04876740 is referenced by 42 patents and cites 13 patents.

A cellular radiotelephone system is disclosed in which the signalling protocol for the system is embedded in the frame synchronization of the digital messages transmitted on the system. Multiple functions are accomplished by the synchronization signal and include call supervision, mode definition, and data frame synchronization. The synchronization signal is a high auto correlation, low cross correlation sequence of a predetermined number of data bits. Different bit sequences may be employed as a synchronization signal while conveying call supervision information defining the serving fixed site. Additionally, the logical inverse of the synchronizing signal may be utilized interchangably with the synchronizing signal to define the fixed site. A repetitive pattern of synchronizing signals and logical inverse synchronizing signals convey system mode information without increasing signalling overhead or losing the correlation performance of the full synchronization word.

Title
Radiotelephone system employing digitized speech/data signalling
Application Number
771460
Publication Number
4876740
Application Date
February 13, 1989
Publication Date
October 24, 1989
Inventor
Albert J Leitich
Chicago
IL, US
Stephen N Levine
Chicago
IL, US
Agent
Rolland R Hackbart
Raymond A Jenski
Assignee
Motorola
IL, US
IPC
H04Q 7/04
View Original Source