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The widespread adoption of IoT-enabled communication owes much to the introduction of the IEEE 802.11ah standard for Wi-Fi communications. Operating within the sub 1 GHz band, this standard offers numerous enhanced features, including scalability to accommodate more stations with lower energy consumption compared to existing technologies. Ensuring optimal energy efficiency in IoT networks is particularly critical in densely populated, high contention environments to support long-range connectivity. Given the promising future of IEEE 802.11ah in enabling autonomous IoT communications, enhancing the Restricted Access Window (RAW) mechanism becomes pivotal for prolonging device lifetimes and fostering innovation in protocol development. This study's highlight lies in investigating energy efficiency within the RAW. Preceding the formulation of an optimization function for maximizing energy efficiency, a comprehensive energy performance analysis was conducted. Both analytical and simulation results across various scenarios corroborate the efficacy of the proposed methodology. [ABSTRACT FROM AUTHOR]

This paper proposes an algorithm for the dynamic assignment of Restricted Access Window (RAW) for IEEE 802.11 ah. The Internet of Things (IoT) has groups of sensors and stations interacting over a common network. Wireless Local Area Network (WLAN) standard IEEE 802.11ah is best for IoT because it has high data rate and wide coverage while consuming low power. IEEE 802.11ah uses cautiously selected fixed RAW through an Access Point (AP), so that the chances of packet collision is minimized and energy efficiency is improved. By keeping it static, however, the effectiveness of RAW to utilize channels is reduced. We are suggesting an algorithm in which AP roughly calculates network packet transmission and the number of transmitting stations, and assigns resources to IoT networks by modifying RAW dynamically. The proposed algorithm shows improvement in average delay, throughput, PDR and jitter. The proposed algorithm achieves one of the best performances with an average delay of 0.43 sec, throughput of about 23 kbps, maximum packet delivery ratio (PDR) of about 98%, and jitter of about 80 sec. [ABSTRACT FROM AUTHOR]

In this paper, we propose a non-orthogonal multiple access (NOMA) based grouping method for IEEE 802.11ah, a promising platform for the internet of things (IoT). The grouping method improves the scalability of IoT networks, by reducing collisions in the access points (APs). The proposed method puts those IoT devices (IoT-Ds) whose channel gains are far enough from each other, i.e., who satisfy NOMA constraints, in the same group. Therefore, using successive interference cancellation (SIC), the AP is able to decode the simultaneous signal transmissions from IoT-Ds in a group. To assign IoT-Ds into groups and determine their transmission power, we formulate a total throughput maximization problem as a joint optimal grouping and power allocation problem, which is a non-convex mixed-integer programming problem. We convert it to a convex problem using quadratic fractional programming, and then we solve it using augmented Lagrange multiplier (ALM) method. Moreover, to reduce the complexity of the solution, we propose a fast grouping method to allocate power to each group in parallel. Simulation results show that the proposed methods have outstanding performance compared to conventional association identifier (AID)-based grouping method; besides, scalability of the network in terms of throughput, power consumption and channel utilization improves dramatically because of the collision reduction of IoT-Ds, which is achieved by deploying NOMA and SIC. Furthermore, the fast grouping method decreases the computational complexity greatly at the expense of a small reduction in network performance. [ABSTRACT FROM AUTHOR]

In Machine-to-Machine (M2M) networks, an enormous number of stations with low energy budgets contend for the channel access in order to get the transmission opportunity, leading to huge amount of congestion. Energy beamforming technology enables wireless devices to replenish their energy much faster than the traditional energy harvesting strategies. In this paper, a group-scheduled Medium Access Control (GSMAC) protocol is proposed as a solution of managing the access of stations that transmit bursts of data packets while taking into account the benefit of energy beamforming technology in M2M networks. In the proposed protocol, nodes are grouped by multiple Power Beacons in order to reduce the high collision probability. Nodes first contend the channel access in each group for reservation opportunities so that the reserved nodes can transmit data and harvest energy simultaneously by Access Point scheduling the data and energy transfer order. Simulation and analytical results show that GSMAC has significant improvements compared with the traditional distributed coordination function in terms of saturation throughput, delay, and energy-related performances. [ABSTRACT FROM AUTHOR]

A great number of Internet of Things (IoT) and machine-to-machine (M2M) based applications, which are telecommunication areas with the highest foreseen growth in the future years, require energy efficient, long range and low data rate wireless communication links. In order to offer a competitive solution in these areas, IEEE 802.11 standardization group has defined the 'ah' amendment, the first sub-1 GHz WLAN standard, with flexible channel bandwidths, starting from 1 MHz, up to 16 MHz, and many other physical and link layer improvements, enabling long-range and energy efficient communications. However, for some regions, like Europe, the maximum transmitted power in dedicated frequency band is limited to only 10 mW, thus disabling the achievement of ranges which would be close to targeted of up to 1 km. In this paper we examine possibilities for range extension through implementation of half-duplex decode-and forward (DF) relay station (RS) in communication between an access point (AP) and an end-station (ST). Assuming a Rician fading channel between AP and RS, and a Rayleigh fading channel on RS-ST link, we analytically derive results on achievable ranges for the most robust modulation and coding schemes (MCSs), both on downlink (DL) and uplink (UL). Analyses are performed for two different standard adopted deployment scenarios on RS-ST link, and variable end-to-end link outage probabilities. Moreover, we have analyzed whether the considered most robust MCSs, known for supporting the longest range, but the lowest data rates, can meet the defined requirement of at least 100 kb/s for the greatest attainable AP-RS-ST distances. We examine data rate enhancements, brought by coding and using of short packets, for both DL and UL. Finally, we present bit error rate results, obtained through simulations, of a dual-hop DF IEEE 802.11ah relay system for the considered MCs. All presented results confirm that IEEE 802.11ah systems through deployment of relay stations, become an interesting solution for M2M and IoT based applications, due to flexibility they offer in many aspects, meeting requirements for wide transmission ranges in such applications. [ABSTRACT FROM AUTHOR]

The IoT domain is characterized by many applications that require low-bandwidth communications over a long range, at a low cost and at low power. Low power wide area networks (LPWANs) fulfill these requirements by using sub-GHz radio frequencies (typically 433 or 868 MHz) with typical transmission ranges in the order of 1 up to 50 km. As a result, a single base station can cover large areas and can support high numbers of connected devices (>1000 per base station). Notorious initiatives in this domain are LoRa, Sigfox and the upcoming IEEE 802.11ah (or 'HaLow') standard. Although these new technologies have the potential to significantly impact many IoT deployments, the current market is very fragmented and many challenges exists related to deployment, scalability, management and coexistence aspects, making adoption of these technologies difficult for many companies. To remedy this, this paper proposes a conceptual framework to improve the performance of LPWAN networks through in-network optimization, cross-technology coexistence and cooperation and virtualization of management functions. In addition, the paper gives an overview of state of the art solutions and identifies open challenges for each of these aspects. [ABSTRACT FROM AUTHOR]