A system for the delivery of high speed data mission critical, private broadband wireless networks based on a modified version of the ieee802.16e-2005 standard and subsequent versions of this standard referred to, known as “mobile WiMAX”. The system comprises a plurality of base stations, each of said base stations covering at least one sector, which maintain two-way data communication, with a plurality of mobile stations and fixed subscriber stations in its serving area, over licensed frequency bands below 1 GHz in accordance with the mobile WiMAX standard. The mobile WiMAX air interface standard (ieee802.16e) is modified for channel sizes below 1.25 MHz.