TestBench, March 2010: Multiple-handset emulation for DC-HSDPA
In the demanding world of developing new cellular equipment, base stations typically arrive long before mobiles. But without a mobile, how can the base station be tested? The TM500 Test Mobile from Aeroflex provides an answer. The TM500 DC-HSDPA Multi-UE Test Mobile enables 3G infrastructure equipment manufacturers to perform rigorous load testing. With the TM500, they can test the performance of their DC-HSDPA base stations under conditions of increasing user demand, speeding up the development of infrastructure equipment and its deployment in networks.
When emulating a single handset, the Aeroflex TM500 DC-HSDPA Test Mobile provides low-level control and configuration; it combines detailed measurement data required by infrastructure engineers for rapid diagnosis of engineering issues. However, testing a base station against a single handset is not sufficient. Scheduling algorithms must be optimized, and the base station must be load tested.
And recently, the TM500 Test Mobile became the first to market with support for multiple UE (user equipment, or handset) emulation in conjunction with measurements for the 3GPP W-CDMA Release 8 DC-HSDPA (Dual Cell High-Speed Download Packet Access) standard. The TM500 DC-HSDPA Multi-UE Test Mobile now supports the ability to test a base station and network against a multiple handset configuration. The TM500 enables base station and core network designs to be load tested, stressed, and optimized to ensure that robust, flexible and high-performance products are delivered to network operators.
The Multi-UE DC-HSDPA model (part of the TM500 family), includes support for 3G and 4G standards from HSDPA through HSUPA, HSPA+, and DC-HSDPA to LTE. The TM500 Test Mobile offers all the capabilities of a mobile handset or set of mobile handsets, with advanced test functionality for comprehensive 3GPP verification, validation, and optimization.
DC-HSDPA delivers a peak data rate of 42 Mbps without the need for MIMO (multiple input/multiple output). DC-HSDPA offers improved network efficiency and load balancing through better resource allocation and frequency selectivity. DC-HSPDA also delivers improved Quality of Service (QoS) in poor environments where MIMO is not necessarily an option.
The Aeroflex TM500 Test Mobile family has established itself as the “gold standard” for cellular infrastructure equipment manufacturers worldwide and is "continually evolving to track the standards roadmap that wireless network operators are following," according to Tim Beard, WCDMA product manager at Aeroflex Test Solutions. "We expect the new DC-HSDPA standard to be widely adopted by operators who are looking for ways to improve the performance and extend the life of their existing networks at minimal cost. The TM500 is the first test mobile to support multi-UE capability for the DC-HSDPA feature."
Every major infrastructure vendor and a majority of femtocell manufacturers use TM500 throughout the development cycle for 3GPP verification, validation and optimization. From HSDPA through HSUPA and HSPA+ to LTE, TM500 offers all the capabilities of a mobile terminal with advanced test functionality.
Testing a single base station against a single mobile isn’t enough though. Scheduling algorithms need to be optimised and the base station needs to be load tested. With the TM500 Multi-UE variants, complex scheduler and load capacity testing can be performed early in the design cycle and help deliver robust, flexible and high performance solutions to network operators.
Manufacturers must test network equipment under realistic operating conditions. All the major infrastructure vendors, as well as a majority of femtocell manufacturers, currently use the TM500 Test Mobile. The Multi-UE DC-HSDPA model is the latest in the TM500 family, which includes support for 3G and 4G standards from HSDPA through HSUPA, HSPA+, and DC-HSDPA to LTE. The TM500 Test Mobile offers all the capabilities of a mobile handset or set of mobile handsets, with advanced test functionality for comprehensive 3GPP verification, validation, and optimization.
Once the device is integrated, the overall performance needs to be fully characterized. During this stage, it will be necessary to trace and eliminate bottlenecks to maximize data throughput. This needs to be done under normal and extreme conditions of temperature and power supply voltage. Power consumption, thermal characteristics, electromagnetic compatibility (EMC), emissions, and susceptibility also all need to be measured under full load conditions. Generally, this will involve using 2x2 downlink multiple-input multiple-output (MIMO).
Aeroflex’s range of LTE test products includes signal generators such as the 3410 series, with extended bandwidth to suit the new OFDMA radio link, the versatile PXI modular instruments, the TM500 test mobile for eNB and infrastructure testing, and the 7100 LTE UE test set. The ability to seamlessly hand over between cells while minimizing the interruption to data throughput needs to be assessed, as does the ability to hand over between different radio access technologies while maintaining the data connection. Compact, flexible, and modular instruments are already available from multiple vendors. For example, Aeroflex’s LTE test products support all the features necessary to characterize the performance of LTE devices.
Ensuring performance is maintained throughout the cell will be the most difficult challenge, especially as the number of users in the cell grows—and with it the signal noise level. The thorough and efficient testing of LTE devices requires comprehensive test coverage: RF, baseband, and protocol. Test equipment vendors such as Aeroflex are providing this capability with both new and upgraded instruments, test sets, and systems already available.