Receive (RX) diversity and advanced receiver technologies are used in mobile radios in both 3GPPUMTS and GERAN. Their job is to increase downlink performance in terms of capacity and coverage. In "Testing HSDPA UE Receiver Diversity," Rohde & Schwarz (Munich, Germany) demonstrates how such receivers can be easily tested. At the heart of this 26-page document are the Universal Radio Communication Tester, R&S CMU200, and the R&S SMU200A vector signal generator. Tests are described for user equipment (UE) with Rx antenna diversity and single-link performance. These tests can be found in the TS34.121 standard under sections 9.2.1D, 9.2.1E, and 9.4.1A.
The 9.2.1D and 9.2.1E tests measure the information bit throughput on the high-speed downlink shared channel (HS-DSCH). They indicate the bit rate of a unit under test for comparison to the minimum values specified in the standard. In contrast, test 9.4.1A checks how reliably the high-speed shared control channel (HS-SCCH) will be detected by the UE. This downlink channel signals to the UE connected to the Node B base station when a high-speed downlink-packet-access (HSDPA) receive slot is assigned to it.
Instead of using RF faders, the instruments opt for fading at baseband. Baseband fading ensures optimum signal quality. If the SMU200A is used, automatic calibration is provided inside it. No external measurements are necessary.
A section is devoted to testing with CMUgo, the company's free software tool for running remote-control tests using the CMU and additional instruments. For the test procedure, the CMUgo software is installed on a PC with an IEEE 488 (GPIB) instrument controller card. The CMU and SMU instruments connect to the GPIB card in the PC. Directions are given for configuring basic initializing; HSDPA call setup; and HSDPA Enhanced, Type 1. Once the last test item of the last measurement is complete, the hardware setup will show up as wallpaper or a temporary Measurement Report window will appear.
The note succeeds in providing a seemingly easy-to-use test setup for the Enhanced Performance Requirements Type 1 of standard TS 34.121. Together, the CMU universal radio-communication tester and SMU vector signal generator provide two downlink channels for UE Rx diversity under multipath fading conditions. The entire test procedure is described along with a measurement report for tests 9.2.1 and 9.4.1.
Rohde & Schwarz GmbH & Co. KG, Muehldorfstrasse 15, 81671 Muenchen, Germany; +49 89 4129-0, FAX: +49 89 4129-12164, Internet: www.rohde-schwarz.com
