High-Density and De-Densified Smart Campus Communications

2Traditional WLAN Technologies

High‐Density Communication (HDC) technologies include the extension of traditional technologies (e.g. Multi‐User Multiple‐Input[s] And Multiple‐Output[s] [MU‐MIMO] approaches, also sometimes known as Massive MIMO), as well as new or evolving technologies.¹ In this basic overview chapter, some of the underlying technologies and principles that are applicable to HDC in local environments are surveyed,² but the discussion is not focused per se on the high‐density specifics, which are covered in the chapters that follow.

2.1 OVERVIEW

The Electrical and Electronics Engineers (IEEE) developed Wireless LAN (WLAN) standards starting in the late 1990s; IEEE 802.11b was ratified in July 1999. The 802.11b Wi‐Fi standard had a maximum link speed of 11 Mbps; the 2003 802.11a/g revision increased the speed to 54 Mbps with the introduction of Orthogonal Frequency Division Multiplexing (OFDM) technology. The 2009 802.11n allowed a single stream link to operate up to 150 Mbps. The 2013 802.11ac revision of the standard offered the possibility of link speeds around 866 Mbps on a single spatial stream with wider channels (on 160 MHz) and higher modulation orders (256‐QAM) (433 Mbps on smaller channels). While using the maximum number of spatial streams allowed in the standard, this system could support a speed of 6.97 Gbps (these maximum speeds are only achievable in the controlled Radio Frequency [RF] lab environments³). 802.11ax, also called High‐Efficiency ...