# Optimized DM-RS Configuration for Improved 5G New Radio Network Capacity and Performance.
## 5 DM-RS Optimization, Achieved Network Capacity and Performance Improvements
### DM-RS Optimization for MBB Use Case and Improved Peak User Experienced Downlink Throughput  
The second DM-RS optimization example is a 5G NR network with a dominant MBB use case. The network is not congested as, unlike in the previous network, the FWA use case is not deployed, and there are more spectrum assets available, with two channels on different frequencies (3.5 GHz and 3.4 GHz), both with a bandwidth of 100 MHz. It is worth mentioning that the traffic management and carrier aggregation deployment strategy that was implemented in this network did not balance traffic between two carriers. The network load and PRB utilization on the primary cell were higher compared to the secondary cell. The main goal of optimization and overhead reduction was to improve peak performance in terms of downlink user throughput. This network had the same initial DM-RS configuration as the first network analyzed in Section 5.1, with initial parameters set to the following values: dmrs-Type = 1, dmrs-maxLength = 2, dmrs-AdditionalPosition = 1. The same DM-RS optimization measures were implemented, with a decrease in the parameter dmrs-maxLength to a value of 1, while the parameter dmrs-AdditionalPosition was, like in the previous case, set to adaptive configuration. Figure 8: DM-RS optimization for FWA use case, capacity improvements, data transferred through network vs. PRB utilization: (**a**) optimized sites and (**b**) control group of sites with original settings. Figure 7: DM-RS optimization for FWA use case, capacity improvements, longer observation period: spectral efficiency for (**a**) optimized sites and (**b**) control group of sites with original settings. New optimized parameter settings were tested in one city with more than one hundred base stations deployed. Like the tests described in the previous section, an analysis of the impact of DM-RS optimization measures on network performance was conducted based on counters obtained from the 5G NR performance management (PM) system, with a focus on KPIs measuring data payload, resource utilization and spectral efficiency. All KPI measurements were collected from the PM system on the cell level, with a granularity period of 1 h. The analysis focused on performance comparison during three consecutive weeks, where standard network configuration was implemented during the first and third weeks while optimized parameters were configured during the second week (marked with green in Figure 8(b)). Furthermore, drive test measurements were used in the analysis due to the importance of mobility for the MBB use case. Measurements were conducted on two consecutive days, with standard and optimized setting configurations, where the same drive test route was used during the same hours during the day, and traffic was generated in the same way (long FTP download testing scenario). Figure 8(a) presents the cumulative distribution function (CDF) of user experience throughput during two drive test campaigns, before and after parameter changes, where a 15% improvement for median downlink throughput may be observed, with similar gain over different percentiles. Spectral efficiency measured as throughput per RB with the same methodology described in Section 5.1 shows an 11% improvement. It is worth mentioning that the assessment of spectral efficiency based on counters from the PM system provides pessimistic values compared to drive test results that will be shared later. The main reason behind this is the fact that network statistics are not able to segment heavy traffic use cases (like FTP download or streaming services generated during the drive test) from use cases with bursty traffic where the buffer is not full and cannot utilize the full potential of 5G NR system. The CDF of spectral efficiency measured from a drive test is presented in the following figure for primary (Figure 9(a)) and secondary cells (Figure 9(b)), where significant performance improvement is observed for both carriers, while gains on the less loaded secondary cell seem higher.