Microwave Engineering Europe - November 2007 - (Page 25)

WiMAX NETWORK PLANNING 25 The ﬁrst step in any network design is to develop a detailed work plan. The work plan is typically broken down into three stages: (1) — Network dimensioning and design (2) — RF planning and mapping (3) — Network rollout and commissioning The ProPhecy prediction and optimising tools are used together in all three stages of the process. Network dimensioning and design This ﬁrst stage – determining the number and locations of basestations – is extremely critical in the design of a successful and cost-effective WiMAX network, but is often performed empirically when traditional planning tools are employed. Much better results will be achieved if the network is dimensioned accurately, taking account Figure 2(a): Shows the Ranked Solution Viewer in the ProPhecy optimisation module comparing the cost and coverage of the top 23 basestation sites. Figure 2(b): Shows the 3D Solution Viewer. Figure 3: Shows the optimised mean data throughput (aggregated DL + UL) for all users. of the speciﬁc needs of each application, which commonly include: desired coverage regions; desired capacity values; required trafﬁc densities; microwave or ﬁbre backhaul network capacity; and target capital expense. In addition to the siting of WiMAX basestations, a microwave backhaul network may be required to enable trafﬁc to be sent to and from each base-site, and a set of projected locations, or control sites, can be developed to meet the speciﬁc requirements. These will be distributed over the proposed coverage area – at either roof-top or street level – and a soft weighting factor can be applied to each site to reﬂect the geographic importance or anticipated trafﬁc demand. Next a list of possible basestation locations is produced: these locations are spread over the entire planning area, choosing only locations where actual basestation deployment is likely. A soft metric can be applied to each basestation site to reﬂect its expected installation and rental cost, which allows algorithms in the planning tools to endeavour to reduce the capital expenditure of the total network. Once a hardware vendor and operating frequency have been selected, then actual values for antenna gains, transmit powers and RF sensitivity levels are used to conﬁgure the network planning tools. The tools can also be used to determine the impact of different carrier frequencies, vendor speciﬁc hardware or antenna solutions: the antenna gain/directivity, for both the basestation and CPE, and the number of basestation sectors can all have a particularly signiﬁcant network impact. Samples of the ﬁnal basestation, CPE and mobile antenna parts can be characterised in a certiﬁed anechoic chamber, and the resulting 3D ﬁeld patterns incorporated into the planning tools. Using the vendor-speciﬁc parameters, the propagation links from each possible basestation to each customer or control site can then be determined by the planning tools. For a typical optimisation study, as many as 100 possible basestation and 1,000 control sites may be used, resulting in 100,000 point-to-point prediction studies. Using this matrix of data, the planning tools can then be used to determine the best basestation sites: the exact number of these depends on the size of the network rollout, but 20 - 25 might be typical. The ProPhecy optimiser solutions viewer displays a ranked list of solutions for a planner to review and select the optimum solution for their network based on their priorities, as shown in Figure 2. Each solution can then be viewed in three dimensions, as shown in Figure 2(b), where Microwave Engineering ● November 2007 ● www.mwee.com 024_025_026_MWEE.indd 25 25/10/07 14:02:10 http://www.mwee.com

Table of Contents Feed for the Digital Edition of Microwave Engineering Europe - November 2007

Microwave Engineering Europe - November 2007 Contents News Comment Metamaterials: Metamaterials Tackle Communications Wavelengths Microwave Components — EM tools: Microwave Component Design Easier With New EM and EDA Tools Cover Feature: RF Testing for OFDMA in LTE Base-Stations Startup Eyes Battery-Free Wireless Sensor Nets High-speed ADC Technology Paves the Way for Software Defined Radios Planning a WiMAX network: Maximising the ROI by Using Advanced Optimisation Tools Transporting Video Over Wireless Networks Ultrawideband Under the Gun Specifying the Proper SAW Filter Products Product Feature: RF Test Solution Supports Emerging 4x4 MIMO as Well as Multiple Commercial Standards Calendar

Microwave Engineering Europe - November 2007

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