Base Station Subsystem Operation and Maintenance Application Part

Description

BSSOMAP (Base Station Subsystem Operation and Maintenance Application Part) is a protocol used in GSM/EDGE networks for the operation and maintenance (O&M) of the Base Station Subsystem (BSS). It is part of the 3GPP TS 21.905 vocabulary and is defined in the context of the GSM/EDGE radio access network. The BSS comprises the Base Transceiver Station (BTS) and the Base Station Controller (BSC), and BSSOMAP provides the application layer protocol for managing these elements from a centralized Operations and Maintenance Center (OMC). It allows the OMC to configure, monitor, and troubleshoot the BSS, ensuring reliable network operation.

BSSOMAP operates over the A-bis interface between the BSC and the BTS, and over the A interface between the BSC and the core network (specifically the Mobile Switching Center, MSC). However, its primary use is for O&M functions, which are typically carried over the A-bis interface or a dedicated O&M channel. The protocol is based on the OSI model and uses the Common Management Information Protocol (CMIP) or similar management protocols for exchanging management information. BSSOMAP defines the messages and procedures for functions such as configuration management, fault management, performance management, and security management. For example, it allows the OMC to download configuration parameters to the BTS, retrieve alarm reports, and perform software upgrades.

The protocol is structured into several functional areas: configuration management, which handles the setting of parameters like frequency, power, and neighbor lists; fault management, which reports alarms and events; performance management, which collects statistics on traffic and resource usage; and security management, which manages authentication and encryption keys. BSSOMAP uses an object-oriented approach, where managed objects represent network resources such as cells, channels, and devices. Each managed object has attributes, operations, and notifications. The OMC can perform operations like get, set, create, delete, and action on these objects. Notifications are used for alarms and event reports.

In terms of architecture, BSSOMAP is implemented in the BSS and the OMC. The BSS acts as an agent, exposing managed objects to the OMC, which acts as a manager. The communication is typically over an IP-based network, although legacy systems may use X.25 or other protocols. The protocol ensures interoperability between equipment from different vendors, as it is standardized by 3GPP. This allows operators to manage multi-vendor networks seamlessly. BSSOMAP is part of the overall Telecommunications Management Network (TMN) framework, which defines a hierarchical management architecture.

BSSOMAP has been used since the early days of GSM and continues to be relevant for GSM/EDGE networks, although newer technologies like UMTS and LTE use different O&M protocols (e.g., UTRAN O&M, E-UTRAN O&M). In Release 19, BSSOMAP is still referenced in TS 21.905 as part of the vocabulary, indicating its continued existence in legacy networks. However, with the sunset of GSM/EDGE in many operators, its usage is declining. Nonetheless, it remains an important protocol for understanding the evolution of network management in cellular systems.

Overall, BSSOMAP is a critical enabler for efficient and reliable operation of GSM/EDGE networks, providing a standardized way to manage BSS elements. Its principles have influenced later O&M protocols, and it serves as a foundation for modern network management practices.

Purpose & Motivation

BSSOMAP was created to provide a standardized protocol for the operation and maintenance of the Base Station Subsystem in GSM networks. Before its introduction, each vendor used proprietary O&M protocols, which made it difficult for operators to manage multi-vendor networks and integrate different equipment. BSSOMAP solves this by defining a common application part that allows the OMC to manage BSS elements from any vendor. It enables remote configuration, fault detection, performance monitoring, and software management, reducing the need for manual intervention and improving network reliability. The protocol also supports the scalability of GSM networks, as operators could add more base stations and manage them centrally. Over time, BSSOMAP has been adapted for EDGE and remains a key part of legacy network management. Its existence highlights the importance of standardized O&M in cellular networks, a principle that continues in 5G with protocols like NETCONF and RESTCONF.