Translation: IEEE 802.15.4z Standard. What awaits us in the future?

Hi, Habr! I present to you the translation of the article “IEEE P802.15. Wireless Personal Area Networks .







<sup>Translation of the article: mentor.ieee.org/802.15/documents?is_dcn=coexistence%20document&is_group=004z

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File:

09-Apr-2019 ET

Coexistence Document 15.4z

Benjamin A. Rolfe (BCA / UWBA / NXP / et al)

15-18-0523-05-004z-coexistence-document-15-4z.docx</sup>



In February 2019, the non-profit organization UWB Alliance was created. The alliance includes such companies as: Apple, Hyundai, Kia, Zebra, Decawave, Alteros, Novelda, Ubisense and others.



In order to coordinate the work on the promotion and improvement of radio signal transmission technology in the ultra-wide band (UWB or UWB). Within this organization, a working group has been created to develop the IEEE 802.15.4z standard.



Good day. My name is Eugene, I work for RealTrac Technologies. I offer to your court the translation of the report on the work of the IEEE 802.15.4z standard development team, and I will also be happy to answer questions on the current situation with ultra-wideband technologies, ways of development and scope.

Introduction

This document provides a brief compatibility analysis that was performed to evaluate the performance of systems using the 802.15.4-2015 HRP and LRP PHY as amended by the P802.15.4z relative to other 802 wireless standards that can work in the same range. .

1. Terminology

Terms used in this document have the following meanings:



“Base Standard” means the 802.15.4-2015 standard and all amendments approved at the time of the preparation of this document.



"802.15.4" means the base standard.



“This amendment” means the P802.15.4z amendment: Standard Amendment for Low-Speed ​​Wireless Networks: Advanced High-Speed ​​Pulses (HRP), Low-Speed ​​Pulses (LRP), UWB in a Physical Medium (PHYs), and appropriate methods for determining the frequency range.

2. Overview

802.15.4 UWB based systems are widely used throughout the world. The original 802.15.4a-2007 version included the HRP UWB PHY in the standard, and the LRP UWB PHY was added to the 802.15.4f-2010. The P802.5.4z Amendment extends to both the UWB PHY and new and existing applications. Current UWB systems operate worldwide with very low power spectral densities. This document presents an analysis of compatibility with other 802-standard wireless systems, including older versions of the 802.15.4 standard and current 802.11 systems.



There are many sources of UWB compatibility information. The method used in this document is to summarize the results in terms of compatibility between wireless 802 systems capable of operating in the same frequency bands. Links to 802.15.4a [8] and 802.15.4f [9] CADs and studies [10] [11] describe the compatibility of the UWB PHY with the following systems:

• 802.15.4 PHY operating in overlapping frequency bands
• 802.16 operating in the range from 3.4 to 3.8 GHz
• 802.11 OFDM operating in the 5GHz and 6GHz bands.

Worldwide, UWB systems transmit with very low power, usually limited to power spectral density (PSD) limits, consistent with side and / or unintentional electromagnetic emissions set for unintended emitters. For example, in the USA, as well as in many parts of Asia and Europe, the PSD limit is -41.3 dBm.

2.1 UWB 802.15.4z Overview

2.1.1 Frequency ranges under consideration

Figure 1 shows the 802.15.4 UWB channel plans defined in the base standard and supplemented with this amendment. The 802.15.4z amendment defines new devices with extended range capabilities that work in terms of high-speed channels; no changes to devices operating in low-speed channel plans are included in this amendment.





Figure 1: Spectral Graphics



This amendment expands the LRP channel plan, as shown in the figure with the addition of channel definitions to the upper UWB range. This amendment does not change the HRP channel plan. The highlighted “Globally Available UWB Spectrum” illustrates the channels in terms of UWB channels that are available in all regulatory domains that operate the LRP and HRP devices as defined in the base standard and this amendment. Other channels are available in a more limited number of regulatory domains.

2.1.2 Relevant 802 standards

Table 1 lists other 802 standards that can operate in overlapping ranges. This information is taken from Appendix E of [5] and [6].



Table 1: Other 802 wireless standards in thematic bands





Note that most WLAN applications use a channel spacing of 20 to 80 MHz. The analysis referred to in this document mainly concerns the channel spacing from 5 to 160 MHz.

2.1.3 LRP PHY

This amendment extends LRP PHY to support the following features:

• New PHY package formats
  
  The frame duration is likely to be shorter - less exposure and less exposure.
  
  
  
  Fewer pulses and shorter packet lengths
  
  More reliable in terms of interference
  
  PSD and peak level coincides with the former UWB
  
  Energy levels remain unchanged.
  
  It takes less time and energy to transmit a packet.
  
  
• New modulation and PRF
  
  
  
  No change in exposure
  
  May be more robust
  
  

2.1.4 HRP

This amendment adds the following characteristics to the HRP PHY:

• New modulation and PRF
  
  
  
  Does not use BPM
  
  PRF peak has not changed
  
  The average value of PRF may vary, but equals the same energy within the regulatory limits.
  
  New codes allow data to be transmitted at a higher PRF rate, fewer frames will reduce the frame transmission time.
  
  The increase in data transfer rates has led to lower costs.
  
  
• Adding additional preamble codes
• Impact on previous HRP form
  
  
  
  New codes ignored by old devices.
  
  Compatible PHY modes for interfacing with legacy devices
  
  
• More reliable transmission
  
  
  
  Better controlled instantaneous peak power
  
  Reduces the number of retransmissions required
  
  

2.1.5 MAC improvements and their effect on compatibility

New MAC functions added by this amendment use existing MAC functions to ensure compatibility with legacy 802.15.4 devices, as well as to maintain the proven compatibility characteristics provided by the standard.

The MAC is supplemented by this amendment with the provisions used in measuring the distance in the transmission medium as follows:

• Broadcast / Multicast: Ensuring Broadcast Planning and Multicast Data Exchange
• New information elements for the transmission of information used to measure the distance exchange of relevant information
• MAC characteristics for monitoring distance measurement with improved integrity checking
• Changes in SAP MAC to support new ranking and sharing tools

The channel access methods used to estimate the channel status and the start of data transmission are not affected by these additional MAC functions. The impact on compatibility is minimal.

2.2 Overview of Compatibility Mechanisms in 802.15.4

Compatibility mechanisms in clause 802.15.4 are described in [8] and [9]. Compatibility is also enhanced by the short running cycle of 802.15.4, thanks to the MAC architecture, as explained in [13].



MAC changes to this amendment will have a minimal impact on compatibility performance:

• New scheduling capabilities are similar and compatible with existing channel access control mechanisms (CSMA-CA)
• New features remain compatible in terms of load reduction, effective duty cycle, and channel access control, as described in [8]

UWB PHYs operate at very low power, usually at or below the limits of background electromagnetic emissions. This, as a rule, limits the effect of UWB emitters on other systems.

2.3 Compatibility Analysis Methodology

Compatibility studies referred to in this document are generally carried out in accordance with the methodology described in [12] and considering each system both in the role of subject and object of influence. In this document, the compatibility analysis was reviewed for compliance with the current 802 standards, and here we present the relevant results. 802 wireless standards are changing, so more research has been conducted and distributed that specifically assess compatibility between 802.15.4 UWB and 802.11 systems. The findings of these studies are presented in this paper.



The compatibility studies [10] and [11] cited in this paper use the Monte Carlo simulation method to evaluate potential impacts when sharing spectrum.

3. Different systems with the same frequency bands.

This clause presents compatibility factors with other 802 systems that operate in the same frequency bands. In this clause, different means different from IR-UWB operating in accordance with the 802.15.4 LRP or HRP PHY specifications.

3.1 802.11 Compatibility

As described in detail in Appendix E of [5] and [6], 802.11 systems can operate in different bands, as shown in Table 1, with a distance between channels from 5 MHz to 160 MHz. 802.11 WLAN based devices can operate at relatively high EIIRP power up to 1000 mW (30 dBm) in some regions. UWB devices operate with an average EIRP value limited to - 41.3 dBm / MHz. 802.15.4 UWB devices use a nominal bandwidth of 500 MHz and higher.



Studies [10] and [11] present simulation results illustrating the effects of 802.11 systems operating near 802.15.4 UWB systems. The study explores various deployment scenarios and operating conditions.

3.1.1 The impact of a WLAN on 802.15.4 UWB

The results for the scenarios described in [10] and [11] illustrate potential impacts. The WGSE PT45 study [10] considers both individual interference and aggregate interference using simulation methods in combination with active signal measurements. The results show that 802.11 wireless LAN interference at a distance of up to 946 meters results in a sensitivity reduction of more than 3 dB in UWB communication and location tracking systems. For sensing, the corresponding distance is 212 meters. The cumulative estimate of the interference in the Monte Carlo simulation shows that with a WLAN duty cycle of 1.97%, the probability of reducing sensitivity to UWB communications and location tracking devices is more than 3 dB and ranges from 5 to 15%.



For sensors, the probability of reducing sensitivity by more than 3 dB is from 3 to 6%. In [11], additional configurations and scenarios are investigated using modeling methods. Studies show a significant impact on both communication and range / location. This study also includes mitigation recommendations for improving interoperability rates.

3.1.2 Impact of 802.15.4 UWB on 802.11 WLAN

UWB devices operate with an average EIRP value limited to -41 dBm / MHz, the signal attenuation required to limit the sensitivity loss of a UWB 802.11 device by 3 dB is shown in the table below.



Table 2: Calculation of the interference threshold for the 802.11 system





In the worst case, the attenuation model of the signal at a control distance d0 = 1m.



In the 6 GHz band is 48 dB, based on the Friis equation.



Using this model, the required separation for 67 dB of signal attenuation is less than 9m. Note that this is the worst case scenario, as shielding effects and areas of indirect visibility are not taken into account; they will further reduce the required diversity.

For illustration, the following table shows the attenuation of the signal at the control distance d0, as well as the minimum required separation distances, for example, frequencies from 3 GHz to 6 GHz:



Table 3 Path Loss Reference

3.2 802.15.4 Compatible Systems

RCC PHYs can operate in bands, as shown in Table 1. It appears that PCC PHYs will not be operated in close proximity to UWB systems. RCC is used mainly outdoors and near railway tracks.

3.3 Other Considered Wireless Systems 802

Reference [8] details the compatibility properties between 802.15.4 UWB and 802.16 based systems. The results show that the PER value falls below 1% at a separation distance of 1 m, and when the separation distance is> 6.9 m, the effect on 802.16 from the LWP signal UWB becomes insignificant.



The results show that when using the 802.16 system as a source of interference and the HRP UWB system as an object of impact, the figure falls below 1% at a separation distance of 44 m and becomes insignificant at a distance of more than 140 m.



The signal structure, bandwidth and power spectral density of the LRP symbol is quite similar to the HRP signal, therefore the results for LRP should be similar to the results shown in Reference [8].

4. 802.15.4 UWB system

This provision describes the compatibility situation for this amendment and existing UWB 802.15.4 systems.

4.1 HRP

In the old 802.15.4a HRP and the new 802.15.4z HRP modes, preamble sequences are used to synchronize and measure distances. Both sequence standards are designed to be more reliable in the presence of interference. The sequences in both standards will have a very low correlation with the sequence in another standard. Inter-standard interference between the preambles will be almost identical to the intra-standard interference. Both standards use a bandwidth of 500 MHz. Both use a 128 ns symbol to operate at ~ 7 Mbps and a 32 ns symbol to work at ~ 30 Mbps. 802.15.4z HRP uses higher PRF values ​​than 802.15.4z HRP. Auto-adjustment of transmit power may be slightly different due to the limitations of the peak emission spectrum. However, interstandard interference will be essentially the same as in-standard interference.

4.2 LRP

Changes to this amendment depend on the same channel access method and are expected to have the same effect as the presence of additional obsolete LRP devices in the field of radio influence. The compatibility mechanisms described in [9] are identical. Fiberglass systems are expected to operate at a very low duty cycle.

5. Conclusion

The UWB systems described in this amendment will have minimal or total no impact on other wireless systems 802 operating in the field of radio influence. Low signal power and low duty cycle reduce the effect of UWB signal interference on systems other than UWB. In particular, the impact on other systems based on 802.15.4 and 802.11 in the same sphere of radio influence is usually not detected.



When operating in the same area of ​​radio influence as the outdated UWB 802.15.4 systems, the impact of systems operating in accordance with this amendment is equal to or less than the impact of additional outdated devices. Adding preambles and STSs reduces the effect on legacy UWBs, since they do not recognize signals in legacy systems and, thus, are below the noise level.



As an object of interference, the UWB systems described in this amendment will be compatible with traditional UWB systems, since the signals from them will be recognized and properly processed. In the presence of 802.11-based systems operating in close proximity, a significant impact on the UWB system is expected due to the use of higher power. The degree of impact is most dependent on the operating cycle of the 802.11 system (s). Physical separation reduces exposure.



Thanks for attention. If you have questions about UWB technology and its current stage of development, I am ready to answer your questions in the comments.