MSAT Network Communications Controller and Network Operations Center
Tony Harvey, Vicky Schumaker · 15th International Communicatons Satellite Systems Conference and Exhibit · 1994
This paper describes the Network Communications Controller (NCC) and the Network Operations Center. (NOC) in the MSAT System. The NCC provides the real-time control for mobile terminal (MT) access to the MSAT services through Virtual Networks. It also performs MT performance and authentication functions that maintain the integrity and security of the system. The NCC manages the allocation of frequencies to mobile voice connections with a circuit pool scheme that allows efficient dynamic withdrawal of frequencies for emergency use in the Aeronautical Mobile Satellite (Route) Service ( AMS(R)S) system. The NOC is designed to perform fault, configuration, accounting, performance, and security management of the network ground segment. It also provides the interfaces to external systems, like the Satellite Operations Center, the Customer's Management Information System, and the AMS(R)S system. It provides operator access to the ground segment via XWindows interfaces, allowing the display of configuration status, events, and call activity. The network configuration is maintained in relational databases and distributed to the network components using a 2phase commit process to ensure the consistency of the distributed views. Network management is provided by state-of-the-art Enterprise Management software from Digital Equipment Corporation based on the emerging ISOIOSI management standards. It provides a flexible framework for automating management systems in an evolving, heterogeneous, multivendor environment. In the initial configuration the NCC and NOC reside on the same fault-tolerant processor platform to provide network components with high availability. Introduction The Network Communications Controller (NCC) and the Network Operations Center (NOC) provide the central control for Mobile Satellite Services (MSS) [I]. The NCC provides the real-time control for mobile terminal (MT) access and the NOC provides fault, configuration, accounting, and security management of the Communications Ground Segment[2]. NCC Functional Overview Mobile Voice Communications The Network Communications Controller (NCC) coordinates access requests between the mobile terminals (MTs) and the terrestrial interfaces provided by multiple Feederlink Earth Stations (FESs) [4]. Figure 1 shows the flow of messages between these network elements resulting from a successful request by a MT for access to the terrestrial network. Figure 1 MT Initiated Access Copyright O 1993 American Institute of Aeronautics and Astronautics, Inc. All rights reserved. 270 MSAT NETWORK COMMUNICATIONS CONTROLLER AND NETWORK OPERATIONS CENTER The NCC validates the MT's access request and assigns resources to the call. The allocated frequencies are sent to both the MT and FES in Channel Assignment messages such that they can complete a duplex voice path. The NCC is then free of any involvement in the call until the FES informs it, using a Channel Release message, that the call has terminated. At this time the NCC sends all its call related data to the NOC for it to merge with the associated FES data to generate billing data records. Figure 2 shows the flow of messages for a successful FES access request. &bVoice Band w ~ L Connection Figure 2 FES Initiated Access Again the NCC validates the request then tries to contact the MT to announce the call by sending a Call Announcement message. If the MT accepts the call it responds with an Announcement Response message. The NCC allocates resources to the call and the MT and FES are informed as before. Then the call is set up and tom down in the same manner as in the MT initiated case. Virtual Networks and Control Grou~s The NCC supports the association of MTs into groups for the purpose of specifying various atmbUtes and placing calling restrictions on the group as a whole. These groups are called Virtual Networks (VNs). They define: the set of frequencies to use the call barring restrictions to apply the FES resources to use Each MT can belong to up to 16 virtual networks. The NCC also supports the division of all network resources into separately controlled sets of resources, called Control Groups. Resources can only belong to one Control Group. Resources divided by Control Group are: