# IEEE 802.11 ah: A Technology to Face the IoT Challenge
## 1 Introduction
In May 2016 the TIG agreed to focus on the issue of low power (leaving aside the long range feature), creating a Study Group (SG), the LP-WUR (low-power wake-up receiver) SG. Therefore, the LRLP TIG has been dissolved. Besides, IEEE 802.11 initiated the task group TGax that aims at investigating as well as delivering next generation WLAN technologies and at characterizing PHY along with MAC modifications/amendments to improve performance and, thus, energy efficiency in transmission mechanisms. New proposals are being explored by TGax to accommodate the IoT use case [7], and thus, to adopt some of the LRLP propositions. The forthcoming IEEE 802.11 ax amendment is expected by 2019. Figure 1: Internet of Everything concept. It is well known that IEEE 802.11 specifies the mechanisms corresponding to MAC and PHY layers. On the other hand, the Internet Engineering Task Force (IETF) is in charge of the Internet standards development, being responsible of the first reference protocol stack for the IoT after a decade of work, which includes the adaptation layer 6 LoWPAN to support IPv6 over IEEE 802.15.4 networks. New adaptation layers are being proposed in the IETF 6 Lo Working Group, such as the one addressed to get an efficient transport of IPv6 packets over IEEE 802.11 ah [8]. IEEE 802.11 ah is not the only technology trying to cover the requirements of IoT communications. IEEE 802.11 will have to compete with other technologies that are already established in the IoT arena, such as ZigBee/IEEE 802.15.4e, BLE (Bluetooth Low Energy) and different Low Power Wide Area Network (LPWAN) proprietary technologies. In Table 1, we briefly summarize the most notable characteristics of those technologies. Each technology presented in Table 1 has particular features that are attractive for different IoT scenarios. ZigBee/IEEE 802.15.4e has been used in most of the Wireless Sensor Networks (WSN) due to its low implementation cost, the large number of supported devices, the offered data rates (i.e., 20 to 250 kbps) and the low power consumption, which makes it attractive for some IoT short-range low-rate applications. Similarly, BLE (which is an amendment of Bluetooth 4.0) is focused on low energy consumption and short-range low-rate communication. At present, Bluetooth Special Interest Group (SIG) is developing next Bluetooth 5 that promises enhancements in data rates and coverage ranges. 3 rd Generation Partnership Project (3 GPP) through Machine Type Communications (MTC) technology is also making an effort to standardize M2M (Machine to Machine) communications offering features such as Quality of Service (QoS), mobility and roaming support based on cellular technologies. In addition to the higher frequency bands used in 3 GPP MTC, the refarming of licensed Global System for Mobile Communications (GSM) spectrum brings the possibility to use sub 1 GHz frequencies. 3 GPP MTC, which is mentioned in release 12 and 13 and will be further developed in future releases, presents the largest coverage feature and the highest number of supported devices in comparison to the other aforementioned technologies, but operates in licensed spectrum. 3 GPP has also introduced Narrowband Internet of Things (NB-IoT) that allows operators to use a minimal portion of the available spectrum (Long-Term Evolution, LTE, or GSM networks) to target ultra-low-end IoT applications. However, NB-IoT is expected to suffer from not being full backward compatible with existing 3 GPP devices. It is anticipated that this specification will be completed in 2016 [9]. In addition, in the past few years, LPWAN solutions have appeared in competition to conquer the IoT market. Probably, the most outstanding solutions nowadays are LoRa and SigFox which present long coverage ranges (less than 3 GPP MTC) and increased number of supported devices [10]. In comparison to the foregoing technologies, IEEE 802.11 presents low implementation cost and consists in a widely spread technology deployed in many consumer electronic devices.