Microwave Engineering Europe - November 2007 - (Page 26)

26 WiMAX NETWORK PLANNING each dimension is a metric selected from total cost, capacity (or throughput), coverage, maximum number of sites, projected revenue etc. as preferred by the planner. From this data the planner can work to conﬁrm site acquisition and cost. Once the tentative acquisition of 80 percent of the sites has been conﬁrmed, a ﬁnal network design study is carried out to deﬁne the minimum number of required basestations with speciﬁc locations and radio resource requirements identiﬁed. Line-ofSight connections between the base sites can also be conﬁrmed to ensure that a suitable backhaul network can be constructed. Following contractual acquisition of the sites, with further design iterations if required, a detailed network plan is then developed, based on the speciﬁc basestation locations, heights and antenna patterns, and the expected coverage and capacity/throughput are estimated (Figure 3). In optimising a network the ProPhecy optimising tool load balances the trafﬁc across all cells resulting in a more even trafﬁc distribution across the whole network and, as illustrated in Figure 4, providing a fairer distribution of data to end users. The advanced optimising function signiﬁcantly reduces the number of basestations required compared to traditional site deployment – by up to 20 percent – while increasing the user data throughput by up to 30 percent. RF planning and mapping Once the initial network design process has been completed and the exact location of each basestation is known, the detailed RF planning and mapping stage can begin. The ProPhecy prediction engine can be used to predict the RF coverage levels from each WiMAX site over the entire coverage region. Generally, locations within 3 km of each base site are modelled in full 3D, to ensure accurate non-line-of-sight Figure 4: Shows a plot of user served trafﬁc ratio (percentage of demanded trafﬁc that is met), for an optimised and load balanced network. predictions, while more distant locations are normally analysed using a 2D vertical plane model, which is highly accurate for the lineof-sight operation that is necessary for most deployments at these distances. It should be noted that in dense urban areas the dominant path for WiMAX coverage is actually the non line-of-sight path (Figure 5); hence the prediction tool must accurately predict NLOS coverage. For each basestation site, a single prediction grid is generated for each sector. Frequency planning and interference analysis are then performed, and a detailed coverage map is generated for each basestation and sector. Using knowledge of the link speeds and associated RF sensitivity levels for a given WiMAX system proﬁle, a projected link speed map is generated to indicate the operating mode to each customer location. These data sets can be combined either in the planning tools, or by using a third party GIS tool such as ArcMAP, to produce a detailed composite network plot (ArcMAP supports a wide range of data projection types, including export in WGS84, which allows data to be displayed in Google Earth). Similar planning data can also be generated for the microwave backhaul links. At this stage coverage plots are provided for the signal level and projected link-speed from each basestation (sector) and from the network as a whole. The coverage and capacity prediction data can also be provided for export and subsequent integration into vendor speciﬁc software tools. Rollout and commissioning ProVision can also assist operators during the network rollout and commissioning phase of a project, by carrying out site survey studies using the ProPhecy toolset to check service availability to a given rooftop or street level location. Predicted RF levels and link-speeds are compared with actual levels, to conﬁrm and characterise the operation of the tool and to conﬁrm the successful installation of the basestation, and where appropriate the CPE equipment. By employing sophisticated planning and optimisation tools from the earliest stages of planning a new WiMAX network, deployment costs have been shown to be drastically reduced – by up to 20 percent compared with conventional network planning tools, and user data throughput is increased by up to 30 percent. Figure 5: Connection by LoS versus NLoS nodes. Company Information ProVision Communication Technologies Ltd www.provision-comm.com Microwave Engineering Europe ● November 2007 ● www.mwee.com 024_025_026_MWEE.indd 26 25/10/07 14:02:46 http://www.provision-comm.com 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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