Multi-Standard Radio Operation

Description

MSR operation (Multi-Standard Radio operation) refers to the operation of an Active Antenna System (AAS) base station that is declared to be MSR (Multi-Standard Radio) in particular operating bands. This includes any combination of UTRA (UMTS Terrestrial Radio Access), E-UTRA (Evolved UTRA, i.e., LTE), and/or NR (New Radio) operation, either as a single RAT or as a multi-RAT configuration, based on the MSR base station definition in TS 37.104. The term was introduced in Release 13 to extend the MSR concept to AAS base stations, which integrate the antenna array with the radio frequency (RF) components. MSR operation is defined in specifications such as TS 37.105, TS 37.114, and TS 37.145, which specify the RF requirements and test methods for AAS base stations supporting MSR operation.

An AAS base station is a base station that uses an active antenna system, where the antenna elements are integrated with active transceivers. This allows for advanced features such as beamforming and massive MIMO. When such a base station is declared to support MSR operation, it means that it can process multiple carriers of different RATs simultaneously using the same active antenna system and RF components. The operating bands in which MSR operation is declared are specified by the manufacturer, and the base station must meet the corresponding RF requirements for each band and RAT combination. The MSR operation concept ensures that AAS base stations can support multi-RAT deployments in a flexible and efficient manner, similar to traditional MSR base stations but with the added capabilities of active antenna systems.

The definition of MSR operation has evolved slightly over releases. In Release 13 and 14, it was defined simply as "operation of AAS BS declared to be MSR in particular operating band(s)." In Release 15, the definition was expanded to explicitly include UTRA, E-UTRA, and/or NR operation as single RAT or multi-RAT based on TS 37.104. This change reflected the introduction of 5G NR and the need to clarify that MSR operation encompasses NR as well. In Release 18, the definition was further refined to include references to manufacturer's declarations D6.12 in TS 37.145-1 and D9.25 in TS 37.145-2, which specify the test and declaration requirements for MSR operation. These changes indicate an ongoing effort to align the definition with the evolving specifications and to provide clear guidance for manufacturers and operators.

Key components of MSR operation include the AAS base station's active antenna array, which must be capable of processing multiple carriers of different RATs simultaneously. The base station's RF components, such as power amplifiers and filters, must be designed to handle the combined power and frequency requirements of all carriers. The base station also requires advanced digital processing to support beamforming, MIMO, and multi-RAT scheduling. The MSR operation declaration specifies the operating bands and RAT combinations that the base station supports, and the manufacturer must provide test results demonstrating compliance with the relevant RF requirements. These requirements cover aspects such as output power, adjacent channel leakage ratio (ACLR), spurious emissions, and blocking, ensuring that the base station can operate multiple RATs without causing interference.

MSR operation is particularly relevant for 5G deployments, where operators need to support NR alongside LTE and legacy RATs in the same band. By declaring MSR operation, an AAS base station can be configured to support multiple RATs, enabling a smooth evolution to 5G and efficient use of spectrum. The concept also facilitates spectrum refarming, as the same hardware can be reconfigured to support different RATs and bandwidths. Overall, MSR operation represents a key enabler for multi-RAT AAS base stations, providing a standardized framework for ensuring performance and interoperability.

Purpose & Motivation

MSR operation was created to extend the benefits of multi-standard radio (MSR) to Active Antenna System (AAS) base stations. AAS base stations integrate the antenna array with active transceivers, enabling advanced features like beamforming and massive MIMO. However, the original MSR concept was defined for traditional base stations with passive antennas. As operators began deploying AAS for 4G and 5G, there was a need to standardize how these base stations could support multiple RATs simultaneously. MSR operation provides this standardization, allowing AAS base stations to be declared as MSR in specific operating bands and to support combinations of UTRA, E-UTRA, and NR. This enables operators to deploy a single AAS base station that can handle multiple RATs, reducing hardware duplication and simplifying site infrastructure.

Historically, the limitations of previous approaches were that AAS base stations were often designed for a single RAT or required separate RF chains for each RAT, which increased cost and complexity. The MSR operation concept addresses this by allowing the same active antenna system to process multiple carriers of different RATs simultaneously. This is particularly important during the transition to 5G, where operators need to support LTE and NR concurrently. The introduction of MSR operation in Release 13, and its subsequent updates to include NR in Release 15, reflect the evolving needs of the industry. The motivation was to provide a clear framework for manufacturers to declare the multi-RAT capabilities of their AAS base stations and for operators to verify performance through standardized tests.

The purpose of MSR operation is also to ensure interoperability and performance across different vendors' equipment. By defining specific RF requirements and test methods, 3GPP ensures that AAS base stations from different manufacturers can coexist and operate without causing interference. This is crucial for multi-vendor networks and for ensuring a consistent user experience. MSR operation thus plays a vital role in the deployment of multi-RAT AAS base stations, enabling efficient spectrum use and smooth technology evolution.