This private LTE system is customized for metro rail transit. It includes a complete LTE core network, network management equipment, LTE base stations and wireless coverage infrastructure such as antennas and leaky feeders. It provides a high-capacity, stable and reliable bidirectional train-to-ground data channel for urban rail CBTC signaling and other communications services.

Following a thorough analysis of urban rail requirements and operating conditions, we optimized the LTE system for the rail environment to improve performance for CBTC and other services.

Project Highlights

• Dedicated urban rail communications frequencies avoid interference from public mobile networks and public Wi-Fi.

• Dual-network redundancy: base stations provide co-located coverage on two frequencies, onboard terminals operate on both networks simultaneously, and core networks and base station backhaul are deployed independently for reliable CBTC transmission.

• Optimized handovers simplify inter-cell algorithms for the linear movement of trains, improving handover speed and stability.

• Optimized radio transmission simplifies uplink/downlink channel estimation and accelerates scheduling for linear train movement. Modulation orders and coding rates adapt quickly, allocating radio resources efficiently for optimal performance.

• Integrated private LTE base stations combine the BBU and RRU in one enclosure, reducing equipment size and quantity and simplifying installation, deployment and maintenance. Die-cast aluminum enclosures improve heat dissipation in enclosed rail environments.

Main System Equipment

LTE Base Station (eNodeB)

The base station connects the wired and wireless LTE networks. Compared with conventional 2G/3G Node B equipment, it integrates some RNC functions to reduce protocol layers. Its functional architecture includes baseband control and radio frequency units, with the following features:

• Advanced LTE technologies including OFDM, MIMO and scheduling.

• BBU and RRU integrated into one enclosure for compact deployment in specialized environments.

• Electrical and optical IP transport between the base station and core network, with electrical and optical Ethernet support.

• IEEE 1588v2, GPS and BeiDou synchronization.

eNodeB Specifications

Evolved Packet Core (EPC)

The EPC is a highly integrated server designed to 3GPP Release 9 standards with standardized interfaces. Its integration and reliability meet industry-specific private network requirements and deliver high-speed broadband services. Features include:

• 3GPP R9 compliance, a general-purpose ALL-IP hardware/software platform, support for EPS mobile networks and E-UTRAN access, and an integrated architecture that reduces operating and maintenance costs.

• Integrated MME, S-GW and P-GW functions as standard; PCRF and HSS can also be integrated in one chassis to meet compact private network requirements.

• Standard S1 connectivity to eNodeB and SGi connectivity to external networks, with a shared management platform for seamless E-UTRAN and existing network integration. Electrical and optical IP/Ethernet transport is supported.

• Hardware separation of control and data planes enables flexible distributed deployment while preserving the independence and security of control and user data.

• Dual-server hot standby improves EPC reliability. If one EPC fails, services can transfer within 1 second to maintain LTE network availability.

EPC Specifications

LTE Network Management Server (OMC)

The LTE network management server centrally manages all LTE base stations and EPC equipment and monitors the clock server. Centralized maintenance reduces costs. It provides management, configuration, queries and updates, including base station and EPC parameters, gateways, alarms, logs, users, performance and system upgrades, with real-time clock server status and alarm monitoring.

OMC Specifications

PTP Clock Server

This reference clock meets time and frequency synchronization requirements for telecom operators, power systems and rail transit. GPS or BeiDou provides the primary reference, with backup inputs including 1PPS+TOD, PTP and E1. Outputs include PTP, NTP, IRIG-B and 1PPS+TOD time signals and E1, 2048 kHz, T1 and 1554 kHz frequency signals. PTP complies with IEEE 1588v2. Frequency synchronization meets the primary reference clock requirements of YD/T 1012-1999, and time synchronization meets YD/T 2022-2009. It can serve as BITS equipment for digital synchronization or as a time synchronization device.

Clock Server Specifications