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PUBLIC SAFETY

WE'RE NOW SEEING SOME DEMONSTRATED SPEEDS THAT ACTUALLY ENABLE STREAMING VIDEO APPLICATIONS AND ERROR-CORRECTED BAUD RATES IN EXCESS OF 128 KBPS.

Companies serving the SCADA, military and transportation sectors abound. We’ve seen solid system performance on narrow channels from multiple vendors, such as IP Mobilenet (IPMN), CalAmp (DCI), Data Radio, Electronic Systems Technology, Motorola Solutions and others. Based on their published specification sheets, they are still only delivering 32 to 64 Kbps raw data rates for narrowband 25 kHz channels. With FEC, the higher of these rates deliver approximately 48 Kbps to the user (Motorola and IPMN).

Meeting speed and capacity goals In a rather complete paradigm shift, Australia’s CSIRO has introduced a methodology to obtain some substantial gains in both capacity and user speed, coupled with the ability to run substantial power levels and agile software-defined radios (SDRs), giving the correct propagation for extended coverage. Here’s the overall approach: • Multi-user MIMO beamforming • Antenna array and processing at the base station forms spatially separate beams to each mobile user • Each beam uses the full spectrum all the time: simultaneous, independent, continuous transmission to each mobile user • Simple mobile hardware and antenna • Base station antenna array and processing maintains beam alignment with mobile users • Dynamic selection and digital aggregation of non-contiguous spectrum, with no interference to adjacent channels The hardware platform comprises: • Software-defined RF front end that preserves signal phase and amplitude with minimal distortion • High linearity, high dynamic range and FPGA processing, producing any modulation, narrowband or broadband • Bandwidth up to 20 MHz • Agile frequency tuning of 30 to 900 MHz • High RF power • Simultaneous voice and data/video, multiple protocols (P25, Ethernet, TETRA, DMR, DPMR) in one radio, with native simulcast • Common front end for mobiles and base station

Delivering on public safety requirements So what does all of this evolution mean to a typical public safety-grade communications system? Here’s an abbreviated list of the CSIRO system attributes:

30 Critical Comms - Nov/Dec 2015

• World’s highest data rate in 12.5 kHz (160 Kbps MAC throughput, raw data of 260 Kbps, up to 8 P25 channels) while travelling at 110 km/h currently achieved • Ability to aggregate up to eight 12.5 kHz channels for increased bandwidth and data rate: 320 Kbps for 2 channels, multiplying up to a maximum of 2.5 Mbps for eight channels • Predictable, video-capable performance for all users on the entire cell: no shared bandwidth, no reduced performance at cell edges • One hardware platform from 30 to 900 MHz, and a common front end for mobiles and base station • Incremental capital investment: no forklift upgrades of existing P25 equipment • Voice and data/video in one radio • Increased coverage = fewer towers • Minimum greenfield cost: 25–40% vs LTE equivalent • Spectrally efficient — uses all available existing narrowband public safety spectrum, contiguous and non-contiguous, scalable from 12.5 kHz to 10 MHz, dynamically allocated by base station or mobile (will later be compatible with broadband public safety spectrum, eg, FirstNet) • High spectral efficiency and dynamic spectrum management means minimum spectrum use for the application • Intelligent RF management means greater frequency re-use • High security, sure delivery • Physical separation from public network, and secure gateways • RSA security, total visibility and control across the network • RF modulation has built-in security to avoid snooping • Targeted applications and services • Native IP delivery equals easy customisation and efficient delivery of public safety applications CSIRO has a commercialisation partner that will be deploying this technology. With this much evolution arriving just before the start of some pilot wireless broadband systems, it might be time to evaluate the narrowband, frequency-agile approach to eliminate some of the major obstacles to system construction: access to enough sites, strategically located to meet the requirements of a low-power LTE network. TF Smoak is an experienced emergency strike team commander and first responder who works as a project manager and compliance engineer on large wireless projects. He will give a presentation at Comms Connect Melbourne on 2 December 2015.

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Critical Comms Nov/Dec 2015  

The communications industry magazine for the public safety, law enforcement, utilities, transport, mining, security and defence sectors thro...

Critical Comms Nov/Dec 2015  

The communications industry magazine for the public safety, law enforcement, utilities, transport, mining, security and defence sectors thro...