Measurement Journal Issue 6

Figure 5. A 20-ms RLC polling rate interferes with the mobile phone’s ability to sustain maximum data rates Taking the ﬁnal step: validation Before releasing a mobile phone design for certiﬁcation testing, ﬁeld tests or manufacturing, designers want to be absolutely certain that their designs will withstand the rigors of the real world. Consequently, during ﬁnal in-house validation, the phone should be put through a series of “user-experience” tests and stress testing. Wherever possible, these tests should be incorporated even earlier in the design process to get the greatest benefit. the problem, protocol logs were examined. The ﬁnal analysis led to a redesign of the server buffering algorithm. This example illustrates, yet again, the challenge of designing a phone that is able to accommodate the bandwidth changes and delays so prevalent in the mobile Internet environment. Conclusion Advanced HSPA mobile phones — and the networks they use — are designed and built based on certain tradeoffs. Any testing strategy must therefore begin with the 3GPP standards, while also including critical steps for verifying the performance of each unique phone design in the dynamic HSPA environment. Physical layer variables, as well as the design of the protocol stack, can affect the ﬁnal application-layer throughput delivered to the end user. Thorough testing at all stages of integration and validation helps ensure that the phone performs as designed, network resources are allocated most efﬁciently, and, most importantly, that users have a satisfying experience. As an example, consider the testing of a video streaming application intended to keep video playback smooth, regardless of inconsistencies in the mobile network. To accomplish this goal, the application is supposed to enable fast responses to channelquality indication (CQI) changes. However, when the phone was tested running the application, it failed to respond as quickly to the CQI changes as was required. Figure 6 shows the test results on the data throughput monitor display. To troubleshoot Figure 6. Testing an application under real-world conditions 31 Agilent Measurement Journal

Table of Contents Feed for the Digital Edition of Measurement Journal Issue 6

Measurement Journal Issue 6 Using a Few Words to Convey a Deeply-Held Spirit Charting a Unique Path to Technology Innovation Contents Announcing First Commercial GC/MS Metabolites Library Assessing Nonlinear Behavior Testing Combines Form and Function Testing Multiplay Networks Higher Sensitivity LC/MS Easing Military Radio Test Stepping Up Calibration Accuracy Increasing Spectrum Analyzer Bandwidth 3GPP Tool Supports TS 36 Standards The Olympic Story Spotlights Agilent's Continuing Contribution to Technology Innovation Ensuring a Level Playing Field in Competitive Sports GPS: Coming of Age Resolving Design Issues in HSPA Mobile Devices Achieving Accurate Results with Oscilloscope-Based Jitter-Analysis Software RF Handheld Testers Guarantee Traffic Stability Under Olympic-Sized Stress Conditions Utilizing LAN-Based Instrumentation to Measure Total Harmonic Distortion in Remote Facilities IMT-Advanced: 4G Wireless Takes Shape in an Olympic Year EPO Doping: A Speed Engine, Turbo-Charged by Chemistry

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