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An Evolution in Public Safety Networks

Traditional analog and digital trunking networks were not built with the demands imposed by modern public safety systems, such as Global Positioning System (GPS) inputs, new media data types, and channel congestion capable of crashing the system. Among the primary sources for these problems are cellular base stations that are limited to 4,000 subscribers per station, a 25 KHz channel bandwidth, and a 28.8 Kbit/s transmission rate. Legacy trunking systems are not equipped to support the transmission of multimedia video, Big Data, or any other Safe City service that requires a high-bandwidth channel.

To answer the call, Huawei’s Public Safety enterprise Long-Term Evolution (PS-eLTE) platform features high channel bandwidth (5/10/20 MHz), data throughput at speeds up to 100 Mbit/s, as well as:

  • Real-time and non-real-time video transmission for obtaining video images of crime scenes or disaster sites taken by drones, vehicle-mounted cameras, and wearable police cameras
  • Remote database access for instant retrieval of identification verification, including driver’s licenses and criminal records; obtaining medical records before a patient has arrived at the hospital; or performing telemedicine with the aid of real-time video transmission
  • Image transmission for sending relevant images to on-site police officers or building blueprints to fire fighters
  • Biological feature identification for assisting police officers to identify suspects or survivors using fingerprint identification, facial comparison, or iris scanning

An Evolution in Public Safety Networks

Construction Prerequisites

LTE network standards have evolved in clear and distinct steps from early 1G and 2G platforms to the 4G and 4.5G solutions that are available today. The following prerequisites are necessary for the construction of any large-scale PS-LTE network today:

LTE Standard Definition

In Q1 2017, the 3GPP is scheduled to release the R14 version of LTE and define other PS-LTE-based features, such as urgent video and data.

In March 2016, 3GPP released the R13 version of the LTE specification that defined Mission-Critical Push-To-Talk (MCPTT), isolated E-UTRAN Operation for Public Safety (IOPS), and Group Communication System Enablers for LTE (GCSE_LTE) and Proximity Services (ProSe).

In 2014, China Communications Standards Association (CCSA) formulated TD-LTE-based Broadband Trunking Communications (B-TrunC) standards that were later adopted by the International Telecommunication Union (ITU). In 2012, the U.S. Federal Communications Commission (FCC) allocated the 700 MHz Public Safety Spectrum using two 10 MHz B14 frequency segments. The U.K. and Spain have also released their own 700 MHz scenarios. A number of countries in South Asia are actively planning PS-LTE deployments. South Korea is preparing a 700 MHz, B28 scenario for release. China has released a 4.5G LTE-Advanced Pro, 1.4 GB 20 MHz scenario for public service networks.

The Industry Chain Reaches Maturity

PS-LTE solutions are developing rapidly in converged platform, pipe, and terminal service applications. Huawei, Ericsson, NSN, Samsung, ZTE, and other commercial network vendors provide mature pipe-layer solutions to the PS-LTE market; consulting firm Hexagon completed its interface adaptation to the PS-LTE network and now offers services and applications required by public safety users worldwide; and Qualcomm and HiSilicon will provide chip and module solutions following the release of new, related standards. Meanwhile, technical requirements and costs of terminal manufacturing are decreasing.

Carriers Lower Difficulty of PS-LTE Network Construction

Mobile network operators like Verizon (U.S.), EE (U.K.), KT (South Korea), and Telstra (Australia) are engaged in PS-LTE network construction projects to attract customers and expand commercial coverage. Infrastructure resources, availability of physical sites, O&M expertise, and professional technical staff are tools that carriers use to meet the challenges of PS-LTE network construction:

  • Built cell by cell to balance service capacity and coverage, LTE networks are more complex and have more Network Elements (NEs) than traditional narrowband trunking systems.
  • Compared to older, narrowband systems, LTE networks have a smaller effective range and a higher radiated spectrum that is often in the 400 MHz range. Therefore, PS-LTE networks require about four times more base stations than a narrowband system for the same number of users.
  • Planning, construction, and Operations & Maintenance (O&M) of PS-LTE networks present a higher set of requirements for management organizations and personnel.

Here Comes PS-LTE Construction

By the end of 2015, more than 1,000 PS-LTE base stations were in service for over 100,000 users.

  • In 2012, the U.S. Congress authorized USD 7 billion to build the First Responder Network Authority (FirstNet), an interoperating national public safety broadband network.
  • The U.K. began building a broadband national public safety LTE network in 2015, with a first-phase investment of GBP 1.2 billion (USD 1.65 billion); the British government plans to complete the construction by 2025.
  • Kenya began building its national PS-LTE network in 2014 and completed first-phase construction of over 100 base stations and 7,000 terminals covering Nairobi and Mombasa.
  • In 2013, China began building a national PS-LTE network covering more than 10 cities, including Beijing, Shanghai, Nanjing, Shenzhen, and Guangzhou; 256 base stations and over 10,000 terminals are in service in Nanjing.

Owing to the need to leverage existing assets and maintain service continuity — and at the cost of additional complexity in the planning stages — many public safety communication networks must configure the newer generation broadband components to support legacy narrowband terminals.

Dedicated Networks vs. Commercial Networks

The motivation to build dedicated PS-LTE networks is the need to have critical mobile video and broadband data services available to public service agencies twenty-four hours a day, seven days a week. Areas beyond the coverage of dedicated PS-LTE networks are often supplemented with commercial networks.

Cities and countries with operating narrowband trunking networks can add separate broadband infrastructure that converges the two systems at the management layer. In this scenario, the narrowband network may be a backup system that carries trunked voice services until the broadband network has been fully deployed throughout the region. Once certified for reliability, the trunking voice services would be transitioned to the new broadband plants.

Cities and countries with little or no narrowband pubic service infrastructure will be best served by committing their investments to LTE dedicated networks that expand geographic coverage and provide access to the greatest number and variety of subscribers.

PS-LTE Networking Scenarios

PS-LTE scenarios are more complex than narrowband trunking environments in order to meet advanced emergency communication requirements.

  • Commercial Network: Using commercial carrier networks to handle public safety services; no current deployments
  • Virtual PS-LTE Network: PS-LTE core networks perform user management over virtualized public safety channels shared with commercial carriers; currently deployed in the U.K. and Belgium
  • Dedicated PS-LTE Network: Government financed, dedicated spectrum PS-LTE networks; deployed in China and some Gulf Cooperation Council (GCC) countries
  • Mixed Network: Combining dedicated and virtual elements with some areas served by government-operated dedicated networks and others by commercial carrier networks; deployed in the U.S. and South Korea

Planning and Construction Issues for PS-LTE

The next generations of public safety radio networks are heterogeneous systems that include a LTE core network with multiple subnets and layered services. When planning and building PS-LTE networks, governments are advised to consider the following uses and requirements:

  • Converged commercial and dedicated networks that integrate broadband and narrowband trunking
  • Combined fixed and mobile with ground and airborne networks to ensure service continuity and improve command and dispatch efficiency
  • Broadband mobile intelligent terminals to ensure service boundaries and device security
  • QoS guarantees to fulfill key roles and services
  • Construction policies for dedicated LTE networks to account for limited budgets and guide the expansion of coverage from large, developed cities to smaller, less developed areas with lower risk profiles

Modern public safety systems are designed to meet the demand to integrate new and old technologies for the purposes of service continuity and minimum investment.

By Mao Xinjun

Chief Engineer, Wireless Marketing Department, Enterprise Business Group, Huawei Technologies Co., Ltd.

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