Unlike most general wireless users enjoying broadband access to the Internet and so on, a number of mission-critical applications such as PPDR are using narrowband systems that are only capable of transmitting voice and low-rate data. Broadband wireless networks with greater reliability are increasingly demanded by these applications including the emerging Smart Grid. With this vision, the IEEE 802.16 Working Group completed two standard amendments recently, IEEE Std 802.16n-2013 and IEEE Std 802.16.1a-2013. 802.16 network reliability is significantly increased by technical developments dealing with failures of network infrastructure stations, radio path and backhaul connectivity, and so on.
This article serves to analyze the envisaged typical use cases of greater reliable broadband wireless networks, outline the main technical developments of the two standards, and introduce a recently developed practical system for PPDR applications in Japan.