Adjacent-Channel Compatibility Analysis of International Mobile Telecommunications Downlink and Digital Terrestrial Television Broadcasting Reception in the 470–694 MHz Frequency Band Using Monte Carlo Simulation

Round 1

Reviewer 1 Report

This paper studied the compatibility analysis of IMT downlink and DTTB reception in the 470-694 MHz frequency band using Monte Carlo simulation. The authors present using Monte Carlo method to evaluate the probability of interference from IMT base stations into DTTB reception. This work can promote the development of the related research fields. In general, I suggest that this paper should be published after considering my comments. My comments are as below.

1. Please give the differences and advantages between the Monte Carlo method and the existing research methods for analyzing the compatibility of IMT downlink and DTTB reception.

2. What factors affect compatibility issues between IMT downlink and DTTB reception in the 470-694 MHz frequency band?

3. What methods can solve the compatibility issues better?

Author Response

Response to the Reviewer 1

We thank Reviewer 1 for evaluating our article and insightful suggestions that helped us make the paper much better. Our answers to Reviewer 1 remarks are listed below.

Note: The major modifications are marked in green color in the revised manuscript.

Point 1. Please give the differences and advantages between the Monte Carlo method and the existing research methods for analyzing the compatibility of IMT downlink and DTTB reception.

Response: We would like to express our gratitude to the reviewer for this suggestion.

Investigating coexistence issues between Digital Terrestrial Television Broadcasting (DTTB) and International Mobile Telecommunications (IMT) systems in digital dividend bands involves several approaches, including link budget analysis, simulations, laboratory measurements, and field tests. Each of these methodologies serves a distinct purpose and has its advantages and limitations.

We highlighted the distinct purposes, advantages, and limitations of these methodologies in our published article referenced in [6]. This paper underscored that these methodologies complement each other, and the choice of a specific approach depends on the research objectives and available resources. We cited this article in the revised manuscript (specifically in the introduction from Line 70 to Line 76).

Furthermore, in the revised manuscript (specifically in the introduction from Line 150 to Line 164), we have added a paragraph summarizing what was revealed from the literature review on the different approaches used to study issues of coexistence in digital dividend bands.

In this contribution, we have chosen to use simulations, in particular through the specialized software tool SEAMCAT, to investigate coexistence issues between DTTB and IMT systems for several compelling reasons.

This approach is cost-effective, safe, controlled, repeatable, and flexible, expediting analysis and providing insights for decision-making. Simulations grant complete control over test scenarios, allowing the creation of a wide range, including worst-case scenarios, which may be difficult or impossible to conduct in the real world. Additionally, the simulations via the Monte Carlo method are formally adopted by international spectrum regulatory authorities based on international agreements.

(We explained why we chose simulation in the revised manuscript from Line 159 to Line 164).

Point 2. What factors affect compatibility issues between IMT downlink and DTTB reception in the 470–694 MHz frequency band?

Response: We thank the reviewer for this question.

Compatibility issues between IMT downlink and DTTB reception in the 470-694 MHz frequency band can be influenced by various factors.

Below we list the factors considered and investigated in our current paper point by point.

• Frequency Spectrum Allocation: The allocation of frequency bands for IMT and DTTB services is crucial. Overlapping or adjacent frequency bands may lead to interference and compatibility issues.

In our present contribution, three interference scenarios are simulated based on the frequency distribution in adjacent channels, considering DTTB services with 8 MHz bandwidth and IMT downlink with 5 MHz, 10 MHz, or 15 MHz bandwidths. Figures 3 to 5 depict the interleaved spectrum patterns for these three scenarios.

• Guard Bands and Frequency Separation: Insufficient guard bands between IMT and DTTB frequencies or inadequate frequency separation may result in cross-channel interference. Well-defined guard bands are crucial for preventing signal bleed-over.

Regarding this factor, in our current contribution, we observed that reducing the guard bands in Scenarios 2 and 3 had a minor impact.

• Transmit Power Levels: The transmit power levels of IMT and DTTB signals can impact compatibility. Proper power control mechanisms are essential to prevent signal overlap and degradation.

For this factor, in our present contribution, a DTTB High Tower High Power (HTHP) transmitter was considered with DTTB EIRP is 85.15 dBm, while the highest power level the BS can transmit is 46 dBm as per ITU-R M.2292.

• Antenna Characteristics: The design and orientation of antennas used for both IMT and DTTB systems can influence compatibility. Antenna patterns, gain, and directionality play a role in determining how signals interact in the shared frequency band.

Regarding this factor, in our present contribution, Table 1 shows all the IMT-BS antenna properties used in the simulations which include height, downward tilt, pattern, orientation, and polarization. Likewise, Table 3 shows all the characteristics of the DTTB Rx antenna, taking into account antenna discriminations as well.

• Geographical and Terrain Considerations: The local geography and environment, including terrain and building structures, can affect signal propagation and contribute to compatibility challenges. Urban environments with dense structures may face different issues compared to rural areas.

For this factor, in our current contribution, the evaluation covers urban, suburban, and rural environments.

• Signal Processing Techniques: The effectiveness of filtering and signal processing techniques employed by both IMT and DTTB systems can influence their ability to coexist in the frequency band.

Regarding this factor, in our present contribution, we investigated the impact of IMT Tx ACLR on the probability of interference (pI) to adjacent DTTB due to unwanted Out-Of-Block emissions (Uw). Additionally, the DTTB Rx ACS effect on pI due to blocking (Blk) from the IMT adjacent signal and the interfering signal total power on pI due to (Blk+Uw) are investigated comprehensively.

• Regulatory Policies and Standards: Adherence to regulatory frameworks and international standards is crucial for ensuring compatibility.

Regarding this factor, in our current contribution, we recommended that national coordination procedures be implemented to proactively prevent interference risks before IMT downlink deployment and address cases on a case-by-case basis.

Understanding and addressing these factors through effective regulatory measures, technical standards, and collaborative efforts between stakeholders is essential for ensuring smooth coexistence between IMT downlink and DTTB reception in the 470–694 MHz frequency band.

Point 3. What methods can solve the compatibility issues better?

Response: We appreciate the reviewer for raising this question.

Resolving compatibility issues between IMT and DTTB services in digital dividend bands requires a combination of regulatory, technical, and collaborative measures.

Below we list ONLY the investigated methods in our current contribution that have contributed to solving these compatibility issues effectively for the scenarios considered. All of the methods mentioned below are detailed within the context of our article.

• Implementing a secondary allocation for mobile service in downlink-only mode alongside the existing traditional broadcasting services in the 470–694 MHz band helped optimize spectrum utilization and mitigate interference.
• The enhanced ACLR values of the IMT BSs, in line with practices already in place to protect broadcasting from IMT uses in the band 790–862 MHz in Europe, helped reduce the impact of interference on DTTB. Practical implementations of the IMT BS can have even better ACLR characteristics, which will reduce even further the probability of interference.
• When improving the ACLR of the interfering IMT BS, the probability of interference is mainly driven by the ACS value of the DTTB receiver. Thus, improvements in the ACS values of the DTTB receivers also allowed better compatibility conditions.
• The increase in the separation distance only brought a limited improvement in the interference situation at the DTTB coverage edge. This is mainly due to the low useful signal level received by DTTB receivers.
• Technical measures like full antenna discriminations and specialized filters such as band-reject filters for DTTB receivers are necessary to effectively reject IMT adjacent channels.
• Facilitating international collaboration and coordination between regulatory bodies, network operators, and technology developers to proactively prevent interference risks and reduce compatibility challenges.

Combining these methods in a comprehensive strategy can contribute to a more effective resolution of compatibility issues, promoting the coexistence of IMT downlink and DTTB reception in the adjacent channels within the 470–694 MHz frequency range.

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Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript is well organised and it depicts the adjacent channels compatibility. Below are my suggestion to improve.

Keep the error changes as observed in abstract section.

need to elaborate DTTB parameters.

what is cross pol values?

if possible include the experimental results too.

Author Response

Response to the Reviewer 2

We thank Reviewer 2 for evaluating our article and giving insightful suggestions that helped us improve the manuscript. Our answers to Reviewer 2 remarks are listed below.

Note:  The major modifications are marked in green color in the revised manuscript.

Point 1.  Keep the error changes as observed in the abstract section.

Response: We want to convey our appreciation for reviewing our article and thank you for your suggestion.

We are a bit puzzled by your mention of error changes in the abstract section. We didn't observe any variations in the version you reviewed. However, if you are referring to editorial errors, the edits have been preserved as indicated in the version you reviewed.

Point 2.  need to elaborate DTTB parameters.

Response: Thank you for your suggestion.

In the revised manuscript, we have addressed this issue by adding a dedicated paragraph, from Line 254 to Line 273. This paragraph provides a more comprehensive and professional elaboration on the parameters of the DTTB system, offering a clearer understanding for readers.

Point 3.  what is cross pol values?

Response: We appreciate the reviewer for raising this question.

Cross-polarization discrimination (X-pol) is a parameter that describes the ability of an antenna to discriminate against signals with polarization orthogonal (perpendicular) to the desired polarization. In the context of DTTB (Digital Terrestrial Television Broadcasting) receivers, the X-pol discrimination is particularly relevant for fixed outdoor reception.

When the specification mentions “X-pol discrimination = −3 dB (Only applicable in no antenna discrimination case),” it means that the antenna has a sensitivity to signals with polarization perpendicular to the desired orientation, and this sensitivity is quantified by a discrimination level of −3 dB. In simpler terms, the antenna is capable of receiving signals with a certain degree of cross-polarization, but the discrimination level is limited to −3 dB.

In cases where there is no antenna discrimination, this parameter becomes applicable. Antenna discrimination refers to the antenna's ability to selectively receive signals based on their polarization. If there is no antenna discrimination, the X-pol discrimination of −3 dB indicates that the antenna is less effective at rejecting signals with polarization orthogonal to the desired polarization. In practical terms, this means that the DTTB receiver may be somewhat susceptible to interference from signals with cross-polarization, and the system design should take this into consideration to ensure reliable reception under such conditions.

(In the revised manuscript, from Line 271 to Line 273, we included a sentence that briefly explains the value of cross-polarization discrimination).

Point 4.  if possible include the experimental results too.

Response: Thank you for your suggestion.

Including the experimental results obtained through real field measurements or laboratory tests would undoubtedly strengthen our work.

However, conducting such measurements poses significant challenges. We have consulted about this matter with the National Media and Infocommunications Authority in Hungary, but until now, specialists have not been able to organize such measurements in the field and even in the laboratory due to the large power and distances that cannot be simulated.

Also, creating a real-world test environment is expensive and time-consuming, hampered by the need for specialized equipment, licensing, and a skilled workforce. On the other hand, the limited statistical foundation of field measurement campaigns prevents drawing significant conclusions.

In this contribution, we have chosen to use simulations, in particular through the specialized software tool SEAMCAT, to investigate coexistence issues between DTTB and IMT systems for several compelling reasons:

This approach is cost-effective, safe, controlled, repeatable, and flexible, expediting analysis and providing insights for decision-making. Simulations grant complete control over test scenarios, allowing the creation of a wide range, including worst-case scenarios, which may be difficult or impossible to conduct in the real world. Additionally, the simulations via the Monte Carlo method are formally adopted by international spectrum regulatory authorities based on international agreements.

(We explained why we chose simulation in the revised manuscript from Line 159 to Line 164).

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Author Response File: Author Response.pdf

Reviewer 3 Report

Presented paper “Adjacent Channels Compatibility Analysis of IMT Downlink and DTTB Reception in the 470–694 MHz Frequency Band Using Monte Carlo Simulation” investigates the compatibility of IMT downlink deployment with DTTB service in the 470–694 MHz band, focusing on coexistence requirements in adjacent channels. The authors propose Monte Carlo method and SEAMCAT software for evaluating the probability of interference from IMT-2020 downlink transmissions into DTTB reception within the 470–694 MHz band, particularly at the edge of DTTB coverage. The authors obviously have good research experience and ability to present their ideas in simple manner, understandable for different categories scientist.

References cited in the manuscript are enough and present analysis of the problem.

All data in the figures and tables is clear and well visible.

Despite of the above I have the following remarks to the authors reviewing this article:

1. Obviously the authors have decided to combine Introduction section and Literature review section in one. In this respect text in L44 to L47 included is inappropriate. The proper place is at the end of this section because the wording provides to the readers one of the specific features of the research.

2. All statements in the article have to be in impersonal form of the verb (L59, L 75, L185 and many others).

3. Self-citation is not encouraged. In my opinion, the authors have to rewrite text in L59 to L66 and L75 to L82.

4. What is the difference between titles of par. 3.2 and 3.3?

5. The authors have to explain more details about their idea to use Monte Carlo method and SEAMCAT software. Is there any other method which can be applied, other software and so on? All such specific features have to be explained in order to have clear picture about used methods for presented research. 

Author Response

Response to the Reviewer 3

We thank Reviewer 3 for evaluating our article and giving insightful suggestions that helped us improve the manuscript. Our responses to Reviewer 3 remarks are listed below.

Note:  The major modifications are marked in green color in the revised manuscript.

Point 1. Obviously, the authors have decided to combine the Introduction section and Literature review section in one. In this respect text in L44 to L47 included is inappropriate. The proper place is at the end of this section because the wording provides to the readers one of the specific features of the research.

Response: We would like to express our gratitude for this suggestion.

As per your recommendation, the mentioned text has been relocated to the last part of the introduction section. Additionally, certain words have been incorporated into this text to ensure consistency with the overall context and the logical arrangement of ideas.

(You can locate these revisions in the manuscript between Lines 165 and 168).

Point 2. All statements in the article have to be in the impersonal form of the verb (L59, L75, L185, and many others).

Response: Thank you for your suggestion.

The specified text has been rephrased to eliminate its reference in personal form. In the revised manuscript, you can find the paraphrased text on Line 55, Line 70, and Line 192.

Point 3.  Self-citation is not encouraged. In my opinion, the authors have to rewrite the text in L59 to L66 and L75 to L82.

Response: We appreciate the reviewer's recommendation regarding self-citation.

It is important to note that our present contribution builds upon our extensive research experience in the same field, serving as a continuation of the findings presented in our prior publications. Accordingly, citing our previous works is essential to contextualize and acknowledge the foundation of our current study.

In response to this feedback, we have revised the citation text of our publications, eliminating its reference in personal form, and enhancing professionalism and clarity. The refined text can be found in the revised manuscript from Line 55 to Line 61, and from Line 70 to Line 76.

Point 4.  What is the difference between titles of par. 3.2 and 3.3?

Response: We appreciate the reviewer for drawing our attention to this observation.

Indeed, there was a typo in the title of paragraph 3.3, and we have corrected it in the revised manuscript at Line 274.

Point 5.  The authors have to explain more details about their idea to use Monte Carlo method and SEAMCAT software. Is there any other method which can be applied, other software and so on? All such specific features have to be explained in order to have clear picture about used methods for the presented research.

Response: We extend our gratitude to the reviewer for this insightful comment.

Investigating coexistence issues between DTTB and IMT systems in digital dividend bands involves several approaches, including link budget analysis, simulations, laboratory measurements, and field tests. Each of these methodologies serves a distinct purpose and has its advantages and limitations.

We highlighted the distinct purposes, advantages, and limitations of these methodologies in our published article referenced in [6]. This paper underscored that these methodologies complement each other, and the choice of a specific approach depends on the research objectives and available resources. We cited this article in the revised manuscript (specifically in the introduction section from Line 70 to Line 76).

Furthermore, In the revised manuscript (specifically in the introduction section from line 150 to line 164), we have added a paragraph summarizing what was revealed from the literature review on the different approaches used to study issues of coexistence in digital dividend bands.

In this contribution, we have chosen to use simulations, in particular through the specialized software tool SEAMCAT, to investigate coexistence issues between DTTB and IMT systems for several compelling reasons:

This approach is cost-effective, safe, controlled, repeatable, and flexible, expediting analysis and providing insights for decision-making. Simulations grant complete control over test scenarios, allowing the creation of a wide range, including worst-case scenarios, which may be difficult or impossible to conduct in the real world.

Additionally, the simulations via the Monte Carlo method are formally adopted by international spectrum regulatory authorities based on international agreements.

(We explained why we chose simulation in the revised manuscript from Line 159 to Line 164).

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Author Response File: Author Response.pdf