5G Spectrum Clearance and Analysis

Background

The Notice on the Adjustment of Usage Planning for 700MHz Band and Frequency released by China’s Ministry of Industry and Information Technology (MIIT) ruled that the FDD 702-798MHz and 703-743/758-798MHz (2*40MHz) spectrum which was previously allocated for China Broadcasting Network Corporation Ltd (CBN) to be cleared for 5G mobile communication systems.

The 700MHz (band N28) FDD spectrum ranges between 703-748/758-803 (2*45MHz) as defined by 3GPP. The carrier bandwidth is defined as 2*20MHz in R15 and adds 30/40MHz in R16. This result in a maximum of 2*40MHz carrier bandwidth for the band N28.

The 5G 700MHz spectrum clearance requirements (also refer to below diagram) :

• Current CBN’s 700MHz spectrum for Digital Terrestrial Multimedia Broadcast (DTMB) channels
• DS36 to DS49
• 700MHz (band N28) 5G spectrum for 30MHz carrier bandwidth
• Uplink : DS37, DS38, DS39,DS40
• Downlink : DS44, DS45, DS46, DS47
• 700MHz (band N28) 5G spectrum for 40MHz carrier bandwidth
• Entire DS36 to DS49

It is important to test and analyze the overall spectrum clearance of the 700MHz DTMB channel before the construction and operation of the 700MHz 5G network.

Spectrum Clearance Test

The article studies the test and analysis of spectrum clearance by Dingli’s Pilot Pioneer field test solution and Rohde & Schwarz’s TSME 5G scanner.

The Spectrum analyzer function in Pilot Pioneer is used to perform signal analysis on the power measurement, interference sources, and occupied bandwidth of the spectrum based on the following test plan configuration. Specify either the full band and frequency from 694 to 806 MHz or for the band N28 and frequency only. Default values are recommended for "Speed" and "Bandwidth".

Real-time Interface for Spectrum Test

Analysis and Statistics

The spectrum clearance process for the 700Mhz band using spectrum scan and the interference analysis function with Pilot Pioneer

1.Multiple Channels’ Spectrum Analysis

Multi-Channel Spectrum CLR& INF analysis function is shown as below：

• Customize the uplink and downlink channels by specifying the required bands and frequencies.
• Select the 700 MHz bands and frequencies from the list template shown in the highlighted area below.
• Set the interference threshold (default value -114dBm) and click “Analyze”.
• The statistics result is as follows. The analysis result interface displays the statistics for multiple frequency bandwidths; such as RSSI values that are beyond the interference threshold, interference distance and ratio.

• Right-click the frequency range to export the analysis results.

The results are exported as follows where users may view the interference ratio of channels CH7/CH8/CH9/CH11, and the spectrum clearance analysis has been completed.

• The analysis results can be displayed in the map window where users may switch to view the required channel coverage. The parameter threshold ranges can be modified in the configuration interface or the right pane of the map window.

The signal threshold range is shown as below:

Hereinafter, we take CH11(768-773MHz) as an example to show the analysis results in the map window. There is a relatively long test route with strong signal interference in CH11 channel data. The band and frequency are mainly influenced by DS45 (766-774MHz), and different levels of interference can be seen clearly with different colours. The interference coverage is displayed as follows:

The spectrum scan of the test route with strong interference is displayed as below:

The same operation can be performed for each band to analyze the interference and determine whether the interference is caused by which DTMB channel?

2.Single Channels’ Spectrum Analysis

Analysis function is used to analyze and view the test route with interference. Set the frequency range (such as768-773MHz of CH11 for example in the following image) to analyze the channel’s interference:

The results of the analysis are as follows. For channel CH11, there are test routes with a total distance of 16km and an uncleared spectrum that exceeds the interference threshold (RSSI>=-105dBm) for more than 30meters. The interference ratio is 44.94%. The table below summarizes the statistics information of each test route (with 30meters of continuous distance) and strong interference.

The analysis results are displayed in the map as follows. There are still test routes with the uncleared spectrum, which is displayed mainly in the bottom left of the map window.

Result

China Broadcasting Network Corporation Ltd. have thousands of TV towers across the country. The tower is higher and transmitting power will be higher, and low-frequency radio waves will attenuate. This can easily cause strong interference to the 5G 700M band, resulting in reduced network speeds, access failures and other network problems. Therefore, a thorough spectrum clearance of the 700MHz DTMB channel is a prerequisite for the large-scale deployment of 5G 700MHz networks.

The article introduces how to conduct 700M spectrum clearance tests and analysis based on DingLi’s Pilot Pioneer and Rohde & Schwarz’s 5G scanner TSME6, which can accurately analyze the specific spectrum clearance of each DTMB channel in each region, effectively guide the 700MHz spectrum clearance test and verification and improve the construction and optimization efficiency of 700MHz 5G networks