Abstract: Subscriber units are tracked in a cellular communications system including a plurality of cells which communicate with subscriber units. A cell type is assigned to each cell according to a mobility characteristic of a subscriber unit population of the cell. Each cell is associated with at least one of a plurality of districts based on the cell type of the cell, such that each of the plurality of districts may be characterized according to a mobility characteristic of a subscriber unit population of the district. A subscriber unit is registered with one of the plurality of the districts according to the mobility of the subscriber unit. According to preferred method aspects of the invention, at least one district is defined for each cell, each district having a geographical extent with respect to the cell location of the cell, to thereby associate each cell with at least one district.

Abstract: Fading on a data link prevents a mobile station from acknowledging a received base station poll message. Responsive thereto, the data link is transitioned to an unacknowledged mode of operation. A group of frames of a data communication are then transmitted to the mobile station with no base station expectation of receiving a mobile station acknowledgment. Following group frame transmission, the data link is transitioned back to acknowledged mode of operation. To insure delivery of the data communication, the sent frames a queued (stored) by the base station until such time as a delivery confirmation with respect to the group of frames can be obtained.

Abstract: A Data Link is established for communicating messages between the first entity and the second entity via Information Frames communicated between a first Data Link Layer at the first entity and a second Data Link Layer at the second entity. An Information Frame addressed to the second Data Link Layer, preferably indicating a normal condition for the Data Link, is transmitted from the first Data Link Layer. The first and second Data Link Layers are reset if it is determined that a transmitted Information Frames fails to be communicated from the first Data Link Layer to the second Data Link Layer. An Information Frame addressed to the second Data Link Layer, preferably indicating a normal condition for the Data Link, is transmitted from the first Data Link Layer after the first and second Data Link Layers are reset. The Data Link preferably is maintained from the first step of transmitting through the second step of transmitting.