CMAR: Multi-Access Radio for Remote Telephony

Around ten thousand of New Zealand’s most remote households connect to the public switched telephony network (PSTN) via customer multi-access radio (CMAR). Although copper loops connect up these neighborhoods of between ten and sixty houses, the loops are disconnected from major fibre optic backbones because of the cost of running cable across rough territory. These systems provide excellent voice service, but data service is limited to 14,400 bits per second – or around 0.1% of the capacity of a modern ADSL connection.

In the recent demerger of Telecom New Zealand, the CMAR network has gone to Chorus, as indicated the Asset Allocation Plan (PDF).

The diagram below illustrates a typical CMAR topology. It shows a local copper loop linking houses, an outstation linking the loop to a radio tower, and a radio linking network connecting the system back in to a regional centre with fibre optic network access.
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The Police, PPDR & The Digital Dividend

PPDR is an acronym for Public Protection and Disaster Relief, and in the context of New Zealand’s Digital Dividend spectrum, it stands for a new cellular data network that New Zealand’s Police want to build alongside existing commercial carriers 2° Mobile, Telecom, and Vodafone. The Police have been interested in such a network for several years, and a government working group for the issue has existed since 2006.

The network proposed by Police for the 700MHz Digital Dividend band is separate from and in addition to the Tait-supplied digital mobile radio network based on the APCO P25 standard. The Tait P25 network is being put in to upgrade Police radios, while the Digital Dividend PPDR network is intended to provide high-speed data communications to First Responders.
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Digital Dividend Discussion Submission

In August of 2011, New Zealand’s Ministry of Economic Development Radio Spectrum Management group published a discussion paper entitled “Digital Dividend – Opportunities for New Zealand”. The Digital Dividend is defined as the part of the radiofrequency spectrum that is able to be freed up following the switch from analogue to digital television, however this discussion paper only considers the “700MHz band” of spectrum and its most likely repurpose for use by cellular telephone and broadband providers. I discuss the Digital Dividend in some detail in an earlier blog post.

This discussion document is part of a consultation process kicked off by the Ministry in April 2011, with an Auckland meeting of industry participants held under Chatham House Rule. A public workshop was held in September to discuss the paper, and written responses were due for submission on Friday the 7th of October. These submissions, including the one below, will be published by the MED, as the initial positions of various industry participants. Comments on submissions will then be sought in a cross-submissions period, with responses due the 9th of November.
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700MHz and The Digital Dividend

As the process to release Digital Dividend radio spectrum kicks off, media outlets have started covering the issue with enthusiasm. Computerworld, The Dominion Post, NBR, and TUANZ have all featured articles on this spectrum in the last week. There’s plenty of fodder for the news, as matters of contention are both technical and market driven.

From a technical standpoint the most likely bidders (Telecom, Vodafone, and 2Degrees Mobile) agree the spectrum should follow the APT Wireless Forum’s Region 3 Harmonized FDD Arrangement, which divides the 108 MHz available into a pair of 45MHz blocks, separated by guard bands at the bottom, middle, and top of the block. This plan assumes the use of “LTE” or Long Term Evolution technology and allows for subdivision a number of ways, into spectrum for three, four, or five national cellular carriers.
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New Zealand Radiocommunications Map

The map below plots 19,750 radiocommunications licenses across New Zealand in VHF and UHF bands. These licenses support voice and/or data communications from individual towers to multiple end users. They could be paging, data radio, radiotelephone, or cellular mobile licenses.

A number of extracts from New Zealand’s Radio Spectrum Management license database were taken in March 2011 and combined to form the underlying data set. Only public data were considered – no suppressed licenses are included. Data were normalized to common organisation names – i.e. multiple forms of the same name, or multiple organisation IDs tied to the same limited company were given a common name. Licenses were further tagged with colors to represent some unique commercial operators and operator types. Location data were transformed from NZMG to NZTM2000 – which is assumed to be near equivalent to WGS84, the standard used by Google Maps.
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