SYSTEM DESIGN FOR LMDS, MDS AND OTHER BWA NETWORKS

• White Papers
• Business Planning
• Hub Site Planning and Selection
• The HN Field Survey
• LOS Coverage Report
• The LOS Viewer
• Using the HN “LOS” Database to Derive a 3D Database for RF Interference Analysis

HN Telecom has a 40-year history of excellence in world-wide telecom engineering consulting, and a proven track record in designing voice and data networks, including microwave at all frequencies (2 to 40 GHz.). HN offers comprehensive services for the planning, design and implementation of LMDS, MDS, or other BWA (Broadband Wireless Access) networks at any frequency.

This section outlines HN Telecom’s Wireless Access-related services, and also provides an introduction to our photogrammetric survey technology. An innovative approach to the demanding line-of-sight (LOS) requirements of last mile wireless access networks, the HN methodology is accurate and cost effective. Using photos taken from hub rooftops, HN has developed proprietary methods and software to create databases of LOS buildings. These databases can be used directly for system design and implementation, and can be used in conjunction with RF Planning tools to evaluate RF interference. See sections Hub Site Planning and Selection, The HN Field Survey, The LOS Coverage Report, and The LOS Viewer to learn more. HN's methodology is also applicable to NLOS (near-line-of-sight) network design.

White Papers (Top)(Bottom)

Detailed information is available in the following documents available for download. If using Internet Explorer or MSN Explorer, right-click the link(s) and select Save Target As... to download. Otherwise, simply click on the link(s).

Costing LOS: A Comparative Analysis of BWA Network Deployment Methodologies (approx. 2.12 MB) (Microsoft Word Document)

Provides a process overview, and evaluates the cost of the HN Photogrammetric Survey methodology relative to currently accepted practices.

Note: If you do not have Microsoft Word, you can view the Costing LOS document with WordPad.

Hub Selection & LOS Survey: Process Overview with Sample Graphics  (approx. 3.73 MB) (Microsoft PowerPoint Document)

Outlines the major stages of an HN Telecom LOS Survey, from initial planning and hub selection through to the delivery of LOS coverage results.  The sample images and graphics are real-world examples.

Note: If you do not have Microsoft PowerPoint, you can view the Hub Selection & LOS Survey document with the free PowerPoint viewer provided by Microsoft. Click here then click on Download Now.

Business Planning (Top)(Bottom)

Good planning is essential to building a profitable business operation.  Recent market events have demonstrated that the ability to accurately predict and plan for the full costs associated with deployment, and to become revenue generating as soon as possible, is critical to the success of a Wireless Carrier’s business plan. 

Key factors that require evaluation include:

• Pricing
• Types of services to be offered to subscribers
• Buildings or areas to be served
• Source and type of equipment
• Financing

In association with alliance partners, HN can assist you with all the steps in your planning process. Please refer to the white paper Costing LOS: A Comparative Analysis of BWA Network Deployment Methodologies for a cost analysis of the HN Photogrammetric Survey methodology.

Hub Site Planning and Selection (Top)(Bottom)

Def: A hub, or node, is the radio site serving as a central point for two-way microwave transmission with nearby subscriber locations.

Hub site selection is critical to building an effective network.  Typically, the hub selection process begins with a market study (performed by HN or the Wireless Carrier) to assess regional revenue potential and identify key target subscriber buildings.  Candidate hub buildings are identified and evaluated with respect to lease costs and coverage provided.

With the HN Survey Methodology, candidate hubs are selected using a stereoscope in combination with commercially available aerial photography.  (A stereoscope provides a 3D image similar to hovering in a helicopter.)

An aerial photo Hub Selection Report is prepared for each city consisting of:

• A city map showing the proposed service areas;
• A street map locating the primary and alternate candidate hub buildings;
• An aerial photo showing the selected building locations;
• A summary table giving the street location, approximate number of floors and aerial photo reference for each candidate building.

Once the set of candidate buildings has been established, the buildings are surveyed in the field. 

Sample contents of a Hub Selection Report can be seen in the white paper Hub Selection & LOS Survey: Process Overview with Sample Graphics.

The HN Field Survey (Top)(Bottom)

HN staff travel to the city and, in conjunction with Wireless Carrier field staff, identify the two best candidate buildings for each hub to be implemented.  HN then surveys the roof of the two buildings to confirm engineering suitability and take horizon photos from the proposed antenna location. The camera is positioned to match the hub antenna location as closely as possible.  Since the camera sees what the antenna will see, these horizon photos provide an accurate view of the path conditions from the antenna. 

HN also takes a GPS reading on the roof, photos of the rooftop details and measurements for a sketch showing the proposed antenna locations. This process is repeated for each candidate hub to be implemented in the city. Note: In this single survey-visit to the hub site, all data needed to compile an accurate database of target service recipient buildings with LOS visibility from the hub is collected.  No additional field surveying is required. 

HN prepares a Preliminary Survey Report for each surveyed building consisting of:

• Photos of building and rooftop details;
• The 28mm lens horizon photos for each hub surveyed;

·        A location and preliminary shadow map for each candidate hub showing blockage sectors caused by buildings, hills, etc.

The Preliminary Survey Report assists the Wireless Carrier with leasing the candidate hubs offering the best LOS visibility characteristics.

Sample contents of a Preliminary Survey Report can be seen in the white paper Hub Selection & LOS Survey: Process Overview with Sample Graphics.

LOS Coverage Report (Top)(Bottom)

For those buildings that are leased by the Wireless Carrier and are to be implemented as hubs, HN undertakes a detailed coverage analysis.  The Coverage Report literally shows an antenna’s-eye-view of path conditions.  Consequently, the report enables the visual verification of LOS conditions from the office without the requirement for further field checks.  This has the effect of dramatically reducing the amount of field survey time, and therefore lowers the cost typically associated with deployment.    

Along with the horizon photos, HN uses digital orthophotos (rectified aerial photographs) to determine the precise geographical location of buildings within range of the hub.  Using proprietary software, grids with accurate azimuth and elevation are imposed on the horizon photos. 

Horizon photo data is used to determine which buildings (or parts of buildings) are visible, and which buildings are blocked (“shadowed”) from view.  Large shadowed regions are shown as solid sector segments on a Shadow Map (see Figure 2 below).

Footprints and Roofprints of buildings that house potential Wireless Carrier clients are imposed on orthophotos, and are shown on Coverage Maps.  

The end result is a coverage study containing an accurate database of buildings that can be targeted as service recipients.   

HN prepares a two-volume Coverage Study Report using an 11” by 17” format with contents as follows:

Volume I consists of:

• Photos of the hub building taken from street level, rooftop details and a dimensioned sketch showing the proposed antenna locations, ground elevation and building height;

• Scanned images of 28mm horizon photos with an angular grid, i.e., lines of constant azimuth referenced to North and lines of constant angular elevation referenced to the horizontal plane through the camera;

• All horizon photos mounted in a continuous format (from 28 to 600mm) taken from the proposed antenna locations, with azimuth bearing markers referenced to North.

Volume II is delivered in both hard and soft copies and consists of:

• A detailed shadow map prepared on an orthophoto showing areas where LOS visibility is blocked by buildings, etc.;

• An index sheet to the LOS coverage maps, prepared as an overlay on the orthophoto;

• One-minute-by-one-minute coverage maps prepared on an orthophoto showing street names and footprints of buildings with LOS visibility from the hub.

The LOS Viewer (Top)(Bottom)

The Coverage Study Report is provided in both hard and soft copy format.

The soft copy includes additional GIS database information about identified LOS buildings that cannot be easily shown in the printed volumes.  This includes building elevation, coordinates, distance, and bearing from the hub.

The proprietary LOS Viewer software included with the soft copy enables angular measurements to be made on the horizon photo images, similar to that which could be achieved with a surveyor’s transit set up at the hub.

The software also permits, via a point-and-click process, the correlation of horizon photo building images with building footprints on the orthophoto, and vice versa.  This capability permits Wireless Carrier staff to view LOS path details and potential antenna mounting locations at the subscriber building, without going to the field.

With the aid of the LOS Viewer, users can also “zoom-in” to take a closer look at target buildings.  This allows engineers to undertake detailed sector analysis, plan antenna types and optimize antenna down tilt – all from the office.

The soft-copy report is delivered on a MapInfo compatible CD and includes the proprietary LOS Viewer and User’s Guide.  The software is compatible with MapInfo versions 5.0 or later.

Other LOS Viewer features and additional Coverage Study images are contained in the white paper Hub Selection & LOS Survey: Process Overview with Sample Graphics.

Using the HN “LOS” Database to Derive a 3D Database for RF Interference Analysis (Top)(Bottom)

HN photos provide an accurate record of current path conditions from the antenna hub location.  Conventional 3D building databases have proven to be problematic due to errors arising from positional inaccuracies, vegetation obstructions, and resolution limitations etc. Databases generated through the HN photogrammetric survey process avoid these pitfalls, and yield LOS determinations that are absolute, not approximate.  In addition, the HN LOS database can be used to generate an exportable 3D database of that can be used in conjunction with RF interference programs to evaluate RF interference paths.

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