Introduction to Wireless Networks

A wireless network is a computer network that uses radio frequency (RF) signals to communicate between nodes. Each node contains devices that support various communication technologies. These devices include communication endpoints, such as wireless local area network (WLAN) stations, Bluetooth^® peripherals, and 5G UEs, and redistribution points like access points, Bluetooth central devices, and 5G gNodeBs. This topic introduces the types of wireless networks, key elements of a wireless network, and common network scenarios.

Types of Wireless Networks

Depending on their coverage area and intended use, wireless networks fall into three main types, as shown in this figure: wireless personal area networks (WPANs) for short-range personal devices, wireless local area networks (WLANs) for local access within buildings, and wireless wide area networks (WWANs) for long-distance communication.

This table presents an overview of these network types.

Network Type	Range	Example Technologies	Applications
WPAN	~10 meters	Bluetooth	Personal devices, wearables
WLAN	~100 meters	Wi-Fi	Homes, offices
WWAN	>10 kilometers	LTE, 5G, Satellite	Mobile broadband, rural access

Key Elements of Wireless Network

These are the key elements of a wireless network:

• Nodes and devices — Nodes are logical units that contain devices, each with technology-specific protocol layers. These nodes host the necessary communication protocols to enable devices to participate in the network. For example, a phone is a node that includes a Wi-Fi device, a cellular device, and a Bluetooth device.

• Protocol stack — A protocol stack is a layered framework of communication protocols, where each layer performs a specific role to enable efficient data exchange between nodes. This layered structure promotes modularity, enabling you to update or replace individual layers without affecting the entire system. For example, this figure shows the protocol stack of a node, including the application, transport, network, link, and physical layers.

• Service data unit (SDU) and protocol data unit (PDU) — An SDU is the data received by a protocol layer from the layer above. It serves as the input to that layer. The protocol layer then adds its own control information, such as headers or trailers, to the SDU, creating a PDU. The PDU is what the layer actually transmits to the layer below or over the air.

  The table shows how a "Hello" application message travels through the network protocol stack. In this example, the transport, network, and data link layers use TCP, IP, and Ethernet as their respective protocols. At each layer, the protocol treats the incoming data as an SDU, adds its own header (and sometimes a trailer), and passes a PDU to the next layer. The application layer sends "Hello" as user data. The transport layer adds a TCP header to ensure reliable delivery. The network layer adds an IP header to enable routing. The data link layer adds an Ethernet header and trailer to frame the packet for physical transmission.

  Layer	SDU	PDU
  Application	Not applicable	"Hello"
  Transport (TCP)	"Hello"	TCP header + "Hello"
  Network (IP)	TCP header + "Hello"	IP header + TCP header + "Hello"
  Data Link	IP header + TCP header + "Hello"	Ethernet header + IP header + TCP header+ "Hello"

• Wireless packet— A wireless packet represents a signal in a wireless network. It encapsulates the physical layer (PHY) transmission output, either as an abstract format, containing standard-specific information organized as a structure with the necessary fields, or as a full PHY format, which includes the actual time-domain waveform samples.

  For example, in abstract PHY modeling, the system estimates packet error rate (PER) based on link quality without generating waveforms. The link quality model computes the signal-to-interference-plus-noise ratio (SINR) per subcarrier using channel estimates, fading models, and noise variance. The link performance model then combines these SINRs into an effective SINR and predicts PER using modulation, coding, and lookup tables.

  In full PHY modeling, the system performs waveform generation and decoding. At the transmitter, it attaches a cyclic redundancy check (CRC), segments and encodes the data, applies rate matching, modulation, and precoding, and then performs modulation such as OFDM. At the receiver, it executes timing synchronization, demodulation, channel estimation, equalization, and decoding to recover the original data.

• In-phase and quadrature (IQ) samples — IQ samples are detailed physical-layer representations of wireless signals. A transmitter generates IQ samples to define the waveform it sends over the air, and a receiver captures them to reconstruct and analyze the received signal.

  Each IQ sample contains two components: an in-phase (I) component and a quadrature component (Q).

  These components are mathematically perpendicular (orthogonal) sine and cosine waveforms. Together, they represent both the amplitude and phase of the signal at each point in time. This structure enables you to accurately model signal modulation, transmission, and reception in wireless systems. For example, modulation symbols are the physical layer representations of data bits mapped onto waveform elements for transmission.

• Mobility pattern — A mobility pattern defines how nodes move within an area. It directly influences connectivity, link stability, and overall network performance.

• Wireless channel and channel modeling — A wireless channel is a segment of the electromagnetic spectrum used for data transmission. Channel modeling involves calculating the physical effects, such as interference, signal attenuation, and fading, that influence the signal as it travels from the transmitter to the receiver. Common examples of channel models include the path loss model, Rayleigh fading, Rician fading, and clustered delay line.

• Traffic pattern — A traffic pattern defines the type and behavior of application traffic generation within a network. It outlines how nodes generate and transmit information, which affects network load, latency, and overall performance. Common examples of traffic patterns include On-Off, voice over internet protocol (VoIP), video conference, and file transfer protocol (FTP).

• Network topology — Network topology describes how nodes connect and how data travels between them. Common wireless network topologies include star, mesh, and tree.

Network Scenarios

A network scenario describes the overall structure and composition of a network environment. It can be classified as either a homogeneous network, or a heterogeneous network.

• Homogeneous Network — A homogeneous network is a type of communication network in which all devices operate using the same protocols and standards. This figure shows homogeneous 5G, Bluetooth, and WLAN networks.

  A homogeneous network may include multiple subnetworks, such as several 5G cells, WLAN basic service sets (BSSs), or Bluetooth piconets, which might interfere with each other. For example, this sample 5G network topology consists of three cells. Cell-1 and Cell-3 operate on the same frequency band with interference, while Cell-2 uses a different band, avoiding interference with Cell-1 and Cell-3.

• Heterogeneous Network — A heterogeneous network consists of a variety of devices and systems that differ in network technologies. For example, both WLAN and Bluetooth use the 2.4 GHz spectrum. Although these technologies differ in protocol and operation, they share the same wireless spectrum in 2.4GHz band. This overlap can lead to mutual interference, necessitating careful spectrum sharing strategies and compatibility mechanisms to ensure reliable communication and minimize performance degradation.

  This figure shows a WLAN and Bluetooth coexistence scenario.