What Are Communication Networks?

Communication networks are interconnected systems of nodes and links through which information is exchanged between devices, users, and services. Each network consists of endpoints such as computers, phones, or sensors, transmission media such as copper cables or optical fiber, and switching or routing equipment that directs traffic between points. The function of any communication network is to accept data from a source, carry it reliably across the network, and deliver it to one or more destinations, while meeting the capacity, delay, and reliability requirements of the applications it serves.

Networks are characterized by their scale, topology, and the protocols that govern how their nodes interact. The discipline draws on information theory, queuing theory, signal processing, and computer science to analyze network behavior and engineer systems that perform predictably under load. The IEEE Communications Society is the principal technical community for researchers and practitioners working on communication network design, analysis, and standards.

Network Architecture and Protocols

The architecture of a communication network defines how its functions are divided into layers and how those layers interact. The OSI reference model, standardized by ISO, identifies seven layers from the physical transmission of bits to the application-level services visible to users. The TCP/IP model, which underlies the internet, collapses the OSI layers into four: the link, network, transport, and application layers. Protocols at each layer specify exactly how nodes represent, sequence, and acknowledge data units. At the network layer, routing protocols such as OSPF and BGP determine the paths that packets follow through the network. At the link layer, the IEEE 802.3 Ethernet standard specifies how frames are formatted and transmitted over wired links from 1 Mb/s to 400 Gb/s.

Network Security

Network security is the set of practices and mechanisms that protect communication networks from unauthorized access, misuse, and disruption. Because networks carry sensitive data between parties that may not share physical space, the security properties of confidentiality, integrity, and availability must be enforced at multiple layers. Encryption protocols such as TLS protect data in transit at the transport layer. Firewalls and intrusion detection systems operate at the network and application layers to filter unwanted traffic. Powerline communication networks and wireless segments introduce additional attack surfaces because the transmission medium is physically accessible to adversaries. The NIST Cybersecurity Framework provides a widely adopted reference for network security practice, organizing protections around the functions of identify, protect, detect, respond, and recover.

Powerline Communication Networks

Powerline communication networks carry data over the electrical power distribution infrastructure that already reaches homes and industrial facilities, avoiding the cost of running dedicated communication cables. Data signals are superimposed on the AC mains waveform at frequencies above the 50 or 60 Hz power frequency and filtered out at the receiving end. Standards such as IEEE 1901 define the physical and link layers for broadband over powerline systems. These networks are used for smart-grid metering, home automation, and last-mile broadband access in areas where DSL or fiber deployment is not economical. The shared and sometimes electrically noisy nature of the power distribution medium makes signal conditioning and forward error correction especially important in powerline network design.

Applications

Communication networks have applications across a wide range of fields, including:

• Internet access for residential, enterprise, and mobile users via wired and wireless access technologies
• Industrial automation and process control, where deterministic communication between sensors, controllers, and actuators is required
• Financial services infrastructure, where low-latency networks link trading systems and payment processors
• Smart-grid monitoring and control, using powerline and cellular networks to coordinate distributed energy resources
• Emergency services and public safety, where resilient networks support dispatch, coordination, and situational awareness