High-penetration radiocommunication system using a compact character set

(54) HIGH-PENETRATION

RADIOCOMMUNICATION SYSTEM USING
A COMPACT CHARACTER SET

(75) Inventor: David Charles Hall, Raleigh, NC (US)

(73) Assignee: Ericsson Inc., Research Triangle Park, NC (US)

( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.

(21) Appl. No.: 09/103,428

(22) Filed: Jun. 24, 1998

(51) Int. CI.7 H04T 13/00

(52) U.S. CI 370/479; 341/60; 341/90

(58) Field of Search 370/342, 441,

370/479, 317, 318, 335; 340/825.59, 825.69, 825.44, 825.47, 458; 455/426, 31.1, 10; 341/50, 60, 90, 91, 92; 375/262, 265, 295,

316, 340

A high-penetration transmission method uses a compact character set for encoding an alphanumeric message, in which the signal margin is increased by a combination of bit repetition and a relatively small increase in power. The combination of bit repetition and a relatively small increase in power with a encoding via a compact character set avoids unacceptable delay characteristics. Moreover, the combination of repetition and a relatively small increase in power with the compact character set of the present invention avoids the co-channel interference problems of systems which rely solely on a power increase to increase the signal margin, as less power increase is required to obtain the same increase in signal margin for a given delay time. In one embodiment, a mobile radiocommunication system is provided with a short message service feature for transmitting alphanumeric messages to and from a mobile unit. In order to ensure reliable transmission over channels having severe attenuation, the communication system, a short message is encoded with a compact character set. The message may be further encoded with error detection or correction coding; the message is divided into packets or groups of one or more bits each; each packet is transmitted, at a power level greater than the power level for voice transmission, multiple times over a TDMA communication channel, using the same time slot or slots for each transmission. The transmissions are integrated and checked for errors at the receiver to form a signal having an increased margin.

24 Claims, 4 Drawing Sheets

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* cited by examiner