Introduction to TD-SCDMA Spatial Radiation Performance (OTA) Test

    TD-SCDMA, or Time Division-Synchronous Code Division Multiple Access, is a third-generation mobile communication standard proposed by China.
    There is no formal standard for the spatial radiation performance test of TD-SCDMA, and it is only a draft for review. The standard to be approved is "Measurement Method of Spatial RF Radiated Power and Receiver Performance of 2GHz TD-SCDMA Mobile Station". The following is a detailed introduction to the spatial radiation performance test of TD-SCDMA. The
    OTA measurement method of TD-SCDMA is basically the same as that of other OTA measurement methods, but the standard puts forward requirements for the human device mode in data services: when the EUT is a handheld computer, PDA, small game console device, multimedia wireless handheld terminal, etc., it is necessary to test it in the human device mode. The human device mode mainly includes human hands, heads and their spatial combination, as shown in the figure. At this time, the human device is located in the XYZ positioning system, and the coordinate center is placed at the extended line O from the human ear RE point and the upper lip midpoint M point. Take MO=30cm. At this time, the +Z axis points to the top of the human head model. The right-hand rule defines the +X and +Y axes. The human hand keeps holding the device under test with one or two hands. As shown in the figure: 1. TD-SCDMA RF radiated power measurement     measurement steps: Establish a loopback test mode between the mobile station and the base station simulator (for the specific settings of the loopback mode, refer to Section 5.3 of 3GPP 34.109). During the test, the EUT's transmit power control should continuously send a "power up" command to the EUT to ensure that the EUT transmits at the maximum power during the entire test process. It is required to select the high, medium and low channels on the 2GHz frequency band for testing, as shown in the following table:

Frequency band	Channel Number	Designation	Frequency (MHz)
TD-SCDMA 2GHz L	10054	Up	2010.8
TD-SCDMA 2GHz L	10054	Downside	2010.8
TD-SCDMA 2GHz M	10087	Up	2017.4
TD-SCDMA 2GHz M	10087	Downside	2017.4
TD-SCDMA 2GHz H	10121	Up	2024.2
TD-SCDMA 2GHz H	10121	Downside	2024.2

 
 
 
 
 
 
 
    Measurement limit: The complete RF radiated power measurement should include testing of all test channels in both free space and head model configurations (if applicable) and in the main mechanical mode supported by the EUT (such as the flip open state of the flip EUT, the slide open state of the slide EUT, and the antenna unplugged state of the retractable antenna EUT).
2. TD-SCDMA receiver performance measurement
    measurement steps: Use a base station simulator to measure the mobile station receiving sensitivity and record the minimum forward link power when the EUT's BER reaches 1.2% and the confidence level is greater than 95%. Power control uses a closed-loop power control mode, and the EUT transmits at maximum power. During the test, the transmission rate is 12.2kbps, and a minimum of 40,000 bits are tested. Perform a complete TIRS test on the high/medium/low three channels of the frequency band supported by the EUT. For the middle channel, measure the relative receiving sensitivity under the condition of meeting the maximum spacing, as shown in the figure below:     The steps for measuring relative receiving sensitivity are:     a. Find the measurement point with the best receiving sensitivity, adjust the EUT, the positioner, and the measurement antenna position and polarization to be the same as the measurement point, and measure on the channel closest to the measurement point and satisfying the interval between two adjacent continuous channels is not more than 500kHz.     b. Increase the output power of the base station simulator to the best receiving sensitivity + 5dB.     c. Measure the BER of the middle channel, and the BER should not exceed 1.2%.     d. Report the measurement results of the middle channel.     Measurement limit: The complete receiver sensitivity measurement should include testing of all channels in both free space and human head model configurations (if applicable) and the main mechanical mode supported by the EUT (such as the flip open state of the flip EUT, the slide open state of the slide EUT, and the antenna unplugged state of the antenna retractable EUT). In addition, the relative sensitivity test of the middle channel should also be performed.