Portable radio telephones and methods of operation
AssigneeNokia Mobile Phones Ltd.
InventorsNguyen Quan Tat, Robert Stanley Saunders
Life of this patent
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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. 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.
Claims14
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 is operative to select for the radio telephone a communication channel, that is a combination of a carrier frequency and a time slot, by storing information concerning time slots in a list, the list including both non-excluded time slots and excluded time slots, the excluded time slots being excluded by the radio telephone or by a transmission from a communicating base station, and checking the time slots in the list in one of a temporal sequence and a reverse of the temporal sequence of the time slots until a non-excluded time slot is found and the associated communication channel is selected.
A method of communicating between a portable radio telephone and base stations in a digital cellular radio telephone system employing transmission by carrier frequencies in frames each consisting of a predetermined number of time slots, comprising storing information concerning time slots in a list, the list including both non-excluded time slots and excluded time slots, the excluded time slots being excluded by the radio telephone or by a transmission from a communicating base station, and checking the time slots in the list in one of a temporal sequence and a reverse of the temporal sequence of time slots until a non-excluded time slot is found and a communication channel associated to the non-excluded time slot is selected.
A portable radio telephone for communication with a base station in a digital cellular radio telephone system, comprising:
- a processor for selecting an available communication channel for said portable radio telephone;
- a storage device coupled to said processor;
- and
- a communication channel list stored in said storage device, said 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;
- wherein said processor makes received signal strength measurements and stores information in said communication channel list which represents an amount of signal interference in individual ones of said communication channels;
- wherein said processor examines said communication channel list in one of a temporal sequence and a reverse of the temporal sequence of the time slots until an available communication channel therein is selected for establishing communications with said base station.
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 the selected communication channel is within an available time slot;
- (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;
- 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.
Dependencies are inferred from the claim text.