System for testing soft handoff functionality of a mobile station used for a code division multiple access (CDMA) mobile communication system

A system for testing handoff of a mobile station (MS) from a first base station (BS1) to a second base station (BS2);

• a first baseband processor having an output providing digital signals representative of first base station analog signal levels provided from the first base station (BS1) to the mobile station (MS);
• a second baseband processor having an output providing digital signals representative of second base station analog signal levels provided from the second base station (BS2) to the mobile station (MS);
• a noise generator having an output providing a digital signal representative of an analog additive white Gaussian noise (AWGN) signal;
• a controller having a first output providing a gain control signal representative of a first gain level for the first base station (BS1), and a second output providing a gain control signal representative of a second gain level for the second base station (BS2), and a third output providing a gain control signal representative of a third gain level for the AWGN signal;
• a first multiplier having a first input coupled to the output of the first baseband processor, a second input coupled to the first output of the controller, and an output for multiplying the digital signal from the first baseband processor by the first gain level to increase a digital value for the first base station signal levels;
• a second multiplier having a first input coupled to the output of the second baseband processor, a second input coupled to the second output of the controller, and an output for multiplying the digital signal from the first baseband processor by the first gain level to increase a digital value for the second base station signal levels;
• a third multiplier having a first input coupled to the output of the noise generator, a second input coupled to the third output of the controller, and an output for multiplying the digital signal from the noise generator by the first gain level to increase a digital value for the noise generator signal levels;
• an adder having a first input coupled to the output of the first multiplier, a second input coupled to the output of the second multiplier, and a third input coupled to the output of the third multiplier, the adder adding digital signals provided at the first, second and third inputs of the adder to provide a digital sum signal at an output;
• a digital to analog (D/A) converter having an input coupled to the output of the adder to receive the digital sum signal, and an output;
• a quadrature modulator having an input coupled to the output of the D/A converter and an output;
• and
• an upconverter having an input coupled to the output of the quadrature modulator and having an output;
• a duplexer having a first terminal coupled to the output of the upconverter, a second terminal for coupling to the mobile station and a third terminal;
• a downconverter having an input coupled to the third terminal of the duplexer and having an output;
• a quadrature demodulator having an input coupled to the output of the downconverter and having an output;
• an analog to digital (A/D) converter having an input coupled to the output of the quadrature demodulator, and having an output;
• a mobile station performance measurement unit having an input coupled to the output of the A/D converter for measuring a signal level indication signal transmitted from the mobile station (MS) indicative of the first base station analog signal levels and the second base station analog signal levels.

A system for testing handoff of a mobile station (MS) from a base station having a first antenna transmitting to a first sector and a second antenna transmitting to a second sector, the system comprising:

• a first baseband processor having an output for providing digital signals representative of first analog signal levels from the first sector for providing to the mobile station (MS);
• a second baseband processor having an output for providing digital signals representative of second analog signal levels from the second sector for providing to the mobile station (MS);
• an adder having a first input coupled to the output of the first baseband processor, and a second input coupled to the output of the second baseband processor, the adder adding digital signals provided at the first and second inputs to provide a digital sum signal at an output;
• a digital to analog (D/A) converter having an input coupled to the output of the adder to receive the digital sum signal, and an output providing a corresponding analog sum signal for coupling to the mobile station (MS);
• an analog to digital (A/D) converter having an input for coupling to the mobile station to receive an analog signal, and having an output for providing a digital signal corresponding to the analog signal received at the input of the A/D converter;
• a mobile station performance measurement unit having an input coupled to the output of the A/D converter for measuring a signal level indication signal transmitted from the mobile station (MS) indicative of the first analog signal levels and the second analog signal levels.

A method for testing handoff of a mobile station from a first base station to a second base station comprising:

• (a) connecting a base station test system to a mobile station;
• (b) transmitting configuration and access information from the base station test system to the mobile station;
• (c) receiving a signal from the mobile station with the base station test system enabling a registration process to be performed, and converting the base station test system to a conversation state after the registration process is complete;
• (d) generating a forward link digital signal to simulate a signal provided from the first base station and a second base station,
• (e) converting the forward link digital signal to an analog signal;
• (f) transmitting the forward link analog signal from the base station test system to the mobile station;
• (g) varying the forward link digital signal to simulate changing power levels from the first base station and the second base station;
• and
• (h) receiving a data signal from the mobile station in the base station test system representative of power levels received from the first base station and the second base station and providing an indication of the representative power levels to a display.