Positioning systems and methods

A method of determining the position or state of motion or relative position or relative state of motion of a mobile terminal in a communication network, the mobile terminal having a receiver for receiving signals from transmission sources, the method comprising the steps of

• a. acquiring at a data node, measurements of the signals received from one or more of the transmission sources by the receiver in the first mobile terminal whose position or state of motion or relative position or relative state of motion is to be determined;
• b. calculating a coarse position or relative position of the first mobile terminal;
• c. receiving at said data node measurements made by the receiver in a second mobile terminal near to the coarse position or relative position of the first terminal, together with information about the position of the mobile unit if available;
• and
• d. calculating at any one or more computing nodes the position or state of motion or relative position or relative state of motion of either or both of the said mobile terminals using at least some of the measurements made by the first and second mobile terminals.

A communication network having

• terminals whose positions or states of motion or relative positions or relative states of motion are to be determined, the terminals each having a receiver for receiving signals from transmission sources and means for making measurements of the signals received from one or more of the transmission sources;
• at least one data node having means for acquiring said measurements from said terminals and means for creating one or more records of one or more of said measurements;
• and
• a computing node having means for receiving at least some of the records, means for maintaining a table of the records transferred to the computing node, and means for carrying out a computation, using at least part of the table, from which computation the positions or states of motion or relative positions or relative states of motion of said plural terminals and the transmission time offsets of the transmission sources are extractable.