In a multi-site communication system (for example the Terrestrial Trunked RAdio (TETRA) system), a geographical region is divided into a number of cells (or coverage areas), each of which is served by a base station. The switching infrastructure supporting the base stations (BS) (which are also referred to as base transceiver stations (BTS)) may be shared with other BS's. The switching infrastructure in a TETRA system is generally referred to as a switching and management infrastructure (SwMI). A remote unit referred to also as a subscriber, a mobile station (MS), or a communication unit is served via a radio communication link by the BS of a cell within which the remote unit is operating.
One of the basic advantages of the multi-site communication systems is that a subscriber may move from one geographical location to another one while receiving services from the network. To provide seamless service there are regions of overlapping coverage between base transceiver stations. As the subscriber moves from an area served by a first base station towards an area served by a second base station it enters the region of overlapping coverage. Within the region of overlapping coverage, the subscriber changes the serving base transceiver station. This is known as cell reselection or handover. To effectuate this cell reselection or handover, a high number of base stations are installed. Due to installation of the high number of base transceiver stations, there occurs coverage overlap between neighboring base stations.
If one of the neighboring base stations loses connectivity to the SwMI, the base stations operate in a local mode of operation. When operating in a local mode, the base stations operate according to predefined fixed instructions stored in the base stations; these instructions are usually stored in the base station at the time of network setup. However, operating according predefined instructions may not be appropriate according to the current traffic load within the cell.
Accordingly, there is a need for a method and an apparatus for dynamically determining the scope of services for a base station operating in local mode.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments. In addition, the description and drawings do not necessarily require the order illustrated. It will be further appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Thus, it will be appreciated that for simplicity and clarity of illustration, common and well-understood elements that are useful or necessary in a commercially feasible embodiment may not be depicted in order to facilitate a less obstructed view of these various embodiments.