Connecting the dots: two key standards at the heart of the Internet of Things

The Internet of Things (IoT) extends to a wide range of industry verticals, including industrial automation, transportation, logistics, healthcare, home automation and agriculture. Millions of devices connect and communicate with one another in such applications, making the choice of wireless communication technologies for connecting IoT devices a critical factor.

Broadly, wireless network technologies for the IoT can be classified into three categories:

• wireless personal area networks (WPAN) – communication technologies for interconnecting devices centred around an individual's workspace, typically with an operating range of up to tens of metres (eg, ZigBee or Bluetooth);
• wireless local area networks (WLAN) – communication technologies with a range sufficient to cover a limited area such as a home, a school or an office building (eg, IEEE 802.11 a/b/g/n/ac); and
• low-power wide-area networks (LPWAN) – communication technologies with operating ranges of kilometres (eg, NB-IoT, IEEE 802.11ah or LoRaWANT).

Of these, the LPWAN options are of particular interest since these are technologies with low power requirements that have been developed specifically to connect devices over wider regions than those covered by traditional networks. Therefore, LPWANs are preferred candidates, especially when it comes to industrial applications.

This article identifies, reviews and compares patent data pertaining to two prime LPWAN options for the IoT: Narrowband IoT (NB-IoT) and IEEE 802.11ah.

Technical overview of NB-IoT and IEEE 802.11ah

NB-IoT has been developed by 3GPP with the specifications first captured in 3GPP Release 13 (LTE Advanced Pro) in 2016. NB-IoT can coexist with 2G, 3G, 4G and 5G mobile networks and benefits from the security and privacy features of these. It is characterised by improved indoor coverage, the support of massive numbers of low throughput devices, low delays in sensitivity, ultra-low device cost, low device power consumption and optimised network architecture. As such, NB-IoT is expected to apply to industry verticals such as healthcare, consumer electronics, retail, smart metering, smart cities, smart homes and buildings, livestock monitoring and smart parking. IEEE 802.11ah (also referred to as Wi-Fi HaLow) is a wireless networking protocol the basic version of which was approved in 2016, with amendments since then. It uses 900 MHz licence-exempt bands to provide extended-range WiFi networks, compared to conventional WiFi networks operating in the 2.4 GHz and 5 GHz bands. It enables long-range and low-power wireless sensor networks and other massive, multiple-node wireless networks based on stations and multi-hop relays, thereby making it an ideal candidate for the IoT.

IEEE 802.11ah can also be used as back-haul infrastructure to connect sensors to data collectors. As such, it is expected to be adopted in a variety of use cases in agriculture, multimedia, smart e-health applications, smart metering, smart green and integrated transport, home automation, consumer services, smart grids, smart automotive, smart logistics and supply chain and industrial applications.

Table 1 compares the technical aspects of NB-IoT and IEEE 802.11ah.

Analysis of relevant patent data

A comprehensive understanding of the patents relevant to the implementation of a technical standard is a key factor in an industry player’s decision to adopt a standard. Therefore, it is important to get a reliable picture of the patent landscape pertaining to each communication technology being considered for the IoT.

In light of this, we have retrieved patent data relevant to NB-IoT and IEEE 802.11ah and conducted a preliminary analysis to identify the relevance of each patented technology to various aspects of the corresponding standard.

Data retrieval

Identifying the relevant data is a critical component in such an analysis. We have retrieved the data set using customised approaches for each standard. The data retrieval was carried out in the first week of July 2020. Therefore, the retrieved and analysed patent data represents all data published until June 2020.

• NB-IoT:
  • Step 1 – a master data set was first created using data retrieved from two sources: the European Telecommunication Standards Institute (ETSI) Dynamic Reporting portal and the ETSI Special Report;
  • Step 2 – the NB-IoT-related raw data set was retrieved from the master data set of Step 1 using three separate approaches:
    • patent data declared to technical specifications relevant to NB-IoT – these specifications were selected from ETSI’s portal for searching and browsing standards;
    • patent data declared to NB-IoT projects in ETSI; and
    • patent data filtered from the master data set using search strategies containing appropriate combinations of keywords relevant to NB-IoT concepts.
• IEEE 802.11ah:
  • Step 1 – we first compiled a list of individuals who were responsible for contributing submissions in the task group meetings of IEEE 802.11ah;
  • Step 2 – using appropriate combinations of keywords and classifications, we searched for patent data related to technical concepts of IEEE 802.11ah. From this initial data set, we selected patent data having one or more of the retrieved individuals from Step 1 as inventors.

Analysing the data

The active patent data retrieved for NB-IoT and IEEE 802.11ah using the respective customised approaches was collated into patent families. Family representation is useful since it gives a fair indication of the number of innovations, assuming one innovation per family. We also developed hierarchical taxonomies covering key technical aspects of both NB-IoT and IEEE 802.11ah.

Our experts reviewed the key claimed aspects of each patent family in the retrieved patent data sets. Based on this, each patent family was categorised into one or more technical categories from the taxonomy that were relevant to the key technical aspects on which the claims were focused. Moreover, the categorisation was conducted based on analysis of one representative member per family with preference being given to granted family members.

Our analysis did not include identifying patents essential to the standards. Instead, the analysis was focused on identifying patents with the potential to be relevant to the technologies implemented in the standards. Further, our analysis was based on patent data published until June 2020. As such, data for 2019 and 2020 may not be comprehensive because of the inherent delay between filing and publication.

Key insights – the overview

Based on this analytic approach, we identified 1,315 active patent families relevant to NB-IoT and 1,342 active patent families relevant to IEEE 802.11ah.

The innovation hotspots illustrated in Figures 1 (NB-IoT) and 2 (IEEE 802.11ah) have been identified based on analysis of earliest priority country data for the patent family data of each standard.

Figure 1. NB-IoT geographic analysis

Figure 2. IEEE 802.11ah geographic analysis

The innovation trends shown in Figure 3 have been identified based on analysis of earliest priority year data for the patent family data of each standard.

Figure 3. NB-IoT & IEEE 802.11ah innovation trends

Key insights from a technology deep dive

Layer-wise distribution

First, we analysed and compared the distribution of the patent data across various protocol stack layers. The main focus was layers where the technologies have been seriously considered for standardisation in the respective standards.

For NB-IoT, these are the LTE protocol stack layers – that is, the physical (PHY) layer, medium access control (MAC) layer, radio link control (RLC) layer, packet data convergence protocol (PDCP) layer and radio resource control (RRC) layer. The PHY layer is responsible for carrying all information from the MAC transport channels over the air interface, handling link adaptation (AMC) and power control.

The MAC layer is responsible for functions such as mapping between logical channels and transport channels, multiplexing/de-multiplexing of MAC service data units (SDUs) onto/ from transport blocks, reporting of scheduling information and hybrid automatic repeat requests (HARQ). The RLC layer is responsible for the transfer of upper layer protocol data units, error handling through ARQ and concatenation, segmentation and reassembly of RLC SDUs. The PDCP layer is responsible for functions such as header compression/decompression, ciphering/deciphering, ensuring message integrity and removal of duplicate data units. Finally, the RRC layer is responsible for functions such as connection establishment and release functions, broadcast of system information, radio bearer establishment, reconfiguration and release, and paging notification and release.

For IEEE 802.11ah, the PHY and MAC layers have been considered. The PHY layer is responsible for functions such as channelisation and setting transmission modes. The MAC layer is responsible for functions related to channel access, power saving and throughput enhancements.

A comparison of the patent data distribution is shown in Figure 4.

Figure 4. NB-IoT & IEEE 802.11ah layer-wise distribution

Clearly, maximum innovation focus in NB-IoT has been on technologies pertaining to the PHY layer, followed by the RRC and MAC layers. In IEEE 802.11ah, the MAC layer has been prioritised over the PHY layer in terms of innovation activity.

Technology distribution

The second levels of our taxonomies enlist the key technologies being implemented in the standards. A snapshot of the categorisation of the patent data into the taxonomies (via review of key claimed aspects for each patent family by experts) can be seen in Figures 5 (NB-IoT) and 6 (IEEE 802.11ah).

Figure 5. NB-IoT technology distribution

NB-IoT

The PHY layer has been the major hub of innovation activity in NB-IoT. The innovation focus in the PHY layer has been primarily on:

• the narrowband physical downlink control channel (NPDCCH) – prominent innovation activity areas have included DCI formats, mapping to resource elements, modulation aspects, narrowband control channel elements (NCCE), pre-coding, rate matching, scrambling and error detection; and
• reference signals – prominently pertaining to specific reference signals such as cell-specific reference signals (CSR), demodulation reference signals (DMRS), narrowband positioning reference signals (NPRS) and narrowband reference signals (NRS).

The second major protocol stack layer that has seen significant innovation activity is the RRC layer. Within this, the key innovation focus areas have been:

• connected mode – prominent innovation activity areas have included uplink/ downlink information transfer, initial security activation, RRC connection establishment procedure, RRC connection release and UE capability transfer;
• idle mode – prominent innovation activity areas have included cell selection/ reselection, DRX/eDRX (extended DRX), paging, PLMN selection and relaxed monitoring;
• system information block-NB (SIB-NB) – SIB1-NB has been the key focus area;
• master information block-NB (MIB-NB) – innovation activity areas have related majorly to MIB-NB scheduling, system frame number (SFN), access barring, hyper SFN (H-SFN) and operation mode information; and
• radio bearers – data radio bearer (DRB) has been the key focus area.

The MAC layer has also witnessed a significant amount of innovation activity, predominantly in:

• innovations related to acknowledgement/negative acknowledgement, adaptive HARQ, asynchronous HARQ and stop-and-wait protocol;
• configuration parameters – innovations related to parameters pertaining to narrowband random access channel resources, ra-ResponseWindowSize, contention-based random access parameter and contention-free random access parameter; and
• random access response (RAR)/Msg2 – innovations related to aspects such as temporary C-RNTI, timing advance command and UL grant.

IEEE-802.11ah

Figure 6. IEEE 802.11ah technology distribution

Most of the innovation in IEEE 802.11ah has taken place in the MAC layer, with the major innovation focus areas being:

• management frames – the major focus of innovation has been on the S1G beacon frame (extension) and on frames for basic management functions (eg, association requests and responses, reassociation requests and responses, and probe requests and responses);
• elements in management and extension frame – key elements around which innovation activity has been focused include the traffic indication map (TIM) element, the enhanced distributed channel access (EDCA) parameter set element, the target wake time (TWT) element, multiple basic service set identifiers (BSSID) elements, S1G capabilities elements, the AID request element, the AID response element, the AID announcement element, the BSS max idle period element, the header compression element, the AID response element, the S1G relay element, the S1G sector operation element and the RPS element;
• channel access techniques – prominent innovation activity areas include request to send/clear to send (RTS/CTS), channel access timing-related aspects, hybrid coordination function (HCF) contention-based EDCA and network allocation vector (NAV);
• identifiers – including COLOR/BSSID, AID, Dynamic AID, Group AID, Partial AID and UPLINK INDICATION; and
• management functions – such as power management, scanning, authentication, direct link-setup (DLS) operation, tunnelled DLS (TDLS) operation and notification of operating mode changes.

In the PHY layer, the major area for innovation activity has been the frame format and structure and preamble processing for the physical layer protocol data unit (PPDU) formats – that is, S1G LONG, S1G SHORT and S1G_1M. Channelisation is another major innovation focus area in the PHY layer.