introduction

TD-SCDMA has entered a substantive implementation stage. In order to ensure the reliability of the entire network construction, the smooth opening of services and the normal provision of services, strict control of all links is essential. These controls are based on scientific testing methods. Above. This paper provides a comprehensive explanation for how to test the core network, access network, terminal and other entities to ensure their performance, and provide a scientific method for the industry.

TD-SCDMA terminal RF and application test solution

1 TD-SCDMA terminal RF test

The RF test of TD-SCDMA terminal mainly has two aspects: on the one hand, it tests the board level and the whole machine of the terminal design process to ensure that the main indicators of the terminal meet the requirements of the standard/specification. On the other hand, online testing of terminal-scale production to ensure that production-grade terminal performance indicators are stable. The specification for the test is TS34.122. It mainly includes transmission, reception, performance and radio resource management.

In the TD-SCDMA mobile phone RF R&D test and production, the mobile phone comprehensive tester is a necessary test equipment. The MT8820B client can complete the test of TD-SCDMA maximum transmit power, spectrum transmission template, adjacent channel power, minimum transmit power, open loop power control, closed loop power control, occupied bandwidth, error vector magnitude, and reference sensitivity. And all the tests are one-click tests, which greatly facilitates the user.

Figure 1 MT8820B is a comprehensive tester that supports TD-SCDMA to GSM stable switching

In addition to support for the above test items, the MT8820B also supports chip manufacturers' unique calibration and TX SWEEP tests. In this state, the chip can continuously transmit signals in 500 time slots, and the MT8820B can capture. In this way, a large amount of APC calibration time can be saved. With this calibration method, the typical calibration time is around 30s.

The current TD-SCDMA handsets basically support the GSM function, and this is also necessary for some time to come. The MT8820B is a comprehensive tester that supports TD-SCDMA to GSM stable switching. With the "Handover to GSM" button, users can easily switch from the TD-SCDMA connection state to the GSM connection state without having to drop calls.

In order to save the cost of the mobile phone production line, the MT8820B is equipped with a unique dual port function, one instrument can support the test of two mobile phones at the same time. The two ports are independent of each other, and the GPIB is independent and does not affect each other. And the two ports can test different standards at the same time, for example, one port is testing TD-SCDMA mobile phone, and the other port can test GSM mobile phone. The dual port function of the MT8820B minimizes the cost of mobile phone production and increases efficiency.

The MT8820B also supports WCDMA/HSDPA/HSUPA, GSM/GPRS/EDGE, CDMA2000/1XEVDO, PHS, and PDC testing. It is a comprehensive test instrument that supports the communication system in the industry.

2 TD-SCDMA terminal application test

The MD8470A system simulator provides an analog TD-SCDMA network environment. In the current TD-SCDMA network has not been developed on a large scale, the development of TD-SCDMA chips and mobile phones is of great significance. The main functions of the MD8470A are divided into mobile application testing and mobile protocol testing.

Figure 2 MT8820B can support the test of two mobile phones at the same time

The rich multimedia data application is the biggest feature of 3G mobile phones. How to conveniently develop applications such as MMS and videophone becomes a new topic in the network environment without debugging. The MD8470A supports voice, SMS, data communication, MMS, video telephony, supplementary services and other business tests. Under the simulation platform provided by MD8470A, software engineers can focus on developing upper-level application software to speed up the development process.

The MD8470A can also be combined with products from companies such as Setcom and Radvison to form an application conformance test system that complies with the 3GPP standard, and performs standard tests on MMS, PoC, and VT functions of mobile phones.

Another area of ​​application for the MD8470A is the protocol test for TD-SCDMA, which provides an API to control the instrument. The R&D engineer can write the protocol test script in C language, freely define the parameters of the physical layer, MAC layer, and RLC layer, and write the protocol flow arbitrarily in the layer3 layer. The message sent by the base station side is completely defined by the user, and this is difficult to achieve in an actual network. During the test run, the signaling flow of the Uu interface can be monitored at any time, so that troubleshooting and debugging can be easily performed.

Figure 3 Application of TD-SCDMA system simulator in terminal test

The MD8470A can support the simulation of a variety of mobile communication systems, providing a very powerful test environment for multi-mode mobile phones. For example, a protocol application test solution can be provided for TD-SCDMA/GSM dual-mode handset development. In addition to TD-SCDMA, the MD8470A also supports WCDMA/HSPA/GSM/GPRS/EDGE/C2K, etc., and provides a graphical interface for user-friendly operation. In this environment, the user can test various functions just like in the actual network.

TD-SCDMA access network (base station and repeater) test solution

In the development and production measurement of TD-SCDMA, it is usually necessary to measure the transmitter and receiver parts of the base station and repeater products. The measurement range should be based on the corresponding 3GPP and industry standards. The combination of the MG3700A+MS2690A is a test solution for this measurement market.

1 test plan

Solution 1: Base station test

The MS2690A is a vector signal analyzer with TD-SCDMA measurement options for signal analysis of the transmitter of the base station under test. Since the MS2690A also has a vector signal source option, it can generate TD-SCDMA modulated signals for The receiver of the base station under test evaluates. If the neighboring channel selectivity of the base station is measured, the second signal source, that is, the MG3700A, is used to generate the interference signal.

Figure 4a Scheme 1: Base station test plan

Option 2: Repeater test

Because the MS2690A has both signal analysis and vector signal generation capabilities, the test of the repeater becomes very simple. (As shown in Figure 4)

Figure 2b Scheme 2: Repeater test plan

2 Test items and indicators

The MS2690A is a signal analyzer with a vector signal source. Its main features are:

● Large dynamic range: TOI=+22dBm, DANL=-155dBm/Hz.
● High level accuracy: ±0.5dB within 6GHz.
● Signal capture capability: The input RF signal can be digitized, saved as IQ data, and reproduced as a vector source for device development and analysis.
● High-speed measurement capability: Ultra-high-speed testing of ACLR and other indicators, greatly saving test time.
The MS2690A's TD-SCDMA test items are rich and complete, and all test functions basically implement one-button measurement. The main test items are as follows.
● Modulation indicators: frequency error, average power, EVM, PCDE, etc. The measurement results can be read at one time without switching the interface back and forth.
● Chip constellation map, which analyzes the vector constellation and IQ data of each chip in the target time slot.
● Code domain power and code domain error measurement.
● Multi-slot power and multi-carrier power measurement. The target time slot can be accurately located to a certain time slot of a certain carrier. Currently, 6-carrier test can be supported.
● Measurement functions such as ACLR, OBW, and SEM.

TD-SCDMA network construction and maintenance test solution

TD-SCDMA base station installation and maintenance measurement, mainly for the inspection of the electromagnetic environment near the device and the base station during the installation of the base station, and checking whether the various indicators of the base station in operation meet the requirements. For example, devices such as antenna feeders, tower amplifiers, etc., need to be inspected during installation to detect performance degradation of the device due to shipping and installation. The installation optimization and network optimization test after the installation needs to confirm and identify the interference signal and the base station transmission signal. Signal coverage and signal quality may need to be tested during maintenance testing.

Anritsu MT8222A BTS Master Handheld Base Station Tester is a portable test instrument developed for the installation and maintenance test requirements of various wireless communication base stations. It integrates vector network test functions of antenna feeders and high-frequency devices for RF electromagnetic fields. Spectrum analysis function for intensity analysis and interference finding, RF signal demodulation test for base station signal quality test, and code domain test and air signal identification function for CDMA signals.

The MT8222A BTS Master handheld base station tester is battery powered and the rugged chassis is designed to handle a variety of field test environments, from high temperature to low temperature and high altitude environments. For device measurements, dual-port vector measurements of reflection and transmission parameters can be performed with reflective parameter time domain testing for device fault location with a test dynamic range of up to 80dB. For spectrum analysis measurements, the test sensitivity of -163dBm is sufficient for very high test requirements, and the frequency coverage of 7GHz (which can be extended to 20GHz if required) meets the measurement needs of most wireless communication systems, while the interference increases based on spectrum analyzers. The signal analysis function makes it easy to monitor and characterize the interference signal for a long time and to locate the test. The MT8222A's built-in 10MHz RF signal demodulation analysis bandwidth ensures measurement of the signal quality of GSM/GPRS/EDGE/WCDMA/HSDPA/CDMA/CDMA2000/1XEVDO/WiMAX, and directly obtains EVM, multipath information and pairs of modulated signals. Code domain analysis of the CDMA system. In addition, the GPS option not only provides the location of the measurement location to provide information for the MapInfo and MapPoint electronic maps, but also provides a more accurate calibration of the MT8222A internal clock.

Since TD-SCDMA is a communication system that integrates time division multiple access, frequency division multiple access, and code division multiple access. Therefore, in addition to measuring the occupied bandwidth of the base station transmit signal in the frequency domain, in-band power, temporary leakage, etc., it is also necessary to perform time domain measurement on the time-division signal of 7 time slots. If it is necessary to analyze the code domain signal, it is necessary to The signal is demodulated and measured. MT8222A has the frequency and time domain measurement functions for TD-SCDMA RF signals. It has excellent measurement dynamic range. The time-slot measurement switch ratio of each channel can reach more than 120dB. MT8222A is fully equipped for TD-SCDMA. The base station identification and the code domain power and signal quality test functions can meet the test requirements of the time division, frequency division and code division system RF signals of TD-SCDMA.