APCO P25 briefing for E-GIF Working Group

NZ Police• • • • • • •

BRIEFING FOR E-GIF WORKING GROUP ON INCORPORATING THE

APCO P25 STANDARDS INTO THE E-GOVERNMENT INTEROPERABILITY

FRAMEWORK

PREPARED BY

ADDED VALUE APPLICATIONS

Bill DeverallAdded Value Applications

19 September 2006Added Value Applications Page 1

4/8/2023

CONTENTS

1.0 Introduction..............................................................................................................32.0 The e-Government Interoperability Framework......................................................3

2.1 Relevant objectives of the e-Government Initiative.......................................33.0 Operational interoperability for PPDR agencies................................................3

3.1 PPDR land mobile radio networks.................................................................33.2 Call and dispatch centres................................................................................33.3 A national PPDR strategic plan and command structure...............................33.4 Communications between PPDR agencies....................................................3

4.0 Technical interoperability between PPDR agencies..........................................35.0 The APCO P25 standards suite..........................................................................3

5.1 RF sub-system................................................................................................35.2 Common air interface.....................................................................................35.3 Intersystem interface......................................................................................35.4 Telephone interconnect interface...................................................................35.5 Network management interface.....................................................................35.6 Data host or network interface.......................................................................35.7 Data peripheral interface................................................................................35.8 Fixed station interface....................................................................................35.9 Console sub-system interface.........................................................................35.10 Security...........................................................................................................3

6.0 APCO 25 standards and technical interoperability for PPDR networks in New Zealand...........................................................................................................................3

6.1 Mechanisms for technical interoperability using the common air interface. .36.2 Mechanisms for technical interoperability other than at the common air interface......................................................................................................................36.3 Interoperability between APCO P25 networks..............................................36.4 Technical interoperability with an initial deployment of an APCO 25 standard network........................................................................................................36.5 Technical interoperability with the ultimate deployment of the APCO 25 standard in PPDR networks........................................................................................36.6 The requirements of call and dispatch centres, and other related organisations...............................................................................................................36.7 The differing technical capabilities required for urban, rural and remote environments..............................................................................................................36.7 International technical interoperability..........................................................3

7.0 Radio spectrum requirements for APCO 25 based PPDR networks..................37.1 Forecast capacity............................................................................................37.2 VHF Spectrum requirement and its availability.............................................37.3 UHF Spectrum and its availability.................................................................3

Disclaimer:This report is provided exclusively for the New Zealand Police. No part of this report may be distributed to any third parties, without the prior written consent of Added Value Applications Ltd.

While every effort is made to ensure the accuracy of the information contained herein, Added Value Applications Ltd - its officers, employees and agents accept no liability for any errors or omissions or any opinion expressed or recommendations made in this report. Furthermore, Added Value Applications Ltd will not be held liable for any actions or decisions arising from conclusions drawn from this report.

Added Value Applications Page 2 4/8/2023

1.0 IntroductionThe purpose of this paper is to brief the Working Party tasked with ensuring that the adoption of the APCO P25 standards suite for national Public Preparedness and Disaster Recovery (PPDR) Land Mobile Radio Networks (LMRN) meets the requirements of the e-Government Interoperability Framework (e-GIF). This paper should be read in conjunction with the Terms of reference for the Working Party and contains:

a brief introduction to e-GIF and its objectives an overview of the APCO 25 standards, a view of the state of current interoperability between PPDR agencies and their

LMRN networks and a view of the mechanisms by which the adoption of the APCO 25 standards

initially for an LMRN for Police, Fire and Customs would enhance Government’s attainment of its e-GIF objectives

The paper aims to assist with the identification of any issues so that they can be resolved.

2.0 The e-Government Interoperability FrameworkAs part of its digital strategy the New Zealand Government intends to be a leader in e-Government and has adopted that intention as a Vision Statement for its e-Government initiative, with the following Mission:

By June 2004 the Internet will be the dominant means of enabling ready access to government information, services and processes.

By June 2007, networks and Internet technologies will be integral to the delivery of government information, services and processes.

By June 2010, the operation of government will have been transformed through its use of the Internet.

The goals expressed for the Mission are:

Better services - more convenient and reliable, with lower compliance costs, higher quality and value;

Cost effectiveness and efficiency - cheaper, better information and services for customers, and better value for taxpayers;

Improved reputation - building an image of New Zealand as a modern nation, an attractive location for people and business;

Greater participation by people in government - making it easier for those who wish to contribute; and

Leadership - supporting the knowledge society through public sector innovation.

The Government has identified three broad characteristics that mark out successful e-government:

Draft Overview of the APCO 25 Standards Suite and its Relationship to e-GIF V 0.1

Convenience and SatisfactionServices provided anytime, anyhow, anywhere

People will have a choice of channels to government information and services that are convenient, easy to use and deliver what is wanted.

Integration and Efficiency Services that are integrated,customer-centric and efficient

Information and services will be integrated, packaged, and presented to minimise cost and improve results for people, businesses, and providers.

Participation Participation in government

People will be better informed and better able to participate in government.

2.1 Relevant objectives of the e-Government InitiativeRelevant objectives for the e-Government Project are:

Ready Access by 2004 Delivery by 2007

Integration and Efficiency Services that are integrated, customer-centric and efficient

Agencies will begin to integrate services through use of common e-government "foundations" (technology, standards and policies).Agencies will be more citizen- and results-oriented in the way they design services.

Front-office integration will be well developed - many services will have been redesigned and bundled together in ways that meet customers' needs better.Back-office integration will be advancing through adoption of the interoperability framework, and progressive build of components of the service delivery architecture.

What is relevant to PPDR agencies with the e-Government Initiative is the ongoing development of a framework for interoperability (e-GIF) which incorporates the use of common technology, standards and policies. The purpose of the Working Party is to ensure that the APCO 25 Standards adopted for PPDR land mobile networks are incorporated into the e-GIF Framework.

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http://www.e.govt.nz/about-egovt/strategy/e-gif-v-2/index.html


3.0 Operational interoperability for PPDR agenciesThe term “interoperability” has been defined in the USA by the Department of Homeland Security as covering elements "that include governance, standard operating procedures, technology, training/exercises, and usage of interoperable communications".

They have also defined communications interoperability as the “ability of public safety agencies to talk across disciplines and jurisdictions via radio communications systems, exchanging voice and/or data with one another on demand, in real time, when needed, and as authorised".

Further the term “interoperability” is described as a continuum covering levels of interoperability between “minimal” and “optimum” in the fields of Governance, Standards & Operating Procedures, Technology, Training & Exercises and Usage.

A view of how the New Zealand PPDR agencies fit into this continuum follows in Figure 1 below.

Governance

StandardOperatingProcedures

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IndividualAgenciesWorking

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It can be seen that to although there is already a high level of interoperability between agencies, this can be substantially improved in the technology domain through the adoption of a standards based shared system. The adoption of the APCO P25 Standards for PPDR LMRNs will address this issue, although it is not intended to address the issue of an interoperable gateway between control systems. That need is currently addressed through the maintenance of operational agreements and memoranda of understanding between organisations and it is not intended that these be affected by the introduction of the APCO P25 LMRN Standards. A commentary on the PPDR LMRN and its degree of interoperability follows:

3.1 PPDR land mobile radio networks These networks provide instant voice communications to and between operatives in the field. Temporary radio repeaters may also be established to provide coverage in remote areas of NZ or overseas during overseas deployments.

Land Mobile Radio services may be purchased from telecommunications service providers (as in the case of Ambulance, Fisheries and Maritime NZ) or provided and operated by each agency as required to suit their business needs (as in the case of Police/ Fire, Civil Defence, DOC, Customs and NZ Defence Force).

LMRN services are used everyday in tactical situations. The lack of encryption on the present Police LMRN continues to compromise operations and has been highlighted as the top concern in the NZ Police ICT Strategy. Other PPDR users that require encryption include Customs, Fisheries and Defence.

The present NZ Police LMRN has been operating for more than 15 years, is already operating beyond its economic life and is approaching the end of its serviceable life. It needs to be replaced.

3.2 Call and dispatch centresEach agency has its own call and dispatch facilities which have been developed to cover its own specific requirements.

Police, Fire and Ambulance all use a common dispatch technology platform.

Police and Fire share the same communications centres.

Other agencies that do not need a centralised call and dispatch centre establish forward command posts as required for specific operations.

3.3 A national PPDR strategic plan and command structureEach PPDR agency generally remains responsible for its own activities and has its own command structure to reflect this. However, there are a number of interdepartmental



strategies, protocols and memoranda of understanding which define a fit for purpose common command structure for various types of event.

The command structures and relationship between organisations for many routine operations which involve a number of PPDR agencies is as shown in Figure 2. This model was devised by the PSRFMG.

NZ DefenceForce

Police Control Fire ControlOther ServicesAmbulance,

DOC, CD&EM

DefenceRadio

Network

PoliceRadio

NetworkESA

Fire RadioNetworkESA

ESBChannels

IncidentScene Liaison

ChannelESB

Defence SceneCommanderESB/Defence

Police SceneCommanderESB/UHF

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ESBEmergency Services BBand (138-144MHz)

UHFMED “F” Band (480MHz)

AGAAir-Ground-Air (118-136MHZ AM)

MarineMarine Band (170MHz)

Inter-serviceLink

Inter-serviceLink

CommonCommunications

Centres

Figure 2: Inter-agency Operational Model

For extraordinary events the routine model may not apply. There are established procedures for each type of extraordinary event. The type of event will determine the response, the agencies involved and the command structure required to manage the operation. Examples of these types of event are:

For a Civil Defence Emergency and disaster recovery the strategy and command structures are based on the recommendations which resulted from a Review of Emergency Services which was carried out in 1995 by a Task Force headed by Sir Somerford Teagle (refer Report of the Emergency Services Review Task Force). During a national Civil Defence Emergency, command defaults to the Ministry of Civil Defence



and Emergency Management. For a local Civil Defence Emergency, command would default to the local CD&EM group controller.

For Land Search and Rescue (LandSAR) operations there are a number of classes. The type of response and command structure will be determined by the class of operation. The protocols for LandSAR operations are well established and have been in place for many years.

For maritime SAR operations, the event is managed at a national level by the Rescue Co-ordination Centre (RCC).

The Chemical, Biological and Radiological Management (CBRM) group manages events relating to contamination threats from chemical, biological and radiological sources. The type of threat determines which agency will lead the operation. For a bio-security operation, Ministry of Agriculture and Fisheries will become the lead agency. For a chemical threat, Fire will become the lead agency.

Operations relating to terrorist activities are handled by the Terrorist Emergency Group (TEG) which is a national group comprising of high-level representatives from all relevant PPDR agencies.

Although there is not a unified strategic plan and command structure covering PPDR agencies and all the different types of operation, there are already strategies and command structures in place which operate as and when required to account for all PPDR activities, both routine and extraordinary. These strategies continue to be developed as is evident by the preparations undertaken to deal with a possible pandemic resulting from “bird ‘flu”.

3.4 Communications between PPDR agenciesAt the scene of an incident, the incident commanders for each agency interact locally and direct their operatives individually according the agency’s command structure.

If necessary, and where technology is compatible, members of one agency may be given authorisation to operate on the channel of another agency.

Relationships between Police, Fire, CD&EM and Ambulance are being continually developed through the Emergency Services Agencies Partnership (ESAP).

4.0 Technical interoperability between PPDR agenciesThere are a number of examples where IT systems are already compliant with e-GIF at the dispatch centres. These include mapping, inter CAD messaging, Call Line Identification (CLI) and territorial boundaries.



Although not yet specifically covered by e-GIF, radio communications between PPDR agencies do follow its principles and the purpose of this Working Party is to ensure that the APCO 25 Standard is incorporated into e-GIF.

Details of current technical interoperability between each type of PPDR radio communications system are as follows:

Police/Fire/Customs currently have interoperable UHF terminals.

Police/Fire share the same VHF network and have interoperable VHF terminals in the ESA Band.

CD&EM, Ambulance, DOC, Defence, Fisheries all have interoperable VHF terminals in the ESB Band.

Current technical interoperability is depicted in Figure 3 below:



Fire VHF(ESA)

Fire Command

Police Command Police VHF Units

Fire Units

Customs Units

Police UHF(F Band)

Police VHF(ESA)

Customs UHF(460MHz)

AmbulanceCommand

FisheriesCommand

Ambulance VHF(ESB)

Fisheries UHF(Teamtalk)

Ambulance Units

Fisheries Units

CD & EM VHF(ESB)

CD&EM Units

DOC VHF(ESB)

Defence VHF(ESB)

DOC Units

Defence Units

Police UHFUnits

Call & Dispatch Facilities Radio Networks Radio Terminals

Key:

Common Call & DispatchPlatform (Ericsson)

Co-located Call & DispatchCentres

Compatible Radio RadioNetworks

Common Radio Networks

Compatible RadioTerminals

Figure 3: Current Technical Interoperability



5.0 The APCO P25 standards suiteThe APCO P 25 standards suite has been developed to address the needs of public safety communications, originally in the USA and now globally. The standard has been developed in two phases, Phase 1 aimed at a 12.5 KHz channel bandwidth and Phase 11 aiming at a channel bandwidth of 6.25 KHz.

The APCO P25 general system model is depicted below in Figure 4. Within the RF Subsystem (RFSS) all equipment is unique to a single manufacturer. However each of the open interfaces shown is defined in the APCO P 25 Standards.

The Inter Subsystem Interface (ISSI), Network Management Interface, Console Interface and Fixed Station interface are still under development and have yet to be finalized. These interfaces are based on the Internet Protocol.

5.1 RF sub-systemThe RF Sub-systems are the building blocks for wide area system construction and will connect with any other configuration of equipment or RF Sub-system. The RF Sub-system can be made from any collection of site equipment (single station / site or multiple station / site) whose only requirement is that the equipment supports the



Common Air Interface, and contains all the necessary control logic to support the intersystem interfaces and call-processing.

5.2 Common air interfaceThe Common Air Interface (Um or CAI) defines a standard at which communications between P25 radios can occur. The CAI is the core element of the P25 Standard that assures the ability of one agency’s P25 radio to communicate with another agency’s P25 radio in either trunked or conventional mode.

This interface has been finalized and is believed to be reasonably stable. However it is known that there is some further work in process where the interface documents are being made more explicit in response to issues encountered as new manufacturers enter the market with particular interpretations of some aspects of the standard.

5.3 Intersystem interfaceThe Inter-System Interface (G) has only recently been finalized and published for trunked services. It is being extended to cover conventional services.

The ISSI permits multiple RF Sub-systems to be interconnected together into wide area networks. It provides a common meeting place for RF Sub-systems of different technologies (TDMA, FDMA, micro cell) and different RF bands. The interface is optional and need only be supported when interconnection between RFSS’s of LMRN systems is desired.

Although a P25 subscriber radio may only operate freely among systems with the standard P25 common air interface, the P25 ISSI has the potential to connect between different radio or telecommunications networks as long as they support the ISSI interface.

5.4 Telephone interconnect interface The Telephone Interconnect Interface (Et) supports both analogue and ISDN telephone interfaces, providing for selective use of proven standard telephone interfaces currently in use. This interface defines a 2-wire loop start and a 2-wire ground start connection between the RF Sub-system and the PSTN or a PABX. The interface deals only with voice services as it is assumed that circuit connected data services would access a telephone network via a modem and connect to a data port on the radio system.

This interface was originally envisaged as providing connectivity between fixed line and land mobile services. Since its original inception however the use of mobile phones has greatly increased and data based applications and functions such as dispatch use some of the other interfaces. Consequently the demand for continuing development of this interface has fallen. The interface has not been developed to accommodate IP based telephony and it does not appear to be the target of any other current work.



5.5 Network management interface The Network Management Interface (En) is under development. The overview of this interface has been published but none of the other documents have been.However provided that any proposed network management systems can support commonly recognised network management capabilities, it is anticipated that they could generally be expected to encompass APCO 25 standard radio systems.

5.6 Data host or network interface The Data Host or Network Interface (Ed) is under development. It defines four different types of data connectivity. These include a native open interface for connecting host computers, as well as the requirement to support three different types of existing computer network interfacing (TCP/IP, SNA, X.25).

5.7 Data peripheral interface The Data Peripheral Interface (A) is under development. It defines protocols by which mobile and portable subscriber units will support a port through which laptops, terminals, or subscriber unit peripherals may be connected. It is a requirement for the supported open interface protocols to be passed transparently into X.25, SNA or TCP/IP computer networks at another interface on the fixed equipment side.

5.8 Fixed station interfaceThe Fixed Station Interface (Ef) has recently been finalised, and work is proceeding on further documention for completion. The messages and procedures documents have been published, while the testing and compliance documents are still being developed. The first production of equipment to this standard is expected early in 2007. It will provide for communication between a Fixed Station (FS) and an RF Sub-System (RFSS) operating in the following modes:

Conventional analogue Conventional digital Trunked digital Digital telephone interconnect Circuit and packet data

The Fixed Station Interface defines a set of mandatory messages supporting digital voice; data, encryption and telephone interconnect.

The analogue configuration for the fixed station interface is a 4 wire audio configuration.

The digital configuration for the fixed station interface is an IP based interface. The physical interface is an Ethernet 100 base-T or 10 Base-T with an RJ-45 connector.

The Fixed Station Interface can also provide several optional analog interfaces as well:

2 wire circuits using a balanced 600 ohm termination



Standard E&M Control circuits Tone Control providing for remote control using industry standard tone remote

control equipment.

5.9 Console sub-system interfaceThe Console Sub-System Interface is under development. It defines a multi-channel digital interface capable of supporting standard protocols to enable interoperable support functions including dispatch. Note that this interface could be integrated into the RF Subsystem in the future.

5.10 SecurityThe vocoder in an APCO 25 radio produces a digital bit stream that is relatively easy to encrypt. Encryption is an optional feature selectable for each radio. The CAI supports any of the four types of encryption available in the USA;

Type 1 for classified US material (national security) Type 2 for general US federal interagency security Type 3 interoperable between US Federal, State and Local agencies Type 4 for proprietary systems exportable as determined by vendors and the US

State Department.

There are two different Type 3 encryption processes standardized in the P25 documents The US Data Encryption Standard (DES Algorithm which uses 64 bit Output

Feedback (DES-OFB) Advanced Encryption Standard (AES) which uses a 256 bit algorithm.

The AES standard meets with the requirements of the GCSB.

The APCO P 25 Standard includes an Over The Air Rekeying (OTAR) function which allows the transfer of encryption keys via radio. OTAR signaling is sent via Packet Data Units over the Common Air Interface.

6.0 APCO 25 standards and technical interoperability for PPDR networks in New Zealand

The basic requirement for APCO P 25 standard radio equipment is for backward compatibility with standard analog FM radios. Also the radios can operate in either digital or analog mode thus creating the conditions for an orderly migration to the APCO 25 standard. As an LMRN for Police is built, those agencies (Fire, Ambulance, Fisheries and Customs) that have indicated that they would join the Police P25 digital network will be able to migrate their operations to it while retaining the capability to communicate with older analog radios.

A national P25 network can also operate in either analog or digital mode so that the present VHF and UHF terminals used by CD&EM, Ambulance, DOC, Defence, and Fisheries would all immediately be able to use the network in a basic analog conventional



mode if required and if authorized to do so. If they subsequently decided to change to digital technology, the process would be relatively straight forward with minimum impact on their day to day operations. If necessary the migration could be phased over a number of years if necessary.

Other PPDR agencies will also have communications between their mobiles and portables and the APCO 25 mobiles, portables and fixed stations provided their frequencies are compatible and they are authorized to do so.

6.1 Mechanisms for technical interoperability using the common air interface

A basic compatibility framework is depicted in Figure 5 below:

More specifically the use of a standardized common air interface means that any APCO 25 compliant portable or mobile radio can communicate in the following modes:

APCO 25 mobile or portable (regardless of manufacturer) to and from a standard analog FM radio provided they use compatible frequencies and can tune to the same frequencies


Analog Portable

P 25 Portable

P 25 Mobile

P 25 Repeater

Analog Base

Analog Mode

Analog or DigitalMode

Analog or DigitalMode Analog Mode


APCO 25 mobile or portable (regardless of manufacturer) to and from any APCO 25 Repeater in either analog or digital mode provided they use compatible frequencies and can tune to the same frequencies

APCO 25 Repeater (regardless of manufacturer) to any APCO 25 Fixed Station provided they use compatible frequencies

Other key APCO P25 interfaces have yet to be standardized, or have only recently been standardized.. The impact of this is that the Common Air Interface will provide the primary means of interoperability in New Zealand until such time as further interfaces are standardized, and equipment conforming to the more recent standards becomes commonly available. Until such time, equipment compatibility with interfaces other than the CAI should primarily be ensured by sourcing from common vendors.

6.2 Mechanisms for technical interoperability other than at the common air interface

Should it be required the Police APCO 25 LMRN could interconnect a repeater to another agency’s analog control system using the 4 wire analog mode Fixed Station Interface. This would be an alternative to the use of the CAI between fixed stations. This mechanism could be used if the other agency required interoperability with the Police and its own mobiles where it did not have coverage, the Police PPDR did, and appropriate operational agreements were in place. This is depicted in Figure 6 below:

Figure 6: Fixed Station Interoperability


PPDR APCO 25 RFSS

Police P 25 mobileOther agency mobile

Analog mode

Er digital interface

Other agency analog console system

Er Fixed station interface

Analog 4 wire interface with E&M signaling

PPDR Repeater

Digital mode

Analog mode


6.3 Interoperability between APCO P25 networksShould agencies decide that in order to meet their requirements they need to build their own APCO P 25 standard networks they could be interconnected to the Police / Fire PPDR APCO P25 network via the recently published Inter Sub System Interface (ISSI). This is depicted in Figure 7 below:

Figure 7: Interconnected APCO PPDR Networks

6.4 Technical interoperability with an initial deployment of an APCO 25 standard network

Police, Fire, and Customs have all indicated that they would be willing to share a PPDR P25 network as soon as it is available. Ambulance and Fisheries will also join once their respective contractual arrangements with other network service providers have expired. Other agencies have also indicated that they may also join the network in due course.

Figure 8 below depicts a view of the degree of interoperability provided by a proposed initial implementation of an APCO P25 LMRN for Police, Fire, Customs and Fisheries.

An initial APCO P 25 PPDR network would allow all of the above agencies to migrate to the same network. Police and Fire VHF terminals on the PPDR network would have


Agency 1PPDR

RF Subsystem

Police/FirePPDR

RF Subsystem

Agency 2PPDR

RF SubsystemInter Subsystem Interface (ISSI)

ISSI ISSI

Er FixedStationInterface

Er FixedStationInterface

Er Fixed StationInterface

Agency 1Mobiles


interoperability in either analogue or digital mode provided the terminals are tuneable to the same frequencies. The APCO P 25 terminals will be chosen so that they have that capability.

The Police, Customs and Fisheries UHF terminals on the PPDR network would also be interoperable in digital mode where they are tuneable to the same frequencies, which they will be.

Other agencies remaining for the time being on their existing VHF networks and frequency bands will be interoperable with the Police and Fire VHF terminals and fixed stations operating in analog mode through the common air interface. Currently the agencies shown as staying with their current RF Bands and networks all use the ESB Band, and all of their terminals operate in simplex mode. The APCO P 25 mobiles and portables will need to be selected so that they have sufficient frequencies to enable the selection of different transmit and receive channels compatible with the ESB terminals. Encryption can be applied to each APCO P25 terminal as required.



PPDR P25 VHF(ESB)

Fire Command


Fire Units

Customs Units

PPDR P25 UHF(ESC - 494-502MHz)

AmbulanceCommand

FisheriesCommand

Ambulance VHF(ESB)

Ambulance Units

Fisheries Units

CD & EM VHF(ESB)

CD&EM Units

DOC VHF(ESB)

Defence VHF(ESB)

DOC Units

Defence Units

Police UHFUnits


Key:



Compatible Radio RadioNetworks

(ESB Analogue FM)



Figure 8: Technical interoperability with an initial APCO P 25 LMRN

6.5 Technical interoperability with the ultimate deployment of the APCO 25 standard in PPDR networks

Ultimately an APCO P 25 PPDR network covering all agencies would provide the best level of technical interoperability. This situation is depicted in Figure 9 below:



Figure 9: Full technical interoperability with PPDR P 25 network.

6.6 The requirements of call and dispatch centres, and other related organisations

Each agency has developed its own call and dispatch facilities, employing specialised staff trained for the delivery of services to suit its own business requirements. However,


PPDR P25 VHFNetworks

(ESB)

Fire Command


Fire Units

Customs Units

PPDR P25 UHF(ESC - 494-502MHz)

AmbulanceCommand

FisheriesCommand

Ambulance Units

Fisheries Units

CD&EM Units

DOC Units

Defence Units

Police UHFUnits


Key:






there are some significant commonalities between the Police, Fire and Ambulance systems.

Police and Fire share common dispatch systems at common locations. The dispatch systems are based on an Ericsson platform.

Ambulance also uses an Ericsson platform in its own dispatch centres which can provide radio communications to every public hospital in the country.

Police, Fire and Ambulance dispatch systems are backed up at multiple levels:

If one of the 3 regional Communications Centre is unable to operate, dispatch will be taken over by one of the other two communications centres.

For a major disruption affecting multiple communications centres, dispatch operations will be transferred to the local command facilities at each district/regional operations centre.

In addition to providing radio communications to their own operatives, Police, Fire and Ambulance are all able to communicate with rescue helicopters.

Other organisations which do not have a need for centralised dispatch facilities have their own arrangements where they set up an incident office as and when required. Access to radio networks may be via a telephone line or desk-top radio.

There is no plan to amalgamate call and dispatch centres.

6.7 The differing technical capabilities required for urban, rural and remote environments

Voice and narrowband data can be accommodated on a national P25 network. Most PPDR agencies require geographic coverage rather than population-based coverage. Good coverage for voice and narrowband data can be provided nationwide by a P25 network with UHF coverage of the urban areas and VHF coverage of the rest of the country.

Some organisations such as Police and Customs require instant access to voice communications whilst others can wait a few seconds to set up a call.

A P25 network can be designed as:

a conventional network - where fixed resources are available all the time (similar to the Police /Fire analogue FM network);

a trunked network - where a pool of resources exist and are allocated as and when they are required (similar to the Teamtalk network, or a telephone exchange);

or a combination of both conventional and trunked services.



The higher the number of users on the network, the more economic it becomes to use a trunked network. If the number of users is initially relatively small a conventional network can be installed. It can then be upgraded to a trunked network as the number of users increases to the point where trunking is more economic.

P25 systems are capable of operating in both digital and analogue FM mode. This means that existing ESB Band users such as CD, DOC will be able to operate on a conventional ESB Band P25 network in analogue mode with their current equipment.

It typically takes 1 to 2 seconds to set up a call on an encrypted trunked network. This is obviously too slow in some situations (e.g. during a vehicle pursuit) but is adequate in many routine situations. Another drawback for trunked systems is that there may be congestion in times of extraordinary use – e.g. during a disaster or major operation – which is exactly the occasion when the network needs to be at its most available. Priority calls can be made which will lock out other users but determining which users should have priority on a multi agency network may prove contentious. It is therefore very likely that trunking networks will be required when the number of users reaches the breakpoint for economy but some conventional facilities will be retained for users that need instant access to the network and for use in an emergency when the trunking network becomes overloaded. The conventional elements of the network will be compatible with the analogue ESB band radios and most of the analogue UHF radios currently used by all PPDR agencies.

6.7 International technical interoperabilityA national P 25 network would allow international interoperability provided suitable frequencies were assigned within the appropriate band in accordance with international agreements on public safety frequency assignments. This requirement can be catered for through the assignment of some of the channels required in the UHF DNX band.

The fact that some APCO P 25 terminals have already been deployed by Police because of the need for encryption has already proven useful internationally. The APCO terminals deployed with the NZ Police in East Timor worked well on the APCO network established there by the UN.

7.0 Radio spectrum requirements for APCO 25 based PPDR networks

Forecasts of PPDR capacity requirements have been commissioned by Police and validated and updated by the PSRFMG.



7.1 Forecast capacityThe forecast long term voice and narrowband data capacity requirements are given in Table 1 below:

ChannelsAgency UHF Duplex UHF Simplex VHF Duplex VHF Simplex

Police 150 42 100 10Fire 39 29Ambulance & DHB

40 12 14 5

DOC 18Customs 10 10 5CD&EM 46 40 40Defence 5 10Maritime 5Fisheries 7 7 3 3

Totals 292 71 219 68

Table 1: Summary of PPDR Channel Requirements

7.2 VHF Spectrum requirement and its availabilityCharacteristics of the Phase 1 APCO P25 LMRN spectrum mask are that:

Each channel spectrum width is 12.5KHz The duplex spacing between transmit and receive channels is relatively flexible

although the choice of the spacing will affect the cost of equipment.

There is insufficient spectrum available in the ESB Band to allow the long term spectrum requirements for PPDR networks to be met.

The agencies which remain on the ESB Band after the initial PPDR network is developed will be able to communicate in analog mode with P 25 radios since the current ESB terminals operate in simplex mode and the P25 terminals will be able to operate in simplex analog mode at ESB frequencies.

There needs to be a new VHF band created to cater for the long term capacity requirements shown in Table 1 above. This spectrum requirement is depicted in Figure 10 below. It has been suggested that sufficient spectrum (7.25MHz) can be made available. In order to meet interoperability objectives and to facilitate a smooth migration path to the PPDR network(s), the selection of the frequency band will need to accommodate the switching range of presently available equipment.



Figure 10: New VHF PPDR spectrum requirement:

7.3 UHF Spectrum and its availabilityWith the UHF channel requirements shown in Table 1 and a channel width of 12.5 KHz the total duplex spectrum requirements for UHF spectrum are depicted below in Figure 11.

Figure 11: UHF PPDR Spectrum

There is insufficient spectrum available within existing UHF Bands to accommodate the total long term requirements and it has been suggested that this spectrum could be made available in the range 494 to 502 MHz.

The diagram shows how a gap between the base and mobile duplex channels can be used to provide simplex requirements. The extent of this gap will depend on the duplex spacing between Base and Mobile Transmit frequencies and any current use of spectrum. It is possible for some of the simplex requirements to be met through the use of frequencies between the duplex frequencies, and the remainder to be met elsewhere. It may be possible for the remainder of the simplex channels to be provided for in the existing DNX Band (458.34375 MHz to 466.99375MHz) which contains 100 simplex channels. Use of this band would allow for the deployment of simplex PPDR capability in the 450-470 MHZ Band for international operability and co-operation.


292 * 12.5 KHz channels Mobile TX

292 * 12.5KHz channelsBase TX

3.650 MHz

71 * 12.5 KHzsimplexchannels

0.8875 MHz 3.650MHz

New Base TX Band – 220 channels Assigned to PPDR agencies

New Mobile TX Band – 220 channelsAssigned to PPDR agencies

140 simplex Channels in 1.75MHz

2.75MHz 2.75 MHz

Documents

APCO P25 briefing for E-GIF Working Group