Measurement Journal Issue 6

Weighing the design tradeoffs There are several reasons why today’s mobile phones are so functionally complex. The growing presence of multimedia and mobile Internet applications is the greatest factor driving capability requirements. Less obvious perhaps is the requirement for mobile phones to support network-optional features. Additionally, phones have to work globally across many network configurations — even as new designs incorporate new functionality; remain small, attractive, affordable, and easy to use; and provide the longest possible battery life. Under the weight of these expectations, mobile phone designers are often forced to make difﬁcult design tradeoffs to provide the right amount of processing capability to meet current requirements and expected future needs. They attempt to minimize power usage and anticipate the worst-case scenarios that software and applications might encounter in real network environments. Moreover, they try to meet design goals using the fewest, smallest and least-expensive chips — all the while reusing existing hardware designs and software modules as much as possible. Because of these tradeoffs, there are literally hundreds of W-CDMA and HSPA devices on the market today, each with its own distinct size, shape, feature set, and method of operation. Consequently, there is no “typical” HSPA mobile phone and, therefore, no simple, one-time test process for ensuring a phone delivers the required performance. Instead, testing is iterative. It begins when the core components of the mobile device (e.g., RF and baseband chipsets, operating system, protocol stack, and applications) are ﬁrst integrated into a working unit. It ends when a reliable, quality product has been delivered successfully to the end user. Surveying the design challenges The challenges posed in implementing HSPA’s new performance enhancements in high-speed downlink packet access (HSDPA) and high-speed uplink packet access (HSUPA) often become evident during the integration process. Here the designer brings together the hardware, operating system, protocol stack, and applications, and tests them at a system level. Power control is often an issue. At the physical layer, adding HSPA to the technology mix introduces larger power variations — for example, in the uplink at transmission time interval (TTI) boundaries when HSUPA is turned on and off. In this case, relative differences in code channels also can be large. The dynamic nature of the HSUPA uplink makes construction of proper code channels in the phone more difﬁcult and can lead to increased out-of-channel interference and poorer modulation quality. 27 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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