Measurement Journal Issue 6

The new median data rate (red trace) is 8 Mbps with the peak around 17 Mbps. In addition, by ofﬂoading users to the femtocells, the remaining macrocell users see their median data rate move from 50 kbps to around 170 kbps. This simulation clearly shows the difference between trying to improve capacity and median data rates by enhancing a single macro cell versus adding femtocells. This macrocell with 34 distributed users has a capacity of around 1.3 Mbps (0.26 b/s/Hz/call), resulting in the median of 40 kbps. Note that the macrocell is capable of supporting 17 Mbps, but only for one user near the cell center. If efﬁciency gains of 3x were realized, the median would rise to around 120 kbps, but this is a difﬁcult and expensive task with no guarantee of success. In contrast, by deploying low-cost femtocells using existing less-sophisticated technology, median data rates, due to better radio conditions and lower cell loading, are seen to rise a massive 200x to 8 Mbps. It is easy to assume that femtocells are just a further progression down the macro/micro/picocellular model of decreasing cell radius. This is true in terms of the coverage area, which for picocells and femtocells is in the range of 10 m, but it should be evident from Table 2 that the femtocell approach is fundamentally different from today’s cellular. A closer model would be that of a cellular version of Wi-Fi hotspots but with much better control over QoS through use of cognitive radio techniques inherent to cellular’s awareness of its environment, and the ability of the operator to remotely control the femtocell via the Internet-based backhaul. Note that the 200x femtocell improvement is delivered with a peak rate of 17 Mbps, well within range of evolving end-user backhaul. To be fair, femtocells have been tried — unsuccessfully — several times in the past, with the focus having been on telephony. Understanding those failures, and embracing the new potential for data services, will determine if femtocells have now come of age. To this end, one crucial factor now making a big difference is the Femtoforum, which is addressing many of the issues necessary to ensure commercial femtocell success.8 The challenges remain signiﬁcant and include aspects of end-to-end service — such as backhaul network neutrality Looking brieﬂy at femtocells A femtocell differentiates itself from the traditional centrallydeployed model according to the attributes in Table 2. Table 2. Comparison of traditional cellular and femtocellular Attribute Infrastructure cost Infrastructure ﬁnance Backhaul Planning Deployment Control Mobility Performance Traditional cellular $10,000 - $100,000 Operator Expensive leased E1/T1 lines Operator Operator truck roll Operator via O&M Good/excellent Limited Femtocellular $100 - $200 End user Existing end-user DSL or cable broadband End-user (no central planning) End-user one-touch provisioning Best effort Operator via Internet Nomadic/best effort Excellent Quality of Service (QoS) Operator controlled 59 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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