Rohde & Schwarz and MediaTek are working together to provide DSS (Dynamic Spectrum Sharing) validation solutions for 5G-NR. The new verification solution uses the R&S CMX500 5G-NR radio communication tester platform and a device under test (DUT) provided by MediaTek.
Today, frequencies below 6 GHz are heavily utilized due to the successful deployment of 4G LTE. This creates a challenge for network operators worldwide on how to deploy 5G-NR in these low frequency bands. Dynamic Spectrum Sharing (DSS) is a technique that enables mobile network operators to use LTE and 5G-NR in the same frequency band. The in-depth validation of the standardized coexistence methodology is key to the success of this technology.
Almost all initial 5G-NR FR1 deployments are based on time division duplex (TDD), with unpaired frequency bands typically in the 3.5 GHz frequency range. However, about 90% of all spectrum below 6 GHz is organized as paired frequency bands, using frequency division duplex (FDD), where downlink and uplink use different frequencies. At the moment, these frequency bands are already in use by 4G LTE.
This is where DSS comes into play. It introduces smart algorithms and combines several other features that allow the simultaneous coexistence between 4G LTE and 5G-NR users in a single mobile network, while using the same frequency band. In the LTE network, multicast broadcast single frequency network (MBSFN) is activated to allow 5G-NR the transmission of synchronization signal blocks (SSB) and tracking reference signals (TRS).
Depending on the amount of LTE and 5G-NR users in a specific cell, DSS helps balance the LTE or 5G-NR scheduling of mobile devices based on the actual traffic load. That allows the transmission of 5G data in standard LTE subframes, while specific rate-matching techniques are applied that avoid e.g. the always-present LTE cell-specific reference signals (CRS).
The combination of these features, functions and complex algorithms requires extensive testing of mobile devices. DSS will complement the 5G-NR signalling tester feature coverage of Rohde & Schwarz by using the R&S CMX500 5G-NR signalling tester together with the company’s tried-and-tested, industry-leading LTE testing solutions, based on the R&S CMW500 mobile radio tester. This will help expedite the smooth integration of the 5G-NR technology into existing LTE networks for the worldwide ecosystem, from chipset suppliers, modem and smartphone manufacturers to mobile network operators.
In close cooperation between the R&D teams of both Rohde & Schwarz and MediaTek, correct implementation of DSS algorithms on LTE and 5G NR has been tested extensively between the R&S CMX500 radio communication tester and MediaTek’s new 5G chipset Dimensity 1000. This verification will enable MediaTek to roll out their chipsets into markets where 5G-NR technology is being used within existing LTE band allocations.
