The future of Wi-Fi [Guest Editorial]

Driven by the rapidly increasing demand for high data rate services and usage in a spectrum of application areas, wireless systems are compelled to evolve in order to meet the extraordinary performance requirements, especially in terms of spectral efficiency, coverage, latency, and energy efficiency. Regarding wireless local area networks, the first few widely accepted amendments to IEEE 802.11 wireless networking specifications, IEEE 802.11b/a/g, featured low spectral efficiencies, which are becoming insufficient to satisfy explosive traffic growth and the ever increasing consumer connectivity demand. With the soaring cost of the limited bandwidth at the 2.4 GHz frequency band, sustained improvement in spectral efficiency and quality of service has been achieved in IEEE 802.11n, which is mainly driven by advances in communication theory and the use of the 5 GHz frequency band. Specifically, the successive introduction of novel techniques such as multiple-input multiple-output (MIMO) antenna techniques and space-time coding, and the massive improvement in hardware and processing power, have enabled progressive system improvement. The introduction of advanced transmission techniques in recent years, notably multiuser MIMO and transmit beamforming, has provided additional powerful means for boosting the performance of Wi-Fi to gigabit per second speed and leading to the emerging IEEE 802.11ac. This is followed by the future introduction of IEEE 802.11ad products utilizing the 60 GHz frequency band, which are expected to take Wi-Fi speeds to multiple gigabits per second, and IEEE 802.1lax products, which are expected to improve the spectrum efficiency of Wi-Fi, thus enhancing system throughput per area in high-density scenarios of access points and client stations.