Comparison of IEEE 802.15 standards

This post briefly reviews the current status of standardization groups within IEEE 802.15There are IEEE standards covering the optical spectrum,

• IEEE 802.15.7-2011 std., known as VLC
• IEEE 802.15.7m std., (publication in 2018, as expected), including OCC modes
• IEEE 802.15.13 std., (ongoing), adding LiFi (IEEE 802.15.7-2011 std. is also the base document as IEEE 802.15.7m)
• IEEE 802.11, introducing LiFi to 802.11
• IEEE 802.15 VAT Interest Group (ongoing, not yet Task Group)

Under IEEE 802.15, besides IEEE 802.15.7m std., which includes OCC, two other current groups involving light communication are TG13 and VAT IG. TG7m mainly focus on light communication realized by PD receiver (LiFi modes included), while VAT IG is intended for vehicular communication. Note that TG7m already consider V2X particularly within PHY IV modes, VAT IG may add something new for its PHY layer.Excluding VLC and LiFi modes, OCC modes are the ones of interest in this topic. Herein, a short comparison (from my perspective) between two standard groups which have the direct influence on OCC (TG7m and VAT IG) is open as follows. The discussion is involving V2X use case, that might be a (potential) conflict of interest between two groups.

IEEE 802.15.7m std.

Figure 1 – Intended applications using PHY IV modes (drawing from my vision)Among three PHY modes within the draft standard, PHY IV is the best candidate for V2X with following reasons:

• PHY IV includes four significant PHY operating modes. These modes are designed serving their killer applications
  • RoI signaling waveforms (UFSOOK mode, S2-PSK mode): operating at low data rates to support the detection, identification, and tracking of LED lights. //This initial waveform is intended for the link setup phase which is one of the most challenging issues for communication in traffic condition (e.g., mobility speed, massive ambient light sources, far distance, etc.)
  • Twinkle waveforms (or hybrid waveform): operating at tens of kbps for the high-rate data stream. //A high-rate data stream is transferred under a consumption that link setup is successfully initialized.

//More explanation for the need of RoI waveform will be discussed in the next post

IEEE 802.15 VAT IG

Figure 2 – Another illustration for a V2X use caseBefore taking a look at a comparison, PAR and CSD documents of standardization groups are the official start for the ones familiar with IEEE standards association. But if you are not yet, please don’t worry.

• What is PAR?

PAR stands for Project Authorization Request. It is the means by which standards projects are started within the IEEE-SA. PARs define the scope, purpose, and contact points for the new project. //see more explanation here.

• What is CSD?: Criteria for Standards Development

Because VAT IG is not yet a task group, so its PAR and CSD is not yet approved. But you can see the current draft of PAR/CSD for VAT IG here/and here.For someone who does not want to download the files, I copy from the current PAR document and paste its scope and its purpose here:“5.2 Scope: This standard defines a Physical (PHY) and Media Access Control (MAC) layer using light wavelengths from 10,000 nm to 190 nm (VLC to NIR) with optional of laser technology in optically transparent media for optical camera communications. The standard is capable of delivering data rates between 10 bps and 100 Mbit/s for OCC and between 100 Mbit/s and 10 Gbit/s for LiFi. It is designed for point to point and point to multi point communications in both non-coordinated and coordinated topologies. The standard includes adaptation to varying channel conditions and maintaining connectivity during mobility (vehicular ), flicker mitigation, MIMO, RF co-existence, long communication range (up to 200 m). The standard adheres to applicable eye safety regulations. The standard may include MIMO, relaying, and mechanisms enabling heterogeneous operation with existing Radio Frequency(RF) wireless data communications standards.”“5.4 Purpose: This purpose of this standard is to utilize hybrid OCC-LiFi, to provide a global solution initially targeting industrial applications requiring, secure, high performance, long range optical camera communication (up to 200m), high-speed LiFi (up to 10Gbps), safety issues of V2X, and high data rate communications. The standard provides (i) access to unlicensed spectrum; (ii) inherent communication security due to inability to penetrate through optically opaque walls, (iii) data delivery without using RF spectrum; (iv) high reliability and low latency data transferring that meet the unique requirements of vehicular applications; and (v) communication augmenting and complementing existing services (such as illumination, display, indication, decoration, etc.). These are also attributes that will be valuable in commercial and business settings, both of which are expected to be significant emerging markets.”As can be seen, LiFi and OCC are within the scope. This VAT IG may combine OCC and LiFi. Despite there is the significant difference in operation, a dedicate combination of OCC and LiFi may be right to attract researchers/ industrial experts.

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Summary

In conclusion, VAT IG may utilize hybrid OCC-LiFi, and I personally do not know how far this standardization group can go because an Interest Group still needs companies involving to create a Task Group. Maybe this group takes several years to make a standard ready. However, given that IEEE 802.15.7m is going to release its specification by the end of 2018, and Intel technology is coming to real life soon (they might have a perfect plan for commercialization). Accordingly, users will see OCC application soon.