Methods and apparatus for excluding communication channels in a radio telephone
First Claim
1. A portable radio telephone for communication with base stations in a digital cellular radio telephone system employing transmission by a plurality of carrier frequencies in frames each consisting of a predetermined number of time slots, wherein the portable radio telephone comprises processing means operative to select for the radio telephone a communication channel, that is a combination of a carrier frequency and a time slot, by excluding from selection any communication channel associated with a time slot where an attempt at communication to a base station during the associated time slot has failed,wherein the portable radio telephone comprises storage means for storing a blind slot mask representative of the time slots in each frame which are excluded, the remaining time slots being available for the communication attempt, and wherein if all the time slots in the blind slot mask are excluded the processing means constructs a new blind slot mask in which those excluded time slots are rendered available for possible selection of a channel.
2 Assignments
0 Petitions
Accused Products
Abstract
A portable radio telephone (5) communicates with base stations (1, 2) in a digital radio telephone system, such as DECT, employing TDMA transmission. The portable radio telephone is programmed with an algorithm which is operative to select a communication channel by storing a blind slot mask (7) representative of the time slots in each frame which are excluded, either by virtue of being occupied by the base station or by the portable radio telephone itself. Hence, any channel attempted and failed in an occupied time slot is excluded and marked blind in the blind slot mask. Further, the algorithm is operative to check the time slots for availability in a predetermined sequence which corresponds to the temporal sequence of the slots (or the reverse thereof) to promote orderly filling of the time slots at the base stations.
-
Citations
15 Claims
-
1. A portable radio telephone for communication with base stations in a digital cellular radio telephone system employing transmission by a plurality of carrier frequencies in frames each consisting of a predetermined number of time slots, wherein the portable radio telephone comprises processing means operative to select for the radio telephone a communication channel, that is a combination of a carrier frequency and a time slot, by excluding from selection any communication channel associated with a time slot where an attempt at communication to a base station during the associated time slot has failed,
wherein the portable radio telephone comprises storage means for storing a blind slot mask representative of the time slots in each frame which are excluded, the remaining time slots being available for the communication attempt, and wherein if all the time slots in the blind slot mask are excluded the processing means constructs a new blind slot mask in which those excluded time slots are rendered available for possible selection of a channel.
-
10. A method of communicating between a portable radio telephone and a base station in a digital cellular radio telephone system, the method comprising the portable radio telephone executed steps of:
-
(A) storing a communication channel list in the portable radio telephone, the communication channel list being logically ordered as a plurality of rows and a plurality of columns, wherein each row represents one of a plurality of carrier frequencies, and each column represents one of a predetermined number of time slots such that each intersection of a row and a column represents one of a plurality of communication channels; (B) making received signal strength measurements for individual ones of the communication channels; (C) receiving a time slot availability message from the base station, the time slot availability message containing information specifying communication channel usage; (D) storing information in the communication channel list based on the results of the signal strength measurements and the received time slot availability message; (E) selecting a communication channel from the communication channel list; (F) verifying that the selected communication channel is within an available time slot that has not been previously excluded based at least on a failed attempt to establish communication with the base station; (G) wherein if the selected communication channel is within an available time slot, attempting to establish communication on the selected communication channel between the portable radio telephone and the base station; (H) wherein if the attempted communication is unsuccessful, marking all communication channels within the same column as the selected communication channel as unavailable, thereby excluding the marked communication channels; and (I) selecting a next communication channel of the communication channel list, verifying the selected communication channel is within an available time slot, and attempting to establish communication on the selected communication channel until all time slots are marked as unavailable or a successful communication channel is established. - View Dependent Claims (11, 12, 13, 14, 15)
-
Specification