An Efficient Communication Protocol for Real-Time Body Sensor Data Acquisition and Feedback in Interactive Wearable Systems

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors In line 162-163, the authors claim that they propose a novel communication protocol that would enable sensor node data aggregation and actuator feedback intensity transmission to the nodes with reduced overhead compared to known alternatives. However, they do not introduce how to group the sensor nodes, the size of a group, the relationship of groups, so that the overhead could be reduced. Especially, in Figure 1, group 1 has so many members, how to reduce the overhead?

 

Author Response

Comments 1: In line 162-163, the authors claim that they propose a novel communication protocol that would enable sensor node data aggregation and actuator feedback intensity transmission to the nodes with reduced overhead compared to known alternatives. However, they do not introduce how to group the sensor nodes, the size of a group, the relationship of groups, so that the overhead could be reduced. Especially, in Figure 1, group 1 has so many members, how to reduce the overhead?

Response:
Thank you for your valuable feedback. We completely agree with your observations and have made the following changes to address them:

• To clarify that the overhead reduction indicated in the article is calculated for a single group of sensors, the caption of Figure 4 has been updated to provide more detail on the circumstances.
• Since grouping considerations depend on the application, in the “Proposed Protocol” section added a paragraph stating that:
  “Beyond defining the communication order and timeouts, the proposed principle does not restrict how sensors are grouped, whether by order, size, or relationships. The choice of grouping depends on the specific application.”
• In the third paragraph of the “Interactive Jacket” section, we have explicitly clarified the grouping considerations for the nodes in the prototype
• In the beginning of the Discussion section, we added 4 paragraphs detailing considerations for sensor grouping for real-time applications.

Reviewer 2 Report

Comments and Suggestions for Authors

The paper presents a prototype of a wired body area network with several sensors embedded in a smart jacket. The contributions highlighted in the paper as the major innonvations doesn't seem particularly innovative: The sensors are connected to a bus of three wires, two of them to provide them electric power, and a third for data communication using a semiduplex UART. Semiduplex serial communications have been ubiquitously deployed for about 50 years, so I can't clearly see what are the innovations in the proposed systems. There are a lot of different serial interfaces to connect diferent devices, even addressable LEDs for LED strips, like the WS2818. The main strong point of the paper is that is correctly writen and explained. However, there are some aspects that should be clarified: 

1) The authors hint that there can be "collisions" in the data transmissions. If this is the case, how are these collissions handled? The authors do not describe a colission detection/colission avoidance nor any kind of medium access control, which would be necessary to handle this if collissions may happen (on the other hand, if the central gateway polls the sensors, then collisions will never happen, but then why mention them?)

2) How is the "prearranged order" for each sensor asigned in a real scenario? When flashing them? 

3) Could the author better justify the differences between "the theoretical" data transfer rate and the real one that leads them to state that there is room for improvement in their implementation?

Author Response

Comments 1: The paper presents a prototype of a wired body area network with several sensors embedded in a smart jacket. The contributions highlighted in the paper as the major innonvations doesn't seem particularly innovative: The sensors are connected to a bus of three wires, two of them to provide them electric power, and a third for data communication using a semiduplex UART. Semiduplex serial communications have been ubiquitously deployed for about 50 years, so I can't clearly see what are the innovations in the proposed systems. There are a lot of different serial interfaces to connect different devices, even addressable LEDs for LED strips, like the WS2818.

Response 1: Thank you for your thoughtful feedback. We have taken it into account and modified the 3rd an 4th paragraph of the Introduction to better describe highlight the novel aspects of our work including: 1) the group addressing approach to reduce overhead in sensor data acquisition and 2) the demonstration of the protocol with a UART semiduplex configuration, using a 3-wire bus, which, to our knowledge, has not been previously demonstrated in multi-sensor wearable systems. 

We also updated the last paragraph of the Discussion section noting that the benefits of the proposed group addressing approach could be explored with other serial interfaces.

Comments 2: The authors hint that there can be "collisions" in the data transmissions. If this is the case, how are these collissions handled? The authors do not describe a colission detection/colission avoidance nor any kind of medium access control, which would be necessary to handle this if collissions may happen (on the other hand, if the central gateway polls the sensors, then collisions will never happen, but then why mention them?)

Response 2: Thank you for your thoughtful feedback. We agree with your comments and have implemented the following changes:

• We have modified the first paragraph of Node architecture section to name the potential causes of collisions.
• We have identified collision management as an area for future work and included it in the discussion as future work (the last paragraph).

Comments 3: How is the "prearranged order" for each sensor asigned in a real scenario? When flashing them?

Response 3: Thank you for your question. Yes, the order of sensors and their data is individually determined in flashed firmware. We acknowledge that this point should be more clearly stated in the paper, so we have added a clarification at the end of the 3rd paragraph in the Interactive Jacket section.

Comments 4: Could the author better justify the differences between "the theoretical" data transfer rate and the real one that leads them to state that there is room for improvement in their implementation?

Response 4: Thank you for your thoughtful feedback. We agree with your comment and we have added the justification in the 8th paragraph of the Discussion section.

Reviewer 3 Report

Comments and Suggestions for Authors

Authors present a new approach for interactive wearable systems aiming at advanced communication solutions by introducing a high-performance, efficient, and reliable communication method. The paper has a good structure: starting with literature review and relative background on communication technologies used in BSNs. There were 48 references mostly dated in last 5 years. Then they described their original concept of the proposed communication protocol for wired on-body communication  between groups of sensor and actuator nodes in interactive wearable systems. The main goal was to develop an interactive motion-tracking jacket with vibrating feedback, including its hardware implementation and experimental evaluation. Technical solutions, testing and evaluating experiments and theoretical calculations offer a good picture of the design and experimental results. Results seem to be promising for an effective way how to collect effectively reliable data from BSNs.

Authors provided a serious discussion at the end of paper with plans for the further research aiming at improvements in proposed algorithms.

I have not found grammatical errors in the paper.

in my opinion the methodology is clearly described:

The state of the art on that topic is deep and mentions all important issues why the authors planned the experiments. Important part was the background on communication technologies used in BSNs. This was followed with description of their concept with own approach to the communication protocol for wired on-body communication between groups of sensor and actuator nodes in interactive wearable systems. They described also  considerations for its technical implementation, and design of the experimental setup for an interactive motion-tracking jacket with vibrating feedback. The proposed interactive wearable systems offer an optimized acquisition  of real-time data and provide feedback in BSNs with large amount of sensors with minimal wiring using a novel group-based addressing protocol. The principles of both individual and group communication approaches are illustrated in Figures to show differences.

Experiments and results of related calculations confirmed a potential of such solution to overhead reduction. Presented are related graphs. Attached Figures present also Interactive sensor jacket prototype with description of its design and electronic parts.

The MCU firmware logic for executing the adapted protocol is shown in Figure 9. The provided tests are well documented.

This seems to me as a clear research methodology, and sufficient information for readers.

In the discussion, authors declared "The proposed group addressing scheme for wired communication in interactive wear-able sensor networks significantly reduces overhead compared to conventional individual addressing methods. In our interactive jacket prototype with nine sensor/actuator nodes, each producing 32 bytes of data and using UART communication with 8 data bits, one start bit, and one stop bit, we achieved an overhead reduction of 1.98 times (almost twofold)." I am not able to confirm or refuse results. However the methodology of HW and SW used are well described and obtained data are a part of the paper as well. 

The presented evidence and arguments address authors research aims to show importance and effectivity using wired system for multisensorial interactive wearables. Authors understand that "the achieved values could not be compared directly to performance metrics claimed by commercial products (Table 1); however, the extrapolated values indicate great potential for the proposed approach to outperform them." They found some limitations in the proposed design. Results indicate that wire length impacts the maximum reliable baud rate. In their further plans, they plan to continue in the development of the proposed communication approach and node architectures as they have the potential to serve as foundational building blocks in various interactive applications. They plan experiments with larger number of nodes, and additional features like node discovery, dynamic grouping, and node reprogramming, which could enhance versatility and ease of use. 

• I accept tables and figures as readable and sufficient for the presented research work.

Author Response

Comments 1: Authors present a new approach for interactive wearable systems aiming at advanced communication solutions by introducing a high-performance, efficient, and reliable communication method. The paper has a good structure: starting with literature review and relative background on communication technologies used in BSNs. There were 48 references mostly dated in last 5 years. Then they described their original concept of the proposed communication protocol for wired on-body communication  between groups of sensor and actuator nodes in interactive wearable systems. The main goal was to develop an interactive motion-tracking jacket with vibrating feedback, including its hardware implementation and experimental evaluation. Technical solutions, testing and evaluating experiments and theoretical calculations offer a good picture of the design and experimental results. Results seem to be promising for an effective way how to collect effectively reliable data from BSNs.

Authors provided a serious discussion at the end of paper with plans for the further research aiming at improvements in proposed algorithms.

I have not found grammatical errors in the paper.

in my opinion the methodology is clearly described:

The state of the art on that topic is deep and mentions all important issues why the authors planned the experiments. Important part was the background on communication technologies used in BSNs. This was followed with description of their concept with own approach to the communication protocol for wired on-body communication between groups of sensor and actuator nodes in interactive wearable systems. They described also  considerations for its technical implementation, and design of the experimental setup for an interactive motion-tracking jacket with vibrating feedback. The proposed interactive wearable systems offer an optimized acquisition  of real-time data and provide feedback in BSNs with large amount of sensors with minimal wiring using a novel group-based addressing protocol. The principles of both individual and group communication approaches are illustrated in Figures to show differences.

Experiments and results of related calculations confirmed a potential of such solution to overhead reduction. Presented are related graphs. Attached Figures present also Interactive sensor jacket prototype with description of its design and electronic parts.

The MCU firmware logic for executing the adapted protocol is shown in Figure 9. The provided tests are well documented.

This seems to me as a clear research methodology, and sufficient information for readers.

In the discussion, authors declared "The proposed group addressing scheme for wired communication in interactive wear-able sensor networks significantly reduces overhead compared to conventional individual addressing methods. In our interactive jacket prototype with nine sensor/actuator nodes, each producing 32 bytes of data and using UART communication with 8 data bits, one start bit, and one stop bit, we achieved an overhead reduction of 1.98 times (almost twofold)." I am not able to confirm or refuse results. However the methodology of HW and SW used are well described and obtained data are a part of the paper as well. 

The presented evidence and arguments address authors research aims to show importance and effectivity using wired system for multisensorial interactive wearables. Authors understand that "the achieved values could not be compared directly to performance metrics claimed by commercial products (Table 1); however, the extrapolated values indicate great potential for the proposed approach to outperform them." They found some limitations in the proposed design. Results indicate that wire length impacts the maximum reliable baud rate. In their further plans, they plan to continue in the development of the proposed communication approach and node architectures as they have the potential to serve as foundational building blocks in various interactive applications. They plan experiments with larger number of nodes, and additional features like node discovery, dynamic grouping, and node reprogramming, which could enhance versatility and ease of use. 

• I accept tables and figures as readable and sufficient for the presented research work.

Response 1: Thank you for your thoughtful and positive feedback on our work. As we did not identify any request for changes, we do not propose any additions to our manuscript.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

In my opinion the novelty of the paper is still quite limited, but otherwise the methods are adequatelly described and the paper is well written and presented.