Microwave Engineering Europe - September 2008 - (Page 13)

COVER FEATURE — TESTING LTE/WiMAX 13 Figure 2: Comparison of 802.16 wireless technologies. of OFDMA and MIMO schemes. Others come from the integration of both LTE and Mobile WiMAX with legacy systems. In particular, the challenges facing LTE and Mobile WiMAX today include: • RF — LTE’s variable channel bandwidths, use of multiple antenna conﬁguration and OFDMA add to its complexity. The use of SC-FDMA in the uplink results in additional challenges, forcing engineers to make careful design trade-offs to cover each critical part of the transmit/receive chain. • Layer 1/Baseband — LTE’s high data rates require large amounts of processing power, particularly in the baseband, which in turn needs to be modeled using PC simulation on both the UE and network sides. Reduced-speed emulation of hardware prototypes is also necessary. • Layers 2/3 — Design challenges at LTE Layer 2 include the handling of signiﬁcant amounts of data in the Packet Data Convergence Protocol (PDCP) and implementation of the 2ms MAC turnaround time. For Layer 3, speciﬁcations are still under discussion, presenting its own unique challenges, although simulation can be helpful. • OFDMA — As the services expected/ required from WiMAX networks expand, ever greater demands will be placed on the processors, challenging ampliﬁer design and inter-cell interference at the cell edges. • MIMO — While this scheme offers increased signal robustness and capacity improvements, those beneﬁts come at the cost of increased complexity for both the base station and the mobile station, placing large demands on processing power and antenna design. • Multi-format and multi-frequency band — Device test requires both the ability to work in multiple formats and to operate over all the frequency bands speciﬁed for each format, driving up design and product complexity. • Spectral efﬁciency/latency — Mobile WiMAX is a highly dynamic air interface which requires a great deal optimization and management. • Integration with legacy systems — New Mobile WiMAX systems must provide seamless connectivity and user experience. On top of these technology-speciﬁc challenges, designers must also contend with the fact that LTE and Mobile WiMAX are evolving technologies and as such are open to change and interpretation. The early availability of conformance tests will help alleviate interoperability issues and provide basic testing. However, for a successful commercial launch of either technology, comprehensive functional testing and real-world veriﬁcation of LTE and Mobile WiMAX products is a must. Eyeing potential solutions The LTE and Mobile WiMAX challenges require innovative test and measurement solutions, which can span the product development life cycle. As a world leader in test and measurement solutions, Agilent Technologies is at the forefront of the emerging LTE and Mobile WiMAX markets and is actively working to address these challenges by offering products that incorporate measurements speciﬁc to LTE and Mobile WiMAX, as well as capacity enhancement and multiplexing schemes like MIMO and OFDMA. Rigorous test solutions from Agilent, for example, now exist for protocol development and conformance testing. Wireless libraries with signal processing models and pre-conﬁgured simulation setups are available to create waveforms used to produce real-world physical test signals. Additionally, Agilent is actively participating in the standards working groups (e.g., 3GPP) and in the WiMAX Forum® (as a Principal Member) to ensure that as test speciﬁcations are deﬁned, standard-compliant test and measurement solutions will be available to support them. LTE Today Agilent offers a range of up-to-date, reliable LTE design automation and test solutions (Figure 3). Some of Agilent’s currently available solutions address: • Design simulation and veriﬁcation — Agilent offers solutions for helping product developers create spectrally-correct test waveforms that comply with 3GPP requirements for LTE. • Signal generation and analysis — Agilent’s signal analysis and generation tools, as well its Signal Studio and VSA software can be used to generate and analyze LTE test signals. Figure 3: As with its extensive WiMAX line of products, Agilent is committed to providing the most complete LTE measurement coverage — from RF to digital — throughout the entire product development cycle. Microwave Engineering ● September 2008 ● www.mwee.com 012-013-014_MWEE.indd 13 5/09/08 12:11:33 http://www.mwee.com

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Microwave Engineering Europe - September 2008 News Contents Comment Cover Feature: Uncovering Test and Measurement’s Role in Advancing LTE and Mobile WiMAX WiMax: WiMax and LTE Need to Address Issues of Backhaul, Cost and Efficiency for Successful Deployment WiMax: Manufacturing Communications Technology Products in India Test and Measurement Mobile Platforms Evolve to Meet Future Demands Products Calendar

Microwave Engineering Europe - September 2008

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