RF test systems adapt to DARP

Rohde and Schwarz now offers five test scenarios for downlink advanced receiver performance, a method that increases network capacity by reducing interference in mobile radio networks.

Rohde and Schwarz has become the first company to offer five test scenarios for downlink advanced receiver performance (DARP), a method that increases network capacity by reducing interference in mobile radio networks.

The test scenarios can be run on the R and S TS895xG family of RF test systems.

Rohde and Schwarz is involved in compiling the test specification for DARP, which is expected to be completed in April 2005.

Interference occurs in every mobile radio network as transmitted signals are superimposed on each other in the individual radio cells.

DARP can detect these unwanted signals in the radio cell and suppress them.

At the chip level, there are two algorithms that can be implemented in GSM mobile radio phones to detect interference.

One of the factors used to calculate the unwanted signal is the corresponding training sequence of the signals.

Training sequences have a known code and are transmitted by GSM basestations in the middle of every data packet sent.

DARP substantially increases network capacity, and so is particularly important for network operators but is also of interest to mobile phone manufacturers.

Rohde and Schwarz already offers five DARP test cases for the R and S TS895xG family of RF test systems, although the test specification has not yet been completed.

These test cases cover the most important test requirements and will especially support mobile radio manufacturers in the development of DARP compatible mobile radio phones.

Under real network operation conditions, several different signals from adjacent radio cells may be superimposed on the wanted signal.

The interfering basestations transmit their signals simultaneously or with a delay of a few bits.

Therefore, the test scenarios simulate up to four unwanted signals that are transmitted synchronously or asynchronously to the wanted signal.

The unwanted signals can use the same frequency as the wanted signal or an adjacent frequency.

It is also possible to vary the codes of the training sequences which are included in the transmitted data packets of the unwanted signals.

The first five DARP test scenarios for the R and S TS8950G and R and S TS8952G test systems are now available from Rohde and Schwarz.

All test cases specified by the TS 51.010 standard are also expected to be available for the R and S TS895xG family of RF test systems by the middle of this year.

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