Westell MDIU Modular DAS Interface Unit (CS21-005-105Q)

The Westell MDIU (Modular DAS Interface Unit) model CS21‑005‑105Q is a flexible RF interface and distribution platform designed for Distributed Antenna System (DAS) deployments. This unit acts as the central hub for receiving, conditioning, and distributing cellular and public safety RF signals across a network of remote antenna units. It is widely used in in‑building coverage solutions, campus networks, and public venue wireless enhancements.

Overview

The MDIU is a modular chassis that accepts a variety of plug‑in interface modules, each supporting different frequency bands (e.g., 700/800/1900/2100 MHz) and signal types. The CS21‑005‑105Q variant is configured to support specific band combinations and includes built‑in signal conditioning, amplification, and monitoring. The unit interfaces with base station sources (donor antennas or BTS) and distributes the signal over fiber or coaxial cable to remote units. It provides gain control, attenuation, and alarm reporting for comprehensive system management.

Key Features

• Modular architecture supporting multiple frequency bands

• Integrated low‑noise amplifiers (LNAs) and power amplifiers

• Automatic gain control (AGC) for stable output levels

• Built‑in RF power monitoring and VSWR detection

• Support for fiber optic or coax distribution to remote units

• Alarm and status reporting via dry contacts or SNMP

• Front‑panel LCD for local configuration and monitoring

• Rack‑mountable 2U or 3U chassis

Technical Specifications

• Frequency Bands: 700 MHz, 800 MHz, 850 MHz, 1900 MHz, 2100 MHz (depending on modules)

• Gain Range: 20‑50 dB (adjustable)

• Output Power: Up to +33 dBm per band (composite)

• Noise Figure: < 4.5 dB

• Distribution Interfaces: Fiber optic (SFP) or 50Ω coaxial (N‑type)

• Monitoring: Forward/reflected power, temperature, VSWR

• Alarms: 4x dry contact relay outputs

• Power Supply: 110‑240 VAC, 47‑63 Hz, or -48 VDC optional

• Operating Temperature: 0°C to 45°C

• Dimensions: 2U or 3U (depending on configuration), 19‑inch rack

Applications

The MDIU is deployed in large‑scale indoor coverage projects such as stadiums, convention centers, hospitals, airports, and office towers. It ensures uniform signal distribution for multiple operators, supporting both commercial cellular (4G/5G) and public safety (FirstNet) communications.

Management and Integration

The MDIU can be managed locally via the front‑panel interface or remotely via SNMP. It integrates with Westell’s Element Management System (EMS) for centralized monitoring of all remote units and signal conditions. Alarms are reported via SNMP traps or relay contacts to external building management systems.

Installation and Maintenance

Installation involves rack‑mounting the chassis, installing the appropriate band modules, connecting donor and distribution cables, and powering up the unit. The system automatically initializes and reports status. Routine maintenance includes verifying RF output levels, checking alarm logs, and cleaning air filters.

Conclusion

The Westell MDIU CS21‑005‑105Q offers a modular, scalable solution for DAS deployments, ensuring high‑quality wireless coverage in complex indoor environments. Its flexibility, monitoring capabilities, and reliability make it a preferred choice for system integrators.