Measurement Journal Issue 6

The beginnings of such aggregation techniques are already showing up in established technologies, ﬁrst with EDGE Evolution, for which standards are being written to aggregate two nonadjacent 200-kHz channels to potentially double the single-user data rates possible with standard EDGE. Along similar lines, there are 3GPP proposals for “dual-carrier” High Speed Downlink Packet Access (HSDPA) to try to close the “bandwidth” gap between 5-MHz UMTS and 20-MHz LTE. Multi-carrier cdma2000 has also been considered, although its use of adjacent channels avoids the need for multiple transceivers. There is clearly precedence for the ITU’s bandwidth aggregation proposals but there are unanswered questions about the viability of such solutions at 100 MHz due to the implications for user equipment (UE) cost and complexity. This is compounded by the fact that commercially-viable applications for 1-Gbps data rates to a single mobile device have yet to be articulated. It should also be noted that bandwidth-aggregation does not increase network capacity. Taking all these factors into account suggests a very uncertain future for 100-MHz multi-transceiver bandwidth aggregation as a means of delivering extreme single-user peak data rates. Evaluating 4G So how should 4G be evaluated given the history of previous generations? We could analyze many factors — but one undeniable truth supporting the phenomenal growth in the wireless market has been the parallel growth in system capacity. This should be no surprise since capacity is the raw material required to deliver value-added services. If capacity is not growing then neither is the industry. Most of the capacity in today’s infrastructure is consumed with telephony and messaging, with demand being fueled by growth in subscriptions of typical voice usage, which averages globally at around three hours per user per month. However, the advent of higher-rate data services changes this model and it is now possible for one user to demand far more capacity from the system than was possible with voice. If higher-rate 3G and 4G services are to be viable there has to be a corresponding growth in system capacity. Efficiency Summarizing 4G solution proposals During the 4G workshop there were numerous proposals from the industry as to how LTE-Advanced might deliver and even exceed 4G requirements. Space does not permit detailed analysis but the proposals included the following: • Higher-order multiple-input/multiple-output (MIMO) and beamforming (up to 8x8) • Co-operative MIMO • Cell-edge interference coordination and cancellation • Advanced coding and scheduling • In-channel relay for backhaul • Femtocell / Home Node B using self-conﬁguring/ self-optimizing networks Further details can be found in the workshop report and documents.6 e Sp ct ru m Number of cells Figure 2. Volume model for wireless system capacity Figure 2 presents a simple model for evaluating system capacity with three axes: spectrum, spectral efﬁciency and number of cells (which is a form of frequency reuse). The product of these three axes represents the volume or capacity of the system. Over the last 50 years there has been phenomenal capacity growth of around one million. Further analysis shows that efﬁciency has improved 20x and spectrum by around 25x, but the number of cells has grown by a staggering 2000x, making this axis 80 to 100x more signiﬁcant. Figure 3 shows a more detailed view of how peak data rates and system capacity have grown, spanning 1992 (2G) to 2015 (4G projections). The trends shown are based on a European model and are valid in general, though not necessarily in the ﬁne detail. The Y scale is the peak data rate in kbps and the other traces (normalized to single-band GSM in 1992) are: average efﬁciency (b/s/Hz/cell); spectrum; and their product, which is Agilent Measurement Journal 56

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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