US 2001/0026540 A1 · Virtual locating of a fixed subscriber unit to reduce reacquisition time

Abstract

A system and method reduces the time required by a base station to acquire a fixed subscriber unit in a CDMA communication system by virtually locating of the subscriber units. A base station acquires subscriber units by searching only those code phases concomitant with the largest propagation delay possible in the cell, as if all subscriber units were located at the periphery of the cell. A subscriber unit which has never been acquired by the base station varies the delay between the PN code phase of its received and transmitted signals over the range of possible delays in a cell and slowly ramps-up its transmission power until it is acquired by the base station. Upon initial acquisition by the base station, the subscriber unit ceases ramping-up its transmission power, ceases varying the delay and internally stores the final value of the delay in memory.

Claims19

Dependent claims

A method for communicating between a base station and at least one subscriber unit;

comprising:
receiving at said subscriber unit a pilot signal from said base station;
generating at said subscriber unit an access signal, and epoch aligning the access signal to said received pilot signal;
transmitting said epoch-aligned access signal from said subscriber unit to said base station;
receiving a confirmation signal at said subscriber unit in response to the transmission of said epoch-aligned access signal;
determining a timing difference value at the subscriber unit between said access signal and said confirmation signal;
and
storing said difference value.

5 more elements

A method for establishing an initial communication between a base station and at least one subscriber unit;

comprising:
transmitting a pilot signal from the base station;
searching for said pilot signal, at said subscriber unit, within a first code phase delay range;
acquiring said pilot signal at said subscriber unit within said first code phase delay change;
generating at said subscriber unit an access signal and epoch aligning the access signal to said pilot signal;
transmitting the epoch-aligned access signal from said subscriber unit to said base station while continually increasing the transmission power of said epoch-aligned access signal at a first rate;
receiving said epoch-aligned access signal at said base station;
generating at said base station, in response to the receipt of said epoch-aligned access signal, a confirmation signal;
transmitting said confirmation signal from said base station to said subscriber unit;
receiving said transmitted confirmation signal at said subscriber unit;
ceasing the increase in transmission power of said epoch-aligned access signal when said confirmation signal is received;
determining a timing difference value at said subscriber unit between the transmission of said access signal from said subscriber unit and the receipt of said confirmation signal at said subscriber unit;
and
storing said difference value.

11 more elements

Dependencies are inferred from the claim text.

Virtual locating of a fixed subscriber unit to reduce reacquisition time

Life of this patent

Virtual locating of a fixed subscriber unit to reduce reacquisition time

Life of this patent

Abstract

Claims19