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Dynamic Spectrum Sharing (DSS) is an important part of how 5G networks are being rolled out, especially when it comes to making better use of the available spectrum. This is particularly useful in using low-band frequencies and sharing spectrum with older technologies like LTE (4G). DSS allows the same spectrum to be shared between LTE and 5G New Radio (NR), enabling a smoother transition from 4G to 5G without needing to dedicate specific bands solely to one technology. So, now let us look into 5G dynamic spectrum sharing along with User-friendly LTE RF drive test tools in telecom & RF drive test software in telecom and User-friendly 4G Tester, 4G LTE Tester, 4G Network Tester and VOLTE Testing tools & Equipment in detail.

Understanding DSS Ecosystem

The development of DSS is a combined effort between network vendors, chipset makers, and mobile network operators. These groups work together to develop and implement this technology, starting from the initial concept back in 2017. The key challenge was how to allow the older LTE technology to coexist with 5G on the same spectrum.

The 3rd Generation Partnership Project (3GPP), which sets global standards for mobile networks, played a big role in this. The first step was working on LTE user equipment (UE) in the 3GPP Release 8 standard to pave the way for 5G spectrum sharing. By the time 3GPP Release 15 came around in 2018, the specifications were ready, and chipset manufacturers started collaborating with vendors to develop devices that could support DSS.

In early 2019, the first chipsets supporting 5G on low-band spectrum were tested, and static spectrum sharing (where specific parts of the spectrum are reserved for LTE and 5G) was implemented. However, by the end of 2019, dynamic spectrum sharing became available for testing with commercial 5G devices, allowing both LTE and 5G to operate on the same spectrum more efficiently.

Key Features of DSS

DSS works for both uplink (UL) and downlink (DL) transmissions. However, it usually requires both LTE and 5G NR networks to be from the same vendor, as the same radio equipment is used to transmit signals for both technologies. The radio amplifier, which boosts the signal strength, is connected to both technologies, and time and frequency resources are managed by a unified scheduler. This scheduler controls the allocation of resources to ensure that LTE and 5G can coexist without causing interference.

Uplink Spectrum Sharing: In the uplink, sharing spectrum between LTE and 5G is relatively simple because the scheduler can assign different time and frequency resources to each technology.
Downlink Spectrum Sharing: The downlink is more complex, as LTE uses several signals that are always active (referred to as “always-on” signals). These signals include synchronization signals and reference signals that help LTE devices stay connected to the network.

Reserved Resources in Downlink (RR)

In DSS, certain resources in the downlink are reserved to ensure backward compatibility with LTE and forward compatibility with future technologies like 5G and even beyond. This ensures that the same spectrum can be used efficiently without causing issues for either LTE or 5G devices.

The reserved resources can be set up in several ways. One method involves configuring resources around LTE’s synchronization signals, allowing LTE and 5G to coexist without one interfering with the other. This process, known as rate matching, means that some parts of the 5G signal are “punched out” to leave room for LTE signals.

Bitmap Configurations: A method called bitmap configuration allows 5G to avoid transmitting on the same frequency at the same time as LTE. A set of bitmaps defines which parts of the spectrum are reserved for LTE and which can be used by 5G, helping avoid interference between the two.

Synchronization Signal Coexistence

Synchronization signals are crucial for LTE and 5G, helping devices connect and communicate with the network. DSS ensures that resource blocks (the smallest units of spectrum) containing LTE’s primary and secondary synchronization signals (PSS and SSS) are not scheduled for use by 5G. This helps avoid interference and ensures both technologies can coexist on the same spectrum.

To manage this, a coordinated scheduler is used to ensure LTE and 5G signals are scheduled in a way that avoids conflicts. This can involve adjusting the number of symbols (small units of data transmission) used by each technology or adjusting the bandwidth used by each signal. The goal is to ensure both LTE and 5G devices can operate smoothly without one technology disrupting the other.

Handling LTE Cell-Specific Reference Signals (CRS)

One of the challenges in DSS is handling LTE’s cell-specific reference signals (CRS), which are used by LTE devices to measure signal quality and stay connected to the network. To avoid interference, 5G signals are rate-matched around these CRS signals. This means certain parts of the 5G signal are left empty to make room for LTE’s reference signals.

In some cases, the capacity of the 5G network may be reduced to avoid interfering with LTE’s CRS. However, this is a standardized process, and the impact on overall network performance is minimal.

Multimedia Broadcast Single Frequency Network (MBSFN) and DSS

Multimedia Broadcast Single Frequency Network (MBSFN) is a technique used in LTE to broadcast information to multiple users at the same time. In the context of DSS, MBSFN can be used to hide or “conceal” certain 5G signals to ensure they don’t interfere with LTE transmissions. For example, MBSFN can be used to conceal 5G’s System Information Block 1 (SIB1), which contains critical network information for 5G devices.

Using MBSFN for this purpose ensures that LTE and 5G can share the same spectrum without one technology causing interference for the other. In the future, as more 5G devices become available and fewer LTE devices are in use, the need for MBSFN will decrease, and more of the spectrum can be dedicated to 5G.

The Impact of DSS on Network Performance

For example, DSS may lead to a 20% reduction in LTE capacity when 5G is present, and a 10% reduction in 5G capacity when LTE is active. However, this reduction is a trade-off that allows operators to roll out 5G more quickly and efficiently without needing to dedicate specific spectrum solely to 5G.

In summary, Dynamic Spectrum Sharing is a critical technology that allows mobile network operators to make better use of their existing spectrum as they transition from LTE to 5G. By sharing the same spectrum between LTE and 5G, operators can offer 5G services without needing to invest in new spectrum, ensuring a smoother and more cost-effective deployment of 5G technology.

About RantCell

RantCell provides user-friendly yet highly effective solutions for testing and monitoring mobile networks. Our tools offer comprehensive insights into network performance, enabling operators to fine-tune their networks and enhance user experience. Whether it’s improving coverage, strengthening connectivity, or maintaining top-notch service quality, RantCell offers the detailed analytics required to meet your objectives. Also read similar articles from here.