Validation of subscriber signals in a cellular radio network

A system for validating an uplink signal received at a base station of a cellular radio communications network, comprising:

• first transmitter means at a given base station for transmitting a downlink signal from the base station for reception by a network subscriber;
• means associated with said first transmitter means for defining a downlink time slot during which the downlink signal is transmitted, and means for including in said downlink signal a reference signal at a certain time relative to the downlink time slot;
• second transmitter means associated with a network subscriber, for transmitting an uplink signal for reception at a network base station;
• means associated with the second transmitter means for defining an uplink time slot during which an uplink signal is transmitted, and means for including a reference signal in said uplink signal at a certain time relative to the uplink time slot;
• means at said given base station for measuring a time offset between transmission of the reference signal associated with a downlink time slot, and reception of a reference signal associated with an uplink time slot;
• means for determining if said time offset is within a determined range;
• and
• means for processing the uplink signal as valid only if said time offset is within said determined range.

A method of tracking an uplink signal received at a base station of a radio communications network, comprising:

• defining a downlink time slot during which a network base station transmits a downlink signal for reception by a network subscriber validly assigned to said base station;
• defining an uplink time slot during which said subscriber transmits an uplink signal for reception at the base station;
• including in said uplink signal a reference signal at a certain time with respect to said uplink time slot;
• receiving said uplink signal using an antenna array having selectable patterns;
• measuring a relative time offset of the reference signal when received in said uplink signal with respect to said downlink time slot;
• determining if said time offset is within a determined range and judging a received uplink signal as valid only if the time offset is within said range;
• and
• selecting a pattern of said antenna array according to a judgment result in said determining step.

A system for tracking an uplink signal received at a base station of a radio communications network, comprising:

• transmitter means at a network base station for transmitting a downlink signal for reception by a network subscriber validly assigned to the base station, including means for defining a downlink time slot during which the downlink signal is transmitted;
• means for defining an uplink time slot during which said subscriber transmits an uplink signal for reception at the base station;
• means for including in said uplink signal a reference signal at a certain time with respect to said uplink time slot;
• antenna array means at said base station for receiving said uplink signal, including means for selecting one of a number of different receiving antenna patterns;
• means at said base station for measuring a relative time offset of the reference signal when received in said uplink signal with respect to said downlink time slot;
• means for determining if said time offset is within a determined range, and for judging a received uplink signal as valid only if the time offset is within said range;
• and
• means for selecting a pattern of said antenna array according to a judgment result in said determining step.