Beginners: Radio Frequency, Band and Spectrum
Hello and welcome back to our channel. We are excited to share an updated version of one of our most popular videos originally created back in 2017. At that time, many aspects of 5G were still uncertain, but today there's so much more to explore, especially with 6G already on the horizon. So, let's
dive into this fresh update. Before we dive in, a quick heads up. This video offers a simplified explanation of what is in reality a rather complex topic. To keep things
high level, we have skipped over some of the finer details. It might feel a little slow to start with, but stick with us. It gets more interesting as we go along. Here's a quick overview of what we'll be covering in this video.
Let's kick things off with the basics of spectrum. So what exactly is spectrum? The word spectrum is the singular form for which the plural is spectra or spectrums. Spectra is the more traditional and scientific plural while spectrums is more commonly used in general or figurative contexts such as social or political spectrums. Spectrum is used to classify something on a scale between two extreme points. So for
example, in our daily lives, we refer to the political spectrum which consists of hard left-wing parties to extreme right-wing parties and many different political standpoints in between. Another example is the socioeconomic spectrum which in the UK includes the working class, middle class and upper class. In this video though, we will focus on the radio spectrum which is the part of the larger electromagnetic spectrum. Here's a simple chart showing the entire electromagnetic spectrum. Keep in mind there are many ways to represent it visually. One of the best ways to explore this further is to search for electromagnetic spectrum on Google. You'll find plenty of charts and
diagrams. Have a browse and pick the one that makes the most sense to you. Let's take a moment to understand electromagnetic waves. Electromagnetic
waves are synchronized oscillations of electric and magnetic fields. In a vacuum, they travel at the speed of light, which is commonly denoted by the letter C in physics. The illustration shows a linearly polarized electromagnetic wave moving along the x-axis. The electric field shown in blue oscillates vertically while the magnetic field shown in red oscillates horizontally. These two fields are
always perpendicular to each other and also to the direction in which the wave is traveling. What exactly is frequency? In simple terms, frequency refers to something that happens repeatedly, consistently, and over and over again. Technically, frequency is the number of times a specific event occurs within a given time interval. It's measured in hertz, which represents the number of cycles per second. Take a look at this picture of an alternative current wave. The wave
starts at zero, rises to a peak, returns to zero, dips below zero, and then comes back to zero. This full motion completes one cycle, giving it a frequency of 1 hertz if it happens once in a second. In this example, the wave completes five cycles in 1 second. So, it has a frequency of 5 hertz.
The electromagnetic spectrum refers to the entire range of frequencies of electromagnetic radiation spanning from 3 herz to 300 exahertz. To give you an idea of just how big an exahertz is, I have included all the zeros here. It's an incredibly large number. You might
notice that different sources show slight variations. Some start at 30 Hz, others at 30 and even 300 Hz with the upper limit ranging from 100 to 300 exahertz. But don't worry too much about these differences. They are not critical for our discussion. Most of you probably know
this already. A,000 Hz makes a kilohz. 1,00 kilohz makes a megahertz. And 1,000 MHz make a gigahertz. Some people say
gigahertz, but I think the pronoun correct pronunciation is gigahertz. A th00and ghahertz makes a terraertz. And this is where things start to get really interesting in emerging mobile technology. For this presentation, we'll mainly focus on megahertz and gigahertz with a brief look at terraertz when we get to 6G.
Look again at the electromagnetic spectrum chart. The radio spectrum is a portion of the electromagnetic spectrum that spans from 3 herz up to 3 terraertz. In the chart shown here, it's depicted from 3 herz to just under 1 terz. But in general, it's considered to extend up to 3 terraertz. As with many scientific topics, you may come across slight variations in the range depending on the source. So don't be surprised if
the values differ a little. The next thing we need to understand is what is frequency band or a spectrum band. A frequency band, also called a spectrum band, is simply a group of frequencies that are grouped together to make them easier to manage and remember. Bandwidth refers to the
difference between the highest and lowest frequencies within a defined or even undefined band. For example, if we have a band ranging from 700 MGHertz to 800 MHz, the bandwidth of that band would be 100 MHz. Larger bandwidth means more data can flow through. To help visualize this, think of bandwidth as a pipe carrying water. The wider the pipe, the more water can flow through it. In the same way, the larger the bandwidth, the more data can travel through the connection. So just like bigger pipe
allows more water, a larger bandwidth allows more data to be transferred. Now let's try and understand wavelength. Wavelength generally written as Greek letter letter lambda is the distance between two similar points on consecutive waves. It's calculated as C divided by F where C is the speed of light and F is the frequency. While the
exact speed of light is shown here, it's often rounded to 3 into 10 to 8 m/s to keep calculation simple. So for a frequency of 1 MHz the wavelength would be roughly 300 m and for 1 GHz it around 30 cm. Wavelength is an important concept especially when it comes to calculating the length of an antenna. So it's definitely something to keep in mind. Looking at the electromagnetic spectrum chart again, you can see that at 1 ghahertz, the wavelength is roughly 30 cm or about 1 ft. The wavelength is
shown on the first horizontal line while the frequency appears on the fourth. As you move up the chart to higher frequencies such as 100 GHz, the wavelength becomes much smaller down to around 1 mm. The key takeaway here is this. As frequency increases, the wavelength decreases. It's an important point to remember. Let's now try to understand
phase. Phase refers to a situation where two or more waveforms of the same frequency, same cycle and same wavelength are not exactly aligned with each other. Phase can be measured in terms of distance, time or degrees. In the image here, you can see
two waves. The second wave is offset by 90° from the first, meaning it's 90° out of phase. In another example, the two waves are 180° out of phase, meaning they are perfectly opposite to each other. Understanding phase is crucial because it helps explain how waves interact. But
first, let's answer a simple question. Why do waves have different phases in the first place? The short answer is this. When radio waves are transmitted, they don't always follow the same path. One wave might travel directly while another might reflect off a building or a vehicle arriving slightly later and ending up out of phase with the original wave. Now these waves may also differ in
amplitude but we'll come to that in the next couple of slides. In this example, two waves have the same frequency but arrive with different phases. In fact, the phase between them is constantly changing. Notice how the pink wave created by combining the two individual waves sometimes amplifies that is doubles actually and sometimes cancels out. If we were to use a simple combiner, the result could be incorrect. This is why when designing mobile phones and other wireless devices, engineers must ensure that the waves are combined with the correct phase shift.
This phase shift is typically calculated using training or pilot symbols. In modern devices with multiple antennas, the different phases of the signals received at each antenna can also be used to estimate the direction of arrival. That's a more complex topic. We won't go into this tutorial, but it's worth knowing that phase plays a crucial role in wireless communication. Now let's understand amplitude. Amplitude refers to the height, force or power of a wave. The
greater the power, the larger the amplitude. For example, when I speak loudly, my voice has more amplitude. If I speak quietly, the amplitude is smaller and you might struggle to hear me. So you can think of amplitude as the power of the wave.
A common question is how amplitude relates to frequency, wavelength or phase. The truth is amplitude has no direct relationship with any of these. Frequency, wavelength and phase are completely separate from amplitude. A quick tangent here. While most of the non-English-speaking world uses antennas as the plural of antenna, in some English-speaking countries, people also often use the word antony. Frankly, both are correct, but they are used in different contexts. We use the term antennas when
referring to electrical instruments like rods or wires used for sending or receiving radio waves. In in the example here you can see various antennas mounted on the mobile towers. Antine on the other hand refers to the pro prouuberances found on the head of insects, crabs or other anthropods. The photos here show the
antony of a beetle and a honeybee. Okay. Now let's talk about antennas and wavelength. As I mentioned earlier, antennas are closely related to wavelength. In general, for optimal reception, antennas are typically designed to be about half the wavelength or lambda by 2. However, in some cases,
they can be as short as lambda by 10. To give you an example, I have chosen one of my favorite cars, the Honda Jazz. On the left, the car has antennas designed for FM radio only, covering the frequency range of 88 to 108 MHz here in the UK. On the right, the car features antennas that support both FM radio and digital DAB radio, which operates between 175 to 230 MHz. This is a simplified explanation, of course. In reality, the car on the right uses an active antenna, which is more advanced concept that we won't go get into in this video. Now, let's talk about television
antennas. Some of you may remember using rabbit ears antennas. The antennas on the left is optimized for receiving VHF signals which range from 30 to 300 MGHertz. For the best reception, it
requires a strong highquality signal with good amplitude. On the right, we have a more advanced antenna that can capture a wider range of frequencies. It not only receives VHF but also works with higher frequencies and it can still perform well even with a weaker signal. Its
design is a bit like a magnifying glass. It helps amplify the incoming signals making it easier for the TV to receive them and produce a clearer picture. One common question I often hear whether on forums or in conversations is about the importance of low frequency versus high frequency especially in the context of mobile technology. So should mobile networks use low frequencies or high frequencies? It's a great question but unfortunately there's no simple answer. When you use higher frequencies, the signal decays more quickly. For example, if you have two antennas at the same location, one transmitting at low frequency and the other at high frequency and both transmit at the same power, the low frequency signal will travel much further. In this example, I
am comparing 900 MHz uh low frequency and 200 2.1 GHz high frequency. As you can see, the 2.1 GHz signal decays much faster than the 900 MHz one. However, cell capacity is also important. With lower frequencies, you can cover more users within a single cell. But that also means each user gets
a lower data rate. On the other hand, higher frequencies create smaller cells, which means fewer users per cell. and higher data rates per user. So, while high frequencies can
deliver faster data speeds, they come with challenges such as poor penetration through walls and a tendency to reflect more easily. In contrast, low frequency signals may get attenuated but can still penetrate buildings better. That's why some of you may remember that the original GSM frequency was 900 MGHertz. It provided better coverage and inbuilding performance than GSM at 1800 MHz. The higher 1800 MHz signal decays faster and struggles with penetration whereas 900 MHz is much more resilient in such conditions. This chart is a bit dated. It shows the frequency bands in use during the early stages of 4G uh LT rollouts around 2015. It highlights the
spectrum used in different parts of the world. You can see that 900 MHz was primarily used for GSM. In fact, both 900 MHz and 1800 MHz were originally the main frequencies for GSM. That's the blue area on the chart. However, over time, many of the 1800 MHz frequencies were reformed for LT or 4G.
This means they were reused to deliver 4G services. Although the chart doesn't reflect the change, 1,800 MGHertz, also known as band 3, eventually became one of the most common 4G bands worldwide. Similarly, 21 me 2100 MHz shown in green was widely used for 3G. While 3G was deployed on other bands, uh through 2100 MHz was the most common. But 3G at 2100
MHz had a drawback. It struggled with indoor penetration. That's why even when you had GSM signal indoors, you might not have had 3G because 2100 MHz signals don't penetrate buildings as well as lower frequencies. It's generally estimated that to cover the same area using 3G at 2100 MHz, you'd need around four times as many cells compared to something like GSM at 900 MHz.
Another important concept to understand and remember is the difference between FDD and TDD. Frequency division duplex or FDD uses two separate frequency bands, one for uplink and one for down link. This allows for simultaneous transmission in both directions. It's simpler to implement and doesn't require tight synchronization, but it does need paired spectrum and has a fixed up link to down link ratio. On the other hand, time
division duplex or TDD uses the same frequency band for both up link and down link just at different times. That makes it more flexible, especially when adjusting up link and down link capacity based on demand. However, TDD requires precise synchronization across the entire network which makes the implementation more complex. The key advantage, it doesn't require paired spectrum. Let's continue with our
example of antennas. Here we have an old GSM 900 feature phone and you can see that the antenna sticking out. This is because at 900 MHz slightly larger antennas were needed to ensure better signal reception. In the past, GSM phones often had external antennas that extended from the body of the phone. These larger antennas helped improve signal reception by providing more space to capture signals effectively.
They were also often optimized for specific frequency bands, making them particularly useful in areas with weaker coverage. In modern smartphones, the antennas are built into the phone, integrated into the casing. Although these internal antennas are smaller and more compact, they are carefully designed to provide strong and reliable reception. Thanks to advances in antenna technology such as myo multiple input multiple output and antenna diversity, internal antennas today can offer similar or even better performance than older external ones. These technologies
use multiple antennas inside the phone to improve reception, reduce interference, and maintain stable connections. That said, the performance of internal antennas can still be affected by things like phone's design, the materials used, or how the phone is held. But despite these challenges, modern smartphones are engineered to perform well under most conditions.
While external antennas had certain advantages in their time, internal antennas today are highly efficient and optimized for the latest network technologies, including 4G, 5G, and even beyond. Here's an example using the iPhone 4, which shows how modern smartphones need to support a wide range of radio technologies while keeping antennas integrated and out of sight. On the left you can see the antenna design used in most parts of the world. This
supported common standards like GSM and UMTS. However, in the United States, the phone also needed to support the 3GPP2 CDMMA standard also known as EVDO. This required a slightly different antenna layout which you can see highlighted in the red on the right. This gives you an idea of how smartphones must accommodate a wide range of technologies, often with regional variation in design. You will also notice antennas for Bluetooth, Wi-Fi, and GPS. These are much smaller, but they
are still crucial for their specific functions and must be designed to work efficiently alongside mobile network antennas, all within the same compact device. This example features the Samsung Galaxy S8 which at the time of original presentation was either newly released or just about to launch. It highlights the variety of antennas integrated into a modern smartphone. Each antenna is
carefully designed and positioned to maximize performance while still fitting seamlessly into the phone's sleek design. It's a great example of how far antenna technology has come, adapting to increasingly compact devices without compromising functionality. Let's wrap up this section with an example from the Realme GT2 Pro released in January 2022. Most premium 5G smartphones typically feature eight antennas or more, but the GT2 Pro takes things a step further with 12 strategically placed antennas around its body. These form part of its innovative antenna array metric system as shown here.
This clever design allows the phone to automatically select the optimal antenna based on the user scenario, helping to maintain stronger signal strength, better connectivity, and overall improved performance even in more challenging conditions. Now that we have got a good grasp of the basics, let's explore how spectrum works in the world of 5G. Let's revisit the electromagnetic spectrum chart. This time I'm using an
example from Ofcom. It illustrates the full range of spectrum from low frequencies all the way up to extremely high frequencies about 300 exhertz. You'll notice that frequencies are broadly classified into two types. Nonionizing radiation is considered safe for humans and other living organisms as it doesn't have enough energy to ionize atoms or molecules. Ionizing radiation which begins above the visible light range can cause cellular damage and DNA mutations potentially leading to cancer or other health issues. Despite this risk, it
also plays a vital role in medical applications such as X-rays, CT scans, and radiotherapy for cancer treatment. The key takeaway here is that visible light, the light we receive from sun is also a part of the electromagnetic spectrum. In fact, our eyes are natural receivers of electromagnetic waves uniquely tuned to detect a very narrow portion called the visible light spectrum. Understanding
this helps to dispel common myths about mobile communication. While mobile technologies use higher frequencies, they remain within the nonionizing range, which means they are not harmful to human health. Originally 3GPP focused on frequencies from 450 MHz to 52.6 GHz for 5G. These were divided into two parts. Frequency range one or FR1 covering 450 MHz to 7.125 GHz and frequency range 2 or FR2 covering 24.25 25 GHz to 52.6
GHz. However, this information is now outdated as the 5G spectrum continues to evolve and expand. 3GPP has now expanded the 5G frequency range from 410 MHz to 71 GHz. FR1 now starts at 410 MHz and goes up to 7.125 GHz. FR2 has been further subdivided into FR21 that covers the original range from 24.25 to 52.6 GHz and the new FR22 which extends this from 52.6 GHz to
71 GHz. One point worth noting is that technically millimeter wave refers to frequencies from 30 GHz to 300 GHz where the wavelength is less than 1 mm. But in practice people often refer to the entire FR2 range as millimeter wave even though part of it actually starts below 30 GHz. So when someone talks about
millimeter wave, it's worth asking what exactly they mean, especially in technical discussions. Here's a simple comparison between nonmave and mmwave 5G spectrum. Nonmave 5G accounts for the majority of 5G deployments worldwide. It's widely
used because it offers a good balance between coverage and capacity. Millimeter wave 5G on the other hand enables ultra high speeds and low latency, but it's only used in very limited deployments due to its short range and susceptibility to obstacles. So although millimeter wave often gets a lot of attention, the reality is that most 5G users today are connected via nonmwave spectrum. Here's a summary of popular frequency bands across different technologies. Starting with 2G, 3G, and 4G. These technologies primarily operated in bands below 3 GHz. Then we have 5G FR1 deployments.
These use the coverage layer below 1 GHz as well as the midband capacity layer typically using TDD. As we saw earlier, MMWave 5G has had limited deployment mainly in specific scenarios. Now let's look at some complimentary technologies to mobile networks. First there's the 2.4 GHz ISM band which is widely used for older Wi-Fi, Bluetooth, microwave ovens and more. Then we have the 5 GHz band
popular for modern Wi-Fi and various other short range technologies. More recently, the 6 GHz band has become available used by Wi-Fi 6 and Wi-Fi 7 and also being considered for future use in 5G and 6G. We'll explore this in more detail later on. And finally, there's 60 GHz Wi-Fi, also known as Y gig. This chart illustrates the different layers of 5G spectrum, each serving a distinct purpose. The coverage layer
below 1 ghahertz is primarily used to provide wide area coverage and strong indoor penetration. It's ideal for ensuring basic connectivity in both urban and rural areas. However, due to limited bandwidth, it offers low data rates. The capacity layer between 1 and 7 GHz also known as mid-band spectrum strikes a balance between coverage and capacity. This is similar to the
frequency range used in LT today and is essential for delivering higher data rates particularly in densely populated areas. The higher throughput layer above 24.25 GHz is commonly referred to as MMA. Technically mm wave starts at 30 GHz and the range just below that could be considered centimeter wave. But in practice the entire FR2 band is often grouped under the term MM wave. So these
high frequency bands support extremely high data rates. But they come with trade-offs such as limited range uh and weaker penetration that makes them best suited to specific high demand environments like stadiums, airports, and dense urban hotspots. Each of these spectrum layers play a crucial role in meeting the diverse performance needs of 5G networks from wide coverage to ultra high speeded connectivity. The Global Mobile Suppliers Association or GSA has shared data on the 5G spectrum currently in use across public and private networks worldwide. As shown here, the Cband, particularly the 3.4 to 3.8 GHz range, has become the most
widely adopted band for 5G deployments. This mid-band spectrum offers an excellent balance between coverage and capacity which makes it the preferred choice for many operators around the globe. This chart from Qualcomm provides an excellent overview of allocated and targeted 5G spectrum across various countries and regions. It aligns well with the GSA data we looked at earlier, reinforcing the global trends in 5G spectrum deployment. This spectrum layers
diagram, often called the spectrum layer cake, illustrates the different frequency layers we discussed earlier, highlighting their respective coverage and capacity characteristics. Notably, the midband is split into two sections to distinguish between FDD and TDD spectrum. Frequencies above 2.7 GHz are predominantly TDD, while those below 2.3 GHz are mostly FDD. In the range between 2.3 and 2.7 GHz, both FDD and TDD bands
are in use. This version of the spectrum layers diagram includes the most widely used frequency bands not just for 5G but also for legacy technologies like 2G, 3G and 4G. It offers a comprehensive view of how different generations of mobile networks have made use of various parts of the spectrum over time. Earlier we looked at antennas used in feature phones and smartphones. Now that we have discussed mm technology, here's an older slide from Samsung showing a prototype device with antennas operating at 28 GHz. At mmf frequencies, the wavelength is much smaller, which means the antennas themselves can be much smaller. This allows manufacturer to fit
two 16 element antenna arrays into the device. Something that wouldn't be possible at lower frequencies. It's important to remember that new technologies don't replace old ones overnight. These MMA antennas are added in addition to the existing ones because the phone still needs to support legacy networks like 2G, 3G and 4G along with Wi-Fi, Bluetooth and GPS. As a result, modern devices end up with multiple antennas each serving different purpose. One of the key advantages of MM wave is that you can pack in more antenna elements which not only improves reception but also enables advanced techniques like be beam forming allowing for better signal direction and greater efficiency.
Let's shift focus slightly and explore the bandwidth requirements and speeds associated with 4G LTE, 5G non-standalone, NSA, and 5G standalone SA. While many of you may already be familiar with the difference between standalone and non-standalone 5G, it's worth quickly revisiting, especially for those newer to the topic. This simple diagram from Ericson helps explain the differences clearly. A standalone network, whether it's 4G or 5G, relies solely on components from the same generation of technology. In 4G, this
means the LT radio access network, also known as EUR, connects to the 4G core or EPC. In 5G standalone, the network uses 5G new radio along with the 5G core. By contrast, 5G non-standalone is a transitional architecture. Here, the 5G radio network works alongside the existing 4G radio and both connect back to the 4G core. This approach allows
faster rollouts and backward compatibility, giving operators more time to build out their full 5G core networks. Understanding this distinction is important when comparing real world speeds and capabilities across different types of 5G deployments. In 4G LTE, it became possible to combine multiple spectrum bands, a technique known as carrier aggregation. The same principle applies
to 5G as well. In fact, 5G non-standalone takes it a step further by combining carrier aggregated 4G and 5G bands through a feature called dual connectivity. As the note on this slide highlights, the latest evolution of LT known as LT advanced pro supports carrier aggregation of up to 32 component carriers each with a maximum bandwidth of 20 MHz. In comparison, 5G allows carrier aggregation of up to 16 component carriers, but each carrier can be as wide as 400 MGHertz. This dramatic increase in bandwidth per carrier makes it possible to deliver much higher data rates and lower latency, especially in mid-band and mmwave deployments.
It's important to note that just because certain component carriers can be aggregated in LT, it doesn't necessarily mean they can also be aggregated in 5G dual connectivity setup. There are various practical and technical reasons such as device limitations, network configurations or spectrum availability that might prevent this from happening. So, it's entirely possible to encounter situations where aggregation that works in LTE doesn't translate directly to a 5G dual connectivity scenario. It's
something to keep in mind when evaluating or deploying real world networks. Let's now look at the theoretical scenario with dual connectivity. In a 5G non-standalone setup, the total available bandwidth is the sum of carrier aggregated 4G bandwidth and the carrier aggregated 5G bandwidth. In contrast, 5G standalone only uses 5G carrier aggregated bandwidth since it operates independently of the 4G network. As we discussed earlier,
download and upload speeds are directly proportional to the amounts of bandwidth available. So from a purely theoretical perspective, 5G NSA can offer higher peak speeds than 5G SA thanks to the combined use of 4G and 5G spectrum. This slide based on 3GPP specifications shows the theoretical peak data rates for both 5G standalone let's call it SA and 5G non-standalone which we can refer to as NSA. As you can see the NSA figures are significantly higher than those for SA. That's because
NSA combines both 4G and 5G bandwidths as we discussed earlier. Whereas SA relies solely on 5G spectrum. It's a good reminder that while SA is the future of 5G architecture, NSA currently offers higher peak speeds, at least in theory, particularly in deployments where there is already a large 4G footprint in place.
This is the perfect point to introduce the concept of spectrum reforming. Let's consider a typical mobile operator that has accumulated spectrum over the years for 2G, 3G, 4G, and now 5G. Rather than holding on to legacy technologies indefinitely, operators often reallocate or reform their existing spectrum to support newer, more efficient technologies. When 5G was first introduced, not all operators had access to new spectrum specifically allocated for it. As a result, many turned to their existing 4G spectrum to deploy initial 5G services. There are two main approaches
to doing this as illustrated on this slide. The first is static spectrum allocation. Here the operator statically splits the existing band reserving one part for 4G and reallocating the other part for 5G. While this allowed 5G to launch quickly, it came with a trade-off. 4G performance degraded,
especially in busy areas, because it now had less bandwidth to serve the majority of users. Meanwhile, 5G with far fewer users initially had dedicated resources that it didn't fully utilize. The second is the more flexible approach, dynamic spectrum sharing or DSS. In this case, the same 4G band
dynamically serves both 4G and 5G users based on realtime demand. While this sounds ideal in theory, it introduces efficiency losses, in practice, operators have reported that around 15 to 25% of the spectrum becomes unusable due to overheads and guard bands required for coordination. As a result, DSS can often support fewer users than expected, particularly in hight traffic areas. Both methods had their pros and cons, but they played an important role in helping operators launch 5G without having to wait for new spectrum allocations. As 5G rollouts have
gathered momentum and most countries have now held 5G spectrum auctions, operators are increasingly shifting their focus to spectrum reforming, reallocating existing spectrum from older technologies to 5G. Earlier we looked at the typical operator spectrum spanning from 2G to 5G. Now let's take a closer look at how reforming plays out in practice. Let's say an operator decides to gradually shut down part of its 3G network. That freed up spectrum can now
be reformed for 5G, helping to improve coverage and add capacity. At the same time, if the operator has plenty of 4G spectrum, they might choose to reform one of those 4G bands to 5G as well. This allows for more efficient use of spectrum and enhances overall network performance. So alongside acquiring new spectrum through auctions, operator can boost 5G coverage, capacity, and user experience by also repurposing spectrum they already own, gradually phasing out legacy technologies along the way.
Now that we have explored spectrum and how it's allocated across generations, let's shift our focus to the antennas, the critical components that transmit and receive signals in mobile networks. Understanding antenna design and evolution is key to understanding how mobile networks from 2G all the way to 5G and beyond function efficiently across different frequency bands and technology. This slide from Ericson's massive myo handbook provides a clear comparison between conventional antenna setups and more advanced massive myo solution. Massive myo is particularly effective in the capacity layer especially in the mid-band spectrum like Cband where high data throughput is crucial. In the conventional solution which has served 2G, 3G, 4G and even low band 5G as well, the architecture typically includes three main components. The bassband unit or BBU, the remote radio unit or RRU and a passive antenna. These are usually
mounted separately and connected via cables and fiber. In contrast, the Massimum Myimo solution integrates the radio and antenna into a single unit called an active antenna unit. This integration significantly simplifies deployments and improves performance enabling advanced features like beam forming and spatial multiplexing which are essential for highcapacity 5G networks. This is a state-of-the-art cell site for a three sector deployment. At the top of the mast, you can see the active antenna units or AAUs. Remember, they operate at
higher frequencies, so they are smaller in size. They also have the RRU functionality integrated into them. Below the AUS, you'll find the three passive antennas, one for each sector.
Modern passive antennas are able to combine multiple frequencies, meaning a single antenna can transmit and receive multiple bands and even multiple radio technologies like 2G, 3G and 4G. Finally, at the ground level, you have the large cabinets housing the bassband unit, power unit and radio units for the different bands connected to the passive antennas. This is similar configuration to the previous one. But here the active antenna is mounted directly onto the passive antenna and is therefore referred to as large multiband passive active antenna. This slide shows the difference between a conventional passive antenna and a massive myo active antenna. As you
can see, the main difference is that the conventional antenna can only perform limited beam forming. Meanwhile, massive myo enables multiple steerable and shaperable beams. This diagram goes into more detail explaining how massive myo antennas can form multiple beams that are both steerable and shapable, helping to target users more precisely and use network resources more efficiently. One final point over the years I have noticed that many people are not familiar with how coverage is provided in subways, metro systems or underground tunnels. Coverage in these environments is usually provided using leaky feeders or radiating cables. We have a dedicated
tutorial explaining that in more detail. So please do check it out if you are interested. Let's now quickly explore the Wi-Fi spectrum. In the early days, Wi-Fi operated in the 2.4 GHz ISM band. ISM stands for instrumentation, scientific, and medical. This band was shared with
other technologies like car alarms, microwaves, and Bluetooth. To address congestion in the 2.4 4 GHz band. The 5 GHz band was introduced, offering more bandwidth and better performance. However, as Wi-Fi usage grew, even the 5 GHz band became congested. To meet this demand, the 6 GHz band was introduced for technologies like Wi-Fi 6 and Wi-Fi 7. The 6 GHz band is divided into two segments. the lower 6 GHz which is
license free and allocated for Wi-Fi in many countries and the upper 6 GHz which some countries are considering allocating for licensed mobile communications. This is a recent chart from the Wi-Fi alliance showing which countries have allocated the lower and upper 6 GHz bands for unlicensed use including Wi-Fi. It also highlights countries that are still considering how to allocate these bands. A significant portion of the spectrum in 60 GHz band is available for unlicensed use. Y gig operates in this
band based on the ITLE E 802.11 A and 802.11 AY standards. While Y gig offers incredible speeds, its adoption has been limited by range penetration issues and device compatibility. Yig is ideal for high bandwidth applications in light of sight environments, but it has not seen widespread adoption compared to Wi-Fi 6. Now let's look at spectrum for satellite-based mobile communications. Just a quick recap at a high level we can say there are geocatellites. GEIO
can mean geostationary or sometimes even referred to as geocynchronous uh medium earth orbit or MO satellites and lower earth orbit or LEO satellites. In addition, there are high altitude platform stations or haps. Providing mobile coverage using any of these is often referred to as non-aterrestrial networks or NPNs. While there are different approaches to allocating spectrum for satellite services, two main models are followed worldwide. The first is by
allocating dedicated satellite spectrum specific bands allocated for satellite services across a wide range of frequencies from low to high bands. The advantage here is no interference with terrestrial networks and wellestablished regulatory frameworks that prevent satellites from interfering with each other or with terrestrial services. The second model gaining ground recently is sharing spectrum with mobile network operators or MOS. In this case, the MO owns the spectrum but it shares it with the satellite operator to deliver services where terrestrial coverage is missing or poor. However, because satellite cell sizes are very large, this can create challenges in border areas where an MO's coverage might spill into a neighboring country or region where the same spectrum is used by another MO. 3GPP has been working with satellite operators, regions, and regulators to standardize all possible bands for 3GPP based NPN services. In the long term,
this will allow satellite operators currently using proprietary technologies to transition to 3GPP standards with 5G today and 6G in future. This will create economies of scale, helping satellite operators achieve more subscribers and generate higher revenues. Now, let's move to our final topic, 6G. Although 6G is under development, discussions around suitable spectrum have already begun. Future 6G
networks will require a mix of frequency ranges to meet coverage capacity and use case demands, including traditional low and mid-band spectrum for broad coverage and upper mid-band and possibly in the distant future sub terahertz uh frequencies to enable ultra high data rates and low latency. Before we go any further, I want to explain some terminology that's mainly being used for 6G but occasionally for 5G as well. Let's start with millimeter wave or mm wave. As we discussed, this covers frequency from 30 to 300 GHz. The
table on the right splits this into lower and upper MM wave and highlights that the upper MM wave band is sometimes referred to as subtraertz. This is important because many 6G researchers are focusing on this band. The terraertz band itself extends from 300 GHz to 3 terraertz. Even though some large organizations are researching this band for 6G, we don't believe it has a strong support at the moment, especially given the limited success of widespread mmwave deployments. Finally, let's go a bit lower to frequencies between 3 GHz and 30 GHz. You may not have come across the term centime waves before, but it's now widely used. Although the upper
centimeter wave band is technically between 10 and 30 GHz, the industry now often defines it as frequencies above 7.1 to 5 GHz. This upper mid-band spectrum is considered the likely workhorse for 6G.
As we will see shortly, every 4 years or so, the World Radio Communication Conference or WRC takes place. It's a major global event lasting 4 weeks. WRC23 took place in Dubai from 20 November to 15th December 2023. Its main purpose is to review and if necessary revise the radio regulations, the international treaty governing the use of radio frequency spectrum and satellite orbits. From a mobile networks point of view, this slide from Qualcomm offers an excellent summary of WRC23 as well as the study items planned for WRC 27. Here are few points worth highlighting. The 600 MHz band from 470
to 694 MHz was identified as IMT spectrum suitable for mobile technologies like 3G, 4G, 5G and 6G. Of course, the 600 MHz identification came with lots of footnotes and regional differences. We won't get into that here. The 3.5 GHz band which goes from 3.3 to 3.8 GHz that is 500 MHz was harmonized across Europe, the Middle East, Africa and Americas. The upper 6
GHz band was also identified for IMT although it its use still varies between regions and sometimes even between countries. We'll look at this more closely using a slide from KDDDI. Let's focus on the blue shaded area. The upper 6 GHz band we were just discussing. Even though it's been identified for IMT, it can and will continue to be used for Wi-Fi. Wi-Fi is referred to as radio local area networks or RLNs by the ITU.
Now looking at the area shaded in yellow or orange, the 400 MHz band in 4.4 to 4.8 GHz is being studied in regions 1 and three for WRC27. The 7.125 to 8.4 GHz band that is 1.275 275 GHz bandwidth is being studied completely in regions 2 and three and partially in region one. The 14.8 to
15.35 GHz band that is 550 MHz bandwidth is being studied across all regions for WRC 27. I believe that these new bands will be able to provide reasonable bandwidth to operators looking to deploy 6G. For completeness, here's a list of mobile satellite services or MSS bands under consideration for WRC27. I have also added a list of
existing 3GPP defined NTN bands for your reference. Earlier we looked at the spectrum layer cake for technologies from 2G to 5G. Now let's see how that layer cake evolves with 6G in mind. As we saw earlier bands between 7 GHz and 15 GHz are being touted as the workhorse for 6G. They are generally generally referred to as upper midband spectrum or centimeter wave bands. Even though technically all spectrum from 3 GHz to 30 GHz falls under centime wave. Meanwhile,
researchers are exploring bands from 90 GHz to 300 GHz for 6G. Although sub terahertz technically starts at 100 ghahertz in the context of IMT 2030 and 6G research frequencies from 90 GHz onwards are often grouped under subtraertz. As this was a detailed presentation, here's a quick summary of some of the key points we covered. Radio frequency is part of electromagnetic spectrum used for wireless communication across generations from 2G to 6G. Spectrum is divided into bands and layers to balance coverage capacity and speed requirements. Bandwidth determines data
rate. More bandwidth means higher throughput. 5G spectrum spans FR1 sub7 GHz and FR2 24.25 to 71 GHz with FR2 often referred to as millimeter wave. FDDD and TDD are two duplexing methods each suited to different types of spectrum and deployment. Carrier aggregation and dual connectivity enhance speed and flexibility especially in 5G non-standalone deployments. Spectrum reforming allows
reuse of older bands for newer technologies like 5G. Antenna design evolves with frequency. Smaller wavelengths enable technologies like massive myimo and beam forming. It's worth emphasizing again, understanding how radio spectrum works is essential to grasp how mobile networks evolve and how 5G and 6G will shape the future of connectivity. Here are some references and links for further reading. You can download the slides from the 3G 4G homepage.
We hope you enjoyed this updated detailed tutorial on radio frequency band and spectrum. What was the highlight of this tutorial for you and what surprised you the most? Please leave us your feedback and let us know your thoughts in the comments below. Thanks for watching and we hope to see you again on our channel soon. Goodbye.
2025-04-25 03:23
