation delay is the time between the moment the last bit is transmitted at the head node of the link and the moment the last bit is received at the tail node. This is proportional to the physical distance between transmitter and receiver; it can be relatively substantial, particularly for a satellite link or a very high-speed link. The propagation delay depends on the physical characteristics of the link and is independent of the traffic carried by the link.

There are, however, other possibility that a packet is delayed during its transmission, including:

  • Network congestion: When network traffic is high, and there is a significant volume of data being transmitted simultaneously, it can lead to congestion. Congestion occurs when network resources, such as routers and switches, become overwhelmed, causing delays in data delivery
  • Network infrastructure: The quality and performance of the underlying network infrastructure can impact latency. Issues with routers, switches, or cabling can introduce delays in data transmission
  • Network protocol overhead: Network protocols add additional information to the data being transmitted to ensure its proper delivery. This extra data adds overhead and can increase latency, especially for small packets of data
  • Signal interference: In wireless networks, signal interference from other devices or physical obstacles like walls or buildings can degrade the quality of the connection and introduce latency
  • Routing: The process of determining the best path for data to travel across a network involves making decisions at each network node. If suboptimal routing decisions are made, data may take longer to reach its destination, increasing latency

It’s important to note that a combination of these factors can influence network latency, and addressing latency issues often requires troubleshooting and optimization at various levels of the network infrastructure.

3. Impacts of Network Latency on Applications

Network latency can significantly impact various applications, affecting their performance, responsiveness, and user experience. In what follows, we’ll delve into some common impacts of network latency on applications.

3.1. Web Browsing

High network latency can result in slow loading times for web pages. Users may experience delays when requesting web content, leading to a frustrating browsing experience. Latency can affect the time it takes to establish a connection with the server, retrieve resources, and render the web page.

3.2. Real-time Communication

Applications such as voice and video conferencing, online gaming, and live streaming heavily rely on low latency for real-time interaction. High latency can cause audio and video transmission delays, leading to noticeable lags, poor synchronization, and communication difficulties.

3.3. Cloud-based Applications

Cloud-based applications and services, including Software-as-a-Service (SaaS), rely on network connectivity to access remote servers and resources. Latency can impact the response time of these applications, making them feel sluggish and unresponsive. Users may experience delays when interacting with cloud-based software, decreasing productivity.

3.4. Online Transactions

E-commerce and financial applications require low latency to provide a smooth user experience during online transactions. High latency can introduce delays when submitting requests, processing payment transactions, or retrieving data, potentially leading to abandoned transactions and dissatisfied customers.

3.5. Content Delivery

Content-heavy applications, such as media streaming services and file-sharing platforms, depend on efficient content delivery to ensure uninterrupted playback and fast file transfers. Network latency can cause buffering issues, interruptions, and slow download/upload speeds, negatively impacting the user experience.

If 1-2 orders of magnitude can enhance the latency, it will bring a groundbreaking transformation in applications. The primary advantage will be seen in current applications that currently experience significant latency issues, like Facebook or Google’s statistical machine translation. The development of these applications will become much easier as there will be no need for complicated solutions to overcome high latency. Additionally, they will become faster and more adaptable, enabling real-time exploration of more extensive data.

Reducing network latency and ensuring a responsive network infrastructure is crucial to mitigating these impacts and providing a smooth and enjoyable user experience across various applications.

4. Recent Efforts to Reduce Network Latency

In recent years, several efforts and technologies have been developed to reduce network latency. Here are some notable examples:

4.1. Edge Computing

Edge computing involves placing computing resources and data storage closer to the edge of the network, near the source of data generation or the end-users. By reducing the physical distance between the data source and processing, edge computing helps minimize latency by reducing the round-trip time to centralized data centers.

4.2. Content Delivery Networks

Content Delivery Networks (CDNs) are distributed networks of servers strategically placed in various locations worldwide. They store and deliver content to users based on their geographic proximity. CDNs help reduce latency by serving content from servers that are closer to end-users, minimizing the distance data needs to travel.

4.3. Network Optimization Techniques

Various optimization techniques are employed to reduce latency. These include protocol optimizations, compression techniques, and data caching. For example, techniques like TCP optimization and packet loss mitigation algorithms help improve data transfer efficiency and reduce latency.

4.4. Low-latency Networking Protocols

Several networking protocols have been developed to reduce latency. For instance, the QUIC (Quick UDP Internet Connections) protocol is designed to minimize latency by using UDP instead of TCP and incorporating features like multiplexing and encryption.

4.5. 5G Technology

The deployment of 5G networks brings lower latency compared to previous generations. 5G’s reduced latency is achieved through technologies like network slicing, edge/fog computing, and advanced radio access architecture and techniques such as Open Radio Access Network (O-RAN).

These efforts collectively reduce network latency, enhance user experience, and enable new applications and services that rely on real-time data transmission.

5. Conclusion

In this article, we discussed network latency, its origins, its impacts on different kinds of applications, and some efforts to reduce it.

In conclusion, network latency plays a crucial role in various applications’ performance and user experience. Whether it’s web browsing, real-time communication, cloud-based services, or online transactions, high latency can lead to slow response times, delays, and frustrating user interactions.

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