Lucent Technologies Inc.

Malcolm Gordon

Anthony Michael Martin

Douglas Roger Pulley

William Jones

Elizabeth Mary Daniel

The network security of a radio local loop system is highly desirable to avoid fraudulent use of the network by unauthorised users with appropriate subscriber equipment. For fixed subscribers, the propagation delay between base station and subscriber unit will also remain fixed and, provided this is measured with sufficient accuracy, the distance from the subscriber to the base station can be determined. This can be used as an aid to the authentication of a subscriber. Other signal characteristics which are indicative of the physical location of a purported subscriber can be used, such as directional information. In a system in which propagation delay has to be monitored anyway, for other purposes, such as orthogonal CDMA code synchronisation, or for a TDM system, added security can be obtained without great extra cost.

Subscriber authentication for radio local loop system

Apparatus for a radio local loop for a telecommunications system, such as a base station (1) or a subscriber station (2), comprises a first unit (4, 13), which includes call processing and speech transcoding/encryption apparatus (8, 17), and which can be housed in a friendly environment, such as within a telephone exchange or within a subscriber's premises, and a comparatively rugged second unit (3, 14) which includes a modem (11, 22) and radio transceiver (12, 23), and which can be housed, in the case of a base station, at a site remote from the exchange, but central for the subscribers which it is to serve, and in the case of a subscriber station on the outside of the subscriber's premises. The first and second units are linked by a base-band link (5, 15).

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Malcolm Gordon