DSS Part-1

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In this article, we will discuss about Dynamic spectrum sharing abbreviated as DSS

What is spectrum refarming?

It is the process of redeploying spectrum from available users and re-allocating it to others. Legacy technology must be eliminated from a part of the spectrum, which must then be allocated for the new technology. It was not possible for operators to share the spectrum between different technologies but, spectrum refarming from LTE to 5G will be simpler with Dynamic Spectrum Sharing (DSS) which is introduced in 3GPP r15. 

5G and LTE can occupy the same spectrum band from the control channel point of view, and the resources are allocated dynamically between the two technologies depending on the instantaneous device distribution and capacity needs. As many LTE bands have been refarmed as NR bands how to share the same spectrum between LTE and NR is an important issue, which can potentially affect the network efficiency and UE performance significantly.

What is DSS?

Dynamic Spectrum Sharing (DSS) is a technology that allows the deployment of both 5G NR and 4G LTE in the same frequency band and dynamically allocates spectrum resources between the two technologies based on user demand (UE has to support this feature).

Why can’t operators re-use old spectrum from obsolete networks (NR network)?

As we know that huge volumes of connected devices from industrial IOT to emergency services are still using 2G,3G and 4G networks (supported SIM card also). Thus operators face a unique challenge in this technology generation.  According to the GSMA Intelligence’s Network Transformation 2020 report only a 31 percent of operators identified spectrum refarming as a top three RAN priority despite many of the same MNO highlighting spectrum scarcity as a key barrier to 5G rollout.

The widespread rollout of 5G using mmWave spectrum is not realistic due to the very limited coverage of these frequencies demands enormous infrastructure investment. Also, there is simply not enough mid- and low-band spectrum currently available to provide the huge data capacity 5G will require. But there are some short-term solutions to these challenges which will allow operators to better manage their network assets.

The first is carrier aggregation (CA): CA is a technology that allows operators to deploy 5G using two or more bands in tandem, integrated together as one big block. This will enable operators to deploy a high level blanket of 5G using mid-band, while adding capacity in dense urban areas using mmWave.

The second technology is DSS: This emerging technology allows 4G and 5G to exist simultaneously on the same band, while adjusting the BW allocated to each generation dependent on demand. This has clearly ideal for low-band rollout, as it will allow operators to continue to use valuable spectrum for LTE, while adding NR capacity as demand grows. But at the same time whether it will be enough to address the looming issue of massive data demand on 5G networks remains to be seen.

Advances and challenges of DSS in 5G wireless networks with full duplex technology:

FD (Full Duplex) technology is considered to be one of the candidate technologies for 5G and beyond wireless communication systems due to its advantages including potential doubling of the capacity and increased spectrum utilization efficiency. 

It also enables a radio to transmit and receive on the same frequency band at the same time. However, mitigation of strong Self Interference is one of the main challenges of the FD technology. But the recent advances in different Self interference cancellation techniques like analog cancellation, antenna cancellation, and digital cancellation methods have permitted the feasibility of using Full duplex technology in many wireless applications.

Important application area is DSS in NR (5g) networks, where Full Duplex can provide several benefits and possibilities such as Concurrent Transmission and Reception, improved sensing efficiency and secondary throughput, Concurrent Sensing and Transmission and the mitigation of the hidden terminal problem.

In the next section, we will learn more about DSS and its basic and advance level stuff. So keep reading……. And Stay tune……………

Pinal Dobariya………..

Reference:
3GPP TS 38.331
3GPP TS 38.221
3GPP TS 36.331
https://www.researchgate.net/publication/330188547_RF_Self-interference_Cancellation_for_Full-duplex_Communication_by_Using_Photonic_Technique
https://www.researchgate.net/publication/269306294_Adaptive_transmission-reception-sensing_strategy_for_cognitive_radios_with_full-duplex_capabilities
RP-191042, Enhancements for dynamic spectrum sharing in Rel-16, Ericsson, RAN #84, 3-6 June 2019