At the recent 3GSM World Congress, Aeroflex unveiled its strategy to support the new 3G long-term evolution (3G LTE) standard, 3GPP's vision for ensuring that 3G remains the dominant global cellular technology going forward into the next decade. Consequently, the standardization effort for 3G LTE is based on a set of high-level requirements, the principal aim of which is to further improve service provisioning and coverage, but at a reduced cost per bit compared to 3G for both operators and users. According to Aeroflex, all this must be achieved within the context of an enhanced user experience, operational flexibility that covers both existing and new frequency bands, improved data rates and reduced latency.

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However, while 3G LTE provides a major leap forward, it also brings with it significant testing challenges. In order to obtain the performance advantage of a higher data rate for mobile applications, the 3G LTE specifications will be based on orthogonal frequency-division multiplexing (OFDM) modulation technology, which represents a significant change at the very lowest level of the radio communications. Achieving synchronization will be a major challenge, said Aeroflex.

Hence, the test and measurement instrument supplier is designing a pair of test products, the TM500 LTE and 6401 LTE, which will support the physical layer testing of networks and mobile devices respectively. The complete visibility into the lowest layers of the radio modem will allow users to diagnose the actual cause of a synchronization problem rather than just knowing that synchronization has failed.

Without the higher-layer protocol, it is necessary to completely configure the physical layer using test scripts. As a consequence, many early test failures may not be the result of real problems, but rather by a mismatch in the setup between the prototype under test and the test equipment, according to Aeroflex. With hundreds of parameters that need to be selected, the risk of a mismatch is significant, noted the supplier. Consequently, Aeroflex has developed a powerful graphical user interface to allow the TM500 LTE and the 6401 LTE to be easily configured without the need to write software to execute the test. The GUI facilitates parameter configuration through dialog boxes, which allows users to select their values using engineering terms and units.

A further implication of physical layer testing when the higher-layer protocol is not available is that test automation is essential to ensure extensive and complete testing. The TM500 and 6401 have been designed from the start to be integrated into an automated test environment. The incorporation of test script configuration tools will allow the easy generation of all scripts needed to select the different configurations and tests. A test controller can initiate these various scripts as required to synchronize control of the prototype under test and the test equipment.

As a result, it will be possible to alter parameters in real time to enable test coverage to be extended across the range of different configurations used in a live system both in relation to test of the 3G LTE network and test of early 3G LTE prototype mobile devices. This will allow the early detection of software bugs associated with particular parameter values that will not otherwise be found until much later in the design cycle.

The implementation of multi-in multi-out (MIMO) antennas to improve the signal strength received by mobile devices from the network is a key new feature of 3G LTE. Aeroflex will develop test features especially for MIMO to ensure that both the network and mobile devices are able to get the signaling right and then transmit and receive in full synchronization with the signaling.

Because 3G LTE is an evolution of existing UMTS systems based on W-CDMA and will also fully integrate with existing GSM/GPRS/EDGE networks, seamless handovers will be critical to the gradual rollout of the first 3G LTE networks and deployment of the first LTE mobile devices, said Aeroflex. Such hand-overs might be intercell between neighboring 3G LTE cells or they could be handovers to W-CDMA or GSM/GPRS/EDGE as a user moves in or out of LTE coverage. The TM500 and 6401 will allow testing of these handovers at an early physical layer-only test stage and then eventually at the system test stage as Aeroflex develops protocol development test and protocol conformance test options for LTE based on the TM500 and 6401 LTE test platforms, said the maker.

For more information, visit www.aeroflex.com.