EDA & Development


this would include time-stamped message logging and decoding. But it is important that this is available for each sub-layer, providing the ability to trace through signaling message flows in detail, from MAC PDUs up to RRC messages, thus ensuring that timing requirements are met.


The ability to create test scenarios for each layer requires detailed control of the test equipment, but this needs to be kept as easy to use as possible to avoid a painful learning curve. Graphical test description, as provided by the Aeroflex 7100 Scenario Wizard, can offer a clearer method of defining new tests.


Performance testing Once the RF, baseband, protocol stack, and application layer have been integrated, overall device performance needs to be fully characterised. During this stage, it will be necessary to trace and eliminate bottlenecks to maximise data throughput, both 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).


The ability to seamlessly hand over between cells while minimising 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 the features necessary to characterise the performance of LTE devices.


Although the LTE physical layer uses a cyclic prefix to add resistance to multipath effects, it needs to be tested to ensure correct operation. Leaving this testing until the field trial stage adds risk to the development. Fortunately, test equipment suppliers provide facilities for simulating real- world signal conditions in the lab, with built-in fading simulators and noise generators.


An important performance parameter of an LTE device will be its ability to achieve and maintain synchronisation with the downlink signal. The LTE OFDMA scheme uses subcarriers spaced at 15 kHz intervals. The receiver must stay precisely tuned to the subcarriers even under the effect of Doppler shift – a lack of synchronisation can result in inter- subcarrier interference, reducing SNR. To characterise the behaviour of the device, the ability to simulate Doppler shift in the lab is again essential.


Conclusion


The next generation of mobile devices will need to provide a mobile broadband experience that matches the hopes and expectations of the


network operators. It will be necessary to test new LTE devices using a layer- by-layer approach, building up to an end-to-end test scenario that uses real- world signal conditions. Ensuring that 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, protocol and system- level. Test equipment vendors are providing this capability with both new and upgraded instruments, test


Aeroflex Test Solutions | www.aeroflex.co.uk Phil Medd is Product Manager, Aeroflex Test Solutions


References Global Certification Forum www.globacertificationforum.org PTCRB www.ptcrb.com E-tec


sets, and systems already available. Achieving high data throughput and low latency in the most efficient manner possible (in terms of both power consumption and RF spectrum usage) is the main aim of introducing LTE technology. Only through careful testing in the development and deployment stages will this goal be achieved.


Manufacturing Socket & Connector Solutions LED Sockets vertical & horizontal Female Connectors 1.27, 2.00, 2.54mm pitch Low Profile SMD headers 1.27, 2.00, 2.54 pitch Elevated Sockets PC104 and PC104+ BGA Sockets Ultra low profile 2.00mm pitch SMD turned pin socket ZIF, FPC connectors/cables


E-tec manufactures in Switzerland, Taiwan and the UK. In the UK we produce many special sockets and adaptors so if you have a requirement for a specific board to board spacing, need a special footprint with unorthodox pins, need to convert from a PGA to a QFP, need to second source a Harwin or Samtec connector, or simply need assistance on surface mount connectors why not give us a call to solve your problem.


E-tec Interconnect (UK) Ltd, Units A5 & A6, Decimus Park, Kingstanding Way, Tunbridge Wells, Kent, TN2 3GP.


Tel: (01892) 530260 Fax: 01892 515560 info@e-tec.co.uk www.cieonline.co.uk www.e-tec.co.uk Components in Electronics July/August 2010 35


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