Electrical computers and digital processing systems: multicomput – Computer-to-computer session/connection establishing – Session/connection parameter setting
Reexamination Certificate
1994-05-04
2001-08-28
Myers, Paul R. (Department: 2781)
Electrical computers and digital processing systems: multicomput
Computer-to-computer session/connection establishing
Session/connection parameter setting
C710S010000, C710S019000
Reexamination Certificate
active
06282572
ABSTRACT:
BACKGROUND
The present invention relates to protocol negotiation between peer entities in a system, and more particularly to providing a master node with information about which functions are supported by a slave node in a communication system.
Systems are well known in which peer entities communicate with one another. In particular, such systems often include a device designated as a master node which communicates with a number of subordinate devices designated as slave nodes. Because individual slave devices may differ from one another, the master node must have knowledge regarding which functions (also referred to in this specification as “capabilities”) are supported by each slave device in order to be able to communicate with that device. For example, in a cellular mobile telephone system different channel types provided by a cellular transceiver may require communicating at correspondingly different data rates because of the use of different communication protocols. One such system having this configuration is the link between the switching center and the base station in the European radiotelephone cellular communications system standard known as the Global System for Mobile Communications (GSM). Capabilities that a base station may or may not support in this system include: half-rate speech channels, combined signaling and control channel, data communication facilities, and different versions of the communication protocol towards the base station.
Frequently in such systems, new slave devices will either be added, or will replace existing slave devices. When this happens, the master node must obtain information telling it which functions are supported by the new slave device in order to communicate with it.
For example, in a mobile telephone network having a base station controller (BSC) which manages the operations of many base stations (BS) spread out over a large geographic area, the BSC must know which set of functions are supported by which base station. However, the supported functions may change from time to time for a number of reasons. First, new base stations may be added to the network, thus presenting an additional set of functions that the BSC must know about. Furthermore, base stations are usually controlled by software which evolves over time. As new software is released, it may allow a base station to perform previously unsupported functions. Because the software and hardware may differ from one base station to the next, a way must be provided for the BSC to obtain information about which functions are supported at which nodes.
A prior solution to this problem utilizes a predefined negotiation procedure between the master and slave devices. During this negotiation procedure, the master and slave devices utilize a predefined protocol to exchange information about which functions will be supported on the interface connecting the two. An example of this solution may be found in facsimile (“fax”) machines which, prior to transmission, negotiate over which data rate to use. This solution, however, is cumbersome in that it requires undesirable overhead communications on the interface linking the master and slave devices. Furthermore, because the negotiation protocol must be defined, changes and future adaptations of capabilities are not possible without corresponding changes of possibly major proportions to the protocols being used by existing slaves. Therefore, a simpler and more flexible solution is desired.
SUMMARY
It is therefore an object of the present invention to provide a mechanism for providing a master node device with information regarding which functions are supported by a slave device (capability information), without requiring the master and slave devices to perform a negotiation procedure to communicate this information.
It is another object of the present invention to provide an encoding scheme for the capability information which permits a slave device to be added without changing the capability information already encoded for pre-existing slave devices, even if the added slave device supports a new function that is not supported by any pre-existing slave devices.
It is yet another object of the present invention to provide an encoding scheme for the capability information which permits a slave device to be added without changing the capability information already encoded for pre-existing slave devices, even if the added slave device does not support a function that is supported by all pre-existing slave devices.
In accordance with one aspect of the present invention, the foregoing and other objects are achieved by an apparatus in a system having a master device coupled to a slave device by means of an interface, wherein a function of the master device includes downloading a control program to the slave device. The apparatus provides the master device with capability information corresponding to the slave device. The apparatus comprises means for reading the capability information from a predefined portion of the control program, and means for storing the capability information for use by the master device during a communications operation with the slave device. By locating the capability information in a predefined portion of the control program, the master device is provided with new capability information whenever the control program is upgraded. Also, because the capability information is always stored in the master device, the need for a predefined negotiation procedure between the master and slave device is eliminated.
In accordance with another aspect of the present invention, an encoding scheme is provided for the capability information, whereby new slave devices can be added to the system without requiring pre-existing capability information to be re-encoded to accommodate newly defined functions. The capability information for each slave device comprises a first vector and a second vector. Each of the first and second vectors has a number of variables, each indicating whether a corresponding function is supported by the corresponding slave device. When a new slave device is added to the system, there may be a need to redefine one or both of the second vectors to add variables corresponding to new functions not previously defined within the system. However, pre-existing capability information will not have to be modified to include these new variables. Consequently, the capability information for any particular slave device may be missing one or more variables which are defined within the system. To compensate for this, the means for reading comprises first default means, responsive to the number of variables of the first vector being less than a number of defined first vector variables, for supplying first default values for variables that are missing in the first vector. The first default values are selected to indicate that corresponding functions are not supported by the corresponding slave device. The means for reading further comprises second default means, responsive to the number of variables of the second vector being less than a number of defined second vector variables, for supplying second default values for variables that are missing in the second vector. The second default values are selected to indicate that corresponding functions are supported by the corresponding slave device.
In accordance with this aspect of the invention, it is possible for the capability information to consist of two vectors, one or both of which have no variables whatsoever. Having no variables in both of the vectors corresponds to the situation where each slave device in the system supports each and every function that is supported by any other slave device in the system. In this case, the information about the supported capabilities of each slave device are provided entirely by the first and second default means.
In yet another aspect of the present invention, a method is disclosed for adding a new slave device to a system having a master device coupled to a plurality of pre-existing slave devices, each slave device having corresponding capa
Dahlin Mats Hakan
Eriksson Mats Erland
Löfgren Lennart Adolf Nils
Burns Doane Swecker & Mathis L.L.P.
Myers Paul R.
Telefonaktieboalget LM Ericsson (publ)
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