Measurement Journal Issue 6

cell capacity (b/s/cell). The efﬁciency ﬁgures are taken from various sources with the value in 2015 being projected at 1.3 b/s/Hz/cell, which is a safer ﬁgure to use than the 2.6 b/s/Hz/cell 4G target based on 4x2 MIMO. The spectrum growth follows the GSM900, DCS1800, E-GSM, UMTS2100 historical progression with projections for 700 MHz, 2.6 GHz and 3.5 GHz leading to a total of 680 MHz by 2015. In the early days, 2G systems were deployed to operate at a peak rate of around 10 kbps at the cell edge, enabling uniform, if somewhat inefﬁcient, service. In later generations, many techniques have been used to increase average efﬁciency by exploiting better radio conditions further into the cell. The result is better efﬁciency — but service coverage is no longer uniform. Until about 2002, the peak data rates tracked the growth in cell capacity, meaning that, on average, a loaded cell could deliver the higher rates to its users. The number of users will obviously vary depending on the service, but if we take as a reference the number of users in the original GSM cell at its capacity, then these same users would experience a nearly 50x growth in data rates in ten years — quite impressive! However, after 2002 we see a growing gap between cell capacity and the peak rates possible for single users. This is signiﬁcant because our same set of users will, on average, see only one-tenth of the possible peak data rates today’s unloaded systems can deliver. Using the projections for LTE and 4G, we can see the gap widening such that by 2015 the peak rates of the system will have outpaced system capacity by 100x. This means that, on average, the cell’s set of users will experience only one percent of the headline data rates. Even these ﬁgures are optimistic since Figure 3 is simpliﬁed by assuming constant load, ideal scheduling and the absence of deployed legacy terminals. There are many ways 4G systems could be analyzed, but the fundamentals of capacity and coverage are essential. In addition to the predicted capacity limitations, the delivery of very high data rates in a macrocell radio environment is restricted to a small area near the center of the cell (as discussed in Issue Three of Agilent Measurement Journal). If mobile broadband is to become a reality, both the capacity and coverage limitations of current macrocell systems need to be addressed, otherwise the result will be a continuation of the trend towards inconsistent service provision known to have held back the adoption of 3G. Although projected capacity growth through additional spectrum and improvements in efﬁciency are real, neither can deliver the substantial growth that is required for the mobile broadband revolution. To meet this challenge we must turn to the third axis in Figure 2, that being growth in cell numbers. 1,000,000 100,000 10 times capacity gap today growing to 100 times in 2015 10,000 kbps Efficiency, spectrum and capacity are normalized to 1992 levels 1,000 10 times 100 times 1000 100 100 10 10 1990 1995 Peak rates 2000 Average efficiency 2005 Spectrum 2010 Capacity 1 2015 Figure 3. Growth in peak data rates and system capacity 57 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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