Navigating Through The Spectrum: Exploring the Invisible Frequency Bands in Modern Connectivity

In the late 19th century, Heinrich Rudolf Hertz demonstrated the existence of the electromagnetic spectrum, marking a pivotal moment in the evolution of communication. Today, cellular IoT leverages these cellular frequency bands to enable seamless communication between countless connected devices within a connected network.

Later in the 1990s, cellular network technologies such as 2G (GSM, GPRS) became widespread. They were used for the earliest types of IoT applications, by utilizing 900 MHz and 1800 MHz bands in many parts of the world.

In Mid-2000s with the advent of 3G, higher data rates became available, enhancing capabilities for more data-intensive IoT applications. Frequencies around 2.1 GHz (part of the UHF band) started being used more extensively for IoT, enabling better transmission of real-time data and supporting more sophisticated applications in healthcare, logistics, and smarter cities.

The rollout of 4G LTE in the 2010s marked a significant boost in IoT connectivity with even higher data rates and lower latency. LTE cellular bands like 600 MHz to 2.6 GHz offered enhanced efficiency and reliability, ideal for emerging IoT technologies in smart homes, industrial automation, and more complex city infrastructure management.

Learn More: 7 IoT Applications in 2024

The Backbone of Wireless Connectivity: Cellular Frequency Bands

Cellular frequency bands are specific parts of the radio spectrum allocated for cellular network use in telecommunications, enabling communication between mobile devices and cell towers. They carry voice and data across cellular networks, facilitating phone calls, text messages, internet browsing, and streaming services on mobile devices.

Of course, Gen-Z reading this may be astonished to hear that manually tuning TV antennas is a thing of the past.

Just as we once adjusted TV antennas to capture specific channels, now cellular networks use designated frequency bands to power IoT applications. Each cellular frequency band ensures optimal performance for specific IoT devices and applications.

The radio spectrum, divided into bands, is identified by a number or a name, and managed by national and international regulatory bodies like FCC (Federal Communications Commission) and ITU (International Telecommunication Union). These authorities allocate spectrum for various services, like cellular communications and interference management to ensure compatibility.

The Power Duo: Cellular Frequency Bands and Their Cellular Network Technologies

Cellular frequency bands and cellular network technologies are correlated as they work on these designated ranges of radio frequencies for cellular communication.

Low-band Spectrum

• To start with, earlier generations such as legacy 2G and 3G networks used low-band frequencies to provide wide coverage. Typically below 1 GHz, these frequencies offer better range and signal penetration, making them ideal for achieving broader network coverage. However, the data speeds were relatively low, offering only a few Mbps in real-world scenarios, which was sufficient for basic services like voice calls and text messaging.
• With advancements in technology, 4G LTE networks began utilizing low-band frequencies such as 700 MHz and 800 MHz. These frequencies provided data speeds of up to 50 Mbps in LTE Category 4 and up to 100 Mbps in Category 6.

Mid-band Spectrum

• The next generation 5G network operates in the FR1 frequency range, from 1 GHz to 6 GHz (Sub-6 GHz), which falls under the mid-band spectrum. This range offers a balance between coverage and data speed, providing broader coverage than the high-band spectrum.
• The 5G network using mid-band frequencies is theoretically capable of delivering maximum data speeds of 2 Gbps to 5 Gbps with advanced 5G features like carrier aggregation, 4x4 MIMO, and 256-QAM.

To learn further about the Sub-6 GHz range and other 5G features, refer to our blog on 5G NR

High-band Spectrum or Millimeter Wave (mmWave)

• It is commonly used in 5G networks and is known as the 5G mmWave spectrum. The 5G network is designed to work on millimeter waves (FR 2) above 6 GHz. These frequencies offer the highest data speeds but have a shorter range and require more infrastructure like small cells to provide seamless coverage to urban areas effectively. The theoretical peak data rate of 5G NR mmWave is up to 20 Gbps.

To know more about these 5G frequencies, refer to our blog on 5G mmWave and Sub-6 GHz

• Note : The specific cellular bands can vary by country and operator, depending on the spectrum licenses they hold and the technologies they deploy (e.g., 3G, 4G LTE, 5G).

Understanding the Power of Low band LTE Frequencies in Shaping Global IoT Connectivity

LTE bands refer to the specific radio frequencies allocated for the Long Term Evolution (LTE) technology, which is a standard for wireless broadband communication. LTE is used worldwide for internet access and is an essential part of modern telecommunications. These bands allow mobile phones, tablets, and other connected IoT devices to communicate with mobile networks.

LTE frequency bands are crucial in various cellular technologies like

• 4G Networks is synonymous with Long Term Evolution, providing high-speed data and voice communications. It supports streaming, browsing, and downloading at much faster speeds compared to 3G networks.
• NB-IoT (Narrowband IoT) operating on LTE bands, focuses on indoor coverage, low cost, long battery life, and high connection density.
• LTE-M is designed for machine-to-machine communication, a low power wide area technology which operates within the LTE bands. It is used in IoT devices that require long battery life and wide coverage.

LTE Communication Unpacked: TDD and FDD in LTE Cellular Communication Explained

The LTE frequency bands can be categorized into two types: TDD (Time Division Duplex) and FDD (Frequency Division Duplex)

TDD LTE Bands

Consider a traditional walkie-talkie, operating on a single channel for both talking and listening. It switches modes using a technique called “push-to-talk” (PTT), preventing the signals from interfering with each other.

TDD LTE bands similarly use a single frequency band for both uplink and downlink but allocate different time intervals for each direction. This type is more flexible in managing asymmetric traffic, where download and upload demands differ significantly.

FDD LTE Bands

Now imagine using two walkie-talkies, set to different channels: one for talking and one for listening. This separation prevents the signals from interfering with each other.

This method is known as Frequency Division Duplexing (FDD). It allows communication to occur in both directions at the same time without interference. FDD separates frequencies for uplink and downlink to allow simultaneous communication.

These bands use paired spectrum allocations, with separate frequencies for uplink (transmitting from the device to the tower) and downlink (transmitting from the tower to the device). Most of the global LTE network deployments use FDD because it efficiently uses spectrum for symmetric traffic.

NB-IoT Frequency Bands

There are 26 NB-IoT frequency bands in total, and the NB-IoT spectrum does not include Time Division Duplex (TDD) bands. NB-IoT deployments are mainly done in three bands: Standalone, Guard band and In-band.

Standalone

A standalone deployment uses a dedicated frequency band that is not shared with LTE or other cellular technologies.

Guard Band

Guard Band deployment utilizes the unused spectrum between two frequency bands, known as the guard band, to minimize interference between those bands.

In-Band

In-Band deployment means it is integrated within an existing frequency band that is already in use by another cellular technology, like LTE.

So for NB-IoT, in-band deployment involves using resource blocks within the LTE frequency band, allowing both types of technology to coexist efficiently on the same frequency band without interfering with each other.

Amusing Tech Chronicles

Facts and Anecdotes related to this edition of Wireless By Design

Musical Notes

Think of cellular frequency bands as musical notes on a musical instrument. Each note represents a specific frequency, and just as different notes create different melodies, different frequency bands facilitate different types of communication services.

Traffic Lights

Cellular frequency bands can be likened to traffic lights at intersections. Different bands serve different purposes, much like traffic lights control the flow of vehicles from different directions. Each light (band) operates independently to ensure smooth and organized communication.

Water Pipes

Imagine cellular frequency bands as different pipes carrying water of varying sizes. Each pipe represents a band, and the size of the pipe (frequency range) determines how much data can flow through it at once. Just as larger pipes allow more water to flow, wider frequency bands accommodate higher data transfer rates.

Closing Notes

The evolution of cellular networks has led to the development of diverse frequency allocation strategies, including FDD and TDD approaches, each tailored to meet specific needs for uplink and downlink transmission. Coordinated efforts by organizations like the 3GPP have standardized these bands globally, enabling interoperability and facilitating seamless connectivity for users worldwide.

As the demand for mobile data continues to surge, the efficient management and utilization of cellular frequency bands will remain critical to ensuring optimal performance and expanding the reach of wireless networks in the future.

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