Supplier eBooks

16 industrial, scientific, and medical (ISM) spectrum allocations and by introducing newer versions of this technology, which operate in the less congested 5 and 60GHz bands. However, further throughput gains do not solve the key problem facing today's Wi-Fi users. The problem stems from the fact that Wi-Fi is now being used in ways that were not envisaged when the standard was first drawn up. At that time, engineers thought that relatively few users would demand a high-throughput service, which meant that Wi-Fi service was contention based; bandwidth was shared between users; access points covered overlapping areas; and end users could be shifted between access points. Moreover, traffic monitoring was not a priority, so every user was treated the same, and there was no facility to track and manage performance to optimize network efficiency. These drawbacks were not critical when there were relatively few users, but with today's high demands and dense deployments, the spectral inefficiency of contention-based Wi-Fi is beginning to limit the quality of service. Since the first Wi-Fi ® protocol—based on the IEEE 802.11 standard—was introduced in 1997, Wi-Fi has become a globally established wireless technology for consumer and industrial applications because it offers good tradeoffs between throughput, range, and power consumption. The protocol originally targeted wireless local area network (WLAN) applications and has now become the dominant standard in this sector. IEEE 802.11 has continually evolved to meet the demands of new Wi-Fi applications. For example, the introduction of more efficient modulation techniques and additional spatial streams has boosted throughput, and Wi-Fi's coexistence with other wireless technologies has improved by using Elsewhere, engineers are also looking to expand Wi-Fi technology to sub-1GHz spectrum allocations to boost range up to 1km for relatively low-throughput applications, which involve the burgeoning Internet of Things (IoT), and to use TV-white-space spectrum allocations effectively. Four amendments to the IEEE 802.11 standard, dubbed IEEE 802.11ax, ay, af, and ah, now exist to remove these challenges. IEEE 802.11ax IEEE 802.11ax, or "high-efficiency Wi-Fi (HEW)," was designed to meet the growing demand for dense deployments of connected devices and services in offices, schools, and public hotspots. IEEE 802.11ax increases the data rate capability from the legacy standard. It also vastly increases 2.4GHz data rates, as 2.4GHz was not addressed in the 802.11ac standard officially (only 5GHz). IEEE 802.11ax promises a marked improvement to the user experience found in today's common use cases, Wi-Fi Updates for Efficiency and Range What's new about the amendments to IEEE 802.11 (the standard for Wi-Fi) and what applications do they target are the two questions we will discuss in this article. By Steven Keeping, for Mouser Electronics

• Cover